Journal of Astronomical Telescopes, Instruments, and Systems, 2015
The Wide Field InfraRed Survey Telescope-Astrophysics Focused Telescope Asset (WFIRST-AFTA) missi... more The Wide Field InfraRed Survey Telescope-Astrophysics Focused Telescope Asset (WFIRST-AFTA) mission is a 2.4-m class space telescope that will be used across a swath of astrophysical research domains. JPL will provide a high-contrast imaging coronagraph instrumentone of two major astronomical instruments. In order to achieve the low noise performance required to detect planets under extremely low flux conditions, the electron multiplying charge-coupled device (EMCCD) has been baselined for both of the coronagraph's sensorsthe imaging camera and integral field spectrograph. JPL has established an EMCCD test laboratory in order to advance EMCCD maturity to technology readiness level-6. This plan incorporates full sensor characterization, including read noise, dark current, and clock induced charge. In addition, by considering the unique challenges of the WFIRST space environment, degradation to the sensor's charge transfer efficiency will be assessed, as a result of damage from high-energy particles such as protons, electrons, and cosmic rays. Science-grade CCD201-20 EMCCDs have been irradiated to a proton fluence that reflects the projected WFIRST orbit. Performance degradation due to radiation displacement damage is reported, which is the first such study for a CCD201-20 that replicates the WFIRST conditions. In addition, techniques intended to identify and mitigate radiation-induced electron trapping, such as trap pumping, custom clocking, and thermal cycling, are discussed.
The Large Binocular Telescope (LBT) has two adaptive secondary mirrors based on 672 voice-coil fo... more The Large Binocular Telescope (LBT) has two adaptive secondary mirrors based on 672 voice-coil force actuators. The shape of the mirror is controlled using internal metrology based on co-located capacitive sensors. The first mirror unit is currently mounted on LBT for on-sky commissioning as part of the First Light Adaptive Optics System (FLAO). During spring-time 2009 the optical acceptance test was performed using the 14-m optical test tower at the Osservatorio Astrofisico di Arcetri (INAF) showing the capability of flattening the shell at the level of 14nm rms residual surface error. This paper reports the optical layout, calibration procedures and results of the optical acceptance test. Moreover we report the first results obtained during the early runs of FLAO commissioning showing the ability of the mirror to compensate for atmospheric turbulence with extremely high Strehl ratio values (better than 80% in H-band) as permitted by the largest number of correcting degrees of freedom currently available on-sky for astronomical telescopes.
Proceedings of Spie the International Society For Optical Engineering, 2008
The SIM PlanetQuest Mission will perform astrometry to one microarcsecond accuracy using optical ... more The SIM PlanetQuest Mission will perform astrometry to one microarcsecond accuracy using optical interferometers requiring optical path delay difference (OPD) measurements accurate to tens of picometers. Success relies on very precise calibration. Spectral Calibration Development Unit (SCDU) has been built to demonstrate the capability of calibrating spectral dependency of the white light fringe OPD to accuracy better than 20pm. In this article, we present the spectral calibration modeling work for SCDU to achieve the SIM PlanetQuest Engineering Milestone 4. SCDU data analysis shows that the wave front aberrations cause the instrument phase dispersions to vary by tens of nanometers over the bandwidth of a CCD pixel making the previous model inadequate. We include the effect of the wave front aberrations in the white light fringe model and develop a procedure for calibrating the corresponding model parameters using long stroke fringe data based on Discrete Fourier Transform. We make the calibration procedure flight traceable by dividing the whole calibration into the instrument calibration and the source spectral calibration. End-to-end simulations are used to quantify both the systematic and random errors in spectral calibration. The efficacy of the calibration scheme is demonstrated using the SCDU experimental data.
The SIM PlanetQuest Mission will perform astrometry to one microarcsecond accuracy using optical ... more The SIM PlanetQuest Mission will perform astrometry to one microarcsecond accuracy using optical interferometers requiring optical path delay difference (OPD) measurements accurate to tens of picometers. Success relies on very precise calibration. Spectral Calibration Development Unit (SCDU) has been built to demonstrate the capability of calibrating spectral dependency of the white light fringe OPD to accuracy better than 20pm. In this article, we present the spectral calibration modeling work for SCDU to achieve the SIM PlanetQuest Engineering Milestone 4. SCDU data analysis shows that the wave front aberrations cause the instrument phase dispersions to vary by tens of nanometers over the bandwidth of a CCD pixel making the previous model inadequate. We include the effect of the wave front aberrations in the white light fringe model and develop a procedure for calibrating the corresponding model parameters using long stroke fringe data based on Discrete Fourier Transform. We make the calibration procedure flight traceable by dividing the whole calibration into the instrument calibration and the source spectral calibration. End-to-end simulations are used to quantify both the systematic and random errors in spectral calibration. The efficacy of the calibration scheme is demonstrated using the SCDU experimental data.
This paper will present the analysis results taken from a well-designed interferometer SCDU. The ... more This paper will present the analysis results taken from a well-designed interferometer SCDU. The objective is to deliver picometer performance to meet the allocated astrometric error budget from SIM PlanetQuest mission. It will describe the validation of optical designs and analysis procedures to achieve high accuracy of the tip-tilt and shear alignments. Then it will enumerate environmental factors essential to
A breadboard is under development to demonstrate the calibration of spectral errors in microarcse... more A breadboard is under development to demonstrate the calibration of spectral errors in microarcsecond stellar interferometers. Analysis shows that thermally and mechanically stable hardware in addition to careful optical design can reduce the wavelength dependent error to tens of nanometers. Calibration of the hardware can further reduce the error to the level of picometers. The results of thermal, mechanical and optical analysis supporting the breadboard design will be shown.
This paper will present the analysis results taken from a well-designed interferometer SCDU. The ... more This paper will present the analysis results taken from a well-designed interferometer SCDU. The objective is to deliver picometer performance to meet the allocated astrometric error budget from SIM PlanetQuest mission. It will describe the validation of optical designs and analysis procedures to achieve high accuracy of the tip-tilt and shear alignments. Then it will enumerate environmental factors essential to the SCDU performances. Finally it will report color-independent 3 picometer Narrow Angle (NA) performance and all-in-one 17 picometer NA performance. The all-in-one pico-performance will require spectral calibration modeling to remove delay differential induced by color.
<title>Pulsed Laser Deposition Of Amorphous Carbon Films</title>
Diamond Optics II, 1990
ABSTRACT We have deposited thin amorphous carbon films on various substrate materials by irradiat... more ABSTRACT We have deposited thin amorphous carbon films on various substrate materials by irradiating a high purity (5N) graphite target in vacuum with pulsed light at 248 nm from a KrF excimer laser. The films have been characterized by Raman scattering, AES, SEM and chemical inertness tests. The films deposited on silicon are smooth and partially transparent. The preliminary Raman spectra show no evidence of crystalline grains (diamond or graphite) however the films deposited on silicon and quartz survived etching by a solution of HF:HNO3 (1:1). We will report on the substrate temperature dependence of laser deposited films and the variation of film quality on substrate material.
In this paper we present the laboratory characterization and performance evaluation of the First ... more In this paper we present the laboratory characterization and performance evaluation of the First Light Adaptive Optics (FLAO) the Natural Guide Star adaptive optics system for the Large Binocular Telescope (LBT). The system uses an adaptive secondary mirror with 672 actuators and a pyramid wavefront sensor with adjustable sampling of the telescope pupil from 30×30 down to 4×4 subapertures. The
The CHROMA focal plane array: a large-format, low-noise detector optimized for imaging spectroscopy
Imaging Spectrometry XVIII, 2013
ABSTRACT The CHROMA (Configurable Hyperspectral Readout for Multiple Applications) is an advanced... more ABSTRACT The CHROMA (Configurable Hyperspectral Readout for Multiple Applications) is an advanced Focal Plane Array (FPA) designed for visible-infrared imaging spectroscopy. Using Teledyne&#39;s latest substrateremoved HgCdTe detector, the CHROMA FPA has very low dark current, low readout noise and high, stable quantum efficiency from the deep blue (390nm) to the cutoff wavelength. CHROMA has a pixel pitch of 30 microns and is available in array formats ranging from 320×480 to 1600×480 pixels. Users generally disperse spectra over the 480 pixel-length columns and image spatially over the n×160 pixellength rows, where n=2, 4, 8, 10. The CHROMA Readout Integrated Circuit (ROIC) has Correlated Double Sampling (CDS) in pixel and generates its own internal bias signals and clocks. This paper presents the measured performance of the CHROMA FPA with 2.5 micron cutoff wavelength including the characterization of noise versus pixel gain, power dissipation and quantum efficiency.
Planetquest Mission and has successfully demonstrated the calibration of spectral instrument erro... more Planetquest Mission and has successfully demonstrated the calibration of spectral instrument error to an accuracy of better than 20 picometers. This performance is consistent with the 1 micro-arc second goal of SIM. The calibration procedure demonstrated in the test bed is traceable to the SIM flight instrument. This article is a review of all aspects of the design and operation of the hardware as well as the methodology for spectral calibration. Spectral calibration to better than 20 picometers and implications for flight are discussed.
<title>Broadband white light laser combiner system</title>
Photonic Fiber and Crystal Devices: Advances in Materials and Innovations in Device Applications II, 2008
The SIM-Planetquest (Space Interferometry Mission), currently under development at the Jet Propul... more The SIM-Planetquest (Space Interferometry Mission), currently under development at the Jet Propulsion Laboratory, consists of two 6-meter baseline interferometers on a flexible truss. SIM&amp;#39;s science goals require 1muas accuracy in its astrometric measurements[1]. To achieve this level of accuracy for detecting planets SIM built the Spectrum Calibration Development Unit (SCDU) testbed. The testbed requires a white light point source with
The near-earth object camera (NEOCam) is a proposed infrared space mission designed to discover a... more The near-earth object camera (NEOCam) is a proposed infrared space mission designed to discover and characterize most of the potentially hazardous asteroids larger than 140 m in diameter that orbit near the Earth. NASA has funded technology development for NEOCam, including the development of long wavelength infrared detector arrays that will have excellent zodiacal background emission-limited performance at passively cooled focal plane temperatures. Teledyne Imaging Sensors has developed and delivered for test at the University of Rochester the first set of approximately 10 μm cutoff, 1024 × 1024 pixel HgCdTe detector arrays. Measurements of these arrays show the development to be extremely promising: noise, dark current, quantum efficiency, and well depth goals have been met by this technology at focal plane temperatures of 35 to 40 K, readily attainable with passive cooling. The next set of arrays to be developed will address changes suggested by the first set of deliverables.
Inelastic light scattering spectra were measured in MBE grown single crystal films of Dysprosium,... more Inelastic light scattering spectra were measured in MBE grown single crystal films of Dysprosium, Erbium and Yttrium. In order to measure the weak Raman signals of metals a single grating monochromator was designed and constructed and added to an existing double grating monochromator to improve the stray light rejection. Polarized Raman Scattering was used to probe vibrational and electronic excitations in Dy, Er and Y and magnetic excitations in Dy and Er. The vibrational light scattering measurements have revealed an anomalous temperature dependence of the zone-center transverse optical phonon in Dy and Er. Previous measurements of the thermal expansion of bulk Dy and Er indicate that this temperature dependence cannot be explained by lattice anharmonicity and the related volume change. The hardening of this mode may be due in part to the coupling of the TO phonon to the ordered magnetic moments. The linewidth of this mode is observed to increase at low temperature in Dy and Er. T...
Journal of Astronomical Telescopes, Instruments, and Systems, 2015
The Wide Field InfraRed Survey Telescope-Astrophysics Focused Telescope Asset (WFIRST-AFTA) missi... more The Wide Field InfraRed Survey Telescope-Astrophysics Focused Telescope Asset (WFIRST-AFTA) mission is a 2.4-m class space telescope that will be used across a swath of astrophysical research domains. JPL will provide a high-contrast imaging coronagraph instrumentone of two major astronomical instruments. In order to achieve the low noise performance required to detect planets under extremely low flux conditions, the electron multiplying charge-coupled device (EMCCD) has been baselined for both of the coronagraph's sensorsthe imaging camera and integral field spectrograph. JPL has established an EMCCD test laboratory in order to advance EMCCD maturity to technology readiness level-6. This plan incorporates full sensor characterization, including read noise, dark current, and clock induced charge. In addition, by considering the unique challenges of the WFIRST space environment, degradation to the sensor's charge transfer efficiency will be assessed, as a result of damage from high-energy particles such as protons, electrons, and cosmic rays. Science-grade CCD201-20 EMCCDs have been irradiated to a proton fluence that reflects the projected WFIRST orbit. Performance degradation due to radiation displacement damage is reported, which is the first such study for a CCD201-20 that replicates the WFIRST conditions. In addition, techniques intended to identify and mitigate radiation-induced electron trapping, such as trap pumping, custom clocking, and thermal cycling, are discussed.
The Large Binocular Telescope (LBT) has two adaptive secondary mirrors based on 672 voice-coil fo... more The Large Binocular Telescope (LBT) has two adaptive secondary mirrors based on 672 voice-coil force actuators. The shape of the mirror is controlled using internal metrology based on co-located capacitive sensors. The first mirror unit is currently mounted on LBT for on-sky commissioning as part of the First Light Adaptive Optics System (FLAO). During spring-time 2009 the optical acceptance test was performed using the 14-m optical test tower at the Osservatorio Astrofisico di Arcetri (INAF) showing the capability of flattening the shell at the level of 14nm rms residual surface error. This paper reports the optical layout, calibration procedures and results of the optical acceptance test. Moreover we report the first results obtained during the early runs of FLAO commissioning showing the ability of the mirror to compensate for atmospheric turbulence with extremely high Strehl ratio values (better than 80% in H-band) as permitted by the largest number of correcting degrees of freedom currently available on-sky for astronomical telescopes.
Proceedings of Spie the International Society For Optical Engineering, 2008
The SIM PlanetQuest Mission will perform astrometry to one microarcsecond accuracy using optical ... more The SIM PlanetQuest Mission will perform astrometry to one microarcsecond accuracy using optical interferometers requiring optical path delay difference (OPD) measurements accurate to tens of picometers. Success relies on very precise calibration. Spectral Calibration Development Unit (SCDU) has been built to demonstrate the capability of calibrating spectral dependency of the white light fringe OPD to accuracy better than 20pm. In this article, we present the spectral calibration modeling work for SCDU to achieve the SIM PlanetQuest Engineering Milestone 4. SCDU data analysis shows that the wave front aberrations cause the instrument phase dispersions to vary by tens of nanometers over the bandwidth of a CCD pixel making the previous model inadequate. We include the effect of the wave front aberrations in the white light fringe model and develop a procedure for calibrating the corresponding model parameters using long stroke fringe data based on Discrete Fourier Transform. We make the calibration procedure flight traceable by dividing the whole calibration into the instrument calibration and the source spectral calibration. End-to-end simulations are used to quantify both the systematic and random errors in spectral calibration. The efficacy of the calibration scheme is demonstrated using the SCDU experimental data.
The SIM PlanetQuest Mission will perform astrometry to one microarcsecond accuracy using optical ... more The SIM PlanetQuest Mission will perform astrometry to one microarcsecond accuracy using optical interferometers requiring optical path delay difference (OPD) measurements accurate to tens of picometers. Success relies on very precise calibration. Spectral Calibration Development Unit (SCDU) has been built to demonstrate the capability of calibrating spectral dependency of the white light fringe OPD to accuracy better than 20pm. In this article, we present the spectral calibration modeling work for SCDU to achieve the SIM PlanetQuest Engineering Milestone 4. SCDU data analysis shows that the wave front aberrations cause the instrument phase dispersions to vary by tens of nanometers over the bandwidth of a CCD pixel making the previous model inadequate. We include the effect of the wave front aberrations in the white light fringe model and develop a procedure for calibrating the corresponding model parameters using long stroke fringe data based on Discrete Fourier Transform. We make the calibration procedure flight traceable by dividing the whole calibration into the instrument calibration and the source spectral calibration. End-to-end simulations are used to quantify both the systematic and random errors in spectral calibration. The efficacy of the calibration scheme is demonstrated using the SCDU experimental data.
This paper will present the analysis results taken from a well-designed interferometer SCDU. The ... more This paper will present the analysis results taken from a well-designed interferometer SCDU. The objective is to deliver picometer performance to meet the allocated astrometric error budget from SIM PlanetQuest mission. It will describe the validation of optical designs and analysis procedures to achieve high accuracy of the tip-tilt and shear alignments. Then it will enumerate environmental factors essential to
A breadboard is under development to demonstrate the calibration of spectral errors in microarcse... more A breadboard is under development to demonstrate the calibration of spectral errors in microarcsecond stellar interferometers. Analysis shows that thermally and mechanically stable hardware in addition to careful optical design can reduce the wavelength dependent error to tens of nanometers. Calibration of the hardware can further reduce the error to the level of picometers. The results of thermal, mechanical and optical analysis supporting the breadboard design will be shown.
This paper will present the analysis results taken from a well-designed interferometer SCDU. The ... more This paper will present the analysis results taken from a well-designed interferometer SCDU. The objective is to deliver picometer performance to meet the allocated astrometric error budget from SIM PlanetQuest mission. It will describe the validation of optical designs and analysis procedures to achieve high accuracy of the tip-tilt and shear alignments. Then it will enumerate environmental factors essential to the SCDU performances. Finally it will report color-independent 3 picometer Narrow Angle (NA) performance and all-in-one 17 picometer NA performance. The all-in-one pico-performance will require spectral calibration modeling to remove delay differential induced by color.
<title>Pulsed Laser Deposition Of Amorphous Carbon Films</title>
Diamond Optics II, 1990
ABSTRACT We have deposited thin amorphous carbon films on various substrate materials by irradiat... more ABSTRACT We have deposited thin amorphous carbon films on various substrate materials by irradiating a high purity (5N) graphite target in vacuum with pulsed light at 248 nm from a KrF excimer laser. The films have been characterized by Raman scattering, AES, SEM and chemical inertness tests. The films deposited on silicon are smooth and partially transparent. The preliminary Raman spectra show no evidence of crystalline grains (diamond or graphite) however the films deposited on silicon and quartz survived etching by a solution of HF:HNO3 (1:1). We will report on the substrate temperature dependence of laser deposited films and the variation of film quality on substrate material.
In this paper we present the laboratory characterization and performance evaluation of the First ... more In this paper we present the laboratory characterization and performance evaluation of the First Light Adaptive Optics (FLAO) the Natural Guide Star adaptive optics system for the Large Binocular Telescope (LBT). The system uses an adaptive secondary mirror with 672 actuators and a pyramid wavefront sensor with adjustable sampling of the telescope pupil from 30×30 down to 4×4 subapertures. The
The CHROMA focal plane array: a large-format, low-noise detector optimized for imaging spectroscopy
Imaging Spectrometry XVIII, 2013
ABSTRACT The CHROMA (Configurable Hyperspectral Readout for Multiple Applications) is an advanced... more ABSTRACT The CHROMA (Configurable Hyperspectral Readout for Multiple Applications) is an advanced Focal Plane Array (FPA) designed for visible-infrared imaging spectroscopy. Using Teledyne&#39;s latest substrateremoved HgCdTe detector, the CHROMA FPA has very low dark current, low readout noise and high, stable quantum efficiency from the deep blue (390nm) to the cutoff wavelength. CHROMA has a pixel pitch of 30 microns and is available in array formats ranging from 320×480 to 1600×480 pixels. Users generally disperse spectra over the 480 pixel-length columns and image spatially over the n×160 pixellength rows, where n=2, 4, 8, 10. The CHROMA Readout Integrated Circuit (ROIC) has Correlated Double Sampling (CDS) in pixel and generates its own internal bias signals and clocks. This paper presents the measured performance of the CHROMA FPA with 2.5 micron cutoff wavelength including the characterization of noise versus pixel gain, power dissipation and quantum efficiency.
Planetquest Mission and has successfully demonstrated the calibration of spectral instrument erro... more Planetquest Mission and has successfully demonstrated the calibration of spectral instrument error to an accuracy of better than 20 picometers. This performance is consistent with the 1 micro-arc second goal of SIM. The calibration procedure demonstrated in the test bed is traceable to the SIM flight instrument. This article is a review of all aspects of the design and operation of the hardware as well as the methodology for spectral calibration. Spectral calibration to better than 20 picometers and implications for flight are discussed.
<title>Broadband white light laser combiner system</title>
Photonic Fiber and Crystal Devices: Advances in Materials and Innovations in Device Applications II, 2008
The SIM-Planetquest (Space Interferometry Mission), currently under development at the Jet Propul... more The SIM-Planetquest (Space Interferometry Mission), currently under development at the Jet Propulsion Laboratory, consists of two 6-meter baseline interferometers on a flexible truss. SIM&amp;#39;s science goals require 1muas accuracy in its astrometric measurements[1]. To achieve this level of accuracy for detecting planets SIM built the Spectrum Calibration Development Unit (SCDU) testbed. The testbed requires a white light point source with
The near-earth object camera (NEOCam) is a proposed infrared space mission designed to discover a... more The near-earth object camera (NEOCam) is a proposed infrared space mission designed to discover and characterize most of the potentially hazardous asteroids larger than 140 m in diameter that orbit near the Earth. NASA has funded technology development for NEOCam, including the development of long wavelength infrared detector arrays that will have excellent zodiacal background emission-limited performance at passively cooled focal plane temperatures. Teledyne Imaging Sensors has developed and delivered for test at the University of Rochester the first set of approximately 10 μm cutoff, 1024 × 1024 pixel HgCdTe detector arrays. Measurements of these arrays show the development to be extremely promising: noise, dark current, quantum efficiency, and well depth goals have been met by this technology at focal plane temperatures of 35 to 40 K, readily attainable with passive cooling. The next set of arrays to be developed will address changes suggested by the first set of deliverables.
Inelastic light scattering spectra were measured in MBE grown single crystal films of Dysprosium,... more Inelastic light scattering spectra were measured in MBE grown single crystal films of Dysprosium, Erbium and Yttrium. In order to measure the weak Raman signals of metals a single grating monochromator was designed and constructed and added to an existing double grating monochromator to improve the stray light rejection. Polarized Raman Scattering was used to probe vibrational and electronic excitations in Dy, Er and Y and magnetic excitations in Dy and Er. The vibrational light scattering measurements have revealed an anomalous temperature dependence of the zone-center transverse optical phonon in Dy and Er. Previous measurements of the thermal expansion of bulk Dy and Er indicate that this temperature dependence cannot be explained by lattice anharmonicity and the related volume change. The hardening of this mode may be due in part to the coupling of the TO phonon to the ordered magnetic moments. The linewidth of this mode is observed to increase at low temperature in Dy and Er. T...
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Papers by Richard Demers