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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 73 records · Page 4
All sourcesNASA NTRSDOE OSTI
NASA NTRS1992

Research Studies on Advanced Optical Module/Head Designs for Optical Data Storage

Preprints are presented from the recent 1992 Optical Data Storage meeting in San Jose. The papers are divided into the following topical areas: Magneto-optical media (Modeling/design and fabrication/characterization/testing); Optical heads (holographic optical elements); and Optical heads (integrated optics). Some representative titles are as follow: Diffraction analysis and evaluation of several focus and track error detection schemes for magneto-optical disk systems; Proposal for massively parallel data storage system; Transfer function characteristics of super resolving systems; Modeling and measurement of a micro-optic beam deflector; Oxidation processes in magneto-optic and related materials; and A modal analysis of lamellar diffraction gratings in conical mountings.

Source record↗
NASA NTRS2000

Cryogenic Optical Systems and Instrumentation IX (AM 116) Newly Modified Cryogenic Optical Test Facility at the Marshall Space Flight Center

Marshall Space Flight Center (MSFC) has maintained and operated a world-class x-ray optics and detector testing facility known as the X-ray Calibration Facility (XRCF) since the mid 1970's. The ground test and calibration of the Chandra X-ray Observatory optics and detectors were successfully completed at the XRCF in 1997. The beginning of the Next Generation Space Telescope (NGST) development programs (NMSD, SBMD, AMSD, etc.) and the establishment of the Space Optics Manufacturing Technology Center at MSFC have led to an XRCF modification. In 1999 the facility was upgraded to perform cryogenic testing of lightweight visible optics (without compromising the existing x-ray testing capability). A thermal enclosure capable of 20 degrees Kelvin and vibration isolated instrumentation mount were added. A vacuum-compatible five-axis motion table was modified to operate under cryogenic conditions. Optics up to two meters in diameter with radii of curvature of up to twenty meters can be accommodated. Facility characterization tests and one NGST program mirror test have been completed to date. By July 2000, two other mirrors will be tested. Optical wavefront measurements were made at < 35 degrees Kelvin with several instruments located at the test mirror's radius of curvature. The current wavefront measuring instruments include a Shack-Hartman wavefront sensor, a point diffraction interferometer, a point spread function-measuring device, and a radius of curvature measuring instrument. A vibration insensitive phase shifting interferometer is planned for future optical testing. This paper will present a brief history of the facility, a discussion of its current x-ray optic testing capabilities, and a complete description of the new capabilities in the visible optical testing regime.

Eng, Ronnie↗
NASA NTRS2002

Distant Cluster Hunting: A Comparison of X-Ray and Optical Cluster Detection Techniques and Catalogs from the ROSAT Optical X-Ray Survey - II

We present and analyze the optical and X-ray catalogs of moderate-redshift cluster candidates from the ROSA TOptical X-Ray Survey, or ROXS. The survey covers the sky area contained in the fields of view of 23 deep archival ROSA T PSPC pointings, 4.8 square degrees. The cross-correlated cluster catalogs were con- structed by comparing two independent catalogs extracted from the optical and X-ray bandpasses, using a matched-filter technique for the optical data and a wavelet technique for the X-ray data. We cross-identified cluster candidates in each catalog. As reported in Paper 1, the matched-filter technique found optical counter- parts for at least 60% (26 out of 43) of the X-ray cluster candidates; the estimated redshifts from the matched filter algorithm agree with at least 7 of 1 1 spectroscopic confirmations (Az 5 0.10). The matched filter technique. with an imaging sensitivity of ml N 23, identified approximately 3 times the number of candidates (155 candidates, 142 with a detection confidence >3 u) found in the X-ray survey of nearly the same area. There are 57 X-ray candidates, 43 of which are unobscured by scattered light or bright stars in the optical images. Twenty-six of these have fairly secure optical counterparts. We find that the matched filter algorithm, when applied to images with galaxy flux sensitivities of mI N 23, is fairly well-matched to discovering z 5 1 clusters detected by wavelets in ROSAT PSPC exposures of 8000-60,000 s. The difference in the spurious fractions between the optical and X-ray (30%) and IO%, respectively) cannot account for the difference in source number. In Paper I, we compared the optical and X-ray cluster luminosity functions and we found that the luminosity functions are consistent if the relationship between X-ray and optical luminosities is steep (Lx o( L&f). Here, in Paper 11, we present the cluster catalogs and a numerical simulation of the ROXS. We also present color-magnitude plots for several of the cluster candidates, and examine the prominence of the red sequence in each. We find that the X-ray clusters in our survey do not all have a prominent red sequence. We conclude that while the red sequence may be a distinct feature in the color-magnitude plots for virialized massive clusters, it may be less distinct in lower mass clusters of galaxies at even moderate redshifts. Multiple, complementary methods of selecting and defining clusters may be essential, particularly at high redshift where all methods start to run into completeness limits, incomplete understanding of physical evolution, and projection effects.

Donahue, Megan↗
NASA NTRS2018

Optical Performance Prediction of the Thirty Meter Telescope after Initial Alignment Using Optical Modeling

We present an estimate of the optical performance of the Thirty Meter Telescope (TMT) after execution of the full telescope alignment plan. The TMT alignment is performed by the Global Metrology System (GMS) and the Alignment and Phasing System (APS). The GMS first measures the locations of the telescope optics and instruments as a function of elevation angle. These initial measurements will be used to adjust the optics positions and build initial elevation look-up tables. Then the telescope is aligned using starlight as the input for the APS at multiple elevation angles. APS measurements are used to refine the telescope alignment to build elevation and temperature dependent look-up tables. Due to the number of degrees of freedom in the telescope (over 10,000), the ability of the primary mirror to correct aberrations on other optics, the tight optical performance requirements and the multiple instrument locations, it is challenging to develop, test and validate these alignment procedures. In this paper, we consider several GMS and APS operational scenarios. We apply the alignment procedures to the model-generated TMT, which consists of various quasi-static errors such as polishing errors, passive supports errors, thermal and gravity deformations and installation position errors. Using an integrated optical model and Monte-Carlo framework, we evaluate the TMT’s aligned states using optical performance metrics at multiple instrument and field of view locations. The optical performance metrics include the Normalized Point Source Sensitivity (PSSN), RMS wavefront error before and after Adaptive Optics (AO) correction, pupil position change, and plate scale distortion.

Rogers, John↗
NASA NTRSDate not supplied

Initial Test Results for NASA Goddard’s Low-Cost Optical Terminal Adaptive Optics System

This presentation presents the testing approach and initial laboratory test results of the Adaptive Optics (AO) Subassembly (AOS) for the Low-Cost Optical Terminal (LCOT), a low-cost and flexible optical communications ground terminal. Leveraging commercial components and subassemblies wherever possible, LCOT is being developed by the NASA Goddard Space Flight Center (GSFC) Advanced Communications Capabilities for Exploration and Science Systems (ACCESS) project. An economical ground terminal allows NASA to create a global optical terminal network and enables the expansion of direct-to-Earth (DTE) optical communications. Located at the Goddard Geophysical and Astronomical Observatory (GGAO), LCOT is in the development phase and will receive first light during initial testing beginning in 2023. This new optical terminal includes a 700 mm Ritchey-Chretien commercial telescope, able to track Low Earth Orbit (LEO) spacecraft, receive instruments specified from 1500 - 1600 nm, and an uplink transmit optical system. Demodulation of optical coherent modulation formats requires downlink signal coupling into single-mode fiber. Due to atmospheric turbulence, signals experience wavefront distortions creating speckle patterns larger than the fiber core and high jitter requiring precise beam steering. AO is necessary to correct atmospheric turbulence effects and allow efficient coupling of received signals. In 2020, GSFC contracted with General Atomics to provide the LCOT AO system. This system has been delivered to GSFC in September 2021 and has been tested in laboratory to evaluate performance. This paper describes the laboratory testing approach, turbulence phase plate design, test results, and the AO field testing plan when installed on the LCOT telescope.

Adaptive Optics↗
DOE OSTI2017

Controlled optical properties via chemical composition tuning in molybdenum-incorporated β-Ga 2 O 3 nanocrystalline films

An approach is presented to design refractory-metal incorporated Ga2O3-based materials with controlled structural and optical properties. The molybdenum (Mo)-content in Ga2O3 was varied from 0 to 11 at% in the sputter-deposited Ga-Mo-O films. Molybdenum was found to significantly affect the structure and optical properties. While low Mo-content (≤4 at%) results in the formation of single-phase (β-Ga2O3), higher Mo-content results in amorphization. Chemically-induced band gap variability (Eg~1 eV) coupled with structure-modification indicates the electronic-structure changes in Ga-Mo-O. The linear relationship between chemical-composition and optical properties suggests that tailoring the optical-quality and performance of Ga-Mo-O films is possible by tuning the Mo-content.

Environmental Molecular Sciences Laboratory↗
DOE OSTI2019

Optical properties and radiative forcing of fractal-like tar ball aggregates from biomass burning

Tar balls are frequently found in slightly aged biomass burning plumes. They are spherical in shape, have diameters between ~100 and 300 nm, are amorphous and composed mostly of oxygen and carbon. Tar balls are light absorbing and considered to be a component of brown carbon. Tar balls have been typically reported and analyzed as individual spheres; however, in a recent study, we reported the presence of significant fractions of fractal-like tar ball aggregates in fire plumes from different geographical locations. Aggregation affects the optical properties of particles; therefore, we use T-Matrix and Lorenz-Mie simulations to explore the effects of aggregation on the tar balls’ optical properties in the 350 – 1150 nm wavelength range. We also evaluate the effects of different index of refraction values available from the literature, different monomer numbers, and monomer sizes, as these are key factors determining the aggregates optical properties. Furthermore, we estimate the direct radiative forcing for low and high surface albedos. The single scattering albedo of aggregates exceed by up to 77% that of individual tar balls. The hemispherical upscatter fraction of tar ball aggregates are more than 100% larger than for individual tar balls in many cases. The top of the atmosphere simple forcing efficiency over dark surfaces shows large variabilities with differences up to ~53% between the tar ball aggregates and individual tar balls. These results demonstrate that aggregation of tar balls can have a significant impact on their optical properties and radiative forcing.

Tar balls, aggregates, brown carbon, biomass burni↗
DOE OSTI2022

FORTE Measurements of Global Optical Lightning Waveforms and Implications for Optical Lightning Detection

Lightning processes generate a diverse collection of optical pulses from current traversing the lightning channels. These signals are then broadened spatially and temporally via scattering in the clouds. The resulting waveforms measured from space with instruments like the photodiode detector (PDD) on the Fast On-orbit Recording of Transient Events (FORTE) satellite have a variety of shapes. In this study, we use coincident optical and Radio-Frequency measurements to document the properties of optical PDD waveforms associated with different types of lightning, estimate delays from scattering in the clouds, and comment on how pulse shape impacts optical lightning detection. We find that the attributes of optical pulses recorded by the PDD are consistent with prior studies, but vary globally and with event amplitude. The most powerful lightning tends to be single-peaked with faster rise times (median: ~100 µs) and shorter effective widths (median: ~400 µs) than normal lightning. Particularly dim events, meanwhile, include cases of broad optical waveforms with sustained optical emission throughout the PDD record, which the pixelated FORTE Lightning Location System (LLS) instrument has difficulty detecting. We propose that this is due to the optical signal being divided between individual LLS pixels that are each, individually, not bright enough to trigger. We use PDD waveforms and Monte Carlo radiative transfer modeling to demonstrate that increasing the temporal and spatial resolution of a pixelated lightning imager will make it more difficult to detect these broad/dim pulses as their energy becomes divided between additional pixels/integration frames.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2022

High-efficiency microwave-optical quantum transduction based on a cavity electro-optic superconducting system with long coherence time

Abstract Frequency conversion between microwave and optical photons is a key enabling technology to create links between superconducting quantum processors and to realize distributed quantum networks. We propose a microwave-optical transduction platform based on long-coherence time superconducting radio-frequency (SRF) cavities coupled to electro-optic optical cavities to mitigate the loss mechanisms that limit the attainment of high conversion efficiency. We optimize the microwave-optical field overlap and optical coupling losses in the design while achieving long microwave and optical photon lifetime at milli-Kelvin temperatures. This represents a significant enhancement of the transduction efficiency up to 50% under incoming pump power of 140 μW, which allows the conversion of few-photon quantum signals. Furthermore, this scheme exhibits high resolution for optically reading out the dispersive shift induced by a superconducting transmon qubit coupled to the SRF cavity. We also show that low microwave losses enhance the fidelity of heralded entanglement generation between two remote quantum systems. Finally, high precision in quantum sensing can be reached below the standard quantum limit.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2016

Stabilisation of a fibre frequency synthesiser using acousto-optical and electro-optical modulators

A fibre-optic frequency synthesiser is developed that is stabilised to the optical frequency standard based on molecular iodine (Nd : YAG/I{sub 2}). The possibility of transferring stability of the optical frequency standard to other optical frequencies in the IR range 1−2 μm and to the RF range by using synthesiser phase-locked loops (PLLs) with acousto-optical and electro-optical modulators is experimentally demonstrated. The additive instability introduced into the optical frequency comb of the synthesiser (which arises due to PLL residual random errors) is several orders less than the intrinsic instability of the reference optical frequency standard employed (i.e., is noticeably less than 1×10{sup −13} for 1 s and 5×10{sup −15} for 1000 s). (paper)

42 ENGINEERING↗
DOE OSTI2017

EXPRESS: Accurate Measurement of the Optical Constants n and k for a Series of 57 Inorganic and Organic Liquids for Optical Modeling and Detection

For optical modeling and other purposes, we have created a library of 57 liquids for which we have measured the complex optical constants n and k. These liquids vary in their nature, ranging in properties including chemical structure, optical band strength, volatility and viscosity. By obtaining the optical constants one can in principle model most optical phenomena in media and at interfaces including reflection, refraction and dispersion. Based on the original methods of J.E. Bertie et al.1 [1Bert1], we have developed improved protocols using multiple path lengths to determine the optical constants n/k for dozens of liquids, including inorganic, organic and organophosphorus compounds. Detailed descriptions of the measurement and data reduction protocols are discussed; agreement of the derived optical constant n and k values with literature values are presented. We also present results using the n/k values as applied to an optical modeling scenario whereby the derived data are presented and tested for models of 1 µm and 100 µm layers for DMMP (dimethyl methyl phosphonate) on both metal (aluminum) and dielectric (soda lime glass) substrates to show substantial differences between the reflected signal from highly reflective substrates and less-reflective substrates.

infrared↗
NASA NTRS2016

An Optical Receiver Post-Processing System for the Integrated Radio and Optical Communications Software Defined Radio Test Bed

The Integrated Radio and Optical Communications (iROC) project at the National Aeronautics and Space Administration's (NASA) Glenn Research Center is investigating the feasibility of a hybrid radio frequency (RF) and optical communication system for future deep space missions. As a part of this investigation, a test bed for a radio frequency (RF) and optical software defined radio (SDR) has been built. Receivers and modems for the NASA deep space optical waveform are not commercially available so a custom ground optical receiver system has been built. This paper documents the ground optical receiver, which is used in order to test the RF and optical SDR in a free space optical communications link.

optical communication↗
NASA NTRS2016

An Optical Receiver Post Processing System for the Integrated Radio and Optical Communications Software Defined Radio Test Bed

The Integrated Radio and Optical Communications (iROC) project at the National Aeronautics and Space Administrations (NASA) Glenn Research Center is investigating the feasibility of a hybrid radio frequency (RF) and optical communication system for future deep space missions. As a part of this investigation, a test bed for a radio frequency (RF) and optical software defined radio (SDR) has been built. Receivers and modems for the NASA deep space optical waveform are not commercially available so a custom ground optical receiver system has been built. This paper documents the ground optical receiver, which is used in order to test the RF and optical SDR in a free space optical communications link.

waveforms↗
DOE OSTI2017

A unified materials approach to mitigating optical nonlinearities in optical fiber. III. Canonical examples and materials road map

Abstract This paper, Part III in the Trilogy (Ballato, Cavillon, Dragic, 2018; Dragic, Cavillon, Ballato, et al ., 2018a,b), provides a road map for the development of simple core/clad optical fibers whose enhanced performance—in particular, marked reductions in optical nonlinearities—is achieved materially and not through the more conventional present routes of geometrically complex fiber design. More specifically, the material properties that give rise to Brillouin, Raman and Rayleigh scattering, transverse mode instabilities ( TMI ), and n 2 ‐mediated nonlinear effects are compiled and results on a wide range of optical fibers are discussed with a focus on trends in performance with glass composition. Furthermore, optical power scaling estimations as well as binary and ternary property diagrams associated with Rayleigh scattering, the Brillouin gain coefficient ( BGC ) and the thermo‐optic coefficient (d n /d T ) are developed and employed to graphically represent general trends with composition along with compositional targets for a single intrinsically low nonlinearity, silica‐based optical fiber that can achieve the power scaling goals of future high energy fiber laser applications. A foundational finding of this work is that the high‐silica content optical fibers fabricated using conventional chemical vapor deposition methods will not suffice to meet the power scaling demands of future high‐power and high‐energy fiber lasers.

36 MATERIALS SCIENCE↗
DOE OSTI2017

Ligand-Enhanced Optical Response of Gold Nanomolecules and Its Fragment Projection Analysis: The Case of Au 30 (SR) 18

We investigate via first-principles simulations the optical absorption spectra of three different Au 30 (SR) 18 monolayer-protected clusters (MPC): Au 30 (StBu) 18 , Au 30 (SPh) 18 , and Au 30 (SPh-pNO 2 ) 18 . Au 30 (StBu) 18 is known in the literature, and its crystal structure is available. In contrast, Au 30 (SPh) 18 and Au 30 (SPh-pNO 2 ) 18 are two species that have been designed by replacing the tert-butyl organic residues of Au 30 (StBu) 18 with aromatic ones so as to investigate the effects of ligand replacement on the optical response of Au nanomolecules. By analogy to a previously studied Au 23 (SR)16– anionic species, despite distinct differences in charge and chemical composition, a substantial ligand enhancement of the absorption intensity in the optical region is also obtained for the Au 30 (SPh-pNO 2 ) 18 MPC. Furthermore, the use of conjugated aromatic ligands with properly chosen electron-withdrawing substituents and exhibiting steric hindrance so as to also achieve charge decompression at the surface is therefore demonstrated as a general approach to enhancing the MPC photoabsorption intensity in the optical region. In addition, we here subject the ligand-enhancement phenomenon to a detailed analysis based on the fragment projection of electronic excited states and on induced transition densities, leading to a better understanding of the physical origin of this phenomenon, thus opening avenues to its more precise control and exploitation.

36 MATERIALS SCIENCE↗
NASA NTRS1977

Fiber optic multiplex optical transmission system

A multiplex optical transmission system which minimizes external interference while simultaneously receiving and transmitting video, digital data, and audio signals is described. Signals are received into subgroup mixers for blocking into respective frequency ranges. The outputs of these mixers are in turn fed to a master mixer which produces a composite electrical signal. An optical transmitter connected to the master mixer converts the composite signal into an optical signal and transmits it over a fiber optic cable to an optical receiver which receives the signal and converts it back to a composite electrical signal. A de-multiplexer is coupled to the output of the receiver for separating the composite signal back into composite video, digital data, and audio signals. A programmable optic patch board is interposed in the fiber optic cables for selectively connecting the optical signals to various receivers and transmitters.

Bell, C. H.↗
NASA NTRS1991

Optical and mechanical response of high temperature optical fiber sensors

The National Aerospace Plane (NASP) will experience temperatures as high as 2500 F at critical locations in its structure. Optical fiber sensors were proposed as a means of monitoring the temperature in these critical regions by either bonding the optical fiber to, or embedding the optical fiber in, metal matrix composite (MMC) components. Unfortunately, the anticipated NASP temperature ranges exceed the glass transition region of the optical fiber glass. The attempt is made to define the operating temperature range of optical fiber sensors from both optical and mechanical perspectives. A full non-linear optical analysis was performed by modeling the optical response of an isolated sensor cyclically driven through the glass transition region.

Sirkis, Jim↗