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29 August 2008 High-resolution UV relay lens for particle size distribution measurements using holography
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Shock waves passing through a metal sample can produce ejecta particulates at a metal-vacuum interface. Holography records particle size distributions by using a high-power, short-pulse laser to freeze particle motion. The sizes of the ejecta particles are recorded using an in-line Fraunhofer holography technique. Because the holographic plate would be destroyed in an energetic environment, a high-resolution lens has been designed to relay the scattered and unscattered light to a safe environment where the interference fringes are recorded on film. These interference fringes allow particles to be reconstructed within a 12-mm-diameter, 5-mm-thick volume. To achieve resolution down to 0.5 μm, both a high-resolution optical relay lens and ultraviolet laser (UV) light were implemented. The design and assembly of a nine-element lens that achieves >2000 lp/mm resolution and operates at f/0.89 will be described. To set up this lens system, a doublet lens is temporarily attached that enables operation with 532-nm laser light and 1100 lp/mm resolution. Thus, the setup and alignment are performed with green light, but the dynamic recording is done with UV light. During setup, the 532-nm beam provides enough focus shift to accommodate the placement of a resolution target outside the ejecta volume; this resolution target does not interfere with the calibrated wires and pegs surrounding the ejecta volume. A television microscope archives images of resolution patterns that prove that the calibration wires, interference filter, holographic plate, and relay lenses are in their correct positions. Part of this lens is under vacuum, at the point where the laser illumination passes through a focus. Alignment and tolerancing of this high-resolution lens will be presented, and resolution variation through the 5-mm depth of field will be discussed.
© (2008) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Robert M. Malone, Gene A. Capelle, Brian C. Cox, Brent C. Frogget, Mike Grover, Morris I. Kaufman, Peter Pazuchanics, Danny S. Sorenson, Gerald D. Stevens, Aric Tibbitts, and William D. Turley "High-resolution UV relay lens for particle size distribution measurements using holography", Proc. SPIE 7060, Current Developments in Lens Design and Optical Engineering IX, 70600A (29 August 2008);


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