This PDF file contains the front matter associated with SPIE Proceedings Volume 10709 including the Title Page, Copyright information, Table of Contents, Introduction (if any), and Conference Committee listing.

Teledyne e2v continues to develop sensors for ground-based and space applications. These are back-thinned for high QE, exhibit low noise, and other high performance specifications. Large sets of such CCDs have been supplied for space missions- including GAIA and EUCLID, with the ESA PLATO program underway. We also highlight a new 2k2k CMOS space imager. Other examples of CMOS sensors for space missions will be shown. High red sensitivity remains important and CCD and CMOS sensors are presented with enhanced red wavelength quantum efficiency. An exciting new capability for back-biased CMOS imagers with significantly enhanced red-sensitivity is presented. It is now possible to supply CMOS sensors with comparable performance to CCDs. Performance information and the final design will be shown for two CMOS sensors- a 2k4k imager and an 800X800 wave-front sensor. Both are back-thinned and have very low readout noise. Finally, we present information on a sub-electron noise CMOS sensor.

The European Space Agency strongly supports detector development in Europe from the gamma ray up to the far-infrared wavelengths. The requirements associated to these detector developments are linked to the spatial environment and the needed instrument performance. This paper reports on the status of these developments, the roadmap and the actual performance of the manufactured devices.

CEA and Sofradir have been involved for 7 years in studies related to a large format detector development for science and astronomy applications. These studies are linked with ESA's Near Infrared Large Format Sensor Array roadmap which aims to develop a 2Kx2K large format low flux low noise device. The ALFA (Astronomical Large Focal plane Array) detector is currently at design, manufacturing and validation phase at CEA and Sofradir. This paper will present the very last achievements of the ALFA development with a specific focus on the readout integrated circuit design itself. Features and specification of the 2048x2048 15μm pitch with Source Follower Detector (SFD) input stage will be described. Apart from ESA development, European Commission is also contributing to the large detector development thanks to ASTEROID (AStronomical TEchnology EuROpean Infrared detector Development) program founded by REA (Research European Agency). ASTEROID main objectives are to develop very large raw materials (CdZnTe substrate, HgCdTe epilayer…) compatible with the manufacturing of very large detectors in volume keeping the same level of performance. Organization and status of this program will be presented where high synergy with 2K² ALFA detector are included.

The Hawaii-4RG-15 (H4RG-15) Sensor Chip Assembly (SCA) is a 4096×4096 pixel sensor with 15 µm pixel pitch. The H4RG-15 is the newest SCA developed by Teledyne for low light level astronomical applications, providing larger format while retaining the low noise and low power of the H1RG and H2RG arrays with additional new features. The SCAs are currently being produced with mercury cadmium telluride (HgCdTe or MCT) detectors having cutoff wavelengths of 1.7 µm for near-infrared (NIR) and 2.5 µm for short-wave infrared (SWIR) applications. SCAs can also be produced with 5.3 µm cutoff wavelength for mid-wave infrared (MWIR) or optimized for visible only applications with hybrid silicon (HyViSI) detectors. Several science grade detectors have been delivered for use in new astronomical instruments. The H4RG-15 sensor has been developed to enable assembly of mosaics with high pixel fill factor, with a new package design that improves the butt-ability of the SCAs. The new package achieves a high level of flatness and is also appropriate for space flight missions, with assembly using flight qualifiable components.

A 2K x 2K 10 µm cutoff HgCdTe array for background-limited space astronomy has been developed by Teledyne Imaging Sensors to specifications set by JPL, and demonstrated by University of Rochester at a focal plane temperature of 40K for the proposed JPL Near-Earth Object Camera (NEOCam) survey mission under the NASA Planetary Defense Coordination Office. We describe the detector performance for the first large format monolithic HgCdTe detector array tested, including the dark current, well depth, dark current vs. temperature, quantum efficiency, latent image performance, and read noise.

Silicon charge-coupled devices (CCDs) are commonly utilized for scientific imaging in wavebands spanning the near infrared to soft X-ray. These devices offer numerous advantages including large format, excellent uniformity, low read noise, noiseless on-chip charge summation, and high energy resolution in the soft X-ray band. By building CCDs on bulk germanium, we can realize all of these advantages while covering an even broader spectral range, notably including the short-wave infrared (SWIR) and hard X-ray bands. Since germanium is available in wafer diameters up to 200 mm and can be processed in the same tools used to build silicon CCDs, large-format (>10 MPixel, >10 cm² ) germanium imaging devices with narrow pixel pitch can be fabricated. Furthermore, devices fabricated on germanium have recently demonstrated the combination of low surface state density and high carrier lifetime required to achieve low dark current in a CCD. At MIT Lincoln Laboratory, we have been developing germanium imaging devices with the goal of fabricating large-format CCDs with SWIR or broadband X-ray sensitivity, and we recently realized our first front-illuminated CCDs built on bulk germanium. In this article, we describe design and fabrication of these arrays, analysis of read noise and dark current on these devices, and efforts to scale to larger device formats.

Skipper CCD was first introduced in 1990 by Janesick et al. Early works on Skipper CCD reported sub-electron noise without reading signal in the pixel array. Here we present the first successful Skipper CCD sensor with discrete deep sub-electron readout noise and single electron counting capabilities. The Skipper CCD discussed in this work, is a p-channel CCD fabricated on high resistivity, float-zone refined, n-type silicon \cite{holland2003fully}, developed by MicroSystem Labs of Lawrence Berkeley National Laboratory. A substrate bias is applied to fully deplete the substrate, which is 200\,$\rm \mu m$ thick. The high resistivity, $\approx$10\,$\rm k\Omega cm$, allows for fully depleted operation at a substrate voltage over 40V. The detector has 4126 by 866 square pixels of 15$\times$15\,$\rm \mu m^2$. The Skipper CCD vertical and horizontal registers have three-phase clocks that are designed for split readout, through the output stage at each quadrant of the sensor. Ultralow readout noise and stable linear gain allows the Skipper CCD to measure charge at the accuracy of individual electrons simultaneously in pixels with single electrons and with thousands of electrons. This makes the Skipper CCD the most sensitive and robust electromagnetic calorimeter that can operate above liquid nitrogen temperatures. The Skipper CCD can also count individual optical and near-infrared photons. Because nondestructive readout is achieved without any major modification to the CCD fabrication process, this new technology can be directly implemented in existing CCD manufacturing facilities. An exciting application in the low-SNR regime is direct, space-based imaging and spectroscopy of terrestrial exoplanets in the habitable zones of nearby stars . The photon flux from exo-Earths is expected to be Oð1Þ per several minutes, necessitating ultralow noise detectors. A detector with subelectron readout noise could reduce exposure times by a factor of 2, which is essential given the large exposure times required . Skipper CCDs are easily manufactured with large formats and are stable over a large dynamic range. In addition, thick fully depleted CCDs can achieve high quantum efficiency between 0.87 and 1 μm where several important spectral lines from water reside. https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.119.131802 https://arxiv.org/abs/1706.00028

Scientific EMCCD cameras have demonstrated excellent imaging performance under extreme low light conditions. Photon counting capability combined with a very low dark current offered by the CCD technology have made EMCCDs the detector of choice for high-performance applications such as time resolved spectroscopy and low light imaging. However, future astronomical instrumentation requires high spatial resolution while commercially available EMCCD devices are limited by a relatively modest area format of (1kx1k). To address this requirement, the Universitė de Montrėal and Teledyne-e2v have jointly developed a 4kx4k EMCCD, the CCD282. This paper presents the results of cryogenic characterization of the CCD282 operated with Nüvü Camēras’ CCD Controller for Counting Photons version 3. The advantages of a novel large format EMCCD over existing technology for high resolution spectroscopy are discussed.

A photon counting camera based on the Teledyne-e2v CCD201-20 electron multiplying CCD (EMCCD) is being developed for the NASA WFIRST coronagraph, an exoplanet imaging technology development of the Jet Propulsion Laboratory (Pasadena, CA) that is scheduled to launch in 2026. The coronagraph is designed to directly image planets around nearby stars, and to characterize their spectra. The planets are exceedingly faint, providing signals similar to the detector dark current, and require the use of photon counting detectors. Red sensitivity (600-980nm) is preferred to capture spectral features of interest. EMCCDs are baselined both as science and wavefront sensors in the coronagraph in order to simplify the system architecture. We are engaged in a test program to characterize the performance of the EMCCD in the required modes, as well as in a technology development program with Teledyne-e2v to ruggedize the sensors for use in space. In this paper we will summarize our progress, program status, and plans for flight development.

Here we discuss high-performance UV detectors to be used with the planned Star-Planet Activity Research CubeSat (SPARCS). SPARCS is a 6U cubesat designed to monitor M stars (0.1 – 0.6 solar masses) in two photometric bands in the near UV and far UV (S-NUV, 260-300 nm; S-FUV, 150-170 nm). SPARCS targets range in mass and age, including young stars (10-20 Myr), which are likely forming terrestrial planets, to old stars with known transiting planets, allowing us to map the evolution of UV emission and flare rates. The spectral slope, variability and evolution of a host star’s highenergy radiation would provide realistic input stellar fluxes to planet atmospheric models, which would aide in understanding the evolution and habitability of a planet and in interpreting its transmission and emission spectrum. The baseline S-NUV detector is a 2D-doped (delta-doped or superlattice-doped) charge coupled device (CCD) optimized with a custom antireflection (AR) coating to achieve quantum efficiency (QE)>70% throughout the S-NUV band. The SNUV detector would be coupled with a stand-alone red-blocking filter that provides at least three orders of magnitude (i.e., ≥OD3) out-of-band suppression, critical for the observations of such cool, red stars. Their combined throughput would be >25% (peak) in the S-NUV. The baseline S-FUV detector is a 2D-doped CCD optimized for the S-FUV band; it includes an integrated filter designed to maximize in-band throughput with good red-leak suppression. As designed, the solar-blind silicon detector achieves peak QE>35% in the S-FUV band and ≥OD2 out-of-band suppression. SPARCS has baselined a dichroic design that allows for simultaneous S-NUV and S-FUV observation. SPARCS would advance 2D-doped detectors and detector-integrated out-of-band-rejection filter technologies for their potential application in future mission concepts such as LUVOIR and HabEx.

Electron multiplying charged coupled devices (EMCCD’s) can provide significantly greater signal to noise ratios in low light conditions and/or for higher speed readout than traditional CCDs. Due to the electron multiplication before readout, the effective readout noise can be at the sub-electron level, enabling single photon counting. Traditional far UV (150 – 200 nm) imaging detectors have utilized micro-channel plates to detect usually scarce UV photons at low efficiency, amplify them into electron showers which strike a phosphor, allowing a silicon detector array to perform the final detection of the resulting visible light pulse. The typical efficiencies of UV photo detection with MCP systems ranges from a low of a few percent to as high as 25%. Given that the theoretical probability of absorption of UV photons in silicon is at least 30% in this wavelength range, then it should be possible to make use of a photon counting EMCCD to directly detect UV photons that is competitive with MCP performance. We approached Teledyne-e2v and they confirmed that a backside thinned EMCCD with their ‘astro no-coat’ process should provide reasonable quantum efficiency (ie. > 30%) in this range. The primary application in which we are interested is UV imaging of the aurora from space-based platforms. In this application there are system level advantages to replacing an MCP based detector with an EMCCD which is directly sensitive to UV illumination, namely the elimination of a high voltage power supply and higher spatial resolution. An MCP produces an electron shower which degrades image quality and also requires a relatively thick detector window which has to be accommodated in the imager optical design. We acquired five CCD201 engineering model EMCCDs with e2v’s ‘astro no-coat’ process, and incorporated one of these into a standard flexible liquid nitrogen cooled EMCCD camera produced by Nüvü Camēras. Once installed the EMCCD operation was confirmed with standard Nüvü Camēras test procedures. The camera was then mounted in a test vacuum chamber along with a McPherson UV monochromator so that the UV performance could be assessed. A NIST traceable photodiode was used for the absolute calibration. The resulting intrinsic QE was found to be 34% at 180 nm rising to 44% at 150 nm. The quantum yield was found to be quite low, only a few percent at 180 nm rising to only 1.13-1.18 at 150 nm. This is considerably lower than comparable results from CCDs where delta-doping has been used to improve the responsive quantum efficiency and also lower than a Teledyne-e2v CMOS sensor with the same surface treatment.

Publisher’s Note: This paper, originally published on 20 July 2018, was replaced with a corrected/revised version on 12 October 2018. If you downloaded the original PDF but are unable to access the revision, please contact SPIE Digital Library Customer Service for assistance. Next generation X-ray mission concepts (e.g. Lynx) call for a wide field X-ray imager with high detection efficiency from 0.2 keV to 10 keV and fast readout capability (> 10 Hz frame rate). In order to properly sample the planned fine angular resolution of the optical assembly (0:5’’ HPD), small pixel sizes of less than or equal to 16 microns are required. Hybrid CMOS detectors are a type of active pixel sensor that is well suited to the high throughput and wide bandpass requirements of such instruments, and the pixel size goals are well within reach. In collaboration with Teledyne Imaging Sensors, the Penn State X-ray detector lab has developed new small pixel Hybrid CMOS sensors to meet these needs. These prototype 128 x 128 pixel devices have 12.5 micron pixel pitch, 100 micron fully depleted depth, and include crosstalk-eliminating CTIA amplifiers and in-pixel correlated double sampling capability. We report on characteristics of one of these new detectors, including read noise, energy resolution, and pixel-to-pixel gain variation. The read noise was measured to be as low as 5:54 e^- ± 0:05 e^-, while the gain variation was found to be 1:12% ± 0:06%. The energy resolution, including calibration for gain variation, was measured to be as good as 148 eV (2.5%) at 5.9 keV.

Sensors that are based on active pixels enable a flexible adaption to the needs of a scientific instrument. The DEPFET,∗ a p-channel field effect transistor implemented on a fully depleted silicon bulk, contains a so-called internal gate that serves as potential minimum for collected charge carriers generated by incident photons.¹ The potentially collected electrons induce mirror charges in the FET channel and change its conductivity. It changes the current through the DEPFET or – for a fixed current – the source potential proportionally to the collected charge carriers and, therefore, to the energy of the incident photon. By the integration of a storage into each pixel, the accuracy of the energy measurement can be improved, especially for high frame rates in the order of the readout time of one pixel. One implementation of such a concept is the so-called Infinipix.² It is composed of two sub-pixels that share their source node in the center. The functional principle was already demonstrated on single pixel³ and matrix scale⁴ but enhancements are still necessary to improve the robustness of the devices. In this paper we present variations in the processing technology and the layout that enhance the reliability of the DEPFETs with integrated storage. Adaptions in the technology help to increase the operation voltages for the charge suppression at the insensitive sub-pixel which is demonstrated with measurements. A layout variation combines the advantages of existing layout variants. It was tested with 3D TCAD† simulations and is in fabrication to be available for measurements.

We have been developing monolithic active pixel sensors, X-ray Astronomy SOI pixel sensors, XRPIXs, based on a Silicon-On-Insulator (SOI) CMOS technology as soft X-ray sensors for a future Japanese mission, FORCE (Focusing On Relativistic universe and Cosmic Evolution). The mission is characterized by broadband (1-80 keV) X-ray imaging spectroscopy with high angular resolution (< 15 arcsec), with which we can achieve about ten times higher sensitivity in comparison to the previous missions above 10 keV. Immediate readout of only those pixels hit by an X-ray is available by an event trigger output function implemented in each pixel with the time resolution higher than 10 µsec (Event-Driven readout mode). It allows us to do fast timing observation and also reduces non-X-ray background dominating at a high X-ray energy band above 5{10 keV by adopting an anti-coincidence technique. In this paper, we introduce our latest results from the developments of the XRPIXs. (1) We successfully developed a 3-side buttable back-side illumination device with an imaging area size of 21.9 mm x 13.8 mm and an pixel size of 36 µm x 36 µm. The X-ray throughput with the device reaches higher than 0.57 kHz in the Event-Driven readout mode. (2) We developed a device using the double SOI structure and found that the structure improves the spectral performance in the Event-Driven readout mode by suppressing the capacitive coupling interference between the sensor and circuit layers. (3) We also developed a new device equipped with the Pinned Depleted Diode structure and confirmed that the structure reduces the dark current generated at the interface region between the sensor and the SiO2 insulator layers. The device shows an energy resolution of 216 eV in FWHM at 6.4 keV in the Event-Driven readout mode. .

SMILE (Solar wind Magnetosphere Ionosphere Link Explorer) is a joint venture between the European Space Agency (ESA) and the Chinese Academy of Sciences (CAS). The mission will study the dynamic interaction between the solar wind and the Earth’s magnetosphere. Two of the instruments, namely the Soft X-ray Imager (SXI) and the Ultra-Violet Imager (UVI), will observe northern aurora and the boundary of the magnetosphere simultaneously, a first for space-missions. To complement these remote observations, in-situ measurements of the solar wind ion distribution as well as measurements of the strength of magnetic fields will be attained via the Light Ion Analyser (LIA) and the Magnetometer (MAG) respectively. Together, these four instruments will provide a complete picture of the interactions between the solar wind and the response of the Earth’s magnetosphere, which is the main driver of space-weather. The SXI will be used to observe and image Solar Wind Charge eXchange (SWCX) that occurs at the interface between the solar wind and the Earth’s magnetosphere. At this location, ions in the solar wind interact with neutrals in the Earth’s exosphere leading to the production of soft X-rays with key emission lines at energies between 0.1-2 keV. The SXI will use a wide angle silicon micro pore optic to focus the incoming X-rays onto a focal plane of two large area Charge-Coupled Devices (CCDs) from Teledyne-e2v. The CCD for SXI is designated the CCD370, with 4510x4510 pixels of 18 µm, which will be read out with 6x6 on-chip binning to give an effective pixel size of 108 µm square. The binning improves charge transfer efficiency and energy resolution, and allows the pixel area to be divided into asymmetric frame and store regions of the device for frame-transfer operation. The CCD370 design includes a range of modifications from its predecessor (the CCD270 from the PLATO mission), with the goal of optimising it for imaging soft X-rays; a supplementary buried channel in the parallel region, a narrowed serial channel width, and increased output amplifier responsivity will improve the low signal sensitivity and charge transfer efficiency. Here, the CCD370 performance in the SXI telescope will be presented, predicted from the first measurements using the laboratory SXI CCD characterisation camera and CCD270s. The improvements expected from design changes that optimise the SXI CCDs for soft X-ray detection, and plans for pre-flight calibration and radiation damage testing will be described.

In the context of PLATO | ESA's exo-Earth hunting mission due for launch in 2026 | the Science Payload Validation team at ESA/ESTEC have performed a cryogenic proton irradiation and testing campaign of the PLATO CCD radiation test vehicle the Teledyne-e2v CCD280. Following the irradiation in standard conditions (room temperature, unbiased) of one device, and the irradiation of another in close to flight conditions (at T=203K and operated), the devices performance (CTI, dark current, hot pixels, trap population) were concurrently monitored over a two month period, first at a constant temperature and then following several temperature cycles. The results of these investigations will be presented.

We report on the initial results of an experiment to determine the effects of proton radiation damage on an X-ray hybrid CMOS detector (HCD). The device was irradiated at the Edwards Accelerator Lab at Ohio University with 8 MeV protons, up to a total absorbed dose of 3 krad(Si) (4.5 x 109 protons/cm2). The effects of this radiation on read noise, dark current, gain, and energy resolution are then analyzed. This exposure is the first of several which will be used for characterizing detector performance at absorbed dose levels that are relevant for imaging devices operating in a deep-space environment.

P-Channel CCDs may offer improved tolerance of radiation damage compared to the N-Channel equivalent due to favorable differences in the population of silicon defects that impact charge transfer performance following irradiation. The technology may therefore be attractive for applications within harsh radiation environments, yet requires further validation against existing N-Channel technology to better understand the regime where performance benefits can be expected. In this study, a P- and N-Channel CCD204, manufactured by Teledyne-e2v, were irradiated simultaneously biased and under cryogenic conditions. Following irradiation, the devices were tested for charge transfer performance at multiple temperatures and clocking speeds consistent with large-scale space missions. Silicon defects were also probed within each device using the “trap pumping” technique across the parameter space relevant for optimization of charge transfer. Performance differences between each device are presented and linked to the relevant silicon defects identified through trap pumping. We conclude with an outlook on future results that include the impact of both a room temperature (298 K) and high temperature (373 K) anneal on the performance of each device.

MAJIS (Moons and Jupiter Imaging Spectrometer) is the imaging spectrometer of JUICE (JUpiter and ICy moons Explorer), an ESA large-class mission scheduled for launch in 2022 that will start scientific operations in the Jovian system on 2030. MAJIS will deliver observations of the surfaces and exospheres in a wide spectral range from 0.5 up to 5.5 µm, including several flybys of the icy Galilean moons at spatial sampling down to ~ 75 m, as well as a 9-month Ganymede orbit eventually providing full coverage at 3 km/pixel [Langevin et al., DPS 2016]. To achieve these objectives, two focal plane arrays sharing the same telescope's optic will be used, with a splitter in the 2.25-2.35 µm wavelength range. MAJIS is a push-broom spectral imager: the image over one spatial direction will be projected on several hundred spatial x spectral pixels of both HgCdTe CMOS detectors after wavelengths dispersion. Those observations will be highly affected by the intense magnetosphere of Jupiter which traps high-energy particles that may decrease the performances of photo-sensitive layer of detectors or even the electronics. The expected total ionizing dose (TID) for the entire mission is 80 krad in Silicium with the appropriate Aluminium shielding and the equivalent ~ 55 MeV proton fluence integrated over the mission will be 10^10/cm² [JUICE environment specifications, ESA 2015]. We performed a TID and a proton radiation test on candidate MAJIS detectors (SOFRADIR NGP MWIR, 1024x1024 pixels, 15 µm pitch). They both took place at UCL (Belgium) facilities to investigate expected degradations to MAJIS detectors. The TID tests have been conducted with ⁶⁰Co radioactive source emitting mostly 1.3 MeV γ photons: the detector was exposed to radiations for 14 days with 1-hour interruptions twice a day to monitor time evolution by taking images. The cumulative dose was measured at 93 krad on the last day. The protons tests have been conducted with a cyclotron, which provided 10¹⁰ protons/cm² over the 4 hours test with energies distributed between 50 and 62 MeV at detector level, behind 2 mm Aluminium shielding. We characterized detector degradations by monitoring three main parameters: the amount of "bad" (hot, spurious, variable) pixels, the average level of dark current, and the DSNU (Dark Signal Non-Uniformity), for various integration times, especially low values (~ 100 ms) typical of MAJIS integration times. Such short integration times are required by the high photons fluxes from the targeted icy planetary surfaces and the on-board data processing algorithm that will remove electron spikes by selecting data within a set of sub-integrations associated with each acquisition [Langevin and Piccioni, EPSC 2017]. The analysis of data collected before, during and after the TID show no significant increase of the number of bad pixels and no significant variation of the mean dark current level on the candidate detector, for a total dose (93 krad) greater than the one expected during the whole MAJIS mission (80 krad). After proton irradiation we observe a significant but limited increase in the number of bad pixels. Only 0.2% of detector pixels become bad after irradiation for a typical MAJIS integration time of 100 ms. Such a low value does not endanger the operability of the detector during the mission. An update in the amount of protons in Jovian environment, recently delivered by ESA, may result in an increase by a factor of 10 of the expected fluence at Jupiter. According to SSC/EPFL 2009 ESA Courses, proton-induced damages increase linearly with energy after 20 MeV. Assuming that this remains true at lower energies as we are dealing with (3 MeV), and since on these detectors any pixel has the same probability of being deprecated by protons regardless of their initial state, a linear extrapolation of the number of new bad pixels would give 2% of lost pixels at the end of the mission, which is still adequate to fulfill science objectives. The overall conclusion of those test campaigns is a satisfying resilience of the candidate SOFRADIR HgCdTe CMOS detectors to typical operation conditions (integration times, dose rates) of MAJIS.

In the framework of the ESA’s Science programme, the Euclid mission has the objective to map the geometry of the Dark Universe. For the Near Infrared Spectrometer and Photometer instrument (NISP), the state-of-the-art HAWAII-2RG detectors will be used, in association with the SIDECAR ASIC readout electronics. A dedicated test bench has been designed, developed and validated at ESTEC to perform tests on these detectors. This test bench is equipped with a spot projector system as well as a set of LEDs allowing to project the Euclid like beam and perform persistence measurements. The detector under test shows crosshatch patterns that may correspond to sub-pixel variations in Quantum Efficiency or charge redistribution. The goal of the tests was to evaluate the impact of crosshatches patterns on the Euclid photometric performance and centroid calculation after flat fielding correction. The second part of the publication discusses different persistence mitigation tests using the LEDs test set up.

SAPHIRA detectors, which are HgCdTe linear avalanche photodiode arrays manufactured by Leonardo, enable high frame rate, high sensitivity, low noise, and low dark current imaging at near-infrared wavelengths. During all University of Hawaii Institute for Astronomy lab testing and observatory deployments of SAPHIRA detectors, there was approximately one meter of cables between the arrays and the readout controllers. The output drivers of the detectors struggled to stably send signals over this length to the readout controllers. As a result, voltage oscillations caused excess noise that prevented us from clocking much faster than 1 MHz. Additionally, during some deployments, such as at the SCExAO instrument at Subaru Telescope, radio-frequency interference from the telescope environment produced noise many times greater than what we experienced in the lab. In order to address these problems, collaborators at the Australia National University developed a cryogenic preamplifier system that holds the detector and buffers the signals from its outputs. During lab testing at 1 MHz clocking speeds, the preamplifiers reduced the read noise by 45% relative to data collected using the previous JK Henriksen detector mount. Additionally, the preamplifiers enabled us to increase the clocking frequency to 2 MHz, effectively doubling the frame rate to 760 Hz for a full (320x256 pixel) frame or 3.3 kHz for a 128x128 pixel subarray. Finally, the preamplifiers reduced the noise observed in the SCExAO environment by 65% (to essentially the same value observed in the lab) and eliminated the 32-pixel raised bars characteristic of radio-frequency interference that we previous observed there.

Euclid is an ESA mission to map the geometry of the Dark Universe with a planned launch date in 2021.1 Two primary cosmological probes, weak gravitational lensing and baryonic acoustic oscillations, are implemented through a VISible imager (VIS) and a Near-Infrared Spectrometer and Photometer (NISP).² The ground characterization of the NISP Flight Sensor Chip Systems (SCS) followed by the pixel response calibration aims to produce all informations to correct and control the accuracy of the signal. This work reports on the ground characterization of the NISP detector chain. The detector and electrical effects are likely to generate statistical fluctuations and systematic errors on the final flux measurement. The analysis strategies to maintain the pixel relative response accuracy within 1% is proposed in this work. The Euclid NISP test ow is presented and the main concerns of the detector chain calibration, such as non-linearity, charge trapping and de-trapping are discussed on the basis of the analysis of the flight detectors characterization data.

NASA's Wide-Field Infrared Survey Telescope (WFIRST) project has developed the ACADIA ASIC, a next generation detector control and acquisition system-on-a-chip. The purpose of this ASIC is to address the stringent requirements of operating a cryogenic detector in a spacecraft environment. Key performance criteria are low analog noise and low power consumption at temperatures between 150K and 180K while supporting the full dynamic range of the sensor. The ASIC is primarily intended to operate the Teledyne H4RG for WFIRST, but has been designed with considerable flexibility to provide compatibility with a large selection of other detectors. Up to 40 analog sensor outputs can processed in parallel, where each signal is amplified and conditioned by a low-noise pre-amplifier with programmable gain and bandwidth, and then digitized by a 16-bit successive approximation analog-to-digital converter (ADC). The ASIC includes 24 analog output channels that can be configured as programmable voltage or current sources, and are used to generate biases and references to the detector. A simple-to-program sequencer provides timing control for the detector and the ASIC internal circuits, with the option of using an embedded microprocessor for more elaborate readout schemes. This paper presents an overview of the ACADIA ASIC design with detailed descriptions of its analog, mixedsignal, and digital circuit blocks. First prototypes of the ACADIA ASIC have been fabricated, and preliminary test results of functionality and performance have been measured. We discuss the test environment and the obtained results, and conclude by describing the next steps for the project. The ACADIA ASIC is intended to operate the Teledyne H4RG infrared hybrid detector (current baseline for the WFIRST Wide-Field Instrument), but has been designed with considerable flexibility to provide compatibility with a large selection of other detectors. Each analog sensor output is amplified and conditioned by a low-noise pre-amplifier with programmable gain and bandwidth, and then digitized by a 16-bit successive approximation analog-to-digital converter (ADC). Up to 40 signals can be processed in parallel. Some basic math functions like summing, averaging, threshold comparison, and digital gain are available per channel. In addition, the ASIC includes 24 analog output channels that can be configured as programmable voltage or current sources, and are used to provide biases and references to the detector. Overall timing control is provided by a flexible but simple-to-program sequencer, with the option of microprocessor control for more elaborate readout schemes. Further digital capabilities include Direct Memory Access (DMA) engine, timers, Serial Peripheral Interface (SPI), and science data formatting for transmission. All circuitry has been protected against single event effects from ionizing radiation. We will discuss the status of the development effort, with focus on the performance requirements, general design features, and available test results. Over the course of the development, several test chips have been built that have already demonstrated significant improvements in analog performance over prior solutions, and have shown compliance with key WFIRST requirements for both cryogenic and room temperature operation. Prototypes of the full 40-channel ACADIA ASIC have been fabricated and are currently being tested. In addition to the chip itself, the packaging approach, test environment, and control electronics with computer acquisition will be presented.

Many astronomical optical systems have the disadvantage of generating curved focal planes requiring flattening optical elements to project the corrected image on at detectors. The use of these designs in combination with a classical at sensor implies an overall degradation of throughput and system performances to obtain the proper corrected image. With the recent development of curved sensor this can be avoided. This new technology has been gathering more and more attention from a very broad community, as the potential applications are multiple: from low-cost commercial to high impact scientific systems, to mass-market and on board cameras, defense and security, and astronomical community. We describe here the first concave curved CMOS detector developed within a collaboration between CNRS- LAM and CEA-LETI. This fully-functional detector 20 Mpix (CMOSIS CMV20000) has been curved down to a radius of R_c =150mm over a size of 24x32mm². We present here the methodology adopted for its characterization and describe in detail all the results obtained. We also discuss the main components of noise, such as the readout noise, the fixed pattern noise and the dark current. Finally we provide a comparison with the at version of the same sensor in order to establish the impact of the curving process on the main characteristics of the sensor.

An experimental camera system equipped with a novel CMOS image sensor suitable for ground-based astronomy that has both destructive and non-destructive readout capability will be described and the performance characteristics including readout noise, dark current, quantum efficiency, will be given. The optimum data collection algorithms to achieve reduced effective readout noise, cosmic ray rejection, and expanded dynamic range will be described. The ability to use destructive readout in select rows to acquire data for telescope guiding while the main part of the sensor is read using non-destructive readout for main image acquisition will be discussed.

The European Space Agency’s (ESA’s) Jupiter Icy Moon Explorer will spend 8 years transiting to the Jovian environment after launching from French Guiana in 2022. The spacecraft’s 10 scientific instruments, including a high resolution optical imager called JANUS, will explorer the Jovian system for a mission duration of 3 years studying the icy surfaces of Ganymede, Callisto and Europa and atmosphere of Jupiter. Using the combination of a 13 slot filter wheel and a back-illuminated CMOS image sensor, the JANUS camera will perform colour mapping and imaging at wavelengths between 350 nm and 1064 nm and resolutions of up to 10 m/pixel resolution during a Ganymede orbital phase. The CIS115 is a rolling shutter image sensor from Teledyne-e2v that has been selected for JANUS. It is back-illuminated and anti-reflection coated in order to optimise detection efficiency in its 3 MPixel imaging area. Its 4T architecture reduces the dark current in the pinned photodiode collecting area to approximately 13 pA/cm^2 at 20˚C and allows the device to be operated with correlated double sampling for a readout noise performance of 5 electrons rms. In preparation for its use in JANUS, the CIS115 has undergone a thorough qualification programme, including exposure to ionising and non-ionising radiation levels of up to 200 krad(Si) and 2x10^10 protons/cm^2 (10 MeV equivalent), and a single event effect test campaign. The CIS115 device qualification is now complete and results from the radiation test campaigns are being used to predict the expected performance at various phases of the mission as radiation damage is accumulated in the sensor. Dark current is the primary performance characteristic that has been observed to degrade with irradiation, and predicting the device’s performance at the end of life allows the maximum operating temperature of the detector to be set and justified. Additionally, behaviour observed during the qualification testing has led to optimised readout schemes that reduce the device image lag performance across the dynamic range to below the 0.1% level.

The traditional method for measuring CCD non-linearity using constant flux and variable exposure time is compared to a faster and potentially more accurate method that requires just two exposures at low intensity. Signal is varied by parallel-binning a successively greater number of lines. The binned image is compared to a conventional image with identical illumination, co-added digitally in the same pattern. This method requires no shutter calibration and is insensitive to illumination drift or charge transfer inefficiency. With some additional software effort, it can be arranged to tolerate illumination non-uniformity. We present data obtained by both methods for the 64 CD231-C6 outputs and discuss automated performance optimization. We find that the widely held assumption that non-linearity only affects high signals is incorrect when optimizing for minimum gain change over the full signal range, in which case slope increases with signal initially, then peaks in the mid-range before dropping again.

The Zwicky Transient Facility (ZTF)[1] is a CCD mosaic requiring 64 differential output channels to be transmitted to electronics located over 2 m from the CCDs and digitized with less than 10 e- read noise at 1 MHz pixel rate. To minimize pixel overhead, the Reset Gate pulse is generated inside the dewar by a pin driver controlled by a very short pulse using an LVDS interface. Overlapping serial clocks spanning the entire pixel are made entirely triangular with slopes tuned to cancel substrate return current and minimize high frequency content to improve common rejection by the fully differential signal path. We document the trade between settling time after charge dump and linearity and illustrate the desirability of generating both Summing Well and Reset Gate edge close to the CCD. The parallel clocking overhead is exacerbated in ZTF by ganging multiple CCDs but is hidden by overlapping the parallel shift with pixel readout. To suppress fixed pattern due to the concurrent parallel clocks, slow overlapped triangular waveforms panning the entire line time are employed to null the substrate current, in the same manner as the serials. Both noise and speed requirements are exceeded on all 64 channels, with margin. At all pixel rates the median noise is as good as can be expected for differential transmission being √2 times the single sided noise published in the data sheet for the CCD231- C6 CCDs. Linearity is preserved even at 840 ns pixel time, and crosstalk is less than 10 ppm.

We have relayed an extremely stable 1.7µm LED through a cryogenic integrating sphere to uniformly illuminate Leonardo SAPHIRA 320x256 arrays. This has enabled us to determine parameters such as charge gain, voltage gain, and node capacitance as a function of avalanche gain for individual pixels in a centered 64 x 64 pixel sub-array, and our results are reported here. We collected multiple sequences of one hundred 320-frame ramps over a variety of timescales and used them for several analyses. These measurements demonstrate that the intensity of the IR LED source is linear with current and stable to 0.1% over periods of an hour and from day to day, while the data cubes additionally allow determination of charge gain (in e􀀀/ADU) for each pixel. We have separately determined voltage gain (in e-/ADU), and together these yield node capacitance for each pixel. We have repeated these measurements at bias voltages ranging from 1 V (corresponding to unity gain, i.e. negligible avalanche gain) to 10.5 V (corresponding to an avalanche gain of 12.43 and the full onset of tunnel-tunnel current). These measurements are used to determine avalanche gain as a function of avalanche bias voltage, which becomes critical at bias voltages up to 10.5 V bias as dark current is low and junction capacitance varies.

Electron multiplying (EM) CCD technology has been successfully implemented for many ground-based applications (from astronomical telescopes to synchrotrons and life sciences), but has yet to be utilized within the space environment. The technology has the potential to offer superior photon-counting performance compared to competing technologies, however the effects of radiation damage must be understood and mitigated. The primary concern is damage from solar protons that manifests as signal trapping sites within the device. These traps can act to capture and defer signal charge to later pixels, degrading Charge Transfer Efficiency (CTE). With knowledge of the properties of the silicon defects responsible for charge loss, it is possible to optimize transfer performance through customized clocking and illumination patterns. Here, we present techniques to improve the charge transfer performance of irradiated Teledyne e2v CCD201 20 EMCCDs, including optimized clocking and illumination patterns based on the knowledge of silicon defects provided by the “trap pumping” technique following room temperature irradiation.

We characterize a near-infrared C-RED ONE camera from First Light Imaging (FLI). This camera uses a SAPHIRA electron avalanche photo-diode array (e-APD) from Leonardo (previously Selex). To do so, we developed a model of the signal distribution. This model allows a measurement of the gain and the Excess Noise Factor (ENF) independently of preexisting calibration such as the system gain. The results of this study show a gain which is 0.53 ± 0.04 times the gain reported by the manufacturer. The measured ENF is 1.47 ± 0.03 when we expected 1.25. For an avalanche gain of ' 60 and a frame rate larger than 100 Hz, the total noise can be lower than 1 e^-/frame/pixel. The lowest dark current level is 90e^-/s/pixel, in agreement with the expected H-band background passing through the camera window. These performance values provide a significant improvement compared to earlier-generation PICNIC camera and allowed us to improve the performance of the Michigan infrared combiner (MIRC) instrument at the Center for High Angular Resolution Astronomy (CHARA), as part of our MIRC-X instrumentation project.

The detector system for the Euclid Near-Infrared Spectrometer and Photometer (NISP) instrument is a 4×4 mosaic focal plane of 16 H2RG (2K×2K pixels) infrared Sensor Chip Assemblies (SCAs) and 16 SIDECAR ASIC Sensor Chip Electronics (SCE) modules. Teledyne has successfully completed the fabrication, testing, and delivery of 24 sciencegrade flight candidate SCAs to the NASA Jet Propulsion Laboratory (JPL). These SCAs were made with Teledyne’s TRL-9 substrate-removed MBE mercury cadmium telluride (HgCdTe) 2.3 μm cutoff detector material and low-noise H2RG CMOS readout chip. The SCAs are mounted on a buttable molybdenum package that enables close packing of the 16 flight SCAs in the NISP focal plane. In this paper, we present the test results of the 24 Euclid flight candidate SCAs. The key detector performance parameters that are critical to the NISP instrument are: high in-band quantum efficiency with good spatial uniformity, low readout noise, low dark current with tight distribution, low pixel crosstalk, low persistence, and good detector surface metrology profile. All 24 SCAs exceed the Euclid NISP performance and interface requirements. The additional acceptance testing at JPL and NASA Goddard’s Detector Characterization Lab has also been completed. 20 flight SCAs have been delivered to European Space Agency (ESA).

Since the first photon counting systems in the visible, developped by Boksenberg and his collabortors in 1972, many groups around the world improved photon counting techniques. In the 2000's in the visible, EMCCDSs (electron multiplying charge coupled devices) allowed to replace the classical image intensifier photon counting systems by solid state devices and improved a lot the QE. But EMCCDs suffer from several issues, and the most important of them is the excess noise factor which prevents to know what is the exact incoming number pf photons in the case of multiple photons per pixel. In the infrared there was no equivalent to EMCCDs up to the development of e-APD sensors and cameras made with HgCdTe material (electron initiated avalanche photo diode). We will present the concepts of photon counting in the infrared with such devices and the main properties and advantages of infrared e-APDs compared to their visible counterpart, EMCCDs and the possibility to detect the photon energy (color) with such devices.

The WFIRST coronagraph is being designed to detect and characterize mature exoplanets through the starlight reflected from their surfaces and atmospheres. The light incident on the detector from these distant exoplanets is estimated to be on the order of a few photons per pixel per hour. To measure such small signals, the project has baselined the CCD201 detector made by e2v, a low-noise and high-efficiency electron-multiplying charge-coupled device (EMCCD), and has instituted a rigorous test and modeling program to characterize the device prior to flight. An important consideration is detector performance degradation over the proposed mission lifetime due to radiation exposure in space. To quantify this estimated loss in performance, the project has built a detector trap model that takes into account detailed trap interactions at the sub-pixel level, including stochastic trap capture and release, and the deferment of charge into subsequent pixels during parallel and serial clocking of the pseudo-two-phase CCD201 device. This paper describes recent detector trap model improvements and modeling results.

Radiation induced defects in the silicon lattice of Charge Couple Devices (CCDs) are able to trap electrons during read out and thus create a smearing effect that is detrimental to the scientific data. To further our understanding of the positions and properties of individual radiation-induced traps and how they affect space- borne CCD performance, we have created the Centre for Electronic Imaging (CEI) CCD Charge Transfer Model (C3TM). This model simulates the physical processes taking place when transferring signal through a radiation damaged CCD. C3TM is a Monte Carlo model based on Shockley-Read-Hall theory, and it mimics the physical properties in the CCD as closely as possible. It runs on a sub-electrode level taking device specific charge density simulations made with professional TCAD software as direct input. Each trap can be specified with 3D positional information, emission time constant and other physical properties. The model is therefore also able to simulate multi-level clocking and other complex clocking schemes, such as trap pumping.

ESA’s astrometry mission Gaia was launched in 2013 to establish the most accurate and complete map of the Milky Way by measuring the distance, position, proper motion, and astrophysical characteristics of two billion stars. It contains the largest focal plane ever flown in space comprising 106 CCDs. To downlink to Earth only useful data, an on-board algorithm was designed to discriminate between e.g. stars and cosmics- ionizing tracks left by energetic particles. A cosmic ray event generation simulator was developed to train and optimize this on-board source detection algorithm. We can now validate this model against Gaia data.

Pyxel is a novel, open-source and Python-based framework designed to host and pipeline any type of models simulating detector effects such as cosmic rays, detector PSF, various noise sources, Charge Transfer Inefficiency or persistence on images produced by CCD or CMOS-based imaging detectors. It is currently under development at the European Space Agency with the goal of release it to the broader detector scientist community. We present here the architecture of the framework, how to integrate new models in it and give a few examples of its current simulation capabilities.

The persistent signal from bright sources in infrared detectors can significantly pollute subsequent images. While the persistent signal is a small fraction of the stimulus image, the high dynamic range of modern infrared detectors allows this signal to be easily detectable. In this paper we present a method of characterizing the persistence signal over time as a function of the length of time that the bright signal is left on the detector and the number of traps in each pixel. We derive the functional form for both the capture and decay of traps and show that it is analogous to radioactive decay. We show that a model with three exponential families of traps is able to explain the observed persistence. We use electronically induced persistence to simulate a flash of light and show that the observed difference between the electronically induced persistence signal and that from light induced saturation is well fit by our model. The fitted parameters for the tested part show a very fast capture rate for the tested detector. This very fast capture is significantly different than what we found for an engineering part we had tested earlier We then derive and test the capture model for the more real-world situation of the continuous accumulation of charge during an exposure. We use this model to predict the persistence from a given stimulus image that we then remove from the darks after the stimulus image. The resulting corrected darks show that over 90% of the persistence was removed.

Transition Edge Sensors are ultra-sensitive superconducting detectors with applications in many areas of research, including astrophysics. The device consists of a superconducting thin film, often with additional normal metal features, held close to its transition temperature and connected to two superconducting leads of a higher transition temperature. There is currently no way to reliably assess the performance of a particular device geometry or material composition without making and testing the device. We have developed a proximity effect model based on the Usadel equations to predict the effects of device geometry and material composition on sensor performance. The model is successful in reproducing I −V curves for two devices currently under study. We use the model to suggest the optimal size and geometry for TESs, considering how small the devices can be made before their performance is compromised. In the future, device modelling prior to manufacture will reduce the need for time-consuming and expensive testing.

We present the results of ongoing characterization of Cadmium Zinc Telluride (CZT) semiconductors produced by Redlen Technologies for use in X-ray astronomy. The fully fabricated hybrid detectors consist of CZT crystals with a collecting area of 2 cm x 2 cm and thickness of 3mm mounted on a custom ASIC originally designed for the Nuclear Spectroscopic Telescope Array (NuSTAR) mission, which launched in 2012. We present the results of electronic noise, inter-pixel conductance, and leakage current tests as well as spectral calibration using an ²⁴¹Am source. Despite high electronic noise due to errors in fabrication, we are able to compare characteristics of the Redlen CZT detectors to those of the CZT detectors produced by eV Products aboard NuSTAR.

The pair creation energy,ω and the Fano factor of silicon were measured using a CCD sensor and X-rays from an ⁵⁵Fe source. The measurements were performed at a sensor temperature of 185K. The pair creation energy was measured for X-rays in the 1.7-6.5 keV range. The measured pair creation energy is ω = (3:650 ± 0:009) eV at the Mn Kα line energy. The Fano factor at this energy is F = 0:128±0:001. The agreement with theory and previous measurements is satisfactory. The system gain was obtained from at field exposures using the Poisson distribution properties. These results and the details of our measurement procedure are presented below.

X-ray Imaging Spectrometers (XIS) are the X-ray CCD cameras onboard Suzaku. They were operated in orbit from 2005 to 2015 and produced lots of findings with their good energy resolution and low non X-rat background. Precise calibration including the 10 eV accuracy in the energy scale reinforced them. Nevertheless, there has been a unresolved calibration issue in the spectral response around the Si-K edge (1.839 keV) appearing as systematic residuals up to 10%. The residual is negative peaking at 1.85 keV in the front illuminated (FI) sensors and positive peaking at 1.8 keV in the back illuminated (BI) sensor for X-ray sources dominated by continuum X-ray emission. Various attempts to eliminate these residuals by changing response parameters or quantum efficiency models have been insufficient. In this paper, we revisit this problem by focusing on the relation between incident X-ray energy and pulse height. We introduce a jump in that relation at the Si-K edge by modifying the , and optimize its value so as to minimize the residuals in the fit of the X-ray spectra for the black hole binary LMC X-3, a source dominated by continuum emission. We find the introduction of a jump significantly reduces the residuals. The optimized jump values are +4:2 channel, +4:0 channel, and -3:1 channel, corresponding to 15.3 eV, -11:3 eV, and 14.6 eV, for XIS0, XIS3 (FI), and XIS1 (BI), respectively. The direction of the jump is opposite for the FI and for the BI. We revise the response matrices generator so as to include the jump for each XIS sensor, and apply it to the X-ray spectra of the Perseus cluster of galaxies which has various emission lines in the spectra, and the blazar PKS2155-304 which was observed various epoch in the Suzakuoperation. We confirm the residuals are significantly reduced for these sources, too. We finally suggest the jump at Si-K edge in the energy and pulse height relation is qualitatively explained, if some of charges are lost in course of charger collection to the electrode of the CCD in the depletion later, and its amount is large for larger travel length in the depletion layer. If this explanation is correct, the Si-K edge problem and its solution presented in this paper is not specific only for the SuzakuXIS but also for other X-ray CCDs.

Euclid is an ESA mission to map the geometry of the dark Universe with a planned launch date in 2021. Euclid is optimised for two primary cosmological probes, weak gravitational lensing and baryonic acoustic oscillations. They are implemented through two science instruments on-board Euclid, a visible imager (VIS) and a near-infrared photometer/spectrometer (NISP), which are being developed and built by the Euclid Consortium instrument development teams. The NISP instrument contains a large focal plane assembly of 16 Teledyne HgCdTe H2RG detectors with 2.3 μm cut-off wavelength and SIDECAR readout electronics. The performance of the detector systems is critical for the science return of the mission and extended on-ground tests are being performed for characterisation and calibration purposes. Special attention is given also to effects even on the scale of individual pixels, which are difficult to model and calibrate, and to identify any possible impact on science performance. This paper discusses the known effect of random telegraph signal (RTS) in a follow-on study of test results from the Euclid NISP detector system demonstrator model [1], addressing open issues and focusing on an in-depth analysis of the RTS behaviour over the pixel population on the studied Euclid H2RGs.

We present results from several years of laboratory characterization and telescope deployment of the near infrared (NIR) avalanche photodiode (APD) array SAPHIRA from Leonardo S.p.A. Dark current has fallen by three orders of magnitude and we have demonstrated NIR photon counting. Tunnel-tunnel current dominates measured dark current at high bias voltages for temperatures ≤ 65K. At higher temperatures, tunnel-thermal dominates. At low temperatures and bias voltages, dark is glow-limited and not responsive to either temperature or bias voltage. Histograms of individual avalanche events show a broad distribution but allow for photon-counting. Several deployments of the SAPHIRA have also been conducted.

Dynamic charge collection effects (e.g. the "Brighter-Fatter" effect) are present in thick, deeply depleted CCDs. These effects can cause distortion of the point spread function, and correlations between nearby pixel values. Much has been written already about how to characterise and mitigate this effect. This presentation will focus on how the more standard performance parameters of a CCD (e.g. gain, noise, linearity, uniformity, apparent QE, full well) can be influenced by the brighter-fatter effect, and describe some methods of obtaining accurate measurements of these quantities whilst mitigating the impacts of correlated charge collection. These techniques include non-standard methods of processing standard calibration data (correcting gain and full well from flat field and point source data fusion) and/or different clocking schemes for the CCD (investigating how dithering, injected charge distributions, binning, TDI transfer curves might be used to disentangle more traditional charge collection and transfer performance from that due to the brighter-fatter effect) .

The CIS115, the imager selected for the JANUS camera on ESA’s JUICE mission to Jupiter, is a Four Transistor (4T) CMOS Image Sensor (CIS) fabricated in a 0.18 µm process. 4T CIS (like the CIS115) transfer photo generated charge collected in the pinned photodiode (PPD) to the sense node (SN) through the Transfer Gate (TG). These regions are held at different potentials and charge is transferred from the potential well under PPD to the potential well under the FD through a voltage pulse applied to the TG. Incomplete transfer of this charge can result in image lag, where signal in previous frames can manifest itself in subsequent frames, often appearing as ghosted images in successive readouts. This can seriously affect image quality in scientific instruments and must be minimised. This is important in the JANUS camera, where image quality is essential to help JUICE meet its scientific objectives. This paper presents two techniques to minimise image lag within the CIS115. An analysis of the optimal voltage for the transfer gate voltage is detailed where optimisation of this TG “ON” voltage has shown to minimise image lag in both an engineering model and gamma and proton irradiated devices. Secondly, a new readout method of the CIS115 is described, where following standard image integration, the PPD is biased to the reset voltage level (VRESET) through the transfer gate to empty charge on the PPD and has shown to reduce image lag in the CIS115.

The James Webb Space Telescope Fine Guidance Sensor has two Guider channels. Each channel makes use of 2048x2048 pixel, five micron cutoff H2RG HgCdTe detectors from Teledyne Imaging Systems. Due to their simple unit cell architecture, these detectors exhibit a variety of non-ideal behaviours which can impact the guiding function. In this paper, we examine the potential impact of one of these behaviours, the brighter-fatter effect, using a simulation based on a parameter derived from test results. The brighter-fatter effect (BFE) is the deflection of incoming photo-electrons to adjacent pixels due to the accumulated charge in the central pixel. The simulation model we use is based on the assumption that the effective area of a given pixel is reduced by some factor times the current signal contrast (difference) between adjacent pixels. Combining this with a PSF model for the FGS we can assess systematic differences between the image centroids with and without the BFE effect. A BFE strength parameter was defined and model runs were performed with a range of BFE strengths. In physical terms this parameter is the fractional reduction in effective pixel area per accumulated signal electron. Comparison of the modeled PSF FWHM as a function of this strength parameter with FGS test data provided a measure of the BFE strength parameter for the Guider detectors. With this BFE strength parameter we then ran centroiding simulations and found that there were no significant systematic offsets with respect to star brightness for this level of BFE. The magnitude of the BFE effect would have to be more than 10x greater than that observed before significant centroid offsets on the order of a milli-arcsecond would occur.

The 3.2 gigapixel LSST camera, an array of 189 thick fully-depleted CCDs, will repeatedly image the southern sky and accomplish a wide variety of science goals. However, its trove of tens of billions of object images implies stringent requirements on systematic biases imprinted during shift-and-stare CCD observation. In order to correct for these biases which, without correction, violate requirements on weak lensing precision, we investigate CCD systematics using both simulations of charge transport as well as with a unique bench-top optical system matched to the LSST’s fast f/1.2 beam. By illuminating single CCDs with realistic scenes of stars and galaxies and then analyzing these images with the LSST data management pipelines, we can characterize the survey’s imaging performance well before the camera’s first light. We present measurements of several CCD systematics under varying conditions in the laboratory, including the brightness-dependent broadening of star and galaxy images, charge transport anomalies in the silicon bulk as well as the edges, and serial deferred charge. Alongside these measurements, we also present the development and testing of physics-based models which inform corrections or mitigation strategies for these systematics. Optimization of the CCD survey operation under a variety of realistic observational conditions, including systematic effects from the optics, clocking, sky brightness, and image analysis, will be critical to achieve the LSST’s goals of precision astronomy and cosmology.

Mazin Lab at UCSB is developing MKID instrument for astronomy at near infrared, optical and ultraviolet wavelength. We use MIKDs as single photon detectors by measuring the arrival time of incoming photons with an accuracy of a few microseconds and with a relatively high energy resolution (R~10 at 1um). We fabricate kilopixels array of MKIDs and we incorporate them in our own instruments for UVOIR astronomy with the main application being exoplanets direct imaging. We present the work being made in our lab in the development and fabrication of 10 to 20k pixels arrays for the DARKNESS (Dark-speckle Near-IR Energy-resolved Superconducting Spectrophotometer) and MEC (MKID Exoplanet Camera) instruments, respectively. The 6-step fabrication process has been upgraded over the last months in order to improve the sensitivity of the arrays. The detectors are made of platinum silicide (PtSi) since MKIDs with very high internal quality factor have been successfully fabricated from this material. Furthermore, PtSi with very uniform superconducting properties over 4inch substrate are much more easier to deposit than the regular TiN used in most existing MKIDs technology. Among various upgrades, we coated the PtSi sensitive area with a SiO2/Ta2O5 bi-layer in order to reduce the reflection of optical photons hitting the detectors. The light absorption is increased by a factor of 2 in the instruments bandwidth. The DARKNESS instrument has been successfully commissioned last summer and MEC, the world largest superconducting camera, is installed at the Subaru telescope since the beginning of the year. Our effort leads to the fabrication of arrays of detectors with a median internal quality factor of 100 000 with an energy resolution of 10 at 1um and a pixel yield approaching 95%. In addition, we will present new MKID design in which the conventional meander inductor and interdigitated capacitor are replaced by a square inductor and a large parallel plate capacitor made of two metal plates separated by a ~10-nm thick dielectric layer. This parallel plate design allows us to drive the MKIDs at a higher power, which in turns should increase the sensitivity of the detectors. Following promising results from our first design, second generation of parallel plate MKID devices have been made from Hf/HfO2/Nb tri-layers deposited in-sit. We obtained high quality factor from the parallel plate MKIDs and we were able to detect photons with this new MKIDs design. Another way to improve the sensitivity of MKIDs is to use a low Tc material, compared to Tc ~ 1K usually used. We fabricated MKIDs arrays with superconducting Hafnium, Tc = 450mK, and we demonstrated that resonators with very high internal quality factors Qi~300 000 and an energy resolution of 9 at 808nm can be achieved.

With gain-normalized dark currents reduced below 10 e-/s/pixel, HgCdTe Avalanche Photo-Diode arrays operated in linear mode are now widely accepted as the sensors of choice for adaptive optics wavefront sensing of natural guide stars in the wavelength range 1 to 2.5 um. At lower temperatures the intrinsic dark currents in Leonardo’s SAPHIRA 320 x 256 @ 24um pitch arrays have recently been shown to be four orders of magnitude lower, approaching 0.001 e-/s/pixel. This has opened the way to megapixel class APD arrays offering major advantages for a wide range of low background astronomical observations. We report the status of development of a 1k x 1k @ 15um pixel Read-Out Integrated Circuit (ROIC) for a three-side close-buttable, 16 output, MOVPE HgCdTe array with reference pixels and reference outputs. The design has been optimized for minimum ROIC glow following a detailed investigation of glow sources in the SAPHIRA ME1001 ROIC. This involved precisely overlaying J-band glow images on layout drawings from EDA software to identify all the sources of glow. As of the time of submission of this abstract, the Architecture definition is in its third iteration and the program is on track to produce ROICs around mid-2018. In parallel, Mark 20 SAPHIRAs optimized for very low background operation with the goal of delaying the onset of tunnel-tunnel current to bias voltages producing useful avalanche gain are being characterized along with modified SAPHIRAs with 15um pixels.

Using thermal infrared detectors mounted on drones, and applying techniques from astrophysics, we hope to support the field of conservation ecology by creating an automated pipeline for the detection and identification of certain endangered species and poachers from thermal infrared data. We test part of our system by attempting to detect simulated poachers in the field. Whilst we find that we can detect humans hiding in the field in some types of terrain, we also find several environmental factors that prevent accurate detection, such as ambient heat from the ground, absorption of infrared emission by the atmosphere, obscuring vegetation and spurious sources from the terrain. We discuss the effect of these issues, and potential solutions which will be required for our future vision for a fully automated drone-based global conservation monitoring system.

Large-format infrared arrays are enablers for a variety of astronomical applications, from wide-field imaging to very high-resolution spectroscopy over a wide range of wavelength. We present the optimization of the science-grade H4RG array used in the SPIRou high-resolution spectrograph designed for high-precision velocity measurements. In SPIRou nominal science operation, the array is used in a relatively low flux regime, well below the full-well of the arrays and, for some applications, the readout noise is a major contributor to the overall signal-to-noise budget. We describe the detector fine-tuning process as well as the derived properties and their impact on performances. We identify persistence as potentially problematic under certain circumstances for infrared m/s velocimetry.

A 1K*1K CCD camera is designed, implemented and tested for CSTAR telescope in Antarctica, including its mechanics, CCD controller, power and temperature controller unit. Mechanical and electronic design for low temperature environment is taken into consideration fully. The camera has reliable mechanics and stable electronics performance. The readout noise is as low as 3.99݁ି when the CCD readout speed is 100kpixs/s. We fully tested every part of the camera in a Cryogenic refrigerator (-86 degree centigrade) and proved that our camera has the ability to work in Antarctica for a long term. Finally, the camera was tested on the CSTAR telescopes to take observations and the imaging quality meets requirement.

Tomo-e Gozen (Tomo-e) is a wide field optical camera for the Kiso 1.05 m f/3.1 Schmidt telescope operated by the University of Tokyo. Tomo-e is equipped with 84 chips of front-illuminated CMOS image sensors with a microlens array. The field of view is about 20 square degrees and maximum frame rate is 2 fps. The CMOS sensor has 2160x1200 pixels and a size of pixel is 19 microns, which is larger than those of other CMOS sensors. We have evaluated performances of the CMOS sensors installed in Tomo-e. The readout noise is 2.0 e^- in 2 fps operations when an internal amplifier gain is set to 16. The dark current is 0.5 e^-/sec/pix at room temperature, 290K, which is lower than a typical sky background flux in Tomo-e observations, 50 e^-/sec/pix. The efficiency of the camera system peaks at approximately 0.7 in 500 nm.

In order to implement the driver and readout functions for several types of scientific CCD detector, meanwhile decreasing the size of electronics and reducing the total power dissipation for a large scale mosaic CCD detector system, two Application-specified Integrated Circuits (ASIC) were designed. One is for CCD driver and called BCDA (Bias Clock Driver ASIC), which is to provide multi-channel clocks and Bias voltage; the other is for CCD video processing and called CVRA (CCD Video Readout ASIC). In the BCDA chip, the bias drivers are generated by high voltage amplifiers. The clock drivers are made of a clock switch circuit and high voltage amplifier. Two 8-bit current-steering DACs are used to adjust the driver capability and high-level voltage of clocks. The CVRA chip processes the video signal of a CCD detector. The functions of CVRA chip consist of pre-amplifier, single-to-differential circuit, CDS circuit, and integrating circuit. The Global Foundry 180 nm BCDlite technology is used in this chip design. The first round of design has been finished and part of tests of two chips have been done.

Cosmic rays affect the performance of any detector in space through the creation of spurious signal and/or slow build-up of radiation damage. To mitigate the effects of these high-energy particles on the observations of next-generation space missions, the interaction between state-of-the-art detectors will have to be understood through simulation and experimental verification. We present the first measurement results of a new cryogenic system designed to become a common-user test facility to evaluate the effects of high-energy particles on arrays of these high-sensitivity detectors. The system is based on pulse-tube precooled dilution refrigerator with a large experimental volume (ø = 29 cm, H = 30 cm). At 100 mK the system provides 650 µW of cooling power and an out-of-the box thermal stability of 76 µK rms. A first experiment with a semiconducting bolometer from the DIABOLO experiment shows a responsivity and noise level consistent with previous measurement in different cryogenic systems. However, the pulse-tube induced vibrations show as clear features in the noise. To irradiate the detectors a particle beam, such as the 25 MeV proton beam of the nearby ALTO facility, can be coupled to one of four ports. Simulations show that the aluminum-coated Mylar windows do not significantly affect the 25 MeV proton beam of TANDEM. First experiments at the ALTO facility for system verification are expected early 2019. Until that time, the thermal stability, vibration damping and EMI shielding will be improved and a flexible wiring will be developed, to accommodate multiple detector types.

We developed a new CCD readout system for the Kanata 1.5m telescope in Higashi-Hiroshima Astronomical Observatory, Hiroshima University, Japan, based on the system originally developed by the Kiso Array Controller (KAC) project. In this development we aim at reducing the size and the cost of the system. The system consists of CCD drive circuit, three-order low-pass filters, differential input A/D converter, FPGA, LVDC board, and can be operated by Linux host. We report the current design and performances of this system, and the future work as well. This readout system will be easily applicable to many other astronomical instruments.

WEAVE is the new multi-object spectrograph for the William Herschel Telescope on La Palma. The culmination of prime focus, the large number of fibers and the wide resolution range has required a stringent optical design, which in turn demands a spectrograph with tight positional tolerances and large final focal plane. To capture this focal plane each of the two cryostats has two e2v 6k × 6k CCDs mounted as a mosaic. As well as being cooled to 150K via liquid nitrogen, the positional tolerances for the sensitive areas are flatness 60μm p-v over the entire image area, rotation around X and Y axis ±50 arcmin, translation in X, Y and Z ± 50 micron. We have used a Stil confocal measuring head mounted on two Thorlab translation stages to create a X,Y mount, controlled by a Raspberry Pi that is capable of recording measurements in Z to better than 1μm accuracy. This is used to measure the flatness and deformation of the image area under vacuum, and when cooled to 150K and the overall tip and tilt of the image plane to ensure they meet specification and are repeatable. In addition to this measuring system, we use a Thorlabs CMOS camera with a Navitar 50mm lens to ensure each CCDs image area is within specification with regards X and Y translation. In order to satisfy the above requirements, we designed the CCD mount to be adjustable (on initial setup), correctly constrained, isolated from liquid nitrogen boil-off vibration, and thermally insulating.

Charge Coupled Devices (CCD) are detectors widely used in astronomical observation due to their high sensitivity and high spatial resolution. The readout technique is often implemented with analog circuits. The main objective of our research is to replace the analog processing of a CCD signal with the realisation of digital processing. In doing so, low noise levels will be obtained while reducing the area and improving flexibility. Digital Correlated Double Sampling (DCDS) is a readout technique by which the CCD signal is oversampled many times allowing the CDS filter function to move from the traditional analog domain to the digital domain. Two digital processing systems have been tested using the DCDS readout technique by developing algorithms to analyze and process the digital samples taken from reading the CCD. These digital processing systems have low cost, low power and a compact package. An extensive CCD readout characterization based on Photon Transfer (PT) method has been carried out on a vacuum and controlled temperature conditions. It has also been confirmed using an Fe55 X-ray source. The power dissipation achieved is a high improvement with respect to the analog circuit and the noise values obtained are in concordance with the analog processing.

Euclid is a major ESA mission for the study of dark energy planned to launch in 2021. Euclid will probe the expansion history of the Universe using weak lensing and baryonic acoustic oscillations probes. A survey of 15,000 deg² of the sky with the instrument NISP (Near-Infrared Spectro-Photometer), in the 900 – 2100 nm band, will give both the photometric and spectrometric redshifts of tens of millions of galaxies. The 16 H2RG detectors of the NISP focal plane array are still being characterized at CPPM (Marseille). Already 16 out of 20 flight detectors have been tested and a straightforward analysis done. Performance of the dedicated test benches – in particular control of flux and temperature – as well as an overview of the test flow will be presented. This paper will present methods and some preliminary results on two detectors focusing on the determination of a per pixel conversion gain.

We present a summary of the cryogenic detector preamplifier development programme under way at the ANU. Cryogenic preamplifiers have been demonstrated for both near-infrared detectors (Teledyne H1RG and Leonardo SAPHIRA eAPD as part of development for the GMTIFS instrument) and optical CCDs (e2v CCD231-84 for use with the AAT/Veloce spectrograph). This approach to detector signal conditioning allows low-noise instrument amplifiers to be placed very close to an infra-red detector or optical CCD, isolating the readout path from external interference noise sources. Laboratory results demonstrate effective isolation of the readout path from external interference noise sources. Recent progress has focussed on the first on-sky deployment of four cryogenic preamp channels for the Veloce Rosso precision radial velocity spectrograph. We also outline future evolution of the current design, allowing higher speeds and further enhanced performance for the demanding applications required for the on instrument wavefront sensor on the Giant Magellan Integral Field Spectrograph (GMTIFS).

HiPERCAM is a five channel fast photometer to study high temporal variability of the universe, covering from 0.3 to 1.0 microns in five wavebands. HiPERCAM uses custom-made 2Kx1K split-frame transfer CCDs mounted in separate compact camera heads and cooled by thermoelectric coolers to 180K. The demands on the readout system are very unique to this instrument in that all five CCDs are operated in a pseudo drift window mode along with the normal windowing, binning and full-frame modes. The pseudo drift mode involves reading out small window regions from 2 quadrants of each CCD, with the possibility to exceed 1 kHz window rates per output channel. The CCDs are custom manufactured by Teledyne e2v to allow independent serial clock controls for each output. The devices are manufactured in standard and deep-depletion processes with appropriate anti-reflection coatings to achieve high quantum efficiencies in each of the five wavebands. An ESO NGC controller has been configured to control and readout all five CCDs. The data acquisition software has been modified to provide GPS timestamping of the data and access to the acquired data in real time for the data reduction software. The instrument has had its first light and first science observations on the 4.2m William Herschel Telescope, La Palma during a commissioning run in October 2017 and subsequently on the 10.4m Gran Telescopio Canarias in February 2018 and science observations in April 2018. This paper will present the details of the preamplifier electronics, configuration of the readout electronics and the data acquisition software to support the unique readout modes along with the overall performance of the instrument.

Large Size Telescope (LST) is the largest telescope of the Cherenkov Telescopes Array (CTA), the next-generation ground-based γ-ray observatory. Its low weight and powerful motors aim to make it repointing any position in the sky in less than 20 s with a position accuracy lower than 30 arcsec. However, such a fast rotation of a big telescope implies constraints on motors and telescope structure. For this purpose, a Matlab/Simulink model taking into account all the components of LST was developed. This static model of LST is perturbed by several kinds of disturbances such as wind loading or motors effects which apply torques on the structure of LST. Numerous outputs such as pointing accuracy, power consumption and reached velocity can be monitored. These monitored parameters allow us to check the fulfilling of technical requirements by using the chosen components and to have references for the first tests on the real telescope.

With the next generation observatories such as GMT, TMT, and E-ELT looming, the astronomy community is in need of unprecedented number of infrared pixels. To address the affordability of the next generation of infrared instruments, the Center for Detectors (CfD) at the Rochester Institute of Technology (RIT) and Raytheon Vision Systems (RVS) are developing large format, short-wave infrared HgCdTe focal plane arrays grown on silicon (Si) wafers for observational astronomy. The use of silicon wafers offers significant savings and a path to very large format (>; 8K×8K, 15 μm) focal plane arrays. This paper presents the latest results from the detector development effort and its suitability for use in observational astronomy. Currently, the HgCdTe/Si technology is competitive with the state-of-the-art HgCdTe/CZT technology in many performance metrics, and it has the promise to meet stringent performance requirements posed by observational astronomy. A full suite of characterization results, including for dark current, read noise, spectral response, persistence, linearity, full well, and crosstalk probability, will be presented.

The Electron Multiplying Test Chip 1 (EMTC1) was developed with the aim of creating a device which could produce superior Electron Multiplication (EM) gain at a greatly reduced voltage. An EM gain exceeding 3% per stage has been recorded for a relatively low voltage (~13.0V) from two recently developed pixel structures. An electro-optical characterisation of the EMTC1 is presented focusing on charge transfer via experimental and simulation results aiming to provide insight into the transfer and multiplication process. The Charge Transfer Inefficiency (CTI) is analysed with the aim of providing a greater understanding of the charge transfer process. Light starved applications such as Earth observation and automated inspection are known to benefit from Time Delay Integration (TDI) and electron multiplication. Though traditionally implemented in CCDs, implementing TDI in CMOS technology can lead to an increase of functionality, higher readout speeds and reduced noise. This paper presents a discussion of the implication of these results on the potential applications of this sensor.

Lateral charge diffusion is one of the main contributors to the Point Spread Function (PSF) in CMOS image sensors, due to the small depth to which they can be depleted. This can have an adverse effect on the spatial resolution of the sensor and the measured shape of the observed object. In this paper, PSF measurements are made on a novel CMOS detector capable of reverse bias and full depletion. The PSF is measured with the Virtual Knife Edge (VKE) technique at five wavelengths, from 470 nm to 940 nm, to ascertain wavelength dependence. The inter- and intra-pixel non-uniformity is examined to determine the difference between pixels as well as within the pixels themselves. Finally, the pixel structure is also evaluated using a 1 µm spot of light to examine the effect of the internal layout of a pixel on the sensitivity to light. These factors all impact precision astronomical measurements and so need to be understood before use in science missions.

Future space and ground based missions in the near infrared are planning to or will utilize the next generation of Teledyne's HxRG detectors, the HgCdTe 4K x 4K array (H4RG). The science cases of such missions will require optimal stability and noise performance. To assess the detailed performance of the H4RG, we have developed a small single detector testbed in NASA Goddard's Astrophysics Division IR detector lab. The testbed operates a H4RG array inside a large dewar using a room temperature Leach controller. The dewar will include two integrating spheres with controlled apertures using NIR LEDs as light sources as well as a calibrated photodiode to precisely measure ux. We present preliminary results of a banded H4RG-10 array on the bench. In the near future, we plan to use the test bed to investigate the specific origins of electronic noise in the test bed, persistence, and other flux dependent nonlinearities.

The CCD sensors that will be used in the LSST Camera are controlled using a large number of bias and clock voltages. The objective of this project is to explore the large parameter space of operating voltages and optimize the performance of the CCDs made by ITL, one of two vendors manufacturing the LSST CCDs. The CCD voltages were adjusted from their nominal operating values in small increments and the electro-optical characteristics were measured. These measurements were performed first using a single ITL sensor and later with a 3 by 3 CCD mosaic with integrated controller electronics (Raft) of engineering grade ITL sensors, using a test stand at SLAC.

Strained layer superlattice (SLS) detectors are a new class of infrared detectors available in the scientific and commercial markets. The photosensitive bandpass is set by material and engineered properties with typical detectors covering 7.5-10.5 microns, bluer than traditional N-band filters. SLS detectors have the potential to reach lower dark current than traditional infrared materials (like HgCdTe) allowing comparable photometric sensitivity at higher detector temperatures, easing cooling requirements. Conversely, at equal cryogenic temperatures the SLS detector will have lower dark current than HgCdTe allowing better photometric sensitivity under dark current limited operation. This work presents laboratory measurements of SLS detectors to quantify detector linearity and time stability. The potential advantages in using SLS-based detectors in future astronomical instruments is also discussed.

Single sensors or small arrays of manually assembled neutron transmutation doped germanium (NTD-Ge) based microcalorimeters have been widely used as high energy-resolution detectors from infrared to hard X-rays. Several planar technological processes were developed in the last years aimed at the fabrication of NTD-Ge arrays, specifically designed to produce soft X-ray detectors. One of these processes consists in the fabrication of the absorbers. In order to absorb efficiently hard X-ray photons, the absorber has to be properly designed and a suitable material has to be employed. Bismuth offers interesting properties in terms of absorbing capability, of low heat capacity (needed to obtain high energy resolution) and deposition technical feasibility, moreover, it has already been used as absorber for other types of microcalorimeters. Here we present the electroplating process we adopted to grow bismuth absorbers for fabricating planar microcalorimeter arrays for hard X-rays detection. The process was specifically tuned to grow uniform Bi films with thickness up to ~ 70 μm. This work is part of a feasibility study for a stratospheric balloon borne experiment that would observe hard X-rays (20-100 keV) from solar corona.

The Application-Specific Integrated Circuit (ASIC) development plan of the astronomical CCD control system is a special chip development project launched officially by the National Astronomical Observatory of the Chinese Academy of sciences. One of the scientific objectives: Bias and Clock Driver ASIC (CDA), has been designed and manufactured twice. The test shows the performance of CDA completely reach the design requirement. Now this chip can be mass produced at low cost. We claim the CDA is successfully developed in our laboratory. CDA provides bias voltage and clock drives for CCD working. 48 DACs which produce pulse at any amplitude can be used for most CCD controller. The combination of CDA and ASIC lead to integrated multi-CCD system or sub-mini single CCD controller. This high integrated chip make the CCD controller smaller, lower power consumption, more stable and easier to be developed.

Infrared sky background level is an important parameter of grounded infrared astronomy observations, which should be firstly measured in a good infrared observatory site, and only the site with low background level is suitable for infrared observations. Infrared sky background level can provide background data for the design of related infrared instruments. However, there is no such data available for major sites in China. Based on the requirement, In order to supplement the current site survey data and guide the design of future infrared instruments, a multiband near-infrared sky brightness monitor (MNISBM) based on an InSb sensor is designed in this paper. The MNISBM consists of optical system, mechanical structure and control system, detector and cooler, high gain readout electronic system, operational software. It is completed and carried out an experimental measurement in the laboratory. The result shows that the sensitivity of the MNISBM meets the requirements of the measurement of near-infrared sky background level.

In a CCD camera system, the CCD sensor must be cooled to low temperature to reduce the dark current. Many factors will affect the cooling performance as we use TEC. Therefore, quantitative analysis of the effects of the various factors on the cooling performance is very important for designing the cooling structure of the CCD vacuum head. In this paper, the length and diameter of the wires between the CCD and the vacuum feedthrough, the thickness of the cold end, and the vacuum degree are taken into consideration and analysis. Through the simulation, useful conclusions are obtained to guide the machanics and cooling design of the CCD vacuum head.

The Medium Energy X-ray Telescope (ME), covering 5-30 keV, is one of the three main payloads of the Hard X-ray Modulation Telescope (HXMT). ME adopts an array of Si-PIN detectors. The detection area of one pixel is 56.25 mm² , and the total detection area is 952 cm² . The ME has a large active area while the pixel size is smaller. So the front-end electronics and forming electronics are realized by Application Specific Integrated Circuit (ASIC) chips. In this paper, we will describe the matching design of ME Si-PIN detector and ASIC, and the performance of the design. The energy response, temperature response, and dead time of a Two-Pixels Si-PIN detectors with the simplest readout electronics which is similar with ME, were tested on the Max Planck Institute for Extraterrestrial Physics PANTER X-ray test facility at Neuried by Munchen (Germany). The overall performance is quite similar to what was expected.

A reconfigurable set of focal plane control electronics has been developed that can operate a broad range of advanced all-digital focal planes in space- and ground- based applications. To date, the reconfigurable focal plane electronics (RFPE) have successfully operated 7 different state-of-the-art all-digital ROICs from multiple suppliers, including Teledyne Imaging Systems, BAE, and others. The payload is approximately 7.9” x 4.5” x 7.6”, is fully redundant, dissipates between 5 and 25 watts, depending on the sensor and application, and is user programmable after launch. The RFPE has been demonstrated operating sensors with aggregate digital output rates up to 33 Gbits/s, but it supports rates up to 50 Gbits/s. An integrated programmable micro-sequencer generator enables users to create and store dozens of complex image data collection scenarios and modify or add to those once on orbit. Lossy and lossless image compression, pixel level gain and offset (a.k.a. NUC) correction, frame co-adding, decoding/encoding of cyclical redundancy check sensor data, and bad pixel correction are a few of the image processing features that have been demonstrated to date. Bias sources are programmable and include over-voltage and over-current protection to safeguard mission critical image sensors. Enhancements under development include the addition of graphical processors and a large cache of solid state memory. This paper describes the current and planned capabilities of the RFPE payload.

We describe the infrastructure developed to align and measure the focal plane arrays (FPA) for the Subaru Measurement of Images and Redshifts (SuMIRe) Prime Focus Spectrograph (PFS), and detail the results of these efforts at ambient and operating temperatures. PFS will employ four three-channel spectrographs with an operating wavelength range of 380 nm to 1260 nm. Each spectrograph will be comprised of two visible channels and one near infrared (NIR) channel, and each channel will use individual Schmidt cameras to image the captured spectra onto their respective detectors. In the visible channels, Hamamatsu 2k x 4k charge coupled devices (CCDs) will be mounted in pairs to create a 4k x 4k mosaic, while the NIR channel will use a single Teledyne H4RG 4k x 4k Mercury Cadmium Telluride (HgCdTe) complementary metal oxide semiconductor (CMOS) device.

Full characterization of imaging detectors involves subjecting them to spatially and temporally varying illumination patterns over a large dynamic range. Here we present a scene generator that fulfills many of these functions. Based on a modern smartphone, it has a number of good features, including high spatial resolution (13 um), high dynamic range (∼10⁴ ), near-Poisson limited illumination stability over time periods from 100 ms to many days, and no background noise. The system does not require any moving parts and may be constructed at modest cost. We present the optical, mechanical, and software design, test data validating the performance, and application examples.

Astro-Ecology couples ‘off the shelf’ infrared imaging technology and astronomy instrumentation techniques for application in the field of conservation biology. Microbolometers are uncooled, infrared systems that image in the thermal-infrared range (8-15μm). These cameras are potentially ideal to use for the detection and monitoring of vulnerable species and are readily available as ’off the shelf’ systems. However to optimise the quality of the data for this purpose requires thorough detector calibration to account for the systematics that limit readout accuracy. In this paper we apply three analogous, standard astronomical instrumentation techniques to characterise the random and spatial noise present in a FLIR Tau 2 Core thermal-infrared camera. We use flat fielding, stacking and binning to determine that microbolometer FPAs are dominated by large structure noise and demonstrate how this can be corrected by subtracting median stacks of flat field exposures.

A pair of radiation hardened high-voltage mixed signal Application Specific Integrated Circuits (ASICs) are described that provide the biasing and clocking functions required to drive large format CCDs used for space-borne cameras and focal planes. The use of these ASICs allows the CCD drive electronics to be realised in a compact and energy efficient manner saving volume, mass, and power when compared with traditional space-qualified discrete implementations. The STAR ASIC provides 24 independent voltage outputs with a 32.736V range at 10 bit resolution and with <100μV noise. Each voltage output provides a drive current of up to +/-20mA and is stable for capacitive loads of up to 10μF. An on-board telemetry system featuring a 12-bit ADC and programmable gain buffer allows internal monitoring of the output voltages plus up to 32 single ended and 4 differential external voltages, such as from PRT bridge circuits for temperature monitoring. A simple SPI serial interface provides control and telemetry read back, while all required voltages and currents are generated from internal bandgap circuits. The COMET ASIC provides 6 fully independent clock buffering channels each with individually programmable rising/falling current drive and high/low voltage levels. Output voltage levels are controlled with integrated fast response regulators that operate over a 16.368V range without the need for external decoupling capacitors. Clock drive currents can be adjusted for the load capacitance and output slew rate required over a 409.6mA range, with edge speeds <15ns achievable for small loads. Setup and control of the ASIC is also via an SPI interface with integrated safety features to ensure correct sequencing of channel operation and to prevent reverse biasing of the driver programmable voltage supplies. The COMET ASIC also features an under-voltage lock out circuit to safeguard the chip in the event of unexpected power loss. All necessary biases are generated internally and only supply decoupling, a single filtering capacitor, and a resistive divider are required to operate the device. Both devices have been designed in a commercial 0.35μm 50V tolerant HV CMOS technology using Triple Module Redundancy (TMR) and established layout techniques to harden against Total Ionising Dose (TID), Single Event Upset (SEU), and Single Event Latch-up (SEL) radiation effects. The latch-up detection circuits often needed for space electronics are therefore not required for either ASIC. Details of the architectures and circuit implementations of both ASICs will be presented. Test results from manufactured devices will be shown under representative load conditions.

Noise and stability of current state of the art near-infrared (NIR) array detectors are still substantially worse than optical science grade CCDs used in astronomy. Obtaining the maximum signal-to-noise ratio in flux image is important for many NIR instruments, as is stable well understood data reduction and extraction. The Habitable- zone Planet Finder (HPF) is a near-infrared ultra stable precision radial velocity (RV) spectrograph commissioned on 10-m Hobby-Eberly Telescope (HET), McDonald Observatory, Texas, USA. HPF uses a Teledyne H2RG array detector. In order to achieve the high-precision (~ 1 m/s) RV measurements from the NIR spectrum of HPF's science target stars, it is vital to maximize the signal-to-noise ratio and to accurately propagate the uncertainties. Here we present the algorithms we have developed to significantly improve the quality of flux images calculated from the up-the-ramp readout mode of H2RG. The algorithms in the tool HxRGproc presented in this manuscript are used for HPF's bias noise removal, non-linearity correction, cosmic ray correction, slope/flux and variance image calculation.

NuSTAR (the Nuclear Spectroscopic Telescope ARray) is a NASA Small Explorer (SMEX) mission launched in June of 2012. Since its launch, NuSTAR has been the preeminent instrument for spectroscopic analysis of the hard X-ray sky over the 3-80 keV bandpass. The low energy side of the bandpass is limited by the absorption along the photon path as well as by the ability of the pixels to trigger on incident photons. The on-board calibration source does not have a low-energy line that we can use to calibrate this part of the response, so instead we use the "nearest-neighbor" readout in the NuSTAR detector architecture to calibrate the individual pixel thresholds for all 8 flight detectors on both focal plane modules (FPMs). These threshold measurements feed back into the quantum efficiency of the detectors at low (<5 keV) energies and, once well-calibrated, may allow the use of NuSTAR data below the current 3 keV limit.

In past decade, CMOS imagers are becoming increasingly popular in scientific imaging like astronomy. Large format image sensors are the detector of choice for the wide field imaging. The circuit integration capability of the CMOS imager is considered as an advantage while inducing the temperature variation over the sensor area. Dark current of the image sensor is strongly temperature-dependent signal and one of the limiting factors of the low light imaging. Here, we present per-pixel dark current measurement results and analysis of a 7638 x 5004 pixels front-side illuminated CMOS image sensor with a pixel pitch of 6 μm. In this work, global non- uniformity induced by the on-chip temperature variation is controlled by the Peltier junction device. This paper reports results of our dark current study for the temperature range 233 to 273 K with exposure of 0 to 300 s. A reasonably low dark current of 0.014 e-/pixel/s is achieved at 233 K temperature. The dark current spatial distributions at different temperatures are presented. We extracted the activation energy for the dark current in this lower temperature range. Using the Arrhenius law, dark current data analysis shows the Meyer-Neldel Relationship (MNR) between the Arrhenius pre-factor and the apparent activation energy.

We are characterizing a 7638 x 5004 front-side illuminated CMOS detector for astronomical application. Mod- ulation Transfer Function (MTF) of a detector is considered as an important figure of merit for accurate target positioning in astronomy. It states the upper limit of the image quality. MTF knowledge also provides a better understanding of the design trade-off. In this work, two-dimensional (2D) sub-micrometer scanning method is used to extract 2D MTF profile of our CMOS detector with a pixel pitch of 6μm. Our optical measurement setup focuses a collimated beam onto the imaging surface with a microscope objective. The spot was scanned in a raster over a single pixel. We generate an oversampled point spread function (PSF) of the detector which contains sub-pixel elements. 2D MTF map is calculated from the measured oversampled PSF. This 2D MTF map is used to characterize the resolving ability of our detector. We analyze the importance of the 2D MTF map to describe the full pixel MTF of the CMOS pixel having low fill-factor. 1D MTFs are calculated from the 2d MTF to do a quantitative comparison of the MTF in horizontal and vertical directions. This study emphasizes advantages and necessity of the 2D MTF for CMOS detector performance analysis, especially for anisotropic resolution.

The Near-Infrared Spectrograph (NIRSpec) is one of the four science instruments onboard the James Webb Space Telescope (JWST). The instrument features a focal plane array (FPA) consisting of two 2048 × 2048 HAWAII-2RG sensor chip assemblies (SCAs) with a cutoff wavelength of approximately 5.3 μm. The detectors are read out via a pair of SIDECAR ASICs. To ensure a stable operating environment and best performance, the FPA is temperature controlled via a dedicated control loop by the NIRSpec focal plane electronics. The targeted in-orbit operating temperature of the NIRSpec FPA is close to 42.8 K. Due to the low background levels that the JWST will provide, most NIRSpec observations of very faint targets will be detector noise limited. Therefore, stringent noise requirements on the detector system were put in place. In order to meet these requirements, NIRSpec offers a dedicated readout mode for its detectors that is called improved reference sampling and subtraction (IRS² ). In this paper we present the noise performance of the NIRSpec detectors as a function of readout mode and exposure parameters. We find that the NIRSpec detector system meets its stringent noise requirement of 6 electrons total noise in a ∼ 1000 second exposure. We also highlight the types and effects of different kinds of bad pixels that are present in the detectors in small numbers.

The search for biosignatures in the atmospheres of exoplanets will be a key focus of future space telescopes that operate in the ultraviolet, visible, and near-infrared bands. Detection of biosignatures requires an instrument with moderate spectral resolving power (R ∼ 100) and a large bandwidth (∼ 400 nm – ∼ 1.8 μm). Additionally, biosignature detection is a photon-starved science; instruments designed for these measurements would ideally combine high optical efficiency with quantum-limited photon detectors (i.e., detectors that exhibit zero dark current). In this work, we report on our efforts to develop energy resolving transition edge sensor (TES)-based detectors designed for biosignature detection. TESs operated as microcalorimeters are compelling detectors for this application. Unlike semiconductor detectors, TESs eliminate the need for dispersive optics and are truly single photon detectors – fundamental TES noise yields uncertainty in the energies of detected photons, not in the number of detected photons. We introduce TESs designed for this application and discuss the path toward realizing a TES-based dispersionless spectrometer optimized for biosignature detection.

Interpixel capacitance (IPC) is the mechanism for a type of deterministic electrostatic coupling between neighboring pixels in hybridized detector arrays. Indium bumps are used to connect the photo-diode detection layer to the read-out circuitry. These indium bumps act as wires, transmitting voltages and currents between the detector layer and the read-out layer. When placed in close proximity, the voltages of these pixels capacitively couple to each other. The result is that when the voltage on one pixel changes, the voltage on that pixel’s neighbors change as well. IPC coupling results in a blur where a fraction, called the coupling coefficient, of the signal that was generated and collected in a given pixel, appears instead as signal on the neighboring pixels. Semi-conductor and electrostatic physics simulations have been conducted which show that the IPC is expected to change depending on the relative voltages of nearby pixels. The coupling coefficient is a function of signal strength, decreasing as signal strength increases. Characterization of IPC coupling using isolated single pixel events such as hot pixels in dark frames and single pixel resets shows this same signal dependence. The signal dependence of IPC introduces a new wrinkle in using hybridized arrays for scientific imaging. Previous work has anticipated that IPC results in a blurring of signal that can result in decreased contrast, but a signal dependence can result in additional effects on astronomical data. For example, when using pointspread function (PSF) fitting techniques on crowded fields to do astrometry and photometry, the PSF distortions due to IPC can result in an underestimate for the flux of brighter sources and an overestimate for the weaker sources. For an IPC coupling coefficient on the order of 1% with a signal dependence on the order of 0.4% , the full-width-half-max (FWHM) for a source near the sensitivity limit can be as much as 1% wider than the FWHM of a source near saturation. This results in flux estimations being off on the order of 1%. PSF distortion systematically drives down measurements of separation between sources. This error in separation drops to zero for well isolated sources, but when the PSFs are confused, it can result in an underestimate of separation on the order of 1%. To correct these errors, a method to remove a signal dependent IPC using an iterative method of successive approximations has been developed.

Isolated pixels with anomalously-low signal in otherwise normal Hubble Space Telescope Wide-Field Channel 3 (HST/WFC3) CCD data have been dubbed 'sink pixels' or SPs. The SPs appear to contain an exceptionally large number of charge traps and thus, they capture a commensurate amount of charge during readout. The effects of the sinks on science data depend on a number of factors including the image background, SP distance from the amplifier, and data epoch. In images with high backgrounds, the sinks act as essentially negative delta-functions, impacting a relatively small number of pixels. In contrast, in images with low backgrounds, the sinks can remove charge from a significant number of trailing pixels generating trough-like profiles. In this paper, we characterize the sink pixels, evaluate their effect on science data, and summarize how the sinks are flagged in the calibration pipeline.

VERITAS 2.2 is an evolutionary step of the VERITAS readout integrated circuit (ROIC) architecture designed for high speed, low noise DEPFET source follower or drain readout for the Wide Field Imager on the Athena X-ray satellite. Drain readout, also known as current readout, mitigates the RC time of the classical source follower readout. This is particularly beneficial for large DEPFET detectors where the line capacitance is large, with the current measured at the drain of the DEPFET transistor providing an immediate signal proportional to the collected charge in the pixel. VERITAS 2.2 is designed to address the implementation challenges of drain readout and deliver consistent performance at short processing time (2.5 μs) with a system noise better than 3 e - .

The “crosshatch” pattern is a recurring “feature” of HgCdTe arrays, specifically the Teledyne HAWAII family of near infrared detectors. It is a fixed pattern of high frequency QE variations along 3 directions generally thought to be related to the crystal structure of HgCdTe. The pattern is evident in detectors used in WFC3/IR, WISE, JWST, and in candidate detectors for Euclid and WFIRST. Using undersampled point sources projected onto a HAWAII-2RG detector, we show that the pattern induces photometric variations that are not removed by a flat-field calibration, thus demonstrating that the QE variations occur on scales smaller than the 18 micron pixels. Our testbed is the Precision Projector Laboratory’s astronomical scene generator, which can rapidly characterize the full detector by scanning thousands of undersampled spots. If not properly calibrated, detectors showing strong crosshatch may induce correlated errors in photometry, astrometry, spectroscopy, and shape measurements.

Particle-induced background, or “instrument background”, produced from the interaction of background photons and charged particles with a detector, either as primaries or through the generation of secondary photons or particles, is one of the major sources of background for the focal plane sensors in X-ray astronomy missions. In previous studies for the European Space Agency (ESA) X-ray Multi Mirror (XMM-Newton) mission, the dominant source of background was found to be caused by the knock-on electrons generated as high-energy protons pass through the shielding materials surrounding the detector. From XMM-Newton, the contribution of Compton and other photon-generated background was small in comparison to the knock-on electron component. However, for the Wide Field Imager (WFI) on board the ESA Advanced Telescope for High-ENergy Astrophysics (ATHENA) mission Athena, which houses much thicker silicon in the depleted p-channel field effect transistor (DEPFET) active pixel sensors of the focal plane when compared to the Charge Coupled Devices (CCDs) used in the XMM-Newton EPIC MOS cameras, this photon component may no longer be expected to have such a minimal impact and therefore both the photon and proton-induced components must be considered in more detail. In order to minimise the background, studies have been conducted on the use of a graded-Z shield in addition to an aluminium proton shield (employed for radiation damage minimization). For thin detectors, a low-Z component alone may suffice, reducing the fluorescence components of the background. However, with thicker detectors a high-Z component may give added benefit through the combination of the high-Z component to reduce the photon-induced effects and a low-Z component to reduce the fluorescence components from the shielding’s inner-surfaces, thus creating an “aluminium sandwich”. In all cases, careful optimization of the shielding configuration is required to balance each component of background specific to the design of the instrument involved. The optimization of any shielding relies heavily upon a validated and verified simulation toolkit. Here we present the latest progress on our ongoing validation and verification studies of the GEANT4 simulations used for such an optimization process through a series of experimental test campaigns.

Publisher’s Note: This paper, originally published on 1 August 2018, was replaced with a corrected/revised version on 12 August 2019. If you downloaded the original PDF but are unable to access the revision, please contact SPIE Digital Library Customer Service for assistance.