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  • 1
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    Schlieren with a laser diode source (1981)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: The use of a laser diode as a light source for a schlieren system designed to study phase objects such as a wind-tunnel flow is explored. A laser diode schlieren photograph and a white light schlieren photograph (zirconium arc source) are presented for comparison. The laser diode has increased sensitivity, compared with light schlieren, without appreciable image degradiation, and is an acceptable source for schlieren flow visualization.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Optical Engineering; 20; Sept
    Format: text
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  • 2
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    Moire deflectometry with deferred analysis (1983)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: A simplified version of moire deflectometry for flow visualization is presented. The modification comprises replacement of the second grating, the ground glass screen, and the camera with a plate film holder to obtain a shadow picture. Postanalysis proceeds by placing a grid transparency of the same periodicity of the remaining glass grating on the negative for projection viewing. The rotational angle between the grating and the plate alters the moire fringe periodicity. Use of the method in studying flows is predicted to reveal weak density gradient areas and shocks.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Applied Optics; 22; Mar. 1
    Format: text
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  • 3
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    Field-widened pinhole camera (1979)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: Wood demonstrated a method in 1906 that allowed 180-deg FOV but required that the film be immersed in a tank of water. This paper presents a technique that yields the same 180-deg FOV without the necessity of wetting the film. Rays from a 180-deg FOV cone are reduced to 84-deg cone due to refraction at the glass surface. If the cone were then incident on another glass/air plane surface, it would be expanded back to 180 deg.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Applied Optics; 18; Sept. 1
    Format: text
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  • 4
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    The 16-foot transonic tunnel laser velocimeter system (1982)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: The Langley 16-foot transonic wind tunnel is described. The system configuration, optical layout, laser color separator, optical receiver, and tunnel window are discussed.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Flow Visualization and Laser Velocimetry for Wind Tunnels; p 257-272
    Format: application/pdf
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  • 5
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    Two-mirrored galvanometer laser light sheet generator (1988)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: Light sheets generated with either laser or noncoherent sources have found widespread application to flow visualization. Previous light sheet generating systems were usually dedicated to a specific viewing geometry. The technique with the most flexibility is the galvanometer mirror based laser light sheet system. A two-mirrored system was designed and developed to provide flexibility and adaptability to a wide range of applications. The design includes the capability to control the size and location of the laser light sheet in real time, to generate horizontal or vertical sheets, to sweep the sheet repeatedly through a volume, to generate multiple sheets with controllable separation and to rotate single or multiple laser light sheets. The system is capable of producing up to 12 sheets of laser light at an angular divergence of + or - 20 degrees. Maximum scan rate of any one line is 500 Hertz. This system has proven to be uniquely versatile and a patent has been applied for.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: AIAA PAPER 88-4680
    Format: text
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  • 6
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    Laser Doppler velocity simulator (1979)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: A method and apparatus for inducing a Doppler frequency shift in a reference beam laser velocimeter light beam to simulate target velocity are described. The light beam is passed through a rotating refractive transparent block positioned between two reference points along the beam which results in a continuous change in the light beam optical path length between the reference points according to a known function. The velocity indicated by the laser velocimeter is compared to the known simulated velocity function for velocimeter testing and calibration.
    Keywords: LASERS AND MASERS
    Format: application/pdf
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  • 7
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    Direction sensitive laser velocimeter (1981)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: A laser velocimeter is described which determines the direction of movement of particles. A laser produces a transmitted beam that illuminates the volume under investigation. The backscattered light is divided into two equal intensity beams. A first part of a sample of the transmitted beam is mixed with one of the two equal intensity beams and applied to a first photodetector. A second part of the sample is phase shifted by 90 deg, mixed with the other of the two equal intensity beams and applied to a second photodetector. The output of the first photodetector is phase shifted by 90 deg and then multiplied with the output of the second photodetector to produce a signal indicative of direction of movement.
    Keywords: LASERS AND MASERS
    Format: application/pdf
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  • 8
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    Wide angle pinhole camera (1978)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: Hemispherical refracting element gives pinhole camera 180 degree field-of-view without compromising its simplicity and depth-of-field. Refracting element, located just behind pinhole, bends light coming in from sides so that it falls within image area of film. In contrast to earlier pinhole cameras that used water or other transparent fluids to widen field, this model is not subject to leakage and is easily loaded and unloaded with film. Moreover, by selecting glass with different indices of refraction, field at film plane can be widened or reduced.
    Keywords: PHYSICAL SCIENCES
    Type: LAR-11905 , NASA Tech Briefs (ISSN 0145-319X); 3; 2; P. 192
    Format: text
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  • 9
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    Directional laser velocimeter with doppler velocity simulator (1978)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: Technique uses phase-shift networks at optical and baseband frequencies and, as such, is optical adaptation of previously-existing microwave technology. Application is planned for wind-tunnel velocity measurements. Alternative configuration produces finite fringes that move in one direction or other as measured particle approaches or recedes.
    Keywords: PHYSICAL SCIENCES
    Type: LAR-12176 , LAR-12177 , NASA Tech Briefs (ISSN 0145-319X); 3; 1; P. 36
    Format: text
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  • 10
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    Noise reduction in photomultiplier circuits (1977)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: Simple damping device inserted in cable at power supply acts as filter, thus eliminating noise pulses in photomultiplier tube.
    Keywords: ELECTRONIC COMPONENTS AND CIRCUITS
    Type: LAR-12091 , NASA Tech Briefs (ISSN 0145-319X); 2; 2; P. 3
    Format: text
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