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  • 1
    Publication Date: 2005-11-30
    Description: It is reported that the Apollo 16 command module astronomical photography was performed with the specific objective of capitalizing on the uniqueness of the double umbra as a vantage point to collect astronomical data that are obtainable only near our Moon. For this reason, these data will be compared directly to analogous photography performed from Earth orbit during Project Mercury and the Gemini Program as well as to the Apollo-duplicated photography taken from sites on the Earth surface. Comparison with Earth-based photography should yield direct information on the Earth airglow layer and on atmospheric scattering and extinction.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Apollo 16 Prelim. Sci. Rept.; 2 p
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  • 2
    Publication Date: 2005-11-30
    Description: Photographic observations of astronomical interest conducted during the Apollo 15 mission are discussed. Procedures used in photographing the solar corona are described together with calibration and reduction methods. In addition, selected preliminary results obtained from the photography are presented.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Its Apollo 15 Prelim. Sci. Rept.; 39 p
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  • 3
    Publication Date: 2005-11-30
    Description: During Gemini missions, the image orthicon system was used to obtain photographic data on faint and diffuse astronomical phenomena. Results show that the photographs may be used to determine the airglow geometry. Although it was sensitive, the original photographic system was unsuitable for use in the study of dim and diffuse astronomical light sources.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: The Gemini Program: Phys. Sci. Expt. Sum.; p 445-454
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  • 4
    Publication Date: 2006-01-11
    Description: Polarized and red- and blue-filter photographs of zodiacal light obtained by Apollo 17 are analyzed. Attempts were made to identify the cause of subtle change in the observed light and determine the dust composition of the light. A comparison of red and blue images indicates such changes may be caused by particle size distribution and range, number of particles along any given line of sight, particle surface characteristics including dielectric compared to metallic properties, and variations of the parameters as a function of distance from the sun.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Apollo 17 Prelim. Sci. Rept.; 3 p
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  • 5
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    In:  CASI
    Publication Date: 2006-10-26
    Description: Dim light photographs from Gemini VI-A and Gemini VIII missions
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
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  • 6
    Publication Date: 2011-08-19
    Description: A closed loop phase control system using an all-fiber optical configuration has been developed for use in phase-stepping interferometry. This system drives the relative phase of two interfering beams through a sequence of pi/2 rad increments so that the initial relative phase of these beams can be determined. This phase-stepping system uses optical fibers to provide spatially uniform phase steps from a flexible, easily aligned optical configuration. In addition, this system uses phase feedback to eliminate phase modulator errors and to compensate for phase drifts caused by environmental disturbances.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Applied Optics (ISSN 0003-6935); 30; 729-734
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  • 7
    Publication Date: 2019-06-28
    Description: A new instrument, the liquid crystal point diffraction-interferometer (LCPDI), has been developed for the measurement of phase objects. This instrument maintains the compact, robust design of Linnik's point diffraction interferometer (PDI) and adds to it phase stepping capability for quantitative interferogram analysis. The result is a compact, simple to align, environmentally insensitive interferometer capable of accurately measuring optical wavefronts with very high data density and with automated data reduction. This dissertation describes the theory of both the PDI and liquid crystal phase control. The design considerations for the LCPDI are presented, including manufacturing considerations. The operation and performance of the LCPDI are discussed, including sections regarding alignment, calibration, and amplitude modulation effects. The LCPDI is then demonstrated using two phase objects: defocus difference wavefront, and a temperature distribution across a heated chamber filled with silicone oil. The measured results are compared to theoretical or independently measured results and show excellent agreement. A computer simulation of the LCPDI was performed to verify the source of observed periodic phase measurement error. The error stems from intensity variations caused by dye molecules rotating within the liquid crystal layer. Methods are discussed for reducing this error. Algorithms are presented which reduce this error; they are also useful for any phase-stepping interferometer that has unwanted intensity fluctuations, such as those caused by unregulated lasers.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA-TM-106899 , E-9547 , NAS 1.15:106899
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  • 8
    Publication Date: 2019-06-28
    Description: Fiber optic delivery systems promise to extend the application of holography to severe environments by simplifying test configurations and permitting the laser to be remotely placed in a more benign location. However, the introduction of optical fiber leads to phase stability problems. Environmental effects cause the pathlengths of the fibers to change randomly, preventing the formation of stationary interference patterns which are required for holography. An active phase control system has been designed and used with an all-fiber optical system to stabilize the phase difference between light emitted from two fibers, and to step the phase difference by 90 deg without applying any constraints on the placement of the fibers. The accuracy of the phase steps is shown to be better than 0.02 deg., and a stable phase difference can be maintained for 30 min. This system can be applied to both conventional and electro-optic holography, as well as to any system where the maintenance of an accurate phase difference between two coherent beams is required.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA-TM-101295 , E-4277 , NAS 1.15:101295
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  • 9
    Publication Date: 2019-06-28
    Description: A novel projected fringe profilometry system was applied to surface contour measurements of an accelerator electrode from an ion thruster. The system permitted noncontact, nondestructive evaluation of the fine and gross structure of the electrode. A 3D surface map of a dished electrode was generated without altering the electrode surface. The same system was used to examine charge exchange erosion pits near the periphery of the electrode to determine the depth, location, and volume of material lost. This electro-optical measurement system allowed rapid nondestructive digital data acquisition coupled with automated computer data-processing. In addition, variable sensitivity allowed both coarse and fine measurements of objects having various surface finishes.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: AIAA PAPER 91-2121
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  • 10
    Publication Date: 2019-07-13
    Description: A new instrument, the liquid crystal point diffraction interferometer (LCPDI), has been developed for the measurement of phase objects. This instrument maintains the compact, robust design of Linnik's point diffraction interferometer (PDI) and adds to it phase stepping capability for quantitative interferogram analysis. The result is a compact, simple to align, environmentally insensitive interferometer capable of accurately measuring optical wavefronts with high data density and with automated data reduction. The design of the LCPDI is briefly discussed. An algorithm is presented for eliminating phase measurement error caused by object beam intensity variation from frame-to-frame. The LCPDI is demonstrated by measuring the temperature distribution across a heated chamber filled with silicone oil. The measured results are compared to independently measured results and show excellent agreement with them. It is expected that this instrument will have application in the fluid sciences as a diagnostic tool, particularly in space based applications where autonomy, robustness, and compactness are desirable qualities. It should also be useful for the testing of optical elements, provided a master is available for comparison.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA-TM-106922 , E-9634 , NAS 1.15:106922 , International Symposium on Optical Science, Engineering, and Instrumentation; Jul 09, 1995 - Jul 14, 1995; San Diego, CA; United States
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