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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 541 records · Page 30
All sourcesNASA NTRSDOE OSTI
NASA NTRS2010

Vacuum-Compatible Wideband White Light and Laser Combiner Source System

For the Space Interferometry Mission (SIM) Spectrum Calibration Development Unit (SCDU) testbed, wideband white light is used to simulate starlight. The white light source mount requires extremely stable pointing accuracy (<3.2 microradians). To meet this and other needs, the laser light from a single-mode fiber was combined, through a beam splitter window with special coating from broadband wavelengths, with light from multimode fiber. Both lights were coupled to a photonic crystal fiber (PCF). In many optical systems, simulating a point star with broadband spectrum with stability of microradians for white light interferometry is a challenge. In this case, the cameras use the white light interference to balance two optical paths, and to maintain close tracking. In order to coarse align the optical paths, a laser light is sent into the system to allow tracking of fringes because a narrow band laser has a great range of interference. The design requirements forced the innovators to use a new type of optical fiber, and to take a large amount of care in aligning the input sources. The testbed required better than 1% throughput, or enough output power on the lowest spectrum to be detectable by the CCD camera (6 nW at camera). The system needed to be vacuum-compatible and to have the capability for combining a visible laser light at any time for calibration purposes. The red laser is a commercially produced 635-nm laser 5-mW diode, and the white light source is a commercially produced tungsten halogen lamp that gives a broad spectrum of about 525 to 800 nm full width at half maximum (FWHM), with about 1.4 mW of power at 630 nm. A custom-made beam splitter window with special coating for broadband wavelengths is used with the white light input via a 50-mm multi-mode fiber. The large mode area PCF is an LMA-8 made by Crystal Fibre (core diameter of 8.5 mm, mode field diameter of 6 mm, and numerical aperture at 625 nm of 0.083). Any science interferometer that needs a tracking laser fringe to assist in alignment can use this system.

Azizi, Alineza↗
NASA NTRS1994

(abstract) Pluto Integrated Camera-Spectrometer (PICS): a Low Mass, Low Power Instrument for Planetary Exploration

The concept we describe is an integrated instrument (a Pluto Integrated Camera-Spectrometer -- PICS) that will perform the functions of all three optical instruments required by the Pluto Fast Flyby Mission: the near-IR spectrometer, the camera, and the UV spectrometer. This integrated approach minimizes mass and power use. It also forced us early in the conceptual design to consider integrated observational sequences and integrated power management, thus ensuring compatible duty cycles (i.e., exposure times, readout rates) to meet the composite requirements for data collection, compression, and storage. Based on flight mission experience we believe that this integrated approach will result in substantial cost savings, both in reworking instrument designs during accommodation, as well as in sequence planning and integration. Finally, this integrated payload automatically yields a cohesive mission data set, optimized for correlative analysis. The presentation will provide details of the PICS instrument design and describe the fabrication and testing of the integrated SiC structure and optics at SSG Inc. Final integration and test plans for the prototype will also be described.

Pluto↗
DOE OSTI2022

Searching for multimessenger transients and lensed supernovae with the dark energy survey

Advances in data collection technology for optical astronomy, such as the Dark Energy Camera, have facilitated the collection of some of the largest astronomical datasets in terms of sky area, depth, number of objects, number of observations, and frequency of observations. Consequentially, physical systems that have been historically rare become represented in small, but discoverable, numbers. I have developed techniques to identify rare physical systems (counterparts to high-energy neutrinos, counterparts to gravitational waves, and gravitationally lensed supernovae) that can shed new light on the physical processes that govern the Universe. For each system of interest, I collect new or search archival observations with the Dark Energy Camera, develop selection methodologies to find the system of interest in the observations, and quantify the efficiency of the search using simulations. Each of the three analyses has its own scientific implications: I constrain the observing program required to determine the contribution of supernovae to the diffuse high-energy neutrino flux; I set constraints on the physical properties of an optical counterpart to a compact object merger; and I identify candidate lensed supernovae using a novel machine learning technique. Looking forward, the work presented in this dissertation informs future rare object searches and facilitates measurements of the underlying properties of the Universe during the next era of optical survey astronomy.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
NASA NTRS2019

Successful Use of Microporous Polytetrafluoroethylene Flexible Thin Sheets in NASA's OSIRIS-REx Mission

Microporous black polytetrafluoroethylene (PTFE) flexible thin sheets are successfully flown as solar diffusers on NASA's Origins, Spectral Interpretation, Resource Identification, and Security-Regolith Explorer (OSIRIS-REx) spacecraft. They serve as multilayer insulation (MLI) blanket outer covers for the arm of the Touch And Go Sample Acquisition Mechanism (TAGSAM), the sunshade of the OSIRIS-REx Camera Suite (OCAMS) PolyCam imager, and the motor riser of the OCAMS SamCam imager. Additionally, microporous white PTFE flexible thin sheets are successfully flown as a MLI blanket outer cover with a low ratio of absorptance to emittance for the Regolith X-ray Imaging Spectrometer (REXIS). For ground testing, microporous black and white PTFE flexible thin sheets were successfully used as optical targets of the Touch And Go Camera System (TAGCAMS) NavCam imagers in the flight system thermal vacuum test.

OSIRIS-REx↗
NASA NTRS1976

Space telescope optical telescope assembly/scientific instruments. Phase B: Preliminary design and program definition study. Volume 2A. focal plane camera

Trade studies were conducted to ensure the overall feasibility of the focal plane camera in a radial module. The primary variable in the trade studies was the location of the pickoff mirror, on axis versus off-axis. Two alternatives were: (1) the standard (electromagnetic focus) SECO submodule, and (2) the MOD 15 permanent magnet focus SECO submodule. The technical areas of concern were the packaging affected parameters of thermal dissipation, focal plane obscuration, and image quality.

Source record↗
NASA NTRS1992

Water window imaging x ray microscope

A high resolution x ray microscope for imaging microscopic structures within biological specimens has an optical system including a highly polished primary and secondary mirror coated with identical multilayer coatings, the mirrors acting at normal incidence. The coatings have a high reflectivity in the narrow wave bandpass between 23.3 and 43.7 angstroms and have low reflectivity outside of this range. The primary mirror has a spherical concave surface and the secondary mirror has a spherical convex surface. The radii of the mirrors are concentric about a common center of curvature on the optical axis of the microscope extending from the object focal plane to the image focal plane. The primary mirror has an annular configuration with a central aperture and the secondary mirror is positioned between the primary mirror and the center of curvature for reflecting radiation through the aperture to a detector. An x ray filter is mounted at the stage end of the microscope, and film sensitive to x rays in the desired band width is mounted in a camera at the image plane of the optical system. The microscope is mounted within a vacuum chamber for minimizing the absorption of x rays in air from a source through the microscope.

Hoover, Richard B.↗
NASA NTRS1998

Event Pileup in AXAF's ACIS CCD Camera

AXAF's high resolution mirrors will focus a point source near the optical axis to a spot that is contained within a radius of about two pixels on the ACIS Charge Coupled Devices (CCD) camera. Because of the small spot size, the accuracy to which fluxes and spectral energy distributions of bright point sources can be measured will be degrad3ed by event pileup. Event pileup occurs when two or more X-ray photons arrive simultaneously in a single detection cell on a CCD readout frame. When pileup occurs, ACIS's event detection algorithm registers the photons as a single X-ray event. The pulse height channel of the event will correspond to an energy E approximately E-1 + E-2...E-n, where n is the number of photons registered per detection cell per readout frame. As a result, pileup artificially hardens the observed spectral energy distribution. I will discuss the effort at the AXAF Science Center Lo calibrate pileup in ACIS using focused, nearly monochromatic X-ray source. I will discuss techniques for modeling and correcting pileup effects in polychromatic spectra.

McNamara, Brian R.↗
NASA NTRS2018

Optical Alignment of the High-Precision UV Spectro-Polarimeter (CLASP2)

Chromospheric LAyer Spectro-Polarimeter (CLASP2) is our next sounding rocket experiment after the success of Chromospheric Lyman-Alpha Spectro-Polarimeter (CLASP1). CLASP2 is scheduled to launch in 2019, and aims to achieve high precision measurements of the linear and circular polarizations in the Mg II h & k lines near the 280 nm, whose line cores originate in the upper solar chromosphere. The CLASP2 spectro-polarimeter follows very successful design concept of the CLASP1 instrument with the minimal modification. A new grating was fabricated with the same radius of curvature as the CLASP1 grating, but with a different ruling density. This allows us to essentially reuse the CLASP1 mechanical structures and layout of the optics. However, because the observing wavelength of CLASP2 is twice longer than that of CLASP1, a magnifier optical system was newly added in front of the cameras to double the focal length of CLASP2 in order to maintain the same wavelength resolution as CLASP1 (0.01 nm). Meanwhile, a careful optical alignment of the specto-polarimeter is required to reach the 0.01 nm wavelength resolution. Therefore, we established an efficient alignment procedure for the CLASP2 spectro-polarimeter based on an experience of CLASP1. Here, we explain in detail the methods for achieving the optical alignment of the CLASP2 spectro-polarimeter and discuss our results by comparing with the performance requirements.

chromosphere; polarimetry; sounding rocket↗
NASA NTRSDate not supplied

Evaluation of a Laser-Dot Grid-Projection System for Lunar Lander Crater-Shape and Ejecta-Sheet Measurements

Development, testing, and evaluation of an active-illumination laser-dot grid-projection system was performed to evaluate its potential inclusion on an upcoming uncrewed lunar lander mission to the south pole region of the moon. Active illumination may be required for this mission due to the shallow angle of the sun at the landing location, which may cast shadows in the landing region, hindering the stereo camera imaging system’s ability to determine the pre-and post-landing lunar surface/crater shape. Testing includes characterization of the diffractive optical elements used for the grid projection, single-camera tests to determine the imaged laser dot intensity as a function of camera exposure and imaging angle relative to the laser grid projection, laser dot brightness/saturation impact on depth map calculations, angle of imaged laser grid impact on depth map calculations for steep crater edges, impact of density gradients on the depth map calculations, and the feasibility of making measurements of the ejecta sheet.

Joshua M. Weisberger↗
NASA NTRS1989

Joint-transform correlator systems using deformable-mirror spatial light modulators

Two joint-transform correlator systems based on deformable-mirror-device (DMD) spatial light modulators and CCD video cameras are described. The system designs provide for real-time correlation between video-formatted input scenes and stored reference images. The DMD light modulators are used exclusively for inputting data in the optical stages of these systems, and the CCD cameras are used to provide the critical square-law detection required in joint-transform achitectures. Experimental verification of the functionality of these DMD/CCD joint-transform systems is also presented.

Florence, James M.↗
NASA NTRS1993

Optical attenuation mechanism upgrades, MOBLAS, and TLRS systems

This poster presentation describes the Optical Attenuation Mechanism (OAM) Upgrades to the MOBLAS and TLRS Crustal Dynamics Satellite Laser Ranging (CDSLR) systems. The upgrades were for the purposes of preparing these systems to laser range to the TOPEX/POSEIDON spacecraft when it will be launched in the summer of 1992. The OAM permits the laser receiver to operate over the expected large signal dynamic range from TOPEX/POSEIDON and it reduces the number of pre- and post-calibrations for each satellite during multi-satellite tracking operations. It further simplifies the calibration bias corrections that had been made due to the pass-to-pass variation of the photomultiplier supply voltage and the transmit filter glass thickness. The upgrade incorporated improvements to the optical alignment capability of each CDSLR system through the addition of a CCD camera into the MOBLAS receive telescope and an alignment telescope onto the TLRS optical table. The OAM is stepper motor and microprocessor based; and the system can be controlled either manually by a control switch panel or computer controlled via an EIA RS-232C serial interface. The OAM has a neutral density (ND) range of 0.0 to 4.0 and the positioning is absolute referenced in steps of 0.1 ND. Both the fixed transmit filter and the daylight filter are solenoid actuated with digital inputs and outputs to and from the OAM microprocessor. During automated operation, the operator has the option to overide the remote control and control the OAM system via a local control switch panel.

Eichinger, Richard↗
NASA NTRS2016

Overview of LBTI: A Multipurpose Facility for High Spatial Resolution Observations

The Large Binocular Telescope Interferometer (LBTI) is a high spatial resolution instrument developed for coherent imaging and nulling interferometry using the 14.4 m baseline of the 2x8.4 m LBT. The unique telescope design, comprising of the dual apertures on a common elevation-azimuth mount, enables a broad use of observing modes. The full system is comprised of dual adaptive optics systems, a near-infrared phasing camera, a 1-5 micrometer camera (called LMIRCam), and an 8-13 micrometer camera (called NOMIC). The key program for LBTI is the Hunt for Observable Signatures of Terrestrial planetary Systems (HOSTS), a survey using nulling interferometry to constrain the typical brightness from exozodiacal dust around nearby stars. Additional observations focus on the detection and characterization of giant planets in the thermal infrared, high spatial resolution imaging of complex scenes such as Jupiter's moon, Io, planets forming in transition disks, and the structure of active Galactic Nuclei (AGN). Several instrumental upgrades are currently underway to improve and expand the capabilities of LBTI. These include: Improving the performance and limiting magnitude of the parallel adaptive optics systems; quadrupling the field of view of LMIRcam (increasing to 20"x20"); adding an integral field spectrometry mode; and implementing a new algorithm for path length correction that accounts for dispersion due to atmospheric water vapor. We present the current architecture and performance of LBTI, as well as an overview of the upgrades.

The Large Binocular Telescope Interferometer (LBTI↗
NASA NTRS1981

Simultaneous X-ray, ultraviolet, optical, and radio observations of the flare star Proxima Centauri

Results of coordinated program of observations in the X-ray, UV, optical and radio regions of the dM5e flare star Proxima Centauri are presented. Simultaneous observations of the star were obtained on March 6 and March 7, 1979, by the Einstein Observatory IPC, the IUE SWP and LWR cameras at low dispersion, three ground-based optical telescopes in Australia and the Parkes 64-m radio telescope. A total of 10 radio bursts and six optical flares was detected during three nights of simultaneous radio and optical observations, which appear to be broadly correlated. A major X-ray flare event was detected with temperatures of 1.7 x 10 to the 7th and 1.2 x 10 to the 7th K during the rise and decay phases, respectively, respective X-ray fluxes of 3.0 x 10 to the -11th and 3.7 x 10 to the -11th ergs/sq cm per sec, and changes in spectral flux distribution. No radio, optical or UV flare emission corresponding to the X-ray flare was detected. The X-ray flare is interpreted in terms of an arch model with cooling predominantly by X-ray radiation, with an electron density of 1.0 x 10 to the 11th/cu cm during the decay phase and a total arch length comparable to the size of the star itself. The X-ray flare observed is thus more similar to a typical strong solar flare than heretofore seen on a flare star.

Haisch, B. M.↗
NASA NTRS1992

High resolution imaging at Palomar

For the last two years we have embarked on a program of understanding the ultimate limits of ground-based optical imaging. We have designed and fabricated a camera specifically for high resolution imaging. This camera has now been pressed into service at the prime focus of the Hale 5 m telescope. We have concentrated on two techniques: the Non-Redundant Masking (NRM) and Weigelt's Fully Filled Aperture (FFA) method. The former is the optical analog of radio interferometry and the latter is a higher order extension of the Labeyrie autocorrelation method. As in radio Very Long Baseline Interferometry (VLBI), both these techniques essentially measure the closure phase and, hence, true image construction is possible. We have successfully imaged binary stars and asteroids with angular resolution approaching the diffraction limit of the telescope and image quality approaching that of a typical radio VLBI map. In addition, we have carried out analytical and simulation studies to determine the ultimate limits of ground-based optical imaging, the limits of space-based interferometric imaging, and investigated the details of imaging tradeoffs of beam combination in optical interferometers.

Kulkarni, Shrinivas R.↗
DOE OSTI2024

FiberFlex: Real-time FPGA-based Intelligent and Distributed Fiber Sensor System for Pedestrian Recognition

In recent years, security monitoring of public places and critical infrastructure has heavily relied on the widespread use of cameras, raising concerns about personal privacy violations. To balance the need for effective security monitoring with the protection of personal privacy, we explore the potential of optical fiber sensors for this application. This article proposes FiberFlex, an intelligent and distributed fiber sensor system. Ultizing Field Programmable Gate Arrays (FPGA) high-level synthesis (HLS) acceleration, FiberFlex offers real-time pedestrian detection by co-designing the entire pipeline of optical signal acquisition, processing, and recognition networks based on the principles of optical fiber sensing. As a promising alternative to traditional camera-based monitoring systems, FiberFlex achieves pedestrian detection by analyzing the vibration patterns caused by pedestrian footsteps, enabling security monitoring while preserving individual privacy. FiberFlex comprises three modules: First , fiber-optic sensing system: A fiber-optic distributed acoustic sensing (DAS) system is built and used to measure the ground vibration waves generated by people walking. Second , algorithms: We first collect the training data by measuring the ground vibration waves, label the data, and use the data to train the neural network models to perform pedestrian recognition. Third , hardware accelerators: We use HLS tools to design hardware modules on FPGA for data collection and pre-processing and integrate them with the downstream neural network accelerators to perform in-line real-time pedestrian detection. The final detection results are sent back from FPGA to the host CPU. We implement our system FiberFlex with the in-house built DAS system and AMD/Xilinx Kintex7 FPGA KC705 board and verify the whole system using the real-world collected data. We conduct recognition tests on five test subjects of varying ages, heights, and weights in a fixed sensing area. Each subject experienced 20 real-time recognition tests using their daily walking habits, and the subjects were given adequate rest between tests. After 100 tests on five test subjects, the overall real-time recognition accuracy exceeded \(88.0\%\) . The whole system uses 55 W of power, 33 W in the optical DAS system and 22 W in the FPGA. Relying on its end-to-end interdisciplinary design, FiberFlex seamlessly combines fiber-optic sensors with FPGA accelerators to enable low-power real-time security monitoring without compromising privacy, making it a valuable addition to the existing security monitoring network. According to FiberFlex, more valuable research can be conducted in the future, such as fall monitoring for the elderly, migration of identification networks between different application scenarios, and improvement of anti-interference performance in more complex environments. In future perception networks, where the “eyes” are not feasible, let’s use fiber optic touch instead.

Distributed↗
NASA NTRS2004

Effect of Clouds on Optical Imaging of the Space Shuttle During the Ascent Phase: A Statistical Analysis Based on a 3D Model

Clouds are highly effective in obscuring optical images of the Space Shuttle taken during its ascent by ground-based and airborne tracking cameras. Because the imagery is used for quick-look and post-flight engineering analysis, the Columbia Accident Investigation Board (CAIB) recommended the return-to-flight effort include an upgrade of the imaging system to enable it to obtain at least three useful views of the Shuttle from lift-off to at least solid rocket booster (SRB) separation (NASA 2003). The lifetimes of individual cloud elements capable of obscuring optical views of the Shuttle are typically 20 minutes or less. Therefore, accurately observing and forecasting cloud obscuration over an extended network of cameras poses an unprecedented challenge for the current state of observational and modeling techniques. In addition, even the best numerical simulations based on real observations will never reach "truth." In order to quantify the risk that clouds would obscure optical imagery of the Shuttle, a 3D model to calculate probabilistic risk was developed. The model was used to estimate the ability of a network of optical imaging cameras to obtain at least N simultaneous views of the Shuttle from lift-off to SRB separation in the presence of an idealized, randomized cloud field.

FROM↗
NASA NTRS2004

Imaging System For Measuring Macromolecule Crystal Growth Rates in Microgravity

In order to determine how macromolecule crystal quality improvement in microgravity is related to crystal growth characteristics, a team of scientists and engineers at NASA's Marshal Space Flight Center (MSFC) developed flight hardware capable of measuring the crystal growth rates of a population of crystals growing under the same conditions. As crystal growth rate is defined as the change or delta in a defined dimension or length (L) of crystal over time, the hardware was named Delta-L. Delta-L consists of three sub assemblies: a fluid unit including a temperature-controlled growth cell, an imaging unit, and a control unit (consisting of a Data Acquisition and Control Unit (DACU), and a thermal control unit). Delta-L will be used in connection with the Glovebox Integrated Microgravity Isolation Technology (g-LIMIT) inside the Microgravity Science Glovebox (MSG), onboard the International Space Station. This paper will describe the Delta-L imaging system. The Delta-L imaging system was designed to locate, resolve, and capture images of up to 10 individual crystals ranging in size from 10 to 500 microns with a point-to-point accuracy of +/- 2.0 microns within a quartz growth cell observation area of 20 mm x 10 mm x 1 mm. The optical imaging system is comprised of a video microscope camera mounted on computer controlled translation stages. The 3-axis translation stages and control units provide crewmembers the ability to search throughout the growth cell observation area for crystals forming in size of approximately 10 microns. Once the crewmember has selected ten crystals of interest, the growth of these crystals is tracked until the size reaches approximately 500 microns. In order to resolve these crystals an optical system with a magnification of 10X was designed. A black and white NTSC camera was utilized with a 20X microscope objective and a 0.5X custom designed relay lens with an inline light to meet the magnification requirement. The design allows a 500 pm crystal to be viewed in the vertical dimension on a standard NTSC monitor (4:3 aspect ratio). Images of the 10 crystals are collected periodically and stored in sets by the DACU.

Corder, Eric L.↗