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At least 919 records · Page 51
All sourcesNASA NTRSDOE OSTI
NASA NTRS1984

Results from the transition region camera

Three series of high resolution ultra-violet pictures of the sun have been obtained during the three flights of rocket experiment T.R.C. Transition Region Camera) which took place on 3 July 1979, 23 September 1980 and 13 July 1982. These pictures reveal many structures in Ly alpha and ultraviolet continua at 160 nm and 220 nm. The scientific objectives, instrumentation, flight conditions and campaigns of simultaneous observations are described. The contribution of T.R.C. to solar physics is discussed in the framework of chromospheric multicomponent models, magnetic flux tubes, local heating and periodic structures in the chromosphere.

Foing, B. H.↗
NASA NTRS1985

Wind dynamic range video camera

A television camera apparatus is disclosed in which bright objects are attenuated to fit within the dynamic range of the system, while dim objects are not. The apparatus receives linearly polarized light from an object scene, the light being passed by a beam splitter and focused on the output plane of a liquid crystal light valve. The light valve is oriented such that, with no excitation from the cathode ray tube, all light is rotated 90 deg and focused on the input plane of the video sensor. The light is then converted to an electrical signal, which is amplified and used to excite the CRT. The resulting image is collected and focused by a lens onto the light valve which rotates the polarization vector of the light to an extent proportional to the light intensity from the CRT. The overall effect is to selectively attenuate the image pattern focused on the sensor.

Craig, G. D.↗
NASA NTRS1986

Hall station and camera system operation and maintenance manual

The major components of the Hall station and camera system are described. The Hall film record of an event provides the time of flight of the projectile between the slits. A time mark generator is used to supply extremely short pulses of light at a known frequency. These pulses of light are used to produce timing marks on the edge of the film. Comparison of these marks with the spacing of the projectile images provides the information necessary to determine the time of flight of the projectile. Since the slits are installed with a known separation distance, calculation of the velocity of any object passing both slits is a simple matter.

Piekutowski, A. J.↗
NASA NTRS1986

First Halley multicolour camera imaging results from Giotto

The Giotto spacecraft's Halley Multicolor Camera imaging results have furnished flyby images that are centered on the brightest part of the inner coma; these show the silouette of a large, solid and irregularly shaped cometary nucleus and jetlike dust activity. The preliminary assessment of these data has yielded information on the dimensions and shape of the nucleus and dust emission activity. It is noted that only minor parts of the surface are active, with most of the surface being covered by a nonvolatile material. Dust jets dominate the inner coma, and are restricted to a subsolar hemisphere.

Keller, H. U.↗
NASA NTRS1986

Research relative to high resolution camera on the advanced X-ray astrophysics facility

The HRC (High Resolution Camera) is a photon counting instrument to be flown on the Advanced X-Ray Astrophysics Facility (AXAF). It is a large field of view, high angular resolution, detector for the x-ray telescope. The HRC consists of a CsI coated microchannel plate (MCP) acting as a soft x-ray photocathode, followed by a second MCP for high electronic gain. The MCPs are readout by a crossed grid of resistively coupled wires to provide high spatial resolution along with timing and pulse height data. The instrument will be used in two modes, as a direct imaging detector with a limiting sensitivity of 10 to the -15 ergs sq cm sec in a 10 to the 5th second exposure, and as a readout for an objective transmission grating providing spectral resolution of several hundreds to thousands.

Source record↗
NASA NTRS1986

Space infrared telescope facility wide field and diffraction limited array camera (IRAC)

IRAC focal plane detector technology was developed and studies of alternate focal plane configurations were supported. While any of the alternate focal planes under consideration would have a major impact on the Infrared Array Camera, it was possible to proceed with detector development and optical analysis research based on the proposed design since, to a large degree, the studies undertaken are generic to any SIRTF imaging instrument. Development of the proposed instrument was also important in a situation in which none of the alternate configurations has received the approval of the Science Working Group.

Fazio, G. G.↗
NASA NTRS1986

Development of InSb and Si:Ga arrays for ISO camera

The Infrared Space Observatory (ISO) satellite will contain a 60 cm telescope. A 4 faces pyramid mirror feeds each experiment with a 3 arc minute part of the telescope field of view. The camera system is described. The arrays for the 3 to 5 and 5 to 17 micron channel are also discussed.

Sibille, F.↗
NASA NTRS1986

Dust-gas interaction deduced from Halley multicolor camera observations

The dust and gas productions of comet Halley were measured by the dust counter and the mass spectrometers on the Giotto spacecraft. These instruments give only little information about the spatial asymmetry of the activity. The asymmetry in the dust production is clearly evident from the dust jets seen in the Halley Multicolor Camera images. Since the dust is entrained by the gas, gas production must be similarly asymmetric. The intensity profiles along and across several dust jets are related to their source regions on the nucleus. Properties of the dust jets are investigated. A few compact, but highly active source regions on the nucleus produce most of the visible dust and can account for most of the gas produced by the comet.

Huebner, W. F.↗
NASA NTRS1986

The Advanced X-ray Astrophysics Facility high resolution camera

The HRC (High Resolution Camera) is a photon counting instrument to be flown on the Advanced X-Ray Astrophysics Facility (AXAF). It is a large field of view, high angular resolution, detector for the X-ray telescope. The HRC consists of a CsI coated microchannel plate (MCP) acting as a soft X-ray photocathode, followed by a second MCP for high electronic gain. The MCPs are readout by a crossed grid of resistively coupled wires to provide high spatial resolution along with timing and pulse height data. The instrument will be used in two modes, as a direct imaging detector with a limiting sensitivity of 10 to the -15th ergs/sq cm sec in a 10 to the 5th second exposure, and as a readout for an objective transmission grating providing spectral resolution of several hundreds to thousands.

Murray, Stephen S.↗
NASA NTRS1987

The Palomar Observatory CCD camera

Standard designs for Dewars and electronics which have been developed for the Palomar Observatory CCD camera are described in detail. The Dewars described have holding times of about 17 to 24 hours. In-operation readout-noise levels of about 8 electrons are achieved for TI 800 x 800 CCDs; tests of these CCDs reveal that, over their range of operation, the amplifiers and A/D converters are linear to better than 0.2 percent.

Gunn, J. E.↗
NASA NTRS1986

Color rendering of color camera data

Conditions under which a computational procedure can be applied to arbitrary camera sensors to permit estimation of the human photoreceptor response are considered. The adopted procedures recover the effective surface reflectance at the time of measurement, and the reflectance estimates depend not only on the surface, but upon the viewing geometry. The present method for color rendering assumes that the observer's state of adaptation at the time of viewing the original and the rendered images is the same. The analysis aids in specifying which classes of surfaces are required to be accurately rendered, and for which surfaces some error can be tolerated.

Wandell, Brian A.↗
NASA NTRS1987

Land cover/use classification of Cairns, Queensland, Australia: A remote sensing study involving the conjunctive use of the airborne imaging spectrometer, the large format camera and the thematic mapper simulator

In an attempt to improve the land cover/use classification accuracy obtainable from remotely sensed multispectral imagery, Airborne Imaging Spectrometer-1 (AIS-1) images were analyzed in conjunction with Thematic Mapper Simulator (NS001) Large Format Camera color infrared photography and black and white aerial photography. Specific portions of the combined data set were registered and used for classification. Following this procedure, the resulting derived data was tested using an overall accuracy assessment method. Precise photogrammetric 2D-3D-2D geometric modeling techniques is not the basis for this study. Instead, the discussion exposes resultant spectral findings from the image-to-image registrations. Problems associated with the AIS-1 TMS integration are considered, and useful applications of the imagery combination are presented. More advanced methodologies for imagery integration are needed if multisystem data sets are to be utilized fully. Nevertheless, research, described herein, provides a formulation for future Earth Observation Station related multisensor studies.

Heric, Matthew↗
NASA NTRS1987

The AXAF high resolution camera (HRC) and its use for observations of distant clusters of galaxies

The High Resolution Camera being developed for AXAF is briefly described, comparing it with its predecessor, the Einstein HRI, and providing preliminary performance data. The HRC is a 10 cm x 10 cm detector with CsI coated microchannel plates providing a large field of view device with high X-ray quantum efficiency. The overall sensitivity of the HRC on AXAF is about 50 times that of the Einstein HRI. An example of the power of this instrument is discussed in the context of studies of distant clusters of galaxies. The HRC can detect individual galaxies in a cluster of redshift 1, if they are similar to the early-type galaxies in nearby clusters that have been observed by the Einstein instruments. The HRC will be used to measure the luminosity function for clusters of galaxies as a function of their distance up to a redshift of 1. This will allow observation of evolutionary effects in clusters as a whole, while the detection of individual galaxies will permit studies of galaxy evolution in a cluster environment.

Murray, S. S.↗
NASA NTRS1987

Solutions to the linear camera calibration problem

The general linear camera calibration problem is formulated and several classification schemes for various subcases of this problem are developed. For each subcase, simple solutions are found that satisfy all necessary constraints. The results improve those already in the literature with respect to simplicity, efficiency, and coverage. However, the classification scheme is not exhaustive.

Grosky, William I.↗
NASA NTRS1987

Preliminary investigation of Large Format Camera photography utility in soil mapping and related agricultural applications

The use of Space Shuttle Large Format Camera (LFC) color, IR/color, and B&W images in large-scale soil mapping is discussed and illustrated with sample photographs from STS 41-6 (October 1984). Consideration is given to the characteristics of the film types used; the photographic scales available; geometric and stereoscopic factors; and image interpretation and classification for soil-type mapping (detecting both sharp and gradual boundaries), soil parent material topographic and hydrologic assessment, natural-resources inventory, crop-type identification, and stress analysis. It is suggested that LFC photography can play an important role, filling the gap between aerial and satellite remote sensing.

Pelletier, R. E.↗
NASA NTRS1987

Maximum likelihood estimation of parameterized 3-D surfaces using a moving camera

A new approach is introduced to estimating object surfaces in three-dimensional space from a sequence of images. A surface of interest here is modeled as a 3-D function known up to the values of a few parameters. The approach will work with any parameterization. However, in work to date researchers have modeled objects as patches of spheres, cylinders, and planes - primitive objects. These primitive surfaces are special cases of 3-D quadric surfaces. Primitive surface estimation is treated as the general problem of maximum likelihood parameter estimation based on two or more functionally related data sets. In the present case, these data sets constitute a sequence of images taken at different locations and orientations. A simple geometric explanation is given for the estimation algorithm. Though various techniques can be used to implement this nonlinear estimation, researches discuss the use of gradient descent. Experiments are run and discussed for the case of a sphere of unknown location. These experiments graphically illustrate the various advantages of using as many images as possible in the estimation and of distributing camera positions from first to last over as large a baseline as possible. Researchers introduce the use of asymptotic Bayesian approximations in order to summarize the useful information in a sequence of images, thereby drastically reducing both the storage and amount of processing required.

Hung, Y.↗
NASA NTRS1989

Thermal design of the Wide Field/Planetary Camera

The Wide Field/Planetary Camera is an imaging system developed by the Jet Propulsion Laboratory for the NASA Hubble Space Telescope currently scheduled to be launched in December 1989 aboard the space shuttle. The temperature control design of the instrument utilizes multilayered insulation, electric resistance heaters, aluminum/ammonia heat pipes, thermoelectric coolers, temperature control coatings, and space radiators. A feedback control system maintains stable sensor temperatures. Thermal capacitance maintains stable optics and electronics temperatures during transient conditions. Schedule slips and launch delays have allowed extensive thermal testing of the instrument. Six instrument thermal vacuum tests and a spacecraft thermal vacuum test were performed. Several modifications have been made to the instrument to correct icing and contamination problems that have been discovered during thermal vacuum testing. This paper describes the thermal design, last instrument thermal vacuum test, results, and thermal model correlation.

Garcia, R. D.↗