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At least 73 records · Page 4
All sourcesNASA NTRSDOE OSTI
NASA NTRS1989

Development of an infrared imaging system for the surface tension driven convection experiment

An infrared imaging system is used to quantify the imposed surface temperature distribution along a liquid/gas free surface in support of the Surface Tension Driven Convection Experiment, a planned Space Transportation System flight experiment. For ground-based work a commercially available instrument was used to determine the feasibility of using this type of imaging system for this experiment. The ground-based work was used as a baseline for compiling specifications for a flight qualified imager to be designed, fabricated, tested and qualified for flight. The requirements and the specifications for the flight model are given along with the reasons for departures from the ground-based equipment. The flight qualification requirements discussed are a representative sample of the necessary procedures which must be followed to flight qualify diagnostic equipment for use aboard the STS. The potential problems and concerns associated with operating an imaging system on orbit are also discussed.

Pline, Alexander D.↗
NASA NTRS2019

Characterization and Application of Artificial Light Sources for Nighttime Aerosol Optical Depth Retrievals using the Visible Infrared Imager Radiometer Suite Day/Night Band

Using nighttime observations from Visible Infrared Imager Radiometer Suite (VIIRS) Day/Night band (DNB), the characteristics of artificial light sources are evaluated as functions of observation conditions, and incremental improvements are documented on nighttime aerosol retrievals using VIIRS DNB data on a regional scale. We find that the standard deviation of instantaneous radiance for a given artificial light source is strongly dependent upon the satellite viewing angle but is weakly dependent on lunar fraction and lunar angle. Retrieval of nighttime aerosol optical thickness (AOT) based on the novel use of these artificial light sources is demonstrated for three selected regions (United States, Middle East and India) during 2015. Reason-able agreement is found between nighttime AOTs from the VIIRS DNB and temporally adjacent daytime AOTs from the AErosol RObotic NETwork (AERONET) as well as from coincident nighttime AOT retrievals from the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP), indicating the potential of this method to begin filling critical gaps in diurnal AOT information at both regional and global scales. Issues related to cloud, snow and ice contamination during the winter season, as well as data loss due to the misclassification of thick aerosol plumes as clouds, must be addressed to make the algorithm operationally robust.

Jianglong Zhang↗
NASA NTRS1992

Infrared imaging of Mars for volatile distribution and seasonal variability between 2.4 and 5.1 microns

Recent advances in ground-based infrared imaging now allow for sub-arc second spectral imaging. Data collected at the NASA Infrared Telescope Facility using protocam, a 62 x 58 InSb array camera with a circular variable filter and a plate scale 0.2 arc-seconds/pixel, are discussed. These images are a first attempt at extended seasonal infrared coverage of Mars to look for seasonal variations. Currently, data collected in Jun. 1990 at Ls = 241 (southern spring) and in Jan. 1991 Ls = 360 (late southern summer) are being reduced and analyzed. The 3 micron bound water band is the strongest surface absorption feature on Mars in the infrared. Infrared spectroscopy can also be useful in the detection of ice and frost deposits, especially in the polar regions. While imaging and spectroscopy at visible wavelengths allows for the detection of condensates, infrared information is needed to distinguish between water and CO2 ice/frost deposits. In the Jun. images, the southern polar cap totally disappears in the 3.4 micron CO2 frost band and is bright in the 3.1 micron water ice band, indicating that water ice is not a detectable component of the southern polar cap at this season. Further investigations are currently under way to look for residual water ice after the disappearance of the seasonal south polar cap in the Jan. images. The Jun. images that were focused on had a sub-earth point located at 184 longitude, and 23.8 S latitude which put the center of the disk in the southern highland region between Elysium and Amazonis. Examination of the Jun. images show that there are four surface units identifiable: a CO2 frost deposit, a northern plains unit, an equatorial unit, and a southern highland unit. At this resolution there does not appear to be any latitudinal variations in the 3 micron band that is independent of the 2.4 micron albedo features. The northern planes unit and the southern highland unit have very similar 'color' in the three micron band as demonstrated by the rise out of the band, but different brightness levels. The equatorial unit has a distinct three micron color implying a compositional difference. The albedo features at 2.4 microns have decreased contrast at longer wavelengths, till they are unrecognizable at 4 microns.

Blaney, Diana L.↗
NASA NTRS2013

Requirements for a Moderate-Resolution Infrared Imaging Sounder (MIRIS)

The high cost of imaging and sounding from space warrants exploration of new methods for obtaining the required information, including changing the spectral band sets, employing new technologies and merging instruments. In some cases we must consider relaxation of the current capability. In others, we expect higher performance. In general our goal is to meet the VIIRS and CrIS requirements while providing the enhanced next generation capabilities: 1) Hyperspectral Imaging in the Vis/NIR bands, 2) High Spatial Resolution Sounding in the Infrared bands. The former will improve the accuracy of ocean color products, aerosols and water vapor, surface vegetation and geology. The latter will enable the high-impact achieved by the current suite of hyperspectral infrared sounders to be achieved by the next generation high resolution forecast models. We examine the spectral, spatial and radiometric requirements for a next generation system and technologies that can be applied from the available inventory within government and industry. A two-band grating spectrometer instrument called the Moderate-resolution Infrared Imaging Sounder (MIRIS) is conceived that, when used with the planned NASA PACE Ocean Color Instrument (OCI) will meet the vast majority of CrIS and VIIRS requirements in the all bands and provide the next generation capabilities desired. MIRIS resource requirements are modest and the Technology Readiness Level is high leading to the expectation that the cost and risk of MIRIS will be reasonable.

Atmospheric Infrared Sounder (AIRS)↗
NASA NTRS1999

Validation of Airborne Visible-Infrared Imaging Spectrometer Data at Ray Mine, AZ

We validate 1997 Airborne Visible-Infrared Imaging Spectrometer (AVIRIS) reflectance spectra covering 0.4 meu - 2.4 meu from a stable, flat mineralogically characterized man-made target at Ray Mine, AZ, the site for an EPA/NASA assessment of the utility of remote sensing for monitoring acid drainage from an active open pit mine.

AVIRIS visible-infrared spectrometer imaging↗
NASA NTRS2007

Infrared Imaging System for Studying Brain Function

A proposed special-purpose infrared imaging system would be a compact, portable, less-expensive alternative to functional magnetic resonance imaging (fMRI) systems heretofore used to study brain function. Whereas a typical fMRI system fills a large room, and must be magnetically isolated, this system would fit into a bicycle helmet. The system would include an assembly that would be mounted inside the padding in a modified bicycle helmet or other suitable headgear. The assembly would include newly designed infrared photodetectors and data-acquisition circuits on integrated-circuit chips on low-thermal-conductivity supports in evacuated housings (see figure) arranged in multiple rows and columns that would define image coordinates. Each housing would be spring-loaded against the wearer s head. The chips would be cooled by a small Stirling Engine mounted contiguous to, but thermally isolated from, the portions of the assembly in thermal contact with the wearer s head. Flexible wires or cables for transmitting data from the aforementioned chips would be routed to an integrated, multichannel transmitter and thence through the top of the assembly to a patch antenna on the outside of the helmet. The multiple streams of data from the infrared-detector chips would be sent to a remote site, where they would be processed, by software, into a three-dimensional display of evoked potentials that would represent firing neuronal bundles and thereby indicate locations of neuronal activity associated with mental or physical activity. The 3D images will be analogous to current fMRI images. The data would also be made available, in real-time, for comparison with data in local or internationally accessible relational databases that already exist in universities and research centers. Hence, this system could be used in research on, and for the diagnosis of response from the wearer s brain to physiological, psychological, and environmental changes in real time. The images would also be stored in a relational database for comparison with corresponding responses previously observed in other subjects.

Mintz, Frederick↗
NASA NTRS1980

InSb charge coupled infrared imaging device: The 20 element linear imager

The design and fabrication of the 8585 InSb charge coupled infrared imaging device (CCIRID) chip are reported. The InSb material characteristics are described along with mask and process modifications. Test results for the 2- and 20-element CCIRID's are discussed, including gate oxide characteristics, charge transfer efficiency, optical mode of operation, and development of the surface potential diagram.

Thom, R. D.↗
NASA NTRS1981

Advanced InSb monolithic Charge Coupled Infrared Imaging Devices (CCIRID)

The continued development of monolithic InSb charge coupled infrared imaging devices (CCIRIDs) is discussed. The processing sequence and structural design of 20-element linear arrays are discussed. Also, results obtained from radiometric testing of the 20-element arrays using a clamped sample-and-hold output circuit are reported. The design and layout of a next-generation CCIRID chip are discussed. The major devices on this chip are a 20 by 16 time-delay-and-integration (TDI) area array and a 100-element linear imaging array. The development of a process for incorporating an ion implanted S(+) planar channel stop into the CCIRID structure and the development of a thin film transparent photogate are also addressed. The transparent photogates will increase quantum efficiency to greater than 70% across the 2.5 to 5.4 micrometer spectral region in future front-side illuminated CCIRIDs.

Koch, T. L.↗
NASA NTRS1991

Near infrared imaging of the outer planets

In the last year we have continued our program of near infrared imaging of the outer planets of the solar system. Uranus is virtually invisible at 2.3 microns, showing that the methane is an effective absorber of the incident sunlight and that there is very little aerosol content in the upper atmosphere. On the other hand, Neptune shows a haze present over the entire Northern Hemisphere at 2.3 microns. This leads to the inference that there is an aerosol layer at a high altitude. We have recovered the Neptune satellite, 1989 N1, which was first discovered in Voyager images. The satellite is exceedingly faint in the near infrared, and was detectable only because the planet itself was comparatively faint at this wavelength. Observations of this satellite, coupled with the Voyager images, permit us to substantially refine the satellite's orbit, and hence carefully probe the gravitational field of Neptune.

Matthews, K.↗
NASA NTRS1976

Development of InSb charge-coupled infrared imaging devices: Linear imager

The following results were accomplished in the development of charge coupled infrared imaging devices: (1) a four-phase overlapping gate with 9 transfers (2-bits) and 1.0-mil gate lengths was successfully operated, (2) the measured transfer efficiency of 0.975 for this device is in excellent agreement with predictions for the reduced gate length device, (3) mask revisions of the channel stop metal on the 8582 mask have been carried out with the result being a large increase in the dc yield of the tested devices, (4) partial optical sensitivity to chopped blackbody radiation was observed for an 8582 9-bit imager, (5) analytical consideration of the modulation transfer function degradation caused by transfer inefficiency in the CCD registers was presented, and (6) for larger array lengths or for the insertion of isolated bits between sensors, improvements in InSb fabrication technology with corresponding decrease in the interface state density are required.

Phillips, J. D.↗
NASA NTRS1982

Far-infrared imaging antenna arrays

A far-infrared monolithic imaging antenna array with diffraction-limited resolution has been demonstrated. The optical system is similar to an oil-immersion microscope, except that the position of the object and the image are interchanged. The array is a series of evaporated silver bow-tie antennas of 75 nm thick, spaced at 310 microns, on a fused-quartz substrate; the bow angle of 60 deg gives an impedance of 150 ohm to match to bismuth microbolometers. The measured responsivity of the array elements is 1-2 V/W at the relatively low bias of 1 mA. Previous measurements have shown that the bolometers are 1/f noise limited up to 100 kHz and that they have a frequency response of 5 MHz. The antenna array should be adequate for far-infrared plasma interferometer measurements.

Neikirk, D. P.↗
NASA NTRS1992

Near-infrared images of the nuclear region of NGC 5128

High-resolution near-infrared images of NGC 5128 (Centaurus A) are presented, which probe the optically obscured nuclear region. The images show a central source at K (2.23 microns) and 3.26 microns. This central object is not prominent in the shorter wavelength images at J and H (1.23 and 1.65 micron, respectively), probably due to high extinction. The color images (H - K and J - H) provide evidence for a steep gradient in extinction across the array field. The images indicate three components: a red, variable, compact nucleus; the diffuse elliptical galaxy starlight; and a blue extension to the NE. The nucleus has decreased in flux density by a factor of 2.5 over less than about 5 yr at 3.26 microns. However, current spectral constraints on the nuclear source at near-infrared wavelengths cannot definitively determine the relative contributions from the known ratio synchrotron source (AGN) and from various possible dust-enshrouded thermal sources. The blue spot, approximately 7.6 +/- 0.1 arcsec NE of the nucleus appears to be a hole in the extinction, possibly enhanced by scattered light from the active galactic nucleus.

Turner, Paula C.↗
NASA NTRS1992

Deep infrared images of the Small Magellanic Cloud and comparison with the distribution of ultraviolet emission

Deep infrared images of the Small Magellanic Cloud have been produced and compared to an ultraviolet image at an angular resolution of 8 min. There is a strong correlation between the far infrared and the ultraviolet emission but the dispersion in this correlation is unrelated to infrared colors. Comparing with the results for the nearby spiral M33 at different radial distances, it is suggested that the population of dust grains in the Small Magellanic Cloud has very different properties.

Okumura, K.↗
NASA NTRS1988

In-flight flow visualization using infrared imaging

A flight test investigation was conducted to evaluate infrared (IR) flow imaging techniques for boundary-layer flow visualization. The flight tests used a single-engine turboprop aircraft with a fiberglass-skinned natural laminar flow glove mounted on the left wing and an infrared imaging system to obtain flow visualization data. Data were compared to results obtained from other more conventional boundary-layer flow visualization methods and found to agree well. Test flights were conducted to determine the effect of test surface color on IR flow visualization results. In addition, flights were made during both night and daylight hours to assess the effect of solar radiation on the results. The investigation included an effort to visualize a vortex passing over the wing glove, but the tests provided only limited results.

Brandon, J. M.↗
NASA NTRS2014

Validation of Land Surface Temperature Products Derived from the Visible Infrared Imaging Radiometer Suite (VIIRS) Using Ground-based and Heritage Satellite Measurements

Thermal infrared satellite observations of the Earth's surface are widely used to retrieve Land Surface Temperature (LST) and monitor LST changes around the world. Since January 2012, the Visible Infrared Imaging Radiometer Suite (VIIRS) onboard the Suomi National Polar-Orbiting Partnership (S-NPP) has provided daily observations of LST with a spatial resolution of 750 m at nadir. Comparison of the standard VIIRS LST product with the equivalent daily standard product from the Moderate Resolution Imaging Spectroradiometer (MODIS) collection-5 and with ground-based measurements over vegetated and inland water surfaces showed good agreement. Analysis indicated the accuracy and precision of the VIIRS product over these cover types was 0.2 K and 2.0 K respectively provided the analyses included appropriate compensation for any spatial heterogeneity in LST within the validation site. However, comparisons between in situ LST and the VIIRS and MODIS LST.

Land surface temperature↗
NASA NTRS1991

A near-infrared imaging survey of interacting galaxies - The disk-disk merger candidates subset

Near-infrared imaging obtained for systems believed to be advanced disk-disk mergers are presented and discussed. These systems were chosen from a sample of approximately 170 objects from the Arp Atlas of Peculiar Galaxies which have been imaged in the JHK bands as part of an investigation into the stellar component of interacting galaxies. Of the eight remnants which show optical signs of a disk-disk merger, the near-infrared surface brightness profiles are well-fitted by an r exp 1/4 law over all measured radii in four systems, and out to radii of about 3 kpc in three systems. These K band profiles indicate that most of the remnants in the sample either have finished or are in the process of relaxing into a mass distribution like that of normal elliptical galaxies.

Stanford, S. A.↗