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Browsing by Author "Kurtz, Robert L."

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    Frequency stability of a helium neon laser system with external cavity control
    Kurtz, Robert L. (Virginia Polytechnic Institute, 1968)
    Many applications of gas lasers depend upon the extremely high spectral purity of their output signals. To fully exploit this remarkable spectral purity requires a high degree of frequency stabilization and laser mode control. In the past few years much effort has been expended in attempts to devise and test various methods of frequency stabilization. This investigation lists a number of these methods employed over the past few years. Further, it describes a state-of-the-art system employing two identical lasers and utilizing a combination of several of the known methods of frequency stabilization plus the use of an external cavity to passively control the frequency of the Fabry-Perot laser cavity. Data from this system has been analyzed and the state-of-the-art results of long term and short term relative frequency stability is presented.
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    A holographic system that records front-surface detail of a scene moving at high velocity
    Kurtz, Robert L. (Virginia Tech, 1971-06-05)
    It is known that any motion of the scene during the exposure of a hologram results in a spatial modulation of the recorded fringe contrast. On reconstruction this produces a spatial amplitude modulation of the reconstructed wavefront that tends to blur out the image. This paper discusses a novel holographic technique that uses an elliptical orientation for the holographic arrangement. It is shown that the degree of image degradation is not only a function of exposure time but also of the system used. The form of the functional system dependence is given, as well as the results of several systems tested, which verify this dependence. It is further demonstrated that the velocity of the target or the exposure time alone is inconsequential by itself and the important parameter is the total motion of the target Î X = VT. Using the resolution of front-surface detail from a target with a velocity of 17,546 cm/sec, we are able to predict an upper limit on target velocity for resolution of front-surface detail for a given system.