Results of a program to experimentally evaluate existing techniques and develop new high-speed techniques for evaluation of optical distortion in aircraft windscreens are described. Present techniques for evaluation of air-craft windscreens' optical quality are based on grid board photography and point-by-point measurement of optical deviation errors. Experimental evaluation of the grid board techniques have shown them to be simple and easy to perform, but errors as large as 20 percent occur because of the associated data reduction. The approaches to point-by-point measurement of windscreen deviation errors provide high accuracy, but the time required to evaluate a single windscreen is typically 8 to 24 hours. New techniques were studied, developed, and evaluated in order to permit real-time evaluation of aircraft windscreens. Two approaches described will provide the capability for high-speed evaluation of windscreen optical distortion. These techniques utilize raster-scanned laser probe beams in conjunction with retroreflecting screens and holographic lenses. In addition to high-speed scanning techniques, a speckle photographic technique is described that can be used to evaluate binocular disparity in a transparent aircraft windscreen.
James S. Harris,
Kevin G. Hardinci,
Steven H. Mersch,
"Techniques For Evaluation Of Aircraft Windscreen Optical Distortion," Optical Engineering 20(1), 201115 (1 February 1981). https://doi.org/10.1117/12.7972674