Mr. Jeffrey R. Juergens Profile

Jeffrey R. Juergens

Electronics Engineer at NASA Glenn Research Ctr

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Author

Publications (5)

Proceedings Article | 18 July 2018 Presentation

Planetary science capabilities of a UV-visible balloon-borne telescope as a function of wavefront error (Conference Presentation)

Eliot Young, Brian Catanzaro, Nicolas Gorius, Robert Woodruff, Monica Hoffmann, Jeffrey Juergens

Proceedings Volume 10700, 107001H (2018) https://doi.org/10.1117/12.2314323

KEYWORDS: Space telescopes, Telescopes, Planetary science, Wavefronts, Point spread functions, Satellites, Spatial resolution, Ultraviolet radiation, Visible radiation, Clouds

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Several classes of planetary science observations require high spatial resolution in UV and visible wavelengths. Key examples include (a) the detection of satellites and characterization of their orbits, (b) the discovery of faint and small objects among the NEO, asteroid, Kuiper belt or Sedna-like populations and (c) cloud or trace gas observations in planetary atmospheres. Hubble Space Telescope (HST) observations have been very productive in these areas: consider the recent discovery of Makemake's satellite (Parker et al., 2016), the discovery of 2014 MU69 (now the flyby target of the New Horizons spacecraft) or the OPAL (Outer Planet Atmospheres Legacy) program. Like HST, large-aperture ground-based telescopes with adaptive optics can also achieve spatial resolutions of 50 mas, but normally at wavelengths longer than ~1 μm. Projects like MagAO-2K are working on improving image quality at visible wavelengths, but while the core PSF (Point Spread Function) width might be narrow (projected to be 15 mas at the Magellan telescope), the Strehl ratio drops steeply with wavelength (Males et al., 2016). Not all science goals suffer equally from low Strehl ratios, however: cloud tracking on Venus is more tolerant of a low Strehl ratio than searching for a close satellite of Makemake. A telescope on a NASA super-pressure balloon would float above 99.3% of the atmosphere, where the inner Fried parameter is thought to be two meters or more. While atmospheric turbulence is not expected to impact image quality, there are other sources of wavefront error (WFE), such as mirror figuring, misalignment of the OTA (Optical Telescope Assembly) or asymmetric heating from the Sun or Earth. We reference recent work that estimates balloon telescope WFEs from different sources to generate a suite of plausible PSFs. We apply these PSFs to the UV and visible wavelength science cases outlined in the GHAPS/SIDT report (Gondola for High Altitude Planetary Science/Science Instrument Definition Team). We quantify the impact that WFE has on achieving the planetary observations outlined in the SIDT report.

Proceedings Article | 11 July 2018 Paper

Low light level quadriwave lateral shearing interferometer for in-situ wavefront sensing

Brian Catanzaro, Benoit Wattellier, Ekaterina Boldyreva, Eliot Young, Michael Lewis, Jeffrey Juergens, Robert Woodruff, Monica Hoffmann

Proceedings Volume 10703, 107035J (2018) https://doi.org/10.1117/12.2312331

KEYWORDS: Wavefronts, Stars, Wavefront sensors, Mirrors, Telescopes, Optical instrument design, Sensors, Space telescopes, Shearing interferometers, Observatories

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Proceedings Article | 6 July 2018 Paper

Image guider subsystem analysis for the GHAPS project

Michael Lewis, Jeffrey Juergens, Eliot Aretskin-Hariton, Robert Woodruff

Proceedings Volume 10702, 107025D (2018) https://doi.org/10.1117/12.2313994

KEYWORDS: Stars, Image sensors, Cameras, Indium gallium arsenide, Sensors, Signal to noise ratio, Airglow, Telescopes, Visible radiation, Error analysis

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Proceedings Article | 16 May 2005 Paper

Processing of signals from fiber Bragg gratings using unbalanced interferometers

Grigory Adamovsky, Jeff Juergens, Bertram Floyd

Proceedings Volume 5758, (2005) https://doi.org/10.1117/12.601808

KEYWORDS: Interferometers, Fiber Bragg gratings, Signal processing, Sensors, Temperature metrology, Crystals, Fiber optics sensors, Refractive index, Geometrical optics, Photodetectors

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Proceedings Article | 8 March 2004 Paper

Performance evaluation of fiber Bragg gratings at elevated temperatures

Jeffrey Juergens, Grigory Adamovsky, Bertram Floyd

Proceedings Volume 5272, (2004) https://doi.org/10.1117/12.525232

KEYWORDS: Fiber Bragg gratings, Sensors, Fiber optics sensors, Environmental sensing, Refractive index, Structured optical fibers, Optical fibers, Optical filters, Light wave propagation, Polymers

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The development of integrated fiber optic sensors for smart propulsion systems demands that the sensors be able to perform in extreme environments. In order to use fiber optic sensors effectively in an extreme environment one must have a thorough understanding of the sensor’s limits and how it responds under various environmental conditions. The sensor evaluation currently involves examining the performance of fiber Bragg gratings at elevated temperatures. Fiber Bragg gratings (FBG) are periodic variations of the refractive index of an optical fiber. These periodic variations allow the FBG to act as an embedded optical filter passing the majority of light propagating through a fiber while reflecting back a narrow band of the incident light. The peak reflected wavelength of the FBG is known as the Bragg wavelength. Since the period and width of the refractive index variation in the fiber determines the wavelengths that are transmitted and reflected by the grating, any force acting on the fiber that alters the physical structure of the grating will change what wavelengths are transmitted and what wavelengths are reflected by the grating. Both thermal and mechanical forces acting on the grating will alter its physical characteristics allowing the FBG sensor to detect both temperature variations and physical stresses, strain, placed upon it. This ability to sense multiple physical forces makes the FBG a versatile sensor. This paper reports on test results of the performance of FBGs at elevated temperatures. The gratings looked at thus far have been either embedded in polymer matrix materials or freestanding with the primary focus of this paper being on the freestanding FBGs. Throughout the evaluation process, various parameters of the FBGs performance were monitored and recorded. These parameters include the peak Bragg wavelength, the power of the Bragg wavelength, and total power returned by the FBG. Several test samples were subjected to identical test conditions to allow for statistical analysis of the data. Test procedures, calibrations, and referencing techniques are presented in the paper along with directions for future research.

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