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Pulsed holographic interferometry is essentially the only direct method for determining electron density profiles in inertial fusion plasmas. Consequently, it is a very important diagnostic tool in laser fusion experimentation. The tracing of fringe patterns in the reconstructed holograms is required to determine their precise number and location for subsequent Abel inversion. This is a very labor-intensive task, for which computer assistance has long been sought. In the KMS Fusion multiframe optical probing system, a sequence of four time resolved image frames is produced at rates equivalent to over 5 billion/sec. The increased number of images thus generated has spurred the development of improved methods for handling data. A plan has evolved for providing scientists with interactive adaptive image enhancement tools to assist in locating the fringes. The feasibility of applying digital techniques to aid in the analysis of holographic interferograms has been demonstrated by others. However, only limited success has been achieved in tracing highly dense fringes in the presence of noise. Traditional noise reduction methods tend to fail in the case of high density fringes, where the spatial frequency of the noise is close to that of the pattern to be discerned. Other problems are introduced by uneven lighting conditions, competing fringe patterns (due to aberrations in optical components or other attenuators in the optical path), and bonafide discontinuities in the fringes. Newly developed digital enhancement tools apply tailorable neighborhood operators to individual pixels as directed by a cursor that may be manipulated via joystick or keyboard control. Operations may be performed on a sectional blow-up while viewing both the full image and the enlarged section. In this manner, global information can be utilized to aid in the local enhancement operations, and vice versa. This paper constitutes a progress-to-date report on work that is continuing for the U.S. Department of Energy.
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