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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 721 records · Page 40
All sourcesNASA NTRSDOE OSTI
NASA NTRS2005

Polarization Considerations for the Laser Interferometer Space Antenna

A polarization ray trace model of the Laser Interferometer Space Antenna s (LISA) optical path is being created. The model will be able to assess the effects of various polarizing elements and the optical coatings on the required, very long path length, picometer level dynamic interferometry. The computational steps are described. This should eliminate any ambiguities associated with polarization ray tracing of interferometers and provide a basis for determining the computer model s limitations and serve as a clearly defined starting point for future work.

Waluschka, Eugene↗
NASA NTRS1992

Ring-array processor distribution topology for optical interconnects

The existing linear and rectangular processor distribution topologies for optical interconnects, although promising in many respects, cannot solve problems such as clock skews, the lack of supporting elements for efficient optical implementation, etc. The use of a ring-array processor distribution topology, however, can overcome these problems. Here, a study of the ring-array topology is conducted with an aim of implementing various fast clock rate, high-performance, compact optical networks for digital electronic multiprocessor computers. Practical design issues are addressed. Some proof-of-principle experimental results are included.

Li, Yao↗
NASA NTRS1990

Finite element analysis of thermal distortion effects on optical performance of solar dynamic concentrator for Space Station Freedom

An analysis was performed to predict the thermal distortion of the solar dynamic concentrator for Space Station Freedom in low earth orbit and to evaluate the effects of that thermal distortion on concentrator on-orbit performance. The analysis required substructural finite element modeling of critical concentrator structural subsystems, structural finite element modeling of the concentrator, mapping of thermal loading onto the structural finite element model, and the creation of specialized postprocessors to assist in interpreting results. Concentrator temperature distributions and thermally induced displacements and slope errors and the resulting receiver flux distribution profiles are discussed. Results determined for a typical orbit indicate that concentrator facet rotations are less than 0.2 mrad and that the change in facet radius due to thermal flattening is less than 5 percent. The predicted power loss due to thermal distortion effects is less than 0.3 percent. As a consequence the thermal distortions of the solar dynamic concentrator in low earth orbit will have a negligible effect on the flux distribution profiles within the receiver.

Doherty, Michael P.↗
NASA NTRS1979

Forecast analysis of optical waveguide bus performance

Elements to be considered in the design of a data bus include: architecture; data rate; modulation, encoding, detection; power distribution requirements; protocol, work structure; bus reliability, maintainability; interterminal transmission medium; cost; and others specific to application. Fiber- optic data bus considerations for a 32 port transmissive star architecture, are discussed in a tutorial format. General optical-waveguide bus concepts, are reviewed. The electrical and optical performance of a 32 port transmissive star bus, and the effects of temperature on the performance of optical-waveguide buses are examined. A bibliography of pertinent references and the bus receiver test results are included.

Ledesma, R.↗
NASA NTRS1990

Modeling bidirectional reflectance of forests and woodlands using Boolean models and geometric optics

Geometric-optical discrete-element mathematical models for forest canopies have been developed using the Boolean logic and models of Serra. The geometric-optical approach is considered to be particularly well suited to describing the bidirectional reflectance of forest woodland canopies, where the concentration of leaf material within crowns and the resulting between-tree gaps make plane-parallel, radiative-transfer models inappropriate. The approach leads to invertible formulations, in which the spatial and directional variance provides the means for remote estimation of tree crown size, shape, and total cover from remotedly sensed imagery.

Strahler, Alan H.↗
DOE OSTI2023

Spin–orbit effects on the electronic and optical properties of lead iodide

Lead iodide (PbI2) has gained much interest due to its direct electronic gap in the visible range and layered crystal structure. It has thereby been considered as a promising material for applications in atomically thin optoelectronic devices. In this work, we present a detailed investigation of the effect of spin–orbit coupling (SOC) that arises from the presence of heavy atoms on the electronic and optical properties of PbI2 using first-principles calculations based on density-functional theory and many-body perturbation theory. We find that SOC not only alters the bandgap but also induces the mixing of orbital characters, resulting in a significant change in the overall band structure and charge carrier effective masses. Moreover, the band orbital mixing caused by SOC results in the dramatic change in optical transition matrix elements and, correspondingly, the absorption spectrum. Our experimentally measured absorption spectra validate the calculation results and demonstrate the importance of SOC in the optical processes of PbI2. Our findings provide insights that are important for the potential use of PbI2 as a material platform for visible optoelectronic devices.

Physics↗
NASA NTRS1983

On the off-axis tension test for unidirectional composites

The off axis tensile test was examined experimentally to obtain actual displacement fields over the surface of graphite polyimide coupon specimens. The experimental results were compared with approximate analytical solutions and generated finite element results. An optical method of high sensitivity moireinterferometry was used to determine the actual displacements to high precision. The approximate analytical solution and the finite element results compare very favorably with the measured centerline displacements in the test section, and the finite element displacement fields provide excellent agreement with the moiredisplacements throughout the specimen. A 15 degree fiber orientation and coupon aspect ratios of 5 and 15 are presented. Previously announced in STAR as N82-23553

Herakovich, C. T.↗
NASA NTRS1982

On the off-axis tensile test for unidirectional composites

The off axis tensile test was examined experimentally to obtain actual displacement fields over the surface of graphite polyimide coupon specimens. The experimental results were compared with approximate analytical solutions and generated finite element results. An optical method of high sensitivity moire interferometry was used to determine the actual displacements to high precision. The approximate analytical solution and the finite element results compare very favorably with the measured centerline displacements in the test section, and the finite element displacement fields provide excellent agreement with the moire displacements throughout the specimen. A 15 degree fiber orientation and coupon aspect ratios of 5 and 15 are presented.

Nemeth, M. P.↗
NASA NTRS2019

NASA's Next Generation Optical Communications Relay

NASA's Space Communications and Navigation (SCaN) program is creating an operational optical communications network to complement its current radio frequency (RF) networks. NASA is currently planning for a new optical communications relay node in geostationary (GEO) orbit to be commissioned in 2025, developed by NASA's Goddard Space Flight Center (GSFC), as evolved from Goddard's Laser Communications Relay Demonstration (LCRD) GEO relay payload that will launch in 2019. The Next Generation optical relay node will serve as an initial element in a larger optical networking constellation that will consist of Government and commercial, and international relays. NASA's nodes will aggregate traffic at data rates of up to 10 Gigabits per second (Gbps) from users on the Earth's surface and up through suborbital, LEO, MEO, GEO, cislunar and even out to Earth-Sun Lagrange (1.25 Mkm) distances. Users that require low-latency will be serviced with an onboard complementary Ka-band downlink service. The next generation network will deploy > 100 Gbps space-to-ground links and also optical crosslinks between nodes to allow for user traffic backhaul to minimize ground station location constraints.

Israel, David↗
NASA NTRS2019

NASA's Next Generation ≥100 Gbps Optical Communications Relay

NASA’s Space Communications and Navigation (SCaN) program is creating an operational optical communications network to complement its current radio frequency (RF) networks. NASA is currently planning for a new optical communications relay node in geostationary (GEO) orbit to be commissioned in 2025, developed by NASA’s Goddard Space Flight Center (GSFC), as evolved from Goddard’s Laser Communications Relay Demonstration (LCRD) GEO relay payload that will launch in 2019. The Next Generation optical relay node will serve as an initial element in a larger optical networking constellation that will consist of Government and commercial, and international relays. NASA’s nodes will aggregate traffic at data rates of up to 10 Gigabits per second (Gbps) from users on the Earth’s surface and up through suborbital, LEO, MEO, GEO, cislunar and even out to Earth-Sun Lagrange (1.25 Mkm) distances. Users that require low-latency will be serviced with an onboard complementary Ka-band downlink service. The next generation network will deploy ≥ 100 Gbps space-to-ground links and also optical crosslinks between nodes to allow for user traffic backhaul to minimize ground station location constraints.

Park, Elizabeth A.↗
DOE OSTI2023

MAX-Phase Partial Optical Properties

The optical and electrical properties of MAX-phase materials have been thoroughly studied in the past. We present here a new technique to determine and study the partial contributions to the optical properties. Following the same methodology as the decomposition of the density of states to the partial density of states, we have decomposed the optical properties into the partial optical properties. Using this technique the differences of elemental and layer resolved optical properties are displayed for both the 211 and 312 phase of TiSiC and TiAlC MAX-phase materials.

Weigand, Alysse↗
DOE OSTI2022

Element differentiation with a Hartmann- based X-ray phase imaging system

Significant efforts are currently ongoing in X-ray imaging to provide multimodal imaging systems, targeting better sensitivity and specificity for both biomedical or non-destructive testing applications. Knowing the elemental composition of specific structures, such as breast microcalcifications in mammography, would help to differentiate malign and benign tumours. Standard X-ray Phase Contrast Imaging techniques provide only qualitative information on elements with similar absorption properties. However, their chemical composition can be determined from the measurement of the phase as it is directly related to the optical index of elemental materials. We will show new experimental results obtained with an X-ray phase imaging system based on a Hartmann mask. Early data treatment succeeded in retrieving both the real and imaginary parts of the refractive index. The system demonstrates the capability to discriminate materials based on elemental composition.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Luminescence based fiber optic probe for the detection of rare earth elements

The disclosure relates to an apparatus, method and process for detecting rare earth elements. The system includes an LED powered by a first power source and a focusing lens in optical communication with the LED. A shortpass filter is in optical communication with the focusing lens; and a fiber bifurcated cable in optical communication with the shortpass filter. The system includes a probe tip in optical communication with the fiber bifurcated cable and a sample; a first aspheric lens in optical communication with the fiber bifurcated cable. A longpass filter is in optical communication with the first aspheric lens and a second aspheric lens in optical communication with the longpass filter. The system includes a spectrometer connected to a power source, where the spectrometer is in optical communication with the second aspheric lens.

Ahern, John C.↗
NASA NTRS2006

'Nano' Morphology and Element Signatures of Early Life on Earth: A New Tool for Assessing Biogenicity

The relatively young technology of NanoSIMS is unlocking an exciting new level of information from organic matter in ancient sediments. We are using this technique to characterize Proterozoic organic material that is clearly biogenic as a guide for interpreting controversial organic structures in either terrestrial or extraterrestrial samples. NanoSIMS is secondary ion mass spectrometry for trace element and isotope analysis at sub-micron resolution. In 2005, Robert et al. [1] combined NanoSIMS element maps with optical microscopic imagery in an effort to develop a new method for assessing biogenicity of Precambrian structures. The ability of NanoSIMS to map simultaneously the distribution of organic elements with a 50 nm spatial resolution provides new biologic markers that could help define the timing of life s development on Earth. The current study corroborates the work of Robert et al. and builds on their study by using NanoSIMS to map C, N (as CN), S, Si and O of both excellently preserved microfossils and less well preserved, non-descript organics in Proterozoic chert from the ca. 0.8 Ga Bitter Springs Formation of Australia.

Oehler, D. Z.↗
NASA NTRS1998

Injector Mixing Efficiency Experiments

Various optical diagnostic techniques such as laser induce fluorescence, Raman spectroscopy, laser Doppler velocimetry, and laser light scattering have been employed to study the flowfield downstream of a single injector element in a optically accessible rocket chamber at Penn State for a number o years. These techniques have been used with both liquid and gaseous oxygen at pressures up to 1000 psia which is the limit of the facility. The purpose of the test programs at Penn State were to develop the techniques and to study the flow field from various injector designs. To extend these studies to higher pressure and ultimately to multiple injectors require the capabilities of the Marshall Space Flight Center. These studies will extend the data base available for the various injector designs to higher pressure as well as to determine the interaction between multiple injectors. During this effort the Princeton Instruments ICCD camera was set up and checked out. The functionality of the system has been thoroughly checked and the shutter compensation time was found to be not working. The controller was returned to the manufacturer for warranty repair. The sensitivity has been measured and found to be approximately 60 counts per photon at maximum gain which agrees with the test data supplied by the manufacturer. The actual value depends on wavelength. The Princeton Instruments camera was been installed in a explosion proof tube for use with the rocket combustor. A 35 mm camera was also made ready for taking still photos inside the combustor. A fiber optic was used to transmit the laser light from an argon-ion laser to the rocket combustor for the light scattering images. This images were obtained for a LOX-hydrogen swirl coax injector. Several still photos were also obtained with the 35 mm camera for these firings.

Moser, Marlow D.↗
DOE OSTI2022

Elemental Analysis of Bio-Oils by Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES). Laboratory Analytical Procedure (LAP), Issue Date: May 13, 2022

Concentrations of inorganic elements is a key quality metric for bio-oils as certain elements impact upgrading processes and product quality. Unless reduced or removed during production and processing, alkali and alkaline metals native to lignocellulosic biomass can carry over into bio-oils contributing to ash content and degraded catalyst performance during upgrading to hydrocarbon fuels or chemical products. Non-metallic elements such as sulfur and phosphorus can also negatively impact upgrading catalysts and product quality. Inductively coupled plasma optical emission spectroscopy (ICP-OES) can be used to measure inorganic elements of interest in bio-oils. This procedure covers the preparation and analysis of fast pyrolysis (FP) and catalytic fast pyrolysis (CFP) bio-oils. The concentrations of these elements can indicate potential bio-oil quality from the perspective of deoxygenation processes. The implications of elemental composition will depend on process parameters such as upgrading catalyst sensitivities. This Laboratory Analytical Procedure (LAP) covers two methods for quantification of inorganic elements by ICP-OES: Procedure A uses microwave assisted digestion with concentrated nitric acid, and Procedure B is an organic ICP-OES method utilizing a diglyme solvent.

09 BIOMASS FUELS↗
DOE OSTI2023

Multichannel angular spectrometer

A multichannel angular spectrometer includes an array of fiber pickups having an arcuate arrangement and focused about a sample volume. A broadband light source is configured to illuminate a sample within the sample volume. At least one dispersion element is in optical communication with the array of fiber pickups. An imaging sensor is in optical communication with the array of fiber pickups. The imaging sensor is configured to image the broadband light received by the array of fiber pickups and dispersed by the at least one dispersion element. A processor is in electrical communication with the imaging sensor. The processor has a power supply and computer-readable memory.

47 OTHER INSTRUMENTATION↗