Search NASA⌕ Search

SEARCH · Search NASA

Results for “array detector”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 505 records · Page 28
All sourcesNASA NTRSDOE OSTI
NASA NTRS1991

100-micron array polarimetry from the Kuiper Airborne Observatory - Instrumentation, techniques, and first results

The University of Chicago far-infrared array polarimeter, 'STOKES', is the first multiple-beam polarimeter for far-infrared astronomy. Observations are made from the NASA Kuiper Airborne Observatory. Two orthogonal components of linear polarization are detected simultaneously by corresponding pairs of bolometers in two 32-detector arrays. Novel observing and data-analysis techniques are used to overcome the inherent difficulties of array polarimetry. Results from the first observing flights with the new instrument are reported for the molecular clouds W3 and W51. The measurements show that the magnetic-field structure in both clouds is nonuniform on the scale of 0.5-1.5 pc. This is consistent with molecular line and Zeeman observations that indicate the presence of turbulent velocities and significant small-scale structure. Preliminary results from the second flight series have yielded approximately 40 new measurements in the Sgr A complex. These results indicate that modifications made since the first flights have significantly improved the performance of STOKES.

Platt, S. R.↗
NASA NTRS1982

Bolometer and photosensitive detector systems for IR

In order to achieve the full sensitivity required for future space astronomy applications, IR detector systems will have to be cooled to 0.1 K or less. The feasibility of such cryocooling has been demonstrated for the established laboratory technique of adiabatic demagnetization, and it has been shown that bolometers made from compensated silicon, with ion-implanted contacts, come close to calculated ultimate performance limits. Unlike bolometers, silicon and germanium photoconductors are highly wavelength-dependent. Useful wavelengths are presented for the most promising photodetectors based on these materials. It is noted that, as the relevant microelectronic technology advances, array detectors in the near-IR may be expected to approach the size and performance of large, intrinsic silicon CCD arrays now available for optical wavelengths.

Low, F. J.↗
NASA NTRS1986

Characterization of 2.5 microns HgCdTe detectors for low-background applications

A program of testing aimed at the evaluation of systems that have the potential to provide the level of performance required for use in space-based instruments was undertaken and their usefulness appraised for astronomy. The results of the first phase of the program to characterize selected pixels of a HgCdTe photovoltaic array detector were reported.

Depoy, D. L.↗
NASA NTRS1983

Evaluation of a 32 x 32 InSb CCD for use in astronomy

We have been fortunate to receive several infrared CCD array detectors on loan from Santa Barbara Research Center. The devices are evaluation samples, not commercially available at this time. Dr. Alan Hoffman of SBRC has made the arrangements for this loan and provided considerable technical support to this project. One aim of this project has been to evaluate the performance potential of this array technology, using astronomical objects. A quick summary of our findings is given. In short, we have found the imaging properties to be excellent under both low and high background conditions and the sensitivity to be quite good (each pixel is competitive with current InSb single-detector systems in use for astronomy). We anticipate improved low-background performance when we run these detectors at a lower and more stable temperature. The device characteristics are described, laboratory testing is summarized, and the first astronomical imaging is presented. Various circuits developed (clocks, clock drivers, DC supplies, clamp-amplifier, and a real time display system) are given.

Forrest, W. J.↗
DOE OSTI2026

Cryogenic light detectors with thermal signal amplification for 0 νββ search experiments

As a step towards the realization of cryogenic-detector experiments to search for neutrinoless double-beta decay (such as CROSS, BINGO, and CUPID), we investigated a batch of 10 Ge light detectors (LDs) assisted by Neganov-Trofimov-Luke (NTL) signal amplification. Each LD was assembled with a large cubic light-emitting crystal (45 mm side) using the recently developed CROSS mechanical structure. The detector array was operated at milli-Kelvin temperatures in a pulse-tube cryostat at the Canfranc underground laboratory in Spain. We achieved good performance with scintillating bolometers from CROSS, made of Li 2 100 MoO 4 crystals and used as reference detectors of the setup, and with all LDs tested (except for a single device that encountered an electronics issue). No leakage current was observed for 8 LDs with an electrode bias up to 100 V. Operating the LDs at an 80 V electrode bias applied in parallel, we obtained a gain of around 9 in the signal-to-noise ratio of these devices, allowing us to achieve a baseline noise RMS of O(10 eV). Thanks to the strong current polarization of the temperature sensors, the time response of the devices was reduced to around half a millisecond in rise time. The achieved performance of the LDs was extrapolated via simulations of pile-up rejection capability for several configurations of the CUPID detector structure. Despite the sub-optimal noise conditions of the LDs (particularly at high frequencies), we demonstrated that the NTL technology provides a viable solution for background reduction in CUPID.

47 OTHER INSTRUMENTATION↗
NASA NTRS2010

Kepler Instrument Performance: An In-Flight Update

The Kepler Mission is designed to detect the 80 parts per million (ppm) signal from an Earth-Sun equivalent transit. Such precision requires superb instrument stability on time scales up to 2 days and systematic error removal to better than 20 ppm. The sole scientic instrument is the Photometer, a 0.95 m aperture Schmidt telescope that feeds the 94.6 million pixel CCD detector array, which contains both Science and Fine Guidance Sensor (FGS) CCDs. Since Kepler's launch in March 2009, we have been using the commissioning and science operations data to characterize the instrument and monitor its performance. We find that the in-flight detector properties of the focal plane, including bias levels, read noise, gain, linearity, saturation, FGS to Science crosstalk,and video crosstalk between Science CCDs, are essentially unchanged from their pre-launch values. Kepler'sunprecedented sensitivity and stability in space have allowed us to measure both short- and long- term effects from cosmic rays, see interactions of previously known image artifacts with starlight, and uncover several unexpected systematics that affect photometric precision. Based on these results, we expect to attain Kepler's planned photometric precision over 90% of the field of view.

CCD↗
NASA NTRS2017

A Path to High Efficiency Optical Coupling for HIRMES

The high-resolution mid-infrared spectrometer (HIRMES) under development for SOFIA (Stratospheric Observatory for Infrared Astronomy) is an instrument operating in the 25-122 μm spectral range with a spectral resolution R= Δ ʎ /ʎ ~100,000 and has two absorber-coupled transition edge sensor (TES) bolometric detector focal planes. We have developed novel NbTiN low stress absorber coatings which have the required optical impedance across the HIRMES operating band. The low intrinsic stress of these coatings allow for a peak-to-valley corrugation amplitude < 5 μm of the 450 nm thick, 1.4 mm x 1.7 mm detector pixels. Furthermore, these coatings have a superconducting transition temperature ~ 10 K, which allows them to simultaneously serve as an absorber in the desired signal band and a rejection filter at long wavelengths. This attribute makes them especially attractive for ultrasensitive absorber-coupled bolometric detector applications, because it helps in controlling the optical loading from out-of band radiation. We also discuss a novel method for integrating a wedged reflective absorber-termination to the detector array.

bolometers↗
NASA NTRS2002

SUBMM wave superconduction hot-electron direct detectors

Recently, we have presented a concept for a hot-electron direct detector (HEDD) capable of counting single millimeter-wave photons. Such a detector meets the needs of future space far-infrared applications and can be used for background-limited detector arrays on missions like SPIRIT, 10-m filled aperture telescope, SAFIR, and SPECS.

hot-electron electron-phonon direct detectors subm↗
NASA NTRS1991

Infrared technology XVII; Proceedings of the Meeting, San Diego, CA, July 22-26, 1991

Recent advances in IR technologies and their application to all types of IR systems are reported focusing on the JPL Space Infrared Telescope Facility (SIRTF), JPL instruments and systems for observation of earth and the atmosphere, staring arrays and thermal imaging, ten-year updates of IR techniques, infrared in the USSR, simulation and testing, focal-plane and optical technologies, and military and scientific applications. Particular attention is given to SIRTF stray light analysis, SIRTF focal-plane technologies, long-wave IR detectors based on III-V materials, IR lidars for atmospheric remote sensing, a firefly system concept, a high-fill-factor monolithic IR image sensor, atmospheric laser-transmission tables simply generated, ORION semiconductor optical detectors, postprocessing of thermograms in IR nondestructive testing, evaluation of the IR signature of dynamic air targets, the current status of InGaAs detector arrays for 1-3 microns, a dual-band optical system for IR multicolor signal processing, and blackbody radiators for field calibration.

Andresen, Bjorn F.↗
NASA NTRS1987

Mercury cadmium telluride short- and medium-wavelength infrared staring focal plane arrays

Short and medium IR wavelength 64 x 64 hybrid focal plane arrays (FPAs) have been developed using sapphire-grown HgCdTe. The short wavelength arrays were developed for a prototype airborne imaging spectrometer, while those of medium wavelength are suitable for tactical missile seekers and strategic surveillance systems. Attention is presently given to results obtained for these FPAs' current-voltage characteristics, as well as for their characterization at different temperatures. The detector arrays were also mated to a multiplexer and characterized under different operating conditions. The unit cell size used is 52 x 52 microns.

Vural, Kadri↗
NASA NTRS1977

A system definition study for the Advanced Meteorological Temperature Sounder (AMTS)

The functional requirements of Exhibit A (11) were used as the baseline for the conceptual design of a fixed grating out of plane multidetector spectrometer for the Space Shuttle application. Because the grating instrument would be large and the 28 element detector array would be difficult to cool radiatively from a free flying spacecraft and because increasing the spectral resolution of the grating instrument would be difficult in an instrument of reasonable size, a parallel study of a Nichelson interferometer spectrometer was undertaken. This type of instrument offers compact size, fewer detectors to cool, and the possibility of increased spectral resolution. The design and performance parameters of both the grating and interferometer approaches are described. The tradeoffs involved in comparing the two systems for sounding applications are discussed.

Source record↗
NASA NTRS1986

Time and space integrating acousto-optic folded spectrum processing for SETI

Time and space integrating folded spectrum techniques utilizing acousto-optic devices (AOD) as 1-D input transducers are investigated for a potential application as wideband, high resolution, large processing gain spectrum analyzers in the search for extra-terrestrial intelligence (SETI) program. The space integrating Fourier transform performed by a lens channels the coarse spectral components diffracted from an AOD onto an array of time integrating narrowband fine resolution spectrum analyzers. The pulsing action of a laser diode samples the interferometrically detected output, aliasing the fine resolution components to baseband, as required for the subsequent charge coupled devices (CCD) processing. The raster scan mechanism incorporated into the readout of the CCD detector array is used to unfold the 2-D transform, reproducing the desired high resolution Fourier transform of the input signal.

Wagner, K.↗
NASA NTRS1989

Common source cascode amplifiers for integrating IR-FPA applications

Space based astronomical infrared measurements present stringent performance requirements on the infrared detector arrays and their associated readout circuitry. To evaluate the usefulness of commercial CMOS technology for astronomical readout applications a theoretical and experimental evaluation was performed on source follower and common-source cascode integrating amplifiers. Theoretical analysis indicates that for conditions where the input amplifier integration capacitance is limited by the detectors capacitance the input referred rms noise electrons of each amplifier should be equivalent. For conditions of input gate limited capacitance the source follower should provide lower noise. Measurements of test circuits containing both source follower and common source cascode circuits showed substantially lower input referred noise for the common-source cascode input circuits. Noise measurements yielded 4.8 input referred rms noise electrons for an 8.5 minute integration. The signal and noise gain of the common-source cascode amplifier appears to offer substantial advantages in acheiving predicted noise levels.

Woolaway, James T.↗
NASA NTRS2006

Dynamic Pupil Masking for Phasing Telescope Mirror Segments

A method that would notably include dynamic pupil masking has been proposed as an enhanced version of a prior method of phasing the segments of a primary telescope mirror. The method would apply, more specifically, to a primary telescope mirror that comprises multiple segments mounted on actuators that can be used to tilt the segments and translate them along the nominal optical axis to affect wavefront control in increments as fine as a fraction of a wavelength of light. An apparatus (see figure) for implementing the proposed method would be denoted a dispersed-fringe-sensor phasing camera system (DPCS). The prior method involves the use of a dispersed-fringe sensor (DFS). The prior method was reported as part of a more comprehensive method in Coarse Alignment of a Segmented Telescope Mirror (NPO-20770), NASA Tech Briefs, Vol. 25, No. 4 (April 2001), page 15a. The pertinent parts of the prior method are the following: The telescope would be aimed at a bright distant point source of light (e.g., a star) and form a broadband image on an imaging detector array placed at the telescope focal plane. The construction and use of a dispersed-fringe sensor would begin with insertion of a grism (a right-angle prism with a transmission grating on the hypotenuse face) into the optical path. With other segments tilted away from the investigating region of the detector, a dispersed-fringe image would be formed by use of a designated reference segment and a selected mirror segment. The modulation period and orientation of the fringe would be analyzed to determine the magnitude and sign of the piston error (displacement along the nominal optical axis) between the two segments. The error would be used to perform a coarse-phase piston adjustment of the affected mirror segment. This determination and removing of piston error is what is meant by phasing as used above. The procedure as described thus far would be repeated until all segments had been phased.

Shi, Fang↗
NASA NTRS1990

Issues and directions in IR detector readout electronics

An introduction to the major issues encountered in the readout of imaging detector arrays in the infrared are presented. These include circuit issues such as multiplexing, buffering, and noise, as well as materials issues. Future directions in infrared readout electronics will also be discussed. These include on-chip signal processing and advanced hybridization schemes. Finally, recent work at Columbia on 2DEG-charge coupled devices for IR detector multiplexing are described.

Fossum, Eric R.↗
DOE OSTI2026

The sweeper spectrometer for neutron invariant-mass spectroscopy at FRIB

Neutron invariant-mass spectroscopy (NIMS) is a key technique for studying unbound and weakly bound nuclei at the limits of stability. At the Facility for Rare Isotope Beams (FRIB), such measurements are performed using the Sweeper spectrometer, a large-gap, high-rigidity dipole system coupled to the MoNA-LISA neutron detector arrays. To meet the demands imposed by higher beam energies (>130 MeV/u) and the broad cocktail-beam selection available at FRIB, the spectrometer has recently been upgraded to improve particle-identification and detection performance. Upstream of the reaction target, a plastic scintillator with Silicon photomultiplier (SiPM) readout provides the global trigger and time reference, two parallel plate avalanche counters (PPACs) track the trajectories of incoming beam particles, and a silicon PIN detector measures the energy loss, ΔE, for charge (Z) identification. After the Sweeper magnet, the trajectories of the reaction products are tracked by two micro-pattern drift chambers (MPDCs), their charge (Z) is identified by a Frisch-grid ionization chamber (FG-IC), and their mass-to-charge ratio (A/Q) is deduced by time-of-flight measurement using a fast plastic scintillator read out by an array of photomultiplier tubes (PMTs). The detection system also incorporates the Modular Neutron Array (MoNA) for neutron detection and the CAESium-iodide scintillator ARray (CAESAR) for high-efficiency γ-ray measurements to enable full kinematic reconstruction. Performance was evaluated using a cocktail beam around 37 Al accelerated at E ≈ 130 MeV/u during the first FRIB campaign, demonstrating the readiness of the upgraded system for future studies of nuclei at and beyond the neutron drip line.

Particle identification methods↗
NASA NTRS1989

A 58 x 62 pixel Si:Ga array camera for 5 - 14 micron astronomical imaging

A new infrared array camera system has been successfully applied to high background 5 - 14 micron astronomical imaging photometry observations, using a hybrid 58 x 62 pixel Si:Ga array detector. The off-axis reflective optical design incorporating a parabolic camera mirror, circular variable filter wheel, and cold aperture stop produces diffraction-limited images with negligible spatial distortion and minimum thermal background loading. The camera electronic system architecture is divided into three subsystems: (1) high-speed analog front end, including 2-channel preamp module, array address timing generator, bias power suppies, (2) two 16 bit, 3 microsec per conversion A/D converters interfaced to an arithmetic array processor, and (3) an LSI 11/73 camera control and data analysis computer. The background-limited observational noise performance of the camera at the NASA/IRTF telescope is NEFD (1 sigma) = 0.05 Jy/pixel min exp 1/2.

Gezari, D. Y.↗
NASA NTRS1991

HYMOSS signal processing for pushbroom spectral imaging

The objective of the Pushbroom Spectral Imaging Program was to develop on-focal plane electronics which compensate for detector array non-uniformities. The approach taken was to implement a simple two point calibration algorithm on focal plane which allows for offset and linear gain correction. The key on focal plane features which made this technique feasible was the use of a high quality transimpedance amplifier (TIA) and an analog-to-digital converter for each detector channel. Gain compensation is accomplished by varying the feedback capacitance of the integrate and dump TIA. Offset correction is performed by storing offsets in a special on focal plane offset register and digitally subtracting the offsets from the readout data during the multiplexing operation. A custom integrated circuit was designed, fabricated, and tested on this program which proved that nonuniformity compensated, analog-to-digital converting circuits may be used to read out infrared detectors. Irvine Sensors Corporation (ISC) successfully demonstrated the following innovative on-focal-plane functions that allow for correction of detector non-uniformities. Most of the circuit functions demonstrated on this program are finding their way onto future IC's because of their impact on reduced downstream processing, increased focal plane performance, simplified focal plane control, reduced number of dewar connections, as well as the noise immunity of a digital interface dewar. The potential commercial applications for this integrated circuit are primarily in imaging systems. These imaging systems may be used for: security monitoring systems, manufacturing process monitoring, robotics, and for spectral imaging when used in analytical instrumentation.

Ludwig, David E.↗