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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.

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At least 55 records · Page 3
All sourcesNASA NTRSDOE OSTI
NASA NTRS2008

A Novel 24 GHz One-Shot, Rapid and Portable Microwave Imaging System

Development of microwave and millimeter wave imaging systems has received significant attention in the past decade. Signals at these frequencies penetrate inside of dielectric materials and have relatively small wavelengths. Thus. imaging systems at these frequencies can produce images of the dielectric and geometrical distributions of objects. Although there are many different approaches for imaging at these frequencies. they each have their respective advantageous and limiting features (hardware. reconstruction algorithms). One method involves electronically scanning a given spatial domain while recording the coherent scattered field distribution from an object. Consequently. different reconstruction or imaging techniques may be used to produce an image (dielectric distribution and geometrical features) of the object. The ability to perform this accurate~v and fast can lead to the development of a rapid imaging system that can be used in the same manner as a video camera. This paper describes the design of such a system. operating at 2-1 GHz. using modulated scatterer technique applied to 30 resonant slots in a prescribed measurement domain.

Ghasr, M. T.↗
DOE OSTI2021

Ultra-broadband voltage-controlled oscillator linearization for frequency modulated continuous wave MMW imaging systems

Millimeter-wave (MMW) imaging systems require high resolution and spurious free dynamic range (SFDR) to produce images with low artifacts. In these systems, lateral resolution is determined by the center frequency and the ratio of the aperture size to the distance to the target. The downrange resolution is determined by the system bandwidth; for very fine downrange resolution of a target, or material layers/discontinuities, the bandwidth must be very broad. Additionally, the response over the bandwidth must be measured very rapidly to support high speed acquisition over large apertures. A voltage-controlled oscillator (VCO) is a standard means of generating the ultra-broadband frequency chirp. This paper investigates the use of a broadband VCO for use in MMW imaging systems, a linear-phase calibration technique, and digital-to-analog converter (DAC) parameter considerations for controlling the VCO.

FMCW, homodyne, VCO, DAC, difference frequency, SF↗
NASA NTRS1999

Video Imaging System Particularly Suited for Dynamic Gear Inspection

A digital video imaging system that captures the image of a single tooth of interest of a rotating gear is disclosed. The video imaging system detects the complete rotation of the gear and divide that rotation into discrete time intervals so that each tooth of interest of the gear is precisely determined when it is at a desired location that is illuminated in unison with a digital video camera so as to record a single digital image for each tooth. The digital images are available to provide instantaneous analysis of the tooth of interest, or to be stored and later provide images that yield a history that may be used to predict gear failure, such as gear fatigue. The imaging system is completely automated by a controlling program so that it may run for several days acquiring images without supervision from the user.

Broughton, Howard↗
NASA NTRS1997

Global Ultraviolet Imaging Processing for the GGS Polar Visible Imaging System (VIS)

The Visible Imaging System (VIS) on Polar spacecraft of the NASA Goddard Space Flight Center was launched into orbit about Earth on February 24, 1996. Since shortly after launch, the Earth Camera subsystem of the VIS has been operated nearly continuously to acquire far ultraviolet, global images of Earth and its northern and southern auroral ovals. The only exceptions to this continuous imaging occurred for approximately 10 days at the times of the Polar spacecraft re-orientation maneuvers in October, 1996 and April, 1997. Since launch, approximately 525,000 images have been acquired with the VIS Earth Camera. The VIS instrument operational health continues to be excellent. Since launch, all systems have operated nominally with all voltages, currents, and temperatures remaining at nominal values. In addition, the sensitivity of the Earth Camera to ultraviolet light has remained constant throughout the operation period. Revised flight software was uploaded to the VIS in order to compensate for the spacecraft wobble. This is accomplished by electronic shuttering of the sensor in synchronization with the 6-second period of the wobble, thus recovering the original spatial resolution obtainable with the VIS Earth Camera. In addition, software patches were uploaded to make the VIS immune to signal dropouts that occur in the sliprings of the despun platform mechanism. These changes have worked very well. The VIS and in particular the VIS Earth Camera is fully operational and will continue to acquire global auroral images as the sun progresses toward solar maximum conditions after the turn of the century.

Frank, L. A.↗
NASA NTRSDate not supplied

Development of Multi-Edge Slant Target for Unlocalized MTF Measurement of Airborne Imaging System Payloads

Calibration of imaging instruments is a critical step in effectively characterizing imaging data. A comprehensive characterization of an imaging system provides valuable insight into the overall uncertainties in the results derived from the raw data collected. The Scientifically Calibrated In-Flight Imagery (SCIFLI) team (based at NASA Langley Research Center) has designed, built, tested, and successfully flown the optical payload known as the SCIFLI Airborne Multispectral Imager (SAMI). SAMI is a multispectral imaging payload, complete with sensor configurations for the Ultraviolet-Visible spectrum as well as Near- Infrared, Shortwave Infrared, and Midwave Infrared bands and is fitted with various optical hardware designed to turn, split, and focus light beams to the respective in-band sensors. Radiometric calibrations are performed for SAMI such that the accuracy and uncertainty of thermal and spectral measurements are effectively characterized. However, SAMI does not regularly undergo spatial characterizations to evaluate the performance of the imager at high spatial frequencies. This is essential, as understanding the spatial sensor response of discrete sensors is just as important as the spectral sensor response. The payload currently utilizes a calibration cart for lab testing. Equipped with a modular setup and several radiation sources, it is perfect for performing high-quality radiometric calibrations. This work focuses on using the calibration cart to perform spatial calibrations. A custom designed calibration target is being used to evaluate the optical performance of SAMI. Specifically, the target is designed to measure the Modulation Transfer Function (MTF) of the imager in discrete locations around the focal plane. The results of this characterization will provide insight into the spatial resolution capabilities of the SAMI payload in practice. Future work includes using the results of the study to correct optical imperfections in imagery taken with SAMI.

SAMI↗
DOE OSTI2020

An Approach to Characterizing Spatial Aspects of Image System Blur

In imaging applications, such as X-ray radiography, the experimental system setup and data capture process introduce system blur and distortion. In images taken with thick scintillators, a spatially varying system blur is observed, requiring a nonstandard approach to blur and distortion estimation and removal. We demonstrate an approach to estimation of local point spread functions using checkerboard radiographs collected at the Naval Research Laboratory and extend that into a map defining the kernel over the camera field of view.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2024

Solar mirror soiling and heliostat inspection from a mobile imaging system and mobile platform

A system or method for an imaging system is provided for inspecting a heliostat. The imaging system includes a platform and a camera mounted on the platform and a heliostat having a plurality of mirrored facets. The camera is positioned to acquire a first image that serves as a reference image and a second image that is a reflected image from at least one facet. The camera stores image data associated with the first image and the second image, and wirelessly transmits the stored image data to a computing apparatus. The computing apparatus compares the first image with the second image and determines a performance parameter associated with the heliostat.

Yellowhair, Julius↗
NASA NTRS1999

Information-Theoretic Assessment of Sample Imaging Systems

By rigorously extending modern communication theory to the assessment of sampled imaging systems, we develop the formulations that are required to optimize the performance of these systems within the critical constraints of image gathering, data transmission, and image display. The goal of this optimization is to produce images with the best possible visual quality for the wide range of statistical properties of the radiance field of natural scenes that one normally encounters. Extensive computational results are presented to assess the performance of sampled imaging systems in terms of information rate, theoretical minimum data rate, and fidelity. Comparisons of this assessment with perceptual and measurable performance demonstrate that (1) the information rate that a sampled imaging system conveys from the captured radiance field to the observer is closely correlated with the fidelity, sharpness and clarity with which the observed images can be restored and (2) the associated theoretical minimum data rate is closely correlated with the lowest data rate with which the acquired signal can be encoded for efficient transmission.

Huck, Friedrich O.↗
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 the 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 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 in orbit are also discussed.

Pline, Alexander D.↗
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 NTRS2001

Compact Microscope Imaging System Developed

The Compact Microscope Imaging System (CMIS) is a diagnostic tool with intelligent controls for use in space, industrial, medical, and security applications. The CMIS can be used in situ with a minimum amount of user intervention. This system, which was developed at the NASA Glenn Research Center, can scan, find areas of interest, focus, and acquire images automatically. Large numbers of multiple cell experiments require microscopy for in situ observations; this is only feasible with compact microscope systems. CMIS is a miniature machine vision system that combines intelligent image processing with remote control capabilities. The software also has a user-friendly interface that can be used independently of the hardware for post-experiment analysis. CMIS has potential commercial uses in the automated online inspection of precision parts, medical imaging, security industry (examination of currency in automated teller machines and fingerprint identification in secure entry locks), environmental industry (automated examination of soil/water samples), biomedical field (automated blood/cell analysis), and microscopy community. CMIS will improve research in several ways: It will expand the capabilities of MSD experiments utilizing microscope technology. It may be used in lunar and Martian experiments (Rover Robot). Because of its reduced size, it will enable experiments that were not feasible previously. It may be incorporated into existing shuttle orbiter and space station experiments, including glove-box-sized experiments as well as ground-based experiments.

McDowell, Mark↗
NASA NTRS1973

Feasibility test of a solid state spin-scan photo-imaging system

The feasibility of using a solid-state photo-imaging system to obtain resolution imagery from a Pioneer-type spinning spacecraft in future exploratory missions to the outer planets is discussed. Evaluation of the photo-imaging system performance, based on electrical video signal analysis recorded on magnetic tape, shows that the signal-to-noise (S/N) ratios obtained at low spatial frequencies exceed the anticipated performance and that measured modulation transfer functions exhibited some degradation in comparison with the estimated values, primarily owing to the difficulty in obtaining a precise focus of the optical system in the laboratory with the test patterns in close proximity to the objective lens. A preliminary flight model design of the photo-imaging system is developed based on the use of currently available phototransistor arrays. Image quality estimates that will be obtained are presented in terms of S/N ratios and spatial resolution for the various planets and satellites. Parametric design tradeoffs are also defined.

Laverty, N. P.↗
NASA NTRS1999

Venus Aerobot Surface Science Imaging System (VASSIS)

The VASSIS task was to design and develop an imaging system and container for operation above the surface of Venus in preparation for a Discovery-class mission involving a Venus aerobot balloon. The technical goals of the effort were to: a) evaluate the possible nadir-viewed surface image quality as a function of wavelength and altitude in the Venus lower atmosphere, b) design a pressure vessel to contain the imager and supporting electronics that will meet the environmental requirements of the VASSIS mission, c) design and build a prototype imaging system including an Active-Pixel Sensor camera head and VASSIS-like optics that will meet the science requirements. The VASSIS science team developed a set of science requirements for the imaging system upon which the development work of this task was based.

Greeley, Ronald↗
NASA NTRS2003

Portable Fluorescence Imaging System for Hypersonic Flow Facilities

A portable fluorescence imaging system has been developed for use in NASA Langley s hypersonic wind tunnels. The system has been applied to a small-scale free jet flow. Two-dimensional images were taken of the flow out of a nozzle into a low-pressure test section using the portable planar laser-induced fluorescence system. Images were taken from the center of the jet at various test section pressures, showing the formation of a barrel shock at low pressures, transitioning to a turbulent jet at high pressures. A spanwise scan through the jet at constant pressure reveals the three-dimensional structure of the flow. Future capabilities of the system for making measurements in large-scale hypersonic wind tunnel facilities are discussed.

Wilkes, J. A.↗
NASA NTRS2015

An Imaging System for Satellite Hypervelocity Impact Debris Characterization

This paper discusses the design of an automated imaging system for size characterization of debris produced by the DebriSat hypervelocity impact test. The goal of the DebriSat project is to update satellite breakup models. A representative LEO satellite, DebriSat, was constructed and subjected to a hypervelocity impact test. The impact produced an estimated 85,000 debris fragments. The size distribution of these fragments is required to update the current satellite breakup models. An automated imaging system was developed for the size characterization of the debris fragments. The system uses images taken from various azimuth and elevation angles around the object to produce a 3D representation of the fragment via a space carving algorithm. The system consists of N point-and-shoot cameras attached to a rigid support structure that defines the elevation angle for each camera. The debris fragment is placed on a turntable that is incrementally rotated to desired azimuth angles. The number of images acquired can be varied based on the desired resolution. Appropriate background and lighting is used for ease of object detection. The system calibration and image acquisition process are automated to result in push-button operations. However, for quality assurance reasons, the system is semi-autonomous by design to ensure operator involvement. This paper describes the imaging system setup, calibration procedure, repeatability analysis, and the results of the debris characterization.

Moraguez, Matthew↗
NASA NTRS1971

Spaceborne electronic imaging systems

Criteria and recommended practices for the design of the spaceborne elements of electronic imaging systems are presented. A spaceborne electronic imaging system is defined as a device that collects energy in some portion of the electromagnetic spectrum with detector(s) whose direct output is an electrical signal that can be processed (using direct transmission or delayed transmission after recording) to form a pictorial image. This definition encompasses both image tube systems and scanning point-detector systems. The intent was to collect the design experience and recommended practice of the several systems possessing the common denominator of acquiring images from space electronically and to maintain the system viewpoint rather than pursuing specialization in devices. The devices may be markedly different physically, but each was designed to provide a particular type of image within particular limitations. Performance parameters which determine the type of system selected for a given mission and which influence the design include: Sensitivity, Resolution, Dynamic range, Spectral response, Frame rate/bandwidth, Optics compatibility, Image motion, Radiation resistance, Size, Weight, Power, and Reliability.

Source record↗
NASA NTRS1971

Method and apparatus for eliminating coherent noise in a coherent energy imaging system without destroying spatial coherence

A method and apparatus for substantially eliminating noise in a coherent energy imaging system, and specifically in a light imaging system of the type having a coherent light source and at least one image lens disposed between an input signal plane and an output image plane are, discussed. The input signal plane is illuminated with the light source by rotating the lens about its optical axis. In this manner, the energy density of coherent noise diffraction patterns as produced by imperfections such as dust and/or bubbles on and/or in the lens is distributed over a ring-shaped area of the output image plane and reduced to a point wherein it can be ignored. The spatial filtering capability of the coherent imaging system is not affected by this noise elimination technique.

Shulman, A. R.↗