As the complexity of optical instrumentation for astronomy grows, computer simulation becomes an unavoidable task of the design process. Additionally, these designs frequently involve moving parts, making both the kinematic and optical simulations tightly coupled. In some cases, the integration between both kinds of simulations is hard, and software development skills are usually also required. In order to address these difficulties we introduce RayZaler: a free-as-in-freedom opto-mechanical simulation framework. RayZaler features a ray tracer that acts upon a parametric model, stored as one or more humanreadable, plain-text model files. This allows model files to benefit from the power of version control systems like Git, while keeping their syntax accessible to users that are not familiarised with software development tools. The user defines the degrees of freedom of the model explicitly in the model files, and can use them as variables of math expressions that describe the geometry of the model. In this work, we detail its most relevant features and its application to the sensitivity analyses of HARMONI, the first-light integral field spectrograph for the ELT, and discuss several simulation products.
HARMONI is the first light visible and near-IR integral field spectrograph for the ELT. It covers a large spectral range from 450 nm to 2450 nm with resolving powers from 3500 to 18000 and spatial sampling from 60 mas to 4 mas. It can operate in two Adaptive Optics modes - SCAO (including a High Contrast capability) and LTAO - or with NOAO. The project is preparing for Final Design Reviews. HARMONI is a work-horse instrument that provides efficient, spatially resolved spectroscopy of extended objects or crowded fields of view. The gigantic leap in sensitivity and spatial resolution that HARMONI at the ELT will enable promises to transform the landscape in observational astrophysics in the coming decade. The project has undergone some key changes to the leadership and management structure over the last two years. We present the salient elements of the project restructuring, and modifications to the technical specifications. The instrument design is very mature in the lead up to the final design review. In this paper, we provide an overview of the instrument's capabilities, details of recent technical changes during the red flag period, and an update of sensitivities.
HARMONI is the first light visible and near-IR integral field spectrograph for the ELT. It covers a large spectral range from 450nm to 2450nm with resolving powers from 3500 to 18000 and spatial sampling from 60mas to 4mas. It can operate in two Adaptive Optics modes - SCAO (including a High Contrast capability) and LTAO - or with NOAO. The project is preparing for Final Design Reviews. The Calibration Module (CM) is part of the HARMONI Instrument. It includes all the functionalities necessary to remove the instrumental signature from the observed science data, perform the technical calibrations needed to set up other sub-systems, and for monitoring the health of the instrument during operations. The CM is a complex and accurate optical configurable mechanism mainly composed by the following calibration units:
Integral Field Spectrograph Calibration Unit (ICU): It provides calibration for the integral field spectrograph. The ICU mimics the ELT pupil and F/# at the HARMONI entrance and provides with a set of illumination patterns by combining different light sources and focal plane masks.
Adaptive Optics Calibration Unit (AOCU): Intended for “Natural Guide Star Sensors (NGSS)” and “Laser Tomography Adaptive Optics (LTAO)” calibration.
Geometrical Calibration Unit (GCU): Using a well-known geometrical pattern of barely resolved point sources made of 480 optical fibers, this unit is intended for the NGSS guide probes.
In this paper, we present an overview of the CM design, describing its functional and optomechanical implementation.
HARMONI is the first light visible and near-IR integral field spectrograph for the ELT. To achieve its optimal image quality, an accurate measurement of the telescope’s pointing error is necessary. These measurements are affected both by systematic and random error contributions. To characterise the impact of the latter (as well as the performance of any necessary corrective model), simulations of the pointing error measurement process are required. We introduce harmoni-pm: a Python-based prototype which, departing from a geometric optics modelisation of the instrument, attempts to reproduce the main drivers of the instrumental pointing error. harmoni-pm features a software architecture that is resilient to instrument model refinements and enables performance analyses of corrective models based on simulated calibrations. Results showed that the relay optics are the main drivers of the instrumental pointing error (order 100 μm). Additionally, simulated calibrations of corrective models based on truncated Zernike expansions can compensate for systematic pointing errors up to a residual of order 1 μm.
HARMONI is the first light, adaptive optics assisted, integral field spectrograph for the European Southern Observatory’s Extremely Large Telescope (ELT). A work-horse instrument, it provides the ELT’s diffraction limited spectroscopic capability across the near-infrared wavelength range. HARMONI will exploit the ELT’s unique combination of exquisite spatial resolution and enormous collecting area, enabling transformational science. The design of the instrument is being finalized, and the plans for assembly, integration and testing are being detailed. We present an overview of the instrument’s capabilities from a user perspective, and provide a summary of the instrument’s design. We also include recent changes to the project, both technical and programmatic, that have resulted from red-flag actions. Finally, we outline some of the simulated HARMONI observations currently being analyzed.
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