Search NASA⌕ Search

SEARCH · Search NASA

Results for “Optical”

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.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 163 records · Page 9
All sourcesNASA NTRSDOE OSTI
NASA NTRS1975

Fiber optic multiplexed optical transmission systems for space vehicle launch facilities

Low loss Fiber Optic Cable is being evaluated as a potential future replacement for Kennedy Space Center's 13,000 mile Wideband cable system. In order to make economical use of the wide bandwidth characteristic of glass fibers, a Frequency Division Multiplexing (FDM) scheme has been devised to stack many analog and digital data channels on a single fiber. The Multiplexed Optical Transmission System (MOTS) will offer a unique flexibility of plug-in modularity to meet changing data and bandwidth requirements in addition to the standard 'goodies' of immunity to lightning and other EMI, RFI type interferences, and of smaller size and lighter weight.

Bell, C. H.↗
NASA NTRS1976

The role of fiber optics in mass spectrometer electro-optical ion detection

This paper describes the development of an electro-optical ion detector combining the best features of photographic and electrical ion detection (i.e., wide mass range coverage and low ion detection threshold respectively). A nineteen fold fiber optic image dissector is discussed which reformats the 1 mm x 361 mm mass spectrometer focal plane format to a 19 mm x 19 mm format suitable for vidicon imaging and electronic display of the data.

Norris, D. D.↗
NASA NTRS1979

Study of methods for direct optical address of integrated optical circuits

Methods for introducing optical information directly, without intervening recording and storage steps, into integrated optical data-processing devices are surveyed. The information is taken to be in the form of a one-dimensional variation of intensity across the beam. Physical phenomena that may be utilized are evaluated, and the most suitable presently known classes of materials for exploitation of each type of interaction are discussed. A variety of possible device configurations are suggested and general principles are outlined whereby many more device types can be generated. A simple experimental device was demonstrated and its operation was analyzed.

Wood, V. E.↗
NASA NTRS1980

Electro-optics laboratory evaluation: Deutsch optical waveguide connectors

A description of a test program evaluating the performance of an optical waveguide connector system is presented. Both quality and effectiveness of connections made in an optical fiber, performance of the equipment used and applicability of equipment and components to field conditions are reviewed.

Source record↗
NASA NTRS1988

Surface emitting lasers for optical circuitry - Optical interconnect technology

Surface emitting (SE) lasers and their application in VLSI optical interconnect networks are considered. In particular, the advantages provided by SE lasers in optical interconnect circuits and monolithic integration are discussed. Some of the requirements, such as wavelength stability, power dissipation, emission angle, size, etc., are compared with respect to conventional laser diodes. It is noted that the operation of SE lasers will be critically dependent on the properties of the feedback reflectors. Experimental measurements of reflection spectra on AlGaAs/GaAs multilayer reflectors and InAlAs/InGaAs etalons formed with molecular beam epitaxy (MBE) are presented.

Yu, P. K. L.↗
NASA NTRS1989

Optical testing of off-axis parabolic segments without auxiliary optical elements

The traditional optical test for an off-axis segment of a parabolic mirror utilizes an autocollimation flat and requires considerable test-bay space. Several other test configurations that will minimize space requirements are described. One method involves a null corrector, and three others require no auxiliary test optics. Combinations of the methods described will be useful in providing full independent evaluation of the figure of the segment under test.

Meinel, Aden B.↗
NASA NTRS1989

Deep optical and radio searches for a quiescent counterpart to the optical transient source OTS 1809+31

Hudec (1987) has reported the detection of three bright transient optical images from the same celestial location localized to alpha(1950) = 18 h 9 m 26.29 s + or - 0.03 s, delta (1950) = +31 deg 23 arcmin 19.7 arcsec + or - 0.6 arcsec. This paper reports the result of a deep CCD search in four colors undertaken to find the quiescent counterpart of the optical transients. No source is found at the location of the transients to m(B) = 24.5; however, 18 objects in the vicinity of the reported coordinates which are consistent with the source having a proper motion of 1 arcsec/yr. A search at 6 cm with the VLA revealed no source in the mu less than 1 arcsec/yr circle to a 3 sigma limiting flux of 83 micro-Jy.

Ricker, George R.↗
NASA NTRS1991

Optical variability and pigment biomass in the Sargasso Sea as determined using deep-sea optical mooring data

A 9-month time series of optical data, composed of three separate deployments, from the Biowatt 1987 deep-sea mooring located in the oligotrophic waters of the Sargasso Sea at 32 deg N, 70 deg W, is presented. These data were analyzed using several biooptical models for the purpose of providing a continuous estimate of the spectral diffuse attenuation coefficient and pigment biomass. Results of the first 70-day deployment demonstrate the utility of optical observations as proxy measures of biological parameters, and facilitate a preliminary analysis of the temporal variations and a comparison of the present biooptical observations with concurrent physical observations. Biooptical properties exhibit variation in response to physical forcings, such as diel variations of incident solar irradiance, episodic wind forcing, advective mesoscale eddy layer depth, and succession of phytoplankton. The mooring data are discussed in the context of contemporaneous shipboard observations as well as in terms of future ocean satellite observations.

Smith, R. C.↗
NASA NTRS1992

Accuracies Of Optical Processors For Adaptive Optics

Paper presents analysis of accuracies and requirements concerning accuracies of optical linear-algebra processors (OLAP's) in adaptive-optics imaging systems. Much faster than digital electronic processor and eliminate some residual distortion. Question whether errors introduced by analog processing of OLAP overcome advantage of greater speed. Paper addresses issue by presenting estimate of accuracy required in general OLAP that yields smaller average residual aberration of wave front than digital electronic processor computing at given speed.

Downie, John D.↗
NASA NTRS1992

Free-space coherent optical communication receivers implemented with photorefractive optical beam combiners

Performance measurements are reported concerning a coherent optical communication receiver that contained an iron doped indium phosphide photorefractive beam combiner, rather than a conventional optical beam splitter. The system obtained a bit error probability of 10(exp -6) at received signal powers corresponding to less than 100 detected photons per bit. The system used phase modulated Nd:YAG laser light at a wavelength of 1.06 microns.

Davidson, Frederic M.↗
NASA NTRS1992

The optically thick C III spectrum. I - Term populations and multiplet intensities at lower optical depths

The C III spectrum is studied quantitatively under both optically thin and optically thick conditions, yielding term populations and line/multiplet intensities for column lengths from zero to 10 exp 18/sq cm. The roles of escape probabilities and line profiles in the calculation are discussed in some detail. It is shown that use of the fully integrated escape factor, rather than the more appropriate monodirectional escape probability, can lead to appreciable errors in calculated intensities. The results for populations and intensities make it possible to identify two unassigned features in the solar EUV spectrum of Vernazza and Reeves (1978) as C III multiplets, and to establish that an unidentified infrared solar feature at 8500.32 A, seen in both absorption (Fraunhofer) and emission (chromospheric) spectra, is the C III transition 2s3s(1S)-2s3p(1P). Voigt parameters for the C III lines and multiplets, obtained by a modified semiclassical method are tabulated. A new, unambiguous notation for the numerous line ratios present in a typical spectrum, which is argued to be an improvement over present arbitrary notations, is proposed and used.

Bhatia, A. K.↗
NASA NTRS1991

Optical system design for a Lunar Optical Interferometer

The moon offers particular advantages for interferometry, including a vacuum environment, a large stable base on which to assemble multi-kilometer baselines, and a cold nighttime temperature to allow for passive cooling of optics for high IR sensitivity. A baseline design for a Lunar Optical Interferometer (LOI) which exploits these features is presented. The instrument operates in the visible to mid-IL region, and is designed for both astrometry and synthesis imaging. The design uses a Y-shaped array of 12 siderostats, with maximum arm lengths of about 1 km. The inner siderostats are monitored in three dimensions from a central laser metrology structure to allow for high precision astrometry. The outer siderostats, used primarily for synthesis imaging, exploit the availability of bright reference stars in order to determine the instrument geometry. The path delay function is partitioned into coarse and fine components, the former accomplished with switched banks of range mirrors monitored with an absolute laser metrology system, and the latter with a short cat's eye delay line. The back end of the instrument is modular, allowing for beam combiners for astrometry, visible and IR synthesis imaging, and direct planet detection. With 1 m apertures, the instrument will have a point-source imaging sensitivity of about 29 mag; with the laser metrology system, astrometry at the microarcsecond level will be possible.

Colavita, M. M.↗
NASA NTRS1992

Two-stage optics - High-acuity performance from low-acuity optical systems

The concept of two-stage optics, developed under a program to enhance the performance, lower the cost, and increase the reliability of the 20-m Large Deployable Telescope, is examined. The concept permits the large primary mirror to remain as deployed or as space-assembled, with phasing and subsequent control of the system done by a small fully assembled optical active element placed at an exit pupil. The technique is being applied to correction of the fabrication/testing error in the Hubble Space Telescope primary mirror. The advantages offered by this concept for very large space telescopes are discussed.

Meinel, Aden B.↗
NASA NTRS1992

Structural design and analysis for an ultra low CTE optical bench for the Hubble Space Telescope corrective optics

The stringent stability requirements of the Corrective Optics Space Telescope Axial Replacement (COSTAR) necessitates a Deployable Optical Bench (DOB) with both a low CTE and high resonant frequency. The DOB design consists of a monocoque thin shell structure which marries metallic machined parts with graphite epoxy formed structure. Structural analysis of the DOB has been integrated into the laminate design and optimization process. Also, the structural analytical results are compared with vibration and thermal test data to assess the reliability of the analysis.

Neam, Douglas C.↗
NASA NTRS1993

Binary optics at Hughes Danbury Optical Systems

An overview of binary optics development at Hughes Danbury Optical Systems is presented. Design software used for mask design is presented. A brief discussion of fabrication follows. Two examples of actual projects are used to highlight the discussion: (1) a large aspheric lens; and (2) a set of grating and lenslet arrays.

Logue, James↗