IceSat 2 ATLAS photon-counting receiver - initial on-orbit performance
No abstract available
Yang, Guangning↗
Engineering topics
Martino, Anthony J.
Publications and source records attributed to Martino, Anthony J..
IceSat 2 ATLAS Photon-Counting Receiver - Initial On-Orbit Performance
Photon-counting receivers are deployed on the NASA Ice, Cloud and land Elevation Satellite-2 (ICESat2) Advance Topographic Laser Altimeter System (ATLAS). The ATLAS laser altimeter design has total six ground tracks with three strong and three weak tracks. The strong track has nominally 4 times more laser power than the weak track. The receiver is operated in photon counting mode. There are 16 photon-counting channels for each strong track and 4 photon-counting channels for each weak track. Hamamatsu photomultiplier with a 4x4-array anode was used as photon counting detector. This receiver design has high counting efficiency (>15%) at 532 nm, low dark count rate (<400 counts per second), low jitter (less than 285ps), short dead time (<3 ns), long lifetime under large solar background radiation, radiation harden for space operation, and ruggedized for survives the harsh vibration during the launch. In this paper, we will present the initial on-orbit performance of this photon-counting receiver.
Yang, Guangning↗
The Wide-Field Imaging Interferometry Testbed (WIIT): Recent Progress and Results
Continued research with the Wide-Field Imaging Interferometry Testbed (WIIT) has achieved several important milestones. We have moved WIIT into the Advanced Interferometry and Metrology (AIM) Laboratory at Goddard, and have characterized the testbed in this well-controlled environment. The system is now completely automated and we are in the process of acquiring large data sets for analysis. In this paper, we discuss these new developments and outline our future research directions. The WIIT testbed, combined with new data analysis techniques and algorithms, provides a demonstration of the technique of wide-field interferometric imaging, a powerful tool for future space-borne interferometers.
Rinehart, Stephen A.↗
Direct-detection Free-space Laser Transceiver Test-bed
NASA Goddard Space Flight Center is developing a direct-detection free-space laser communications transceiver test bed. The laser transmitter is a master-oscillator power amplifier (MOPA) configuration using a 1060 nm wavelength laser-diode with a two-stage multi-watt Ytterbium fiber amplifier. Dual Mach-Zehnder electro-optic modulators provide an extinction ratio greater than 40 dB. The MOPA design delivered 10-W average power with low-duty-cycle PPM waveforms and achieved 1.7 kW peak power. We use pulse-position modulation format with a pseudo-noise code header to assist clock recovery and frame boundary identification. We are examining the use of low-density-parity-check (LDPC) codes for forward error correction. Our receiver uses an InGaAsP 1 mm diameter photocathode hybrid photomultiplier tube (HPMT) cooled with a thermo-electric cooler. The HPMT has 25% single-photon detection efficiency at 1064 nm wavelength with a dark count rate of 60,000/s at -22 degrees Celsius and a single-photon impulse response of 0.9 ns. We report on progress toward demonstrating a combined laser communications and ranging field experiment.
Krainak, Michael A.↗
The Space Infrared Interferometric Telescope (SPIRIT): Optical System Design Considerations
SPIRIT is a candidate NASA Origins Probe mission. It is a spatial and spectral interferometer operating at 4 K with an operating wavelength range 25 - 400 microns. This paper describes the various components of the candidate optical system, including telescopes, pointing and tracking optics, along with their functions. Some of the tradeoffs involved in selecting various components, with their particular characteristics, are described.
Wilson, Mark E.↗
The Wide-Field Imaging Interferometry Testbed: Enabling Techniques for High Angular Resolution Astronomy
The Wide-Field Imaging Interferometry Testbed (WIIT) was designed to develop techniques for wide-field of view imaging interferometry, using "double-Fourier" methods. These techniques will be important for a wide range of future spacebased interferometry missions. We have provided simple demonstrations of the methodology already, and continuing development of the testbed will lead to higher data rates, improved data quality, and refined algorithms for image reconstruction. At present, the testbed effort includes five lines of development; automation of the testbed, operation in an improved environment, acquisition of large high-quality datasets, development of image reconstruction algorithms, and analytical modeling of the testbed. We discuss the progress made towards the first four of these goals; the analytical modeling is discussed in a separate paper within this conference.
Rinehart, S. A.↗
Tunable Solid-Etalon Filter for the ICESat/GLAS 532 nm Channel Lidar Receiver
The Geoscience Laser Altimeter System (GLAS) was launched into Earth orbit on board the Ice, Cloud and land Elevation Satellite (ICESat) on January 12, 2003. GLAS is a laser altimeter designed to measure ice-sheet topography and associated temporal changes, as well as cloud and atmospheric properties. Each (of the three identical) GLAS lasers is a diode pumped, Q-switched Nd:YAG laser with energy levels of 75 mJ (1064 nm) and 35 mJ (532 nm). The infrared pulse is used for both surface altimetry and atmospheric measurements while the green pulse is used primarily for atmospheric measurements. The receiver uses a 1 meter diameter telescope. We report on the tunable solid-etalon filter used in the ICESat/GLAS 532 nm channel lidar receiver.
Krainak, Michael A.↗
Wind Lidar Edge Technique Shuttle Demonstration Mission: Anemos
A NASA mission is planned to demonstrate the technology for a wind lidar. This will implement the direct detection edge technique. The Anemos instrument will fly on the Space Transportation System (STS), or shuttle, aboard a Hitchhiker bridge. The instrument is being managed by the Goddard Space Flight Center as an in-house build, with science leadership from the GSFC Laboratory for Atmospheres, Mesoscale Atmospheric Processes Branch. During a roughly ten-day mission, the instrument will self calibrate and adjust for launch induced mis-alignments, and perform a campaign of measurements of tropospheric winds. The mission is planned for early 2001. The instrument is being developed under the auspices of NASA's New Millennium Program, in parallel with a comparable mission being managed by the Marshall Space Flight Center. That mission, called SPARCLE, will implement the coherent technique. NASA plans to fly the two missions together on the same shuttle flight, to allow synergy of wind measurements and a direct comparison of performance.
Leete, Stephen J.↗
Reference Interferometer Using a Semiconductor Laser/LED Reference Source in a Cryogenic Fourier-Transform Spectrometer
A combination of a single mode AlGaAs laser diode and broadband LED was used in a Michelson interferometer to provide reference signals in a Fourier transform spectrometer, the Composite Infrared Spectrometer, on the Cassini mission to Saturn. The narrowband light from the laser produced continuous fringes throughout the travel of the interferometer, which were used to control the velocity of the scan mechanism and to trigger data sampling. The broadband light from the LED produced a burst of fringes at zero path difference, which was used as a fixed position reference. The system, including the sources, the interferometer, and the detectors, was designed to work both at room temperature and instrument operating temperature of 170 Kelvin. One major challenge that was overcome was preservation, from room temperature to 170 K, of alignment sufficient for high modulation of fringes from the broadband source. Another was the shift of the source spectra about 30 nm toward shorter wavelengths upon cooldown.
Martino, Anthony J.↗
Throughput of the Composite Infrared Spectrometer (CIRS) Mid Infrared (MIR) Channel for the Cassini Mission to Saturn
The Composite Infrared Spectrometer (CIRS) of the Cassini mission to Saturn has two interferometers covering the far infrared and mid infrared wavelength region. The instrument was aligned at ambient temperature, but operates at 170 Kelvin and has challenging interferometric alignment tolerances. Cryogenic alignment tests of the instrument indicate that it should suffer minimal degradation due to the cooldown from ambient to operational temperature. System level tests performed by the calibration team indicated a lower than expected signal level on the MIR channel, while providing ambiguous optical throughput data. Therefore it became imperative to develop a metric that could be used to determine the instrument performance at both the instrument and system levels, at ambient and cryogenic temperature. Modulation efficiency and throughput measurements were performed and new analytical models developed to evaluate the status of the instrument. Empirical and analytical data were eventually reconciled and deviations from the design values explained.
Hagopian, John G.↗
Shear/Defocus Sensitivity of the Mid Infrared Channel (MIR) of the Composite Infrared Spectrometer (CIRS) for the Cassini Mission to Saturn
The Composite Infrared Spectrometer (CIRS) of the Cassini mission to Saturn has two interferometers covering the far infrared and mid infrared wavelength region. The mid infrared wavelength interferometer has a focal plane consisting of a germanium focus lens and HgCdTe array. System level calibration of the CIRS Flight Unit indicated a discrepancy between the expected and actual signal levels. Testing on the CIRS breadboard and Engineering Unit indicated that defocus of the germanium lens could significantly reduce the modulation efficiency of the interferometer in the presence of a moderate degree of wavefront shear. Defocus of the lens in the focal plane was of concern because of the temperature dependence of the index of refraction of germanium and our nominal operation temperature of 170 K. The shear/defocus interaction was extensively investigated and correlated to a newly developed analytical model, It was eventually determined that the CIRS instrument was in focus, had no appreciable wavefront shear and was operating near theoretical limits. The shear/defocus effect is however, of considerable interest, since it has not been described in previous literature on interferometers.
Martino, Anthony J.↗
Numerical simulation of a 325 Mbit/s QPPM optical communication system
Optical digital receivers are being considered for intersatellite laser communication links. A demonstration system is being designed to operate at 325 MBit/s, using quaternary pulse position modulation (QPPM). Laboratory experiments have been conducted using a 50 MBit/s prototype system. A numerical model has been developed to simulate a QPPM optical receiver. The 50 MBit/s system was simulated to verify the validity of the model. The model was then used to simulate the projected behavior of the 325 MBit/s system. The model predicts a bit error rate of 10.6 at 38 incident photons per bit for 820 nm light.
Martino, Anthony J.↗