| 摘要 |
An improved system for measuring absolute angular deviation through transparencies, such as aircraft windscreens, uses an incoherent light source and a target configuration in the form of an opaque slide with a transparent "L"-shaped pattern. The positions of images of the legs of the "L" after passing through the transparency are detected at separate times by a single CCD array through rotation of the image of the "L"-shaped pattern ninety degrees by rotation of a Pechan prism about the optical axis of the system. In such manner, horizontal (azimuth) and vertical (elevation) components of angular deviations is measured for each tested point on the transparency, uncontaminated by lateral displacement errors.
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