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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 253 records · Page 14

All sources NASA NTRS DOE OSTI

NASA NTRS1980

Study of fiber optics standardization, reliability, and applications

The use of fiber optics in space applications is investigated. Manufacturers and users detailed the problems they were having with the use or manufacture of fiber optic components. The general consensus of all the companies/agencies interviewed is that fiber optics is a maturing technology and will definitely have a place in future NASA system designs. The use of fiber optics was found to have two main advantages - weight savings and increased bandwidth.

Source record↗

NASA NTRS1991

Fiber-optic sensors for aerospace electrical measurements: An update

Fiber-optic sensors are being developed for electrical current, voltage, and power measurements in aerospace applications. These sensors are presently designed to cover ac frequencies from 60 Hz to 20 kHz. The current sensor, based on the Faraday effect in optical fiber, is in advanced development after some initial testing. Concentration is on packaging methods and ways to maintain consistent sensitivity with changes in temperature. The voltage sensor, utilizing the Pockels effect in a crystal, has excelled in temperature tests. This paper reports on the development of these sensors, the results of evaluation, improvements now in progress, and the future direction of the work.

Patterson, Richard L.↗

NASA NTRS2007

Robust Mapping of Incoherent Fiber-Optic Bundles

A method and apparatus for mapping between the positions of fibers at opposite ends of incoherent fiber-optic bundles have been invented to enable the use of such bundles to transmit images in visible or infrared light. The method is robust in the sense that it provides useful mapping even for a bundle that contains thousands of narrow, irregularly packed fibers, some of which may be defective. In a coherent fiber-optic bundle, the input and output ends of each fiber lie at identical positions in the input and output planes; therefore, the bundle can be used to transmit images without further modification. Unfortunately, the fabrication of coherent fiber-optic bundles is too labor-intensive and expensive for many applications. An incoherent fiber-optic bundle can be fabricated more easily and at lower cost, but it produces a scrambled image because the position of the end of each fiber in the input plane is generally different from the end of the same fiber in the output plane. However, the image transmitted by an incoherent fiber-optic bundle can be unscrambled (or, from a different perspective, decoded) by digital processing of the output image if the mapping between the input and output fiber-end positions is known. Thus, the present invention enables the use of relatively inexpensive fiber-optic bundles to transmit images.

Roberts, Harry E.↗

NASA NTRS1986

US long distance fiber optic networks: Technology, evolution and advanced concepts. Volume 1: Executive summary

Over the past two decades, fiber optics has emerged as a highly practical and cost-efficient communications technology. Its competitiveness vis-a-vis other transmission media, especially satellite, has become a critical question. This report studies the likely evolution and application of fiber optic networks in the United States to the end of the century. The outlook for the technology of fiber systems is assessed and forecast, scenarios of the evolution of fiber optic network development are constructed, and costs to provide service are determined and examined parametrically as a function of network size and traffic carried. Volume 1 consists of the Executive Summary. Volume 2 focuses on fiber optic technology and long distance fiber optic networks. Volume 3 develops a traffic and financial model of a nationwide long distance transmission network. Among the study's most important conclusions are: revenue requirements per circuit for LATA-to-LATA fiber optic links are less than one cent per call minute; multiplex equipment, which is likely to be required in any competing system, is the largest contributor to circuit costs; the potential capacity of fiber optic cable is very large and as yet undefined; and fiber optic transmission combined with other network optimization schemes can lead to even lower costs than those identified in this study.

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NASA NTRS1984

Power system applications of fiber optics

Power system applications of optical systems, primarily using fiber optics, are reviewed. The first section reviews fibers as components of communication systems. The second section deals with fiber sensors for power systems, reviewing the many ways light sources and fibers can be combined to make measurements. Methods of measuring electric field gradient are discussed. Optical data processing is the subject of the third section, which begins by reviewing some widely different examples and concludes by outlining some potential applications in power systems: fault location in transformers, optical switching for light fired thyristors and fault detection based on the inherent symmetry of most power apparatus. The fourth and final section is concerned with using optical fibers to transmit power to electric equipment in a high voltage situation, potentially replacing expensive high voltage low power transformers. JPL has designed small photodiodes specifically for this purpose, and fabricated and tested several samples. This work is described.

Kirkham, H.↗

NASA NTRS1994

Optical-Fiber Leak Detector

Proposed optical-fiber sensor detects small changes in pressure in elastomeric O-ring or similar pressure seal, which may indicate deterioration of seal and interpreted as indications of incipient failure. According to concept, length of optical fiber embedded in seal. Light-emitting diode illuminates one end of fiber; photodetector measures intensity of light emerging from other end. Pressure-induced changes in seal bend fiber slightly, altering microbending-induced loss of light from fiber and alter intensity of light at photodetector. Change in intensity approximately proportional to change in pressure.

Workman, Gary L.↗

NASA NTRS1997

Data Analysis for the Scintillating Optical Fiber Calorimeter (SOFCAL)

The scintillating optical fiber calorimeter is a hybrid instrument with both active and passive components for measuring the proton and helium cosmic ray spectra from 0.2 to IO TeV kinetic energy. A thin emulsion/x-ray film chamber is situated between a cerenkov counter and an imaging calorimeter. Scintillating optical fibers sample the electromagnetic showers that develop in the calorimeter and identify the trajectory of cosmic rays that interact in SOFCAL. The emulsion/x-ray film data provide an in flight calibration for SOFCAL. The data reduction techniques used will be discussed and interim results of the analysis from a 20 hour balloon flight will be presented.

Christl, Mark J.↗

NASA NTRS1982

Air data measurement using distributed processing and fiber optics data transmission

Distributed processing, fiber optics technology, and redundancy management in the aircraft environment are discussed. The project features the development of an angle-of-attack and sideslip data collection system hich features: (1) two independent microprocessor controlled data collection and calibration units; (2) transmission of data to the control system on a fiber optic data bus; and (3) software implemented error detection and recovery.

Farry, K. A.↗

NASA NTRS1991

Fiber-optic applications for space-based engines

The use of fiber optic technology is discussed with respect to the instrumentation systems for space based rocket engines. Optical fiber technologies are reviewed with specific attention given to the reliability, light weight, small fiber diameter, and operating life of the components in the space environment. An optical system can facilitate the incorporation of an optical health monitoring system, increase the space available for necessary redundancy, and safe high bandwidth communications that are immune to the effects of electromagnetic radiation.

Sovie, Amy L.↗

DOE OSTI2025

Quality Investigation of Pultruded Carbon Fiber Panels Subjected to Four-Point Flexure via Fiber Optic Sensing

Pultruded carbon fiber-reinforced composites are attractive to the wind energy industry due to the rapid production of highly aligned unidirectional composites with enhanced fiber volume fractions and increased specific strength and stiffness. However, high volume carbon fiber manufacturing remains cost-prohibitive. This study investigates the feasibility of a pultruded low-cost textile carbon fiber-reinforced epoxy composite as a promising material in spar cap production was undertaken based on mechanical response to four-point flexure loading. As spar caps are primarily subjected to flexural loading, large-span four-point flexure was considered, and coupon testing was restricted to tensile modulus and compression strength assessment. High-resolution spatial fiber optic strain sensing was utilized to determine spatial strain distribution during four-point flexure, revealing consistent strain along the length of the part and proved to be an excellent option for process manufacturing quality examination. Additionally, holes with diameters of 2.49 mm, 5.08 mm, and 1.93 mm were drilled through the thickness of full-width parts to determine the feasibility of structural health monitoring of pultruding parts internal to wind blades via fiber optic strain sensing.

Chemistry↗

NASA NTRS1984

Psychophysical Research in Development of a Fiber-optic Helmet Mounted Display

The Fiber Optic Helmet Mounted Display (FOHMD) was conceived as an innovative solution to existing flight simulator display deficiencies. An initial (breadboard) version of the system was fabricated to permit experimentation which would help define design requirements for a more refined engineering prototype. A series of visual/human factors studies are being conducted at the USAF Human Resources Laboratory (AFHRL) Operations Training Division, Williams AFB, Arizona to determine the optimum fit of human observer operating characteristics and fiber optic helmet mounted display technology. Pilot performance within a variety of high resolution insert/binocular overlap combinations is being assessed in two classes of environment. The first two of four studies planned incorporate an air-to-air combat environment, whereas the second two studies will use a low level environment with air to ground weapons delivery.

Kruk, R. V.↗

NASA NTRS2015

Crystal-free Formation of Non-Oxide Optical Fiber

Researchers at NASA Marshall Space Flight Center have devised a method for the creation of crystal-free nonoxide optical fiber preforms. Non-oxide fiber optics are extensively used in infrared transmitting applications such as communication systems, chemical sensors, and laser fiber guides for cutting, welding and medical surgery. However, some of these glasses are very susceptible to crystallization. Even small crystals can lead to light scatter and a high attenuation coefficient, limiting their usefulness. NASA has developed a new method of non-oxide fiber formation that uses axial magnetic fields to suppress crystallization. The resulting non-oxide fibers are crystal free and have lower signal attenuation rates than silica based optical fibers.

Nabors, Sammy A.↗

NASA NTRS1995

Optical-Fiber Fluorosensors With Polarized Light Sources

Chemiluminescent and/or fluorescent molecules in optical-fiber fluorosensors oriented with light-emitting dipoles along transverse axis. Sensor of proposed type captures greater fraction of chemiluminescence or fluorescence and transmits it to photodetector. Transverse polarization increases sensitivity. Basic principles of optical-fiber fluorosensors described in "Making Optical-Fiber Chemical Sensors More Sensitive" (LAR-14525), "Improved Optical-Fiber Chemical Sensors" (LAR-14607), and "Improved Optical-Fiber Temperature Sensors" (LAR-14647).

Egalon, Claudio O.↗

NASA NTRS1995

High-temperature fiber-optic lever microphone

The design and construction of a fiber-optic lever microphone, capable of operating continuously at temperatures up to 538 C (1000 F) are described. The design is based on the theoretical sensitivities of each of the microphone system components, namely, a cartridge containing a stretched membrane, an optical fiber probe, and an optoelectronic amplifier. Laboratory calibrations include the pistonphone sensitivity and harmonic distortion at ambient temperature, and frequency response, background noise, and optical power transmission at both ambient and elevated temperatures. A field test in the Thermal Acoustic Fatigue Apparatus at Langley Research Center, in which the microphone was subjected to overall sound-pressure levels in the range of 130-160 dB and at temperatures from ambient to 538 C, revealed good agreement with a standard probe microphone.

Zuckerwar, Allan J.↗

NASA NTRS1995

Optical fiber strain sensor with improved linearity range

A strain sensor is constructed from a two mode optical fiber. When the optical fiber is surface mounted in a straight line and the object to which the optical fiber is mounted is subjected to strain within a predetermined range, the light intensity of any point at the output of the optical fiber will have a linear relationship to strain, provided the intermodal phase difference is less than 0.17 radians.

Egalon, Claudio Oliveira↗

NASA NTRS1990

Fiber optic systems for mobile platforms III; Proceedings of the Meeting, Boston, MA, Sept. 7, 8, 1989

Various papers on fiber optic systems for mobile platforms are presented. Individual topics addressed include: architecture for fiber optic sensors and actuators in aircraft propulsion systems, fiber optic sensor system readiness for aircraft, microphone headset compatible with power by light, wavelength-division-multiplexed fiber optic sensors for aircraft applications, development of fly-by-light systems, fiber-optic-based inertial measurement unit, fault-tolerant architecture for a fly-by-light flight control computer, optically powered sensors for EMI-immune aviation sensing systems, infrared fiber optic fire sensors for space station applications. Papers on shipboard and automotive applications of fiber optic systems are also included.

Lewis, Norris E.↗

NASA NTRS2010

Method and apparatus for shape and end position determination using an optical fiber

A method of determining the shape of an unbound optical fiber includes collecting strain data along a length of the fiber, calculating curvature and bending direction data of the fiber using the strain data, curve-fitting the curvature and bending direction data to derive curvature and bending direction functions, calculating a torsion function using the bending direction function, and determining the 3D shape from the curvature, bending direction, and torsion functions. An apparatus for determining the 3D shape of the fiber includes a fiber optic cable unbound with respect to a protective sleeve, strain sensors positioned along the cable, and a controller in communication with the sensors. The controller has an algorithm for determining a 3D shape and end position of the fiber by calculating a set of curvature and bending direction data, deriving curvature, bending, and torsion functions, and solving Frenet-Serret equations using these functions.

Moore, Jason P.↗

NASA NTRS1981

Optical fibers for the distribution of frequency and timing references

An optical fiber communications link was installed for the purpose of evaluating the applicability of optical fiber technology to the distribution of frequency and timing reference signals. It incorporated a 1.5km length of optical fiber cable containing two multimode optical fibers. The two fibers were welded together at one end of the cable to attain a path length of 3km. Preliminary measurements made on this link, including Allan variance and power spectral density of phase noise are reported.

Lutes, G. F.↗