Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “high - contrast imaging”

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 955 records · Page 53
All sourcesNASA NTRSDOE OSTI
NASA NTRS1986

The development and test of multi-anode microchannel array detector systems. Part 2: Soft X-ray detectors

Multi-Anode Microchannel Array (MAMA) detector systems with formats of 256 x 1024 pixels and active areas of 6 x 26 square mm are now under evaluation at visible, ultraviolet and soft x-ray wavelengths. Very-large-format versions of the MAMA detectors with formats of 2048 x 2048 pixels and active areas of 52 x 52 square mm are under development for use in the NASA Goddard Space Flight Center's Space Telescope Imaging Spectrograph (STIS). Open-structure versions of these detectors with CsI photocathodes can provide a high-resolution imaging capability at extreme ultraviolet (EUV) and soft x-ray wavelengths and can deliver a maximum count rate from each array in excess of 1 million counts s-1. In addition, these detector systems have the unique capability to determine the arrival time of a detected photon to an accuracy of 100 ns or better. The construction, mode-of-operation and performance characteristics of the MAMA detectors are described and the program for the development of the very-large-format detectors is outlined.

Timothy, J. G.↗
NASA NTRS1996

Magnetospheric Atmospheric X-ray Imaging Experiment (MAXIE)

This report summarizes the activities sponsored by the Office of Naval Research for the Magnetospheric Atmospheric X-ray Imaging Experiment (MAXIE). The MAXIE instrument was developed as a joint activity of Lockheed, The Aerospace Corporation, and the University of Bergen, Norway. Lockheed was responsible for the overall management of the program, interfacing with the appropriate government agencies, the overall electrical and mechanical design, flight software, environmental testing, spacecraft integration activities, on orbit checkout, and data processing activities. The Magnetospheric Atmospheric X-ray Imaging Experiment (MAXIE), the ONR 401 experiment, is the first in a new class of satellite-borne remote sensing instruments. The primary innovation is the ability to obtain rapid, sequential, images with high sensitivity of the earth's X ray aurora from a low altitude polar orbiting satellite. These images can be used to identify dynamic temporal variations in the three-dimensional (energy and position) distribution of electron precipitation into the atmosphere. MAXIE was launched on the TIROS NOAA-13 satellite on 9 August 1993. The experiment performed well during its turn-on sequence; however, the spacecraft bus failed on 21 August 1993. New spacebased technologies successfully used in MAXIE were mixed-mode ASIC microcircuits, a zero torque scanning system with associated viscoelastic damping, a paraffin stow release mechanism, a parallel integrating PHA processor, a low noise Si(Li) sensor telescope, and an advanced thermal cooling system. MAXIE's on orbit operation, control of penetrating particle backgrounds, and scientific data indicated good overall performance.

Imhof, W. L.↗
NASA NTRS2021

First Observations from the SPICE EUV Spectrometer on Solar Orbiter

Aims. We present first science observations taken during the commissioning activities of the Spectral Imaging of the Coronal Environment (SPICE) instrument on the ESA/NASA Solar Orbiter mission. SPICE is a high-resolution imaging spectrometer operating at extreme ultraviolet (EUV) wavelengths. In this paper we illustrate the possible types of observations to give prospective users a better understanding of the science capabilities of SPICE. Methods. We have reviewed the data obtained by SPICE between April and June 2020 and selected representative results obtained with different slits and a range of exposure times between 5 s and 180 s. Standard instrumental corrections have been applied to the raw data. Results. The paper discusses the first observations of the Sun on different targets and presents an example of the full spectra from the quiet Sun, identifying over 40 spectral lines from neutral hydrogen and ions of carbon, oxygen, nitrogen, neon, sulphur, magnesium, and iron. These lines cover the temperature range between 20,000 K and 1 million K (10MK in flares), providing slices of the Sun’s atmosphere in narrow temperature intervals. We provide a list of count rates for the 23 brightest spectral lines. We show examples of raster images of the quiet Sun in several strong transition region lines, where we have found unusually bright, compact structures in the quiet Sun network, with extreme intensities up to 25 times greater than the average intensity across the image. The lifetimes of these structures can exceed 2.5 hours. We identify them as a transition region signature of coronal bright points and compare their areas and intensity enhancements. We also show the first above-limb measurements with SPICE above the polar limb in C III,O VI, and Ne VIII lines, and far off limb measurements in the equatorial plane in Mg IX, Ne VIII, and O VI lines. We discuss the potential to use abundance diagnostics methods to study the variability of the elemental composition that can be compared with in situ measurements to help confirm the magnetic connection between the spacecraft location and the Sun’s surface, and locate the sources of the solar wind. Conclusions. The SPICE instrument successfully performs measurements of EUV spectra and raster images that will make vital contributions to the scientific success of the Solar Orbiter mission

Sun: UV radiation↗
NASA NTRS1990

Processing and analysis of radiometer measurements for airborne reconnaissance

This paper describes selected results of airborne, radiometric imaging measurements at 90 GHz and 140 GHz relevant for the application in reconnaissance. Using a temperature resolution below 0.5 K and an angular resolution of about 1-degree high-quality images show the capability of discriminating between many brightness temperature classes within our natural environment and man-made objects. Measurement examples are given for cloud and fog penetration at 90 GHz, for the detection of vehicles on roads, and for the detection and classification of airports and airplanes. The application of different contour enhancement methods (Marr-Hildreth and Canny) shows the possibility of extracting lines and shapes precisely in order to improve automatic target recognition. The registration of the passive images with corresponding X-band synthetic aperture images from the same area is carried out and the high degree of correlation is discussed.

Suess, Helmut↗
NASA NTRS2018

The LUVOIR Surveyor: Decadal Mission Concept Update

The Large Ultraviolet/Optical/Infrared (LUVOIR) Science and Technology Definition Team (STDT) identified a broad range of science objectives for LUVOIR that include the direct imaging and spectral characterization of habitable exoplanets and an array of general astrophysics and Solar System observations. To meet these objectives, the LUVOIR Study Office completed the first design iteration of a 15-m segmented-aperture observatory that includes four serviceable instruments: the Extreme Coronagraph for Living Planetary Systems (ECLIPS); the LUVOIR UV Multi-object Spectrograph (LUMOS); the High Definition Imager (HDI); and Pollux, a high-resolution UV spectro-polarimeter being contributed by Centre National d'Etudes Spatiales (CNES). The study team is now executing a second design iteration to further improve upon the 15-m concept, while simultaneously studying a 9-m concept. In these proceedings, we provide an update on these architectures.

LUVOIR↗
NASA NTRS2009

A Powerful New Imager for HST: Performance and Early Science Results from Wide Field Camera 3

Wide Field Camera 3 (WFC3) was installed into the Hubble Space Telescope during the highly successful Servicing Mission 4 in May, 2009. WFC3 offers sensitive, high resolution imaging over a broad wavelength range from the near UV through the visible to the near IR (200nm - 1700nm). Its capabilities in the near UV and near IR ends of that range represent particularly large advances vs. those of previous HST instruments. In this talk, I will review the purpose and design of the instrument, describe its performance in flight, and highlight some of the initial scientific results from the instrument, including its use in deep infrared surveys in search of galaxies at very high redshift, in investigations of the global processes of star formation in nearby galaxies, and in the study of the recent impact on Jupiter.

Kimble, Randy↗
DOE OSTI2021

Vector elastic deconvolution migration with dual wavefield decomposition

Here, we report elastic-wave imaging using multicomponent data can provide more useful subsurface information than acoustic-wave imaging, but it is usually algorithmically challenging. We have developed a vector elastic deconvolution migration method for high-resolution imaging of subsurface structures in isotropic and anisotropic elastic media. Our new method uses a vector deconvolution imaging condition based on dual wavefield decomposition, including an explicit directional wavefield separation using the Hilbert transform and a P/S vector wavefield decomposition using the low-rank decomposition method. Using three elastic models, we numerically determine that our new method produces notably higher resolution and more amplitude-balanced elastic images compared with a crosscorrelation-based vector elastic reverse time migration method.

58 GEOSCIENCES↗
NASA NTRS1980

Superposition of supernovae remnant imagery

The superposition of the X-ray, optical, and radio imagery of supernova remnants in the Cygnus Loop region is described. The radio data of the region was obtained using the Westerbork interferometer, and the optical image was recorded by the NASA Wide Field Camera. The X-ray imagery was obtained using the High Resolution Imager. The mechanisms by which the supernova ejecta and the swept-up material shock the interstellar medium are studied by the resampling of the imagery onto a common celestial grid. The initial results indicate a radio arc in the northeastern portion of the region that is along the faintest outermost filaments, and a separate radio arc along the brightest filaments.

Henden, A. A.↗
NASA NTRS1985

Possible optical counterparts to the X-ray point source in the supernova remnant CTB 80

A three color CCD image of the central region of the supernova remnant CTB 80 is presented, along with astrometry and photometry of many stars in the field. The color image does not show evidence of heavy or variable dust absorption in the surrounding region. Using an Einstein High Resolution Imager position for the central X-ray point source, two possible optical counterparts have been identified at magnitudes V = 19.9 and V = 20.9. Comparison of the intrinsic colors and magnitudes of these candidates are made to the optical properties of Crab and Vela pulsars, and they are found to be viable candidates.

Blair, W. P.↗
NASA NTRS1995

ROSAT observations of NGC 2146: Evidence for a starburst-driven superwind

We have imaged the edge-on starburst galaxy NGC 2146 with the Position Sensitive Proportional Counter (PSPC) and the High Resolution Imager (HRI) on board ROSAT and have compared these data to optical images and long-slit spectra. NGC 2146 possesses a very large X-ray nebula with a half-light radius of 1 min (4 kpc) and a maximum diameter of approximately 4 min, or 17 kpc. The X-ray emission is resolved by the PSPC and preferentially oriented along the minor axis, with a total flux of 1.1 x 10(exp -12) ergs/sq cm/s over 0.2 - 2.4 keV and a luminosity of approximately 3 x 10(exp 40) ergs/s. The inner X-ray nebula is resolved by the HRI into at least four bright knots together with strong diffuse emission responsible for at least 50% of the flux within a radius of 0.5 min (approximately 2 kpc). The brightest knot has a luminosity of (2 - 3) x 10(exp 39) ergs/s. The X-ray nebula has a spatial extent much larger than the starburst ridge seen at centimeter wavelengths by Kronberg & Biermann (1981) and is oriented in a `X-like' pattern along the galaxy minor axis at a position angle of approximately 30 degrees. This minor-axis X-ray emission is associated with a region of H alpha and dust filaments seen in optical images. Optical spectra show that the emission-line gas along the minor axis is characterized by relatively broad lines (approximately 250 km/s full width half-maximum (FWHM)) and by `shocklike' emission-line flux ratios. Together with the blue-asymmetric nuclear emission-line and NaD interstellar absorption-line profiles, these optical data strongly suggest the presence of a starburst-driven superwind. The X-ray spectrum extracted from the central 5 min contains a strong Fe L emission-line complex at 0.6 - 1.0 keV and a hard excess above 1.0 keV. The spectrum is best described with a two-component model, containing a soft (kT approximately 400 - 500 eV) Raymond-Smith thermal plasma together with either a Gamma = 1.7 power-law or a kT greater than 2.2 keV bremsstrahlung component. The soft thermal component provides approximately 30% of the total luminosity over 0.2 - 2.4 keV, or approximately 10(exp 40) ergs/s. The pressure derived from the soft component of the X-ray spectrum is consistent with that predicted from a starburst-driven superwind if the filling factor of the warm gas is approximately 1% - 10 %. If the hard X-ray component is thermal gas associated with the galactic outflow, the filling factor must be close to unity. Predictions of the luminosity, temperature, and size of an adiabatic starburst-generated windblown bubble are consistent with those measured for the soft thermal X-ray emission in NGC 2146. The hard X-ray component, however, has a luminosity much larger than predicted by the superwind model if this component is thermal emission from gas heated by an internal shock in the expanding bubble. We briefly review various possibilities as to the nature of the hard X-ray component in NGC 2146.

Armus, L.↗
NASA NTRS2009

Open Solar Physics Questions - What Can Orbiter Do That Could Not Be Addressed By Existing Missions?

Solar Orbiter represents a revolutionary advance in observing the Sun. Orbiter will have optical and XUV telescopes that will deliver high-resolution images and spectra from vantages points that have never been possible before, dose to the Sun and at high latitudes. At the same time, Orbiter will measure in situ the properties of the solar wind that originate from the observed solar photosphere and corona. In this presentation, Ivvi|/ describe how with its unique vantage points and capabilities, Orbiter will allow us to answer, for the first time, some of the major question in solar physics, such as: Where does the slow wind originate? How do CMEs initiate and evolve? What is the heating mechanism in corona/ loops.

Antiochos, S. K.↗
NASA NTRS2016

Application of Optical Measurement Techniques During Stages of Pregnancy: Use of Phantom High Speed Cameras for Digital Image Correlation (D.I.C.) During Baby Kicking and Abdomen Movements

Paired images were collected using a projected pattern instead of standard painting of the speckle pattern on her abdomen. High Speed cameras were post triggered after movements felt. Data was collected at 120 fps -limited due to 60hz frequency of projector. To ensure that kicks and movement data was real a background test was conducted with no baby movement (to correct for breathing and body motion).

Gradl, Paul↗
NASA NTRS2012

High-Speed Scanning Interferometer Using CMOS Image Sensor and FPGA Based on Multifrequency Phase-Tracking Detection

A sub-aperture stitching optical interferometer can provide a cost-effective solution for an in situ metrology tool for large optics; however, the currently available technologies are not suitable for high-speed and real-time continuous scan. NanoWave s SPPE (Scanning Probe Position Encoder) has been proven to exhibit excellent stability and sub-nanometer precision with a large dynamic range. This same technology can transform many optical interferometers into real-time subnanometer precision tools with only minor modification. The proposed field-programmable gate array (FPGA) signal processing concept, coupled with a new-generation, high-speed, mega-pixel CMOS (complementary metal-oxide semiconductor) image sensor, enables high speed (>1 m/s) and real-time continuous surface profiling that is insensitive to variation of pixel sensitivity and/or optical transmission/reflection. This is especially useful for large optics surface profiling.

Ohara, Tetsuo↗
DOE OSTI2026

High-resolution bandpass x-ray imaging with crystal reflectors: Overcoming geometric aberrations

The imaging problem of a specular reflector is revisited. Retaining terms through the second order in the reflector surface expansion, we derive the form of the aberration-limiting aperture for arbitrary magnification, assuming no bandwidth limitations. A permissible relative aperture size of the reflector is limited by a set relative aberration tolerance and scales with the tangent of the central glancing angle of incidence. These limiting aberrations become practically insignificant near backscattering. The results extend to x-ray diffracting crystals in symmetric Bragg geometry shaped as an ellipsoid of revolution. This geometry permits polychromatic imaging for hard x-rays over a bandwidth defined by the accepted range of Bragg angles, thereby suppressing aberrations of higher orders. We assess ellipsoidal crystal imagers using ray tracing simulations for two high-magnification designs with Bragg angles far from and close to backscattering. Finally, in both cases, the ellipsoidal crystals produce images of higher quality compared to those formed by equivalent toroidal crystal imagers.

Bragg reflection↗
NASA NTRS2014

Hindlimb Suspension as a Model to Study Ophthalmic Complications in Microgravity Status Report: Optimization of Rat Retina Flat Mounts Staining to Study Vascular Remodeling

Preliminary data from a prior tissue‐sharing experiment has suggested that early growth response protein‐1 (Egr1), a transcription factor involved in various stress responses in the vasculature, is induced in the rat retina after 14 days of hindlimb suspension (HS) and may be evidence that mechanical stress is occurring secondary to the cephalad fluid shift. This mechanical stress could cause changes in oxygenation of the retina, and the subsequent ischemia‐ or inflammation‐driven hypoxia may lead to microvascular remodeling. This microvascular remodeling process can be studied using image analysis of retinal vessels and can be then be quantified by the VESsel GENeration Analysis (VESGEN) software, a computational tool that quantifies remodeling patterns of branching vascular trees and capillary or vasculogenic networks. Our project investigates whether rodent HS is a valid model to study the effects of simulated‐weightlessness on ocular structures and their relationship with intracranial pressure (ICP). One of the hypotheses to be tested is that HS‐induced cephalad fluid shift is accompanied by vascular engorgement that produces changes in retinal oxygenation, leading to oxidative stress, hypoxia, microvascular remodeling, and cellular degeneration. We have optimized the procedure to obtain flat mounts of rat retina, staining of the endothelial lining in vasculature and acquisition of high quality images suitable for VESGEN analysis. Briefly, eyes were fixed in 4% paraformaldehyde for 24 hours and retinas were detached and then mounted flat on microscope slides. The microvascular staining was done with endothelial cell‐specific isolectin binding, coupled to Alexa‐488 fluorophore. Image acquisition at low magnification and high resolution was performed using a new Leica SP8 confocal microscope in a tile pattern across the X,Y plane and multiple sections along the Z‐axis. This new confocal microscope has the added capability of dye separation using the Linear Unmixing method and allows us to remove the autofluorescence originating from the photoreceptor layer. In summary, we have an improved method for studying the retinal microvasculature that will provide an increase in the quality of images captured and will be applied throughout the various animal cohorts of the recentlyinitiated study that will evaluate rodent HS as a model to study ophthalmic complications in microgravity.

Theriot, Corey A.↗
NASA NTRS2017

Quantitative Image Analysis Techniques with High-Speed Schlieren Photography

Optical flow visualization techniques such as schlieren and shadowgraph photography are essential to understanding fluid flow when interpreting acquired wind tunnel test data. Output of the standard implementations of these visualization techniques in test facilities are often limited only to qualitative interpretation of the resulting images. Although various quantitative optical techniques have been developed, these techniques often require special equipment or are focused on obtaining very precise and accurate data about the visualized flow. These systems are not practical in small, production wind tunnel test facilities. However, high-speed photography capability has become a common upgrade to many test facilities in order to better capture images of unsteady flow phenomena such as oscillating shocks and flow separation. This paper describes novel techniques utilized by the authors to analyze captured high-speed schlieren and shadowgraph imagery from wind tunnel testing for quantification of observed unsteady flow frequency content. Such techniques have applications in parametric geometry studies and in small facilities where more specialized equipment may not be available.

Pollard, Victoria J.↗
NASA NTRS1994

A high resolution atlas of the galactic plane at 12 microns and 25 microns

High resolution images of the 12 micron and 25 micron IRAS survey data from each HCON crossing the Galactic Plane are being created for those regions that the original IRAS processing labeled as confused. This encompasses the area within 100 deg longitude of the Galactic Center and within 3 deg to 10 deg of the Plane. The procedures used to create the images preserve the spatial resolution inherent in the IRAS instrument. The images are separated into diffuse and point source components and candidate sources are extracted from the point source image after non-linear spatial sharpening. Fluxes are estimated by convolving the candidate sources with the point response function and cross-correlating with the original point source image. A source is considered real if it is seen on at least two HCON's with a rather generous flux match but a stringent position criterion. A number of fields spanning a range of source densities from low to high have been examined. Initial analysis indicates that the imaging and extraction works quite well up to a source density of about 100 sources per square degree or down to roughly 0.8 Janskys.

Price, Stephan D.↗
DOE OSTI2024

Quantifying Seasonal and Diurnal Cycles of Solar‐Induced Fluorescence With a Novel Hyperspectral Imager

Abstract Solar‐induced fluorescence (SIF) is a proxy of ecosystem photosynthesis that often scales linearly with gross primary productivity (GPP) at the canopy scale. However, the mechanistic relationship between GPP and SIF is still uncertain, especially at smaller temporal and spatial scales. We deployed a ultra‐hyperspectral imager over two grassland sites in California throughout a soil moisture dry down. The imager has high spatial resolution that limits mixed pixels, enabling differentiation between plants and leaves within one scene. We find that imager SIF correlates well with diurnal changes in leaf‐level physiology and gross primary productivity under well‐watered conditions. These relationships deteriorate throughout the dry down event. Our results demonstrate an advancement in SIF imaging with new possibilities in remotely sensing plant canopies from the leaf to the ecosystem. These data can be used to resolve outstanding questions regarding SIF's meaning and usefulness in terrestrial ecosystem monitoring.

60 APPLIED LIFE SCIENCES↗