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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 37 records · Page 2
All sourcesNASA NTRSDOE OSTI
NASA NTRS1995

Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) Onboard Calibration System

The AVIRIS instrument uses an onboard calibration system to provide auxiliary calibration data. The system consists of tungsten halogen cycle lamp imaged onto a fiber bundle through an eight position filter wheel. The fiber bundle illuminates the back side of the foreoptics shutter during a pre-run and post-run calibration sequence. The filter wheel contains 2 neutral density filters, 5 spectral filters and blocked position.

spectrometer↗
NASA NTRS1988

Image Control In Automatic Welding Vision System

Orientation and brightness varied to suit welding conditions. Commands from vision-system computer drive servomotors on iris and Dove prism, providing proper light level and image orientation. Optical-fiber bundle carries view of weld area as viewed along axis of welding electrode. Image processing described in companion article, "Processing Welding Images for Robot Control" (MFS-26036).

Richardson, Richard W.↗
NASA NTRS1980

Conceptual design study for an advanced cab and visual system, volume 1

A conceptual design study was conducted to define requirements for an advanced cab and visual system. The rotorcraft system integration simulator is for engineering studies in the area of mission associated vehicle handling qualities. Principally a technology survey and assessment of existing and proposed simulator visual display systems, image generation systems, modular cab designs, and simulator control station designs were performed and are discussed. State of the art survey data were used to synthesize a set of preliminary visual display system concepts of which five candidate display configurations were selected for further evaluation. Basic display concepts incorporated in these configurations included: real image projection, using either periscopes, fiber optic bundles, or scanned laser optics; and virtual imaging with helmet mounted displays. These display concepts were integrated in the study with a simulator cab concept employing a modular base for aircraft controls, crew seating, and instrumentation (or other) displays. A simple concept to induce vibration in the various modules was developed and is described. Results of evaluations and trade offs related to the candidate system concepts are given, along with a suggested weighting scheme for numerically comparing visual system performance characteristics.

Rue, R. J.↗
NASA NTRS1994

Diagenetic Microcrystalline Opal Varieties from the Monterey Formation, CA: HRTEM Study of Structures and Phase Transformation Mechanisms

Microcrystalline opal varieties form as intermediary precipitates during the diagenetic transformation of biogenically precipitated non-crystalline opal (opal-A) to microquartz. With regard to the Monterey Formation of California, X-ray powder diffraction studies have shown that a decrease in the primary d-spacing of opal-CT toward that of cristobalite occurs with increasing diagenesis. The initial timing of opal-CT/quartz formation and the value of the primary opal-CT d-spacing, are influenced by the sediment. lithology. Transmission electron microscopy methods (CTEM/HRTEM) were used to investigate the structure of the diagenetic phases and establish transformation mechanisms between the varieties of microcrystalline opals in charts and porcelanites from the Monterey Formation. HRTEM images revealed that the most common fibrous varieties of microcrystalline opals contain varying amounts of structural disorder. Finite lamellar units of cristobalite-and tridymite-type. layer sequences were found to be randomly stacked in a direction perpendicular to the fiber axis. Disordered and ordered fibers were found to have coprecipitated within the same radial fiber bundles that formed within the matrix of the Most siliceous samples. HRTEM images, which reveal that the fibers within radial and lepispheric fiber bundles branch non-crystallographically, support an earlier proposal that microspheres in chert grow via a spherulitic growth mechanism. A less common variety of opal-CT was found to be characterized by non-parallel (low-angle) stacking sequences that often contain twinned lamellae. Tabular-shaped crystals of orthorhombic tridymite (PO-2) were also identified in the porcelanite samples. A shift in the primary d-spacing of opal-CT has been interpreted as an indication of solid-state ordering g toward a predominantly cristobalite structure, (opal-C). Domains of opal-C were identified as topotactically-oriented overgrowths on discrete Sections of opal-CT fibers and as lamellar domains within relict opal-CT fibers. These findings indicate that the type of transformation mechanism depends upon the primary structural characteristics of the authigenic opaline. varieties that are in turn influenced by the sediment lithology.

Cady, Sherry L.↗
NASA NTRS1983

Scintillator-fiber charged-particle track-imaging detector

A scintillator-fiber charged-particle track-imaging detector has been developed using a bundle of square cross-section plastic scintillator fiber optics, proximity focused onto an image intensified Charge Injection Device (CID) camera. Detector to beams of 15 MeV protons and relativistic Neon, Manganese, and Gold nuclei have been exposed and images of their tracks are obtained. This paper presents details of the detector technique, properties of the tracks obtained, and range measurements of 15 MeV protons stopping in the fiber bundle.

Binns, W. R.↗
NASA NTRS2003

Robust incoherent fiber optic bundle decoder

Apparatus and method for calibrating an incoherent fiber optic bundle for use in transmitting visual or infrared coherent images. The apparatus includes a computer, a computer video monitor, an objective lens adjacent to the input end of the bundle, a second lens adjacent the output end of the bundle, and a CCD camera. The camera transmits video data to the monitor to produce an illuminated fiber optic image. The coordinates for the center of each fiber is found through an imaging process and the output fibers coordinates are related to the input fiber coordinates and processed in the computer to produce a mapping lookup-table (LUT) unique to the specific fiber bundle. Remapping of the LUT due to changes in the lens focus, CCD camera, or the addition of an infrared filter is accomplished by a software utility in the computer.

Roberts, Hilary E.↗
NASA NTRS1990

Radial Profilometry

Radial profilometry is combination of optical and electronic techniques for measurement of inner surfaces of cylindrical or nearly cylindrical cavities. Profilometer inserted in pipe or other cavity to measure its shape optically. Illumination supplied through optical fiber, and image of inspected area of cavity transmitted through bundle of optical fibers. Applications include inspection of pipes, tubes, boreholes, and possibly measurements of contours in blood vessels or other internal organs.

Gilbert, J. A.↗
NASA NTRS1987

Welding monitoring system

This invention relates to systems for remotely monitoring automatic welding operations, and more particularly to a system wherein the welder is readily positionable, while components of the optical system remain fixed. A welder having an electrode is mounted in an enclosure containing a pair of mirrors. The electrode passes through an opening in the first mirror and a gas cup. The mirror reflects an image of a welding operation taken through the opening of the gas cup to the second mirror. The second mirror then reflects the image through a rotary coupling to a third mirror which, in turn, reflects the image to a receiving lense mounted to a second rotatable coupling. The image is then projected via a fiber optic bundle to a filter unit where selected wavelengths of light are filtered from the welding image. The filter unit is coupled to an enlarger which enlarges the image and passes it to a camera. The camera is connected to an electronic eclipser which selectively darkens the brightest portions of the image. Finally, the image is recorded by a video tape recorder and displayed by a monitor.

Babcock, Stephen G.↗
NASA NTRS1981

Fiber-optics couple arthroscope to TV

Convenient, hand-held coupler images output of arthroscope onto coherent fiber bundle. Arthroscope allows surgeons to examine internal organs through any small opening in body. Coupler is also used for engine inspection, instrument repair, and around-corner visual inspection. Image from arthroscope travels along flexible bundle and appears at other cable end where it is recollimated by lens. Image is read from lens or projected on color TV camera.

Franke, J. M.↗
NASA NTRS2010

Boundary Layer Measurements in a Supersonic Wind Tunnel Using Doppler Global Velocimetry

A modified Doppler Global Velocimeter (DGV) was developed to measure the velocity within the boundary layer above a flat plate in a supersonic flow. Classic laser velocimetry (LV) approaches could not be used since the model surface was composed of a glass-ceramic insulator in support of heat-transfer measurements. Since surface flare limited the use of external LV techniques and windows placed in the model would change the heat transfer characteristics of the flat plate, a novel approach was developed. The input laser beam was divided into nine equal power beams and each transmitted through optical fibers to a small cavity within the model. The beams were then directed through 1.6-mm diameter orifices to form a series of orthogonal beams emitted from the model and aligned with the tunnel centerline to approximate a laser light sheet. Scattered light from 0.1-micron diameter water condensation ice crystals was collected by four 5-mm diameter lenses and transmitted by their respective optical fiber bundles to terminate at the image plane of a standard two-camera DGV receiver. Flow measurements were made over a range from 0.5-mm above the surface to the freestream at Mach 3.51 in steady state and heat pulse injected flows. This technique provides a unique option for measuring boundary layers in supersonic flows where seeding the flow is problematic or where the experimental apparatus does not provide the optical access required by other techniques.

Meyers, James F.↗
NASA NTRS2019

Advanced Electronics for the SONTRAC Neutron Spectrometer

Solar neutrons are the tell-tale of highly energetic processes (e.g. solar flares) at the Sun in which particle acceleration is taking place over a broad range in energy. Unlike charged radiation, neutrons escape unscathed from the ambient magnetic fields, providing a view of particle acceleration unhindered by the effects of transport. High-energy neutrons are challenging to measure with the traditional double scatter technique based on time-of-flight (ToF). This technique is limited by the finite flight path and active scintillator sizes required by small satellite platforms. The new SOlar Neutron TRACking (SONTRAC) concept, based on scintillating-fiber bundles, will provide high resolution imaging of fast neutrons at energies where the bulk of solar and magnetospheric neutrons resides. Recent development of the new SONTRAC instrument concept's advanced electronics and processing algorithms are presented.

SiPM readout↗
NASA NTRS1989

High-Resolution, Two-Wavelength Pyrometer

Modified two-color pyrometer measures temperatures of objects with high spatial resolution. Image focused on hole 0.002 in. (0.05 mm) in diameter in brass sheet near end of bundle, causing image to be distributed so fibers covered by defocused radiation from target. Pinhole ensures radiation from only small part of target scene reaches detector, thus providing required spatial resolution. By spreading radiation over bundle, pinhole ensures entire active area of detectors utilized. Produces signal as quiet as conventional instruments but with only 1/64 input radiation.

Bickler, Donald B.↗
DOE OSTI2014

Photonic Doppler Velocimetry Probe Designed with Stereo Imaging

The velocity distribution of an imploding curved surface is measured with a miniature fiber-optic probe. The probe uses fiber matrix arrays that are focused onto different regions of this curved surface. A pyramid reflector deflects the interrogation onto specific regions of this curved surface. The fiber arrays record velocity along several hundred lines of sight with sub-nanosecond resolution. Reflected light from each spot on the moving surface is Doppler shifted with a small portion of this light propagating backwards through the launching fiber. The reflected light is mixed with a reference laser in a technique called Photonic Doppler velocimetry, providing continuous time records. Within the probe, seven groups of miniature optical relay lenses are grouped into a close-packed array, allowing the interrogation of seven regions of interest. A six-faceted pyramid reflector with a conical hole drilled into its center is used to direct the light beams onto different regions. To minimize back reflections, the fiber matrix arrays are index matched onto the first relay lens made of fused silica. The optical lens design minimizes the laser beam diameters and also provides excellent imaging capabilities. Therefore, two of the fiber matrix arrays are replaced by coherent bundles for stereo imaging recorded by a high-speed framing camera. This requires additional cutouts of the pyramid reflector to allow imaging overlap. Six additional 1.5 mm diameter incoherent bundles are attached to the edges of the pyramid reflector and are used for illumination. Precision metrology on the direction cosines of the trajectories is measured to satisfy environmental requirements for vibration and temperature.

photonic doppler velocimetry, PDV, pyramid reflect↗
DOE OSTI2019

Resolution Limits of Near IR and IR Thermography Applied to Imaging Thermal Heterogeneities in Nuclear Fuel Surrogate Materials

ABSTRACT The main goal of the project is: To develop an IR thermographic method to monitor fuel pellet cracking inside the hostile environment of the nuclear core. This method will use a high temperature and radiation resistant fiber optic bundle to monitor the fuel pellet inside the core and transmit the information outside to an IR camera. This method will give a visual cue (using IR video) as to when the crack started to form and how it progresses. To achieve this goal, we identified the following as major milestones of the project: 1. Perform 1D modeling of temperature and blackbody radiation intensity across a crack. 2. Image a crack on a fuel cell surrogate using an IR camera with free-space optics and high power laser setup. 3. Simulate cracking in the surrogate sample through inductive heating method, and demonstrate imaging crack formation using the free-space optics setup. 4. Determine parameters for a suitable fiber optic bundle compatible with the IR camera based on the results from the free-space optics experiments. 5. Demonstrate imaging using fiber bundle and integrate viewing system with nuclear core at INL. This report focuses on Goals 1-3. We have successfully achieved Goals 1-3 and are making steady progress towards achieving Goals 4-9. Goals 2 and 4 are very similar and require 2 basic parts: the imaging system and the method to crack the fuel surrogate to replicate the fuel pellet cracking in the nuclear reactor core. The following sections describe the 1D modeling of temperature and blackbody radiation intensity across a crack (Goal 1), procedure to create crack on fuel surrogates and results (Goals 2 and 3), and the IR imaging system and results (Goal 2).

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2017

Photonic Doppler velocimetry probe used to measure grain boundaries of dynamic shocked materials

Material scientists have developed computational modeling to predict the dynamic response of materials undergoing stress, but there is still a need to make precision measurements of surfaces undergoing shock compression. Miniature photonic Doppler velocimetry (PDV) probes have been developed to measure the velocity distribution from a moving surface traveling tens of kilometers per second. These probes use hundreds of optical fibers imaged by optical relays onto different regions of this moving surface. While previous work examined large surface areas, we have now developed a PDV microscope that can interrogate 37 different spots within a field of view of <1 mm, with a standoff distance of 17 mm, to analyze the motion differences across grain boundaries of the material undergoing dynamic stress. Each PDV fiber interrogates a 10 μm spot size on the moving surface. A separate imaging system using a coherent bundle records the location of the PDV spots relative to the grain boundaries prior to the dynamic event. Designing the mounting structures for the lenses, fibers, and coherent bundle was a challenge. To minimize back reflections, the fibers are index matched onto the first relay lens, which is made of fused silica. The PDV fibers are aligned normal to the moving surface. The imaging probe views the surface at an 18° angle. The coherent bundle is tilted 11° to its optical relay. All components are assembled into a single probe head assembly. The coherent bundle is removed from the probe head to be used for the next dynamic event. Alignment issues will also be discussed.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2015

A dual wavelength imaging system for plasma-surface interaction studies on the National Spherical Torus Experiment Upgrade

A two-channel spectral imaging system based on a charge injection device radiation-hardened intensified camera was built for studies of plasma-surface interactions on divertor plasma facing components in the National Spherical Torus Experiment Upgrade (NSTX-U) tokamak. By means of commercially available mechanically referenced optical components, the two-wavelength setup images the light from the plasma, relayed by a fiber optic bundle, at two different wavelengths side-by-side on the same detector. Remotely controlled filter wheels are used for narrow bandpass and neutral density filters on each optical path allowing for simultaneous imaging of emission at wavelengths differing in brightness up to 3 orders of magnitude. Applications on NSTX-U will include the measurement of impurity influxes in the lower divertor strike point region and the imaging of plasma-material interaction on the head of the surface analysis probe MAPP (Material Analysis and Particle Probe). The diagnostic setup and initial results from its application on the lithium tokamak experiment are presented.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2014

TU-F-12A-06: BEST IN PHYSICS (IMAGING) - A Novel Catheter-Based Radionuclide Imaging System to Characterize Atherosclerotic Plaque

Purpose: Atherosclerosis underlies coronary artery diseases, the leading cause of death in the United States and worldwide. In this study, we developed a novel catheter-based radionuclide imaging (CRI) system to image 18F-fluorodeoxyglucose (18F-FDG), a radionuclide, a marker of vascular inflammation, in murine carotid arteries and characterized the system for spatial resolution from multiple scintillating materials. Methods: The catheter system includes 35 mm and 8 mm fixed focal length lenses, which are subsequently connected to a CMOS camera and fiber holder. The distal ferrule of an image bundle is terminated with a wide-angle lens. The novelty of this system is a scintillating balloon with a crystal tip in the front of the wide angle lens to image light from the decay of 18F-FDG emission signal. The scintillating balloon is fabricated from 1mL of silicone RTV catalyst mixed with 1 mL base and 50 mg/mL calcium fluoride doped with Europium (CaF2:Eu). To identify the optimal scintillating materials with respect to resolution, we calculated modulation transfer function (MTF) of Yttrium Aluminum Garnet doped with Cerium (YAG:Ce), anthracene, and CaF2:Eu phosphors using a thin line optical phantom (Fig. 1a-1b). Macrophage-rich FVB murine atherosclerotic carotid plaque model (n = 4) was used in ex vivo experiments. Confirmatory imaging was also performed by an external optical imaging system (IVIS-200). Results: Analysis of the different phosphors (Fig 1b) showed that CaF2:Eu enabled the best resolution of 1.2μm. The CRI system visualized 18F-FDG in atherosclerotic plaques (Fig. 1d). The ligated left carotid (LR) artery exhibited 4× higher 18F-FDG signal intensity compared to the non-ligated right carotid (negative control) artery (1.65×10{sup 2} ±4.07×10{sup 1} vs. 4.44×10{sup 1}±2.17×10{sup 0}, A.U., p = 0.005) and confirmed with IVIS-200 (Fig. 1d). Conclusion: This CRI system enables high-resolution and sensitive detection of 18F-FDG uptake by murine atherosclerotic plaques.

60 APPLIED LIFE SCIENCES↗
NASA NTRS1994

Plasma arc welding weld imaging

A welding torch for plasma arc welding apparatus has a transparent shield cup disposed about the constricting nozzle, the cup including a small outwardly extending polished lip. A guide tube extends externally of the torch and has a free end adjacent to the lip. First and second optical fiber bundle assemblies are supported within the guide tube. Light from a strobe light is transmitted along one of the assemblies to the free end and through the lip onto the weld site. A lens is positioned in the guide tube adjacent to the second assembly and focuses images of the weld site onto the end of the fiber bundle of the second assembly and these images are transmitted along the second assembly to a video camera so that the weld site may be viewed continuously for monitoring the welding process.

Rybicki, Daniel J.↗