Partial coherence mitigation in video measurement systems via illumination apodization

Abstract

A video measurement system for measuring a test object comprising an imaging system having an imager having an imaging pupil, the imager arranged for viewing at least a portion of a silhouette of a test object by receiving light transmitted by the test object over a first angular extent, an illumination system having an optical axis and emitting an illumination distribution of light along an optical path, the illumination system comprising a lens system and a subassembly having an illumination source, a pupil aperture, and a first polarizer, the first polarizer having a diameter that is smaller than the pupil aperture, and a second polarizer overlapping the first polarizer, the second polarizer having a diameter that is larger than the first polarizer, the second polarizer configured to rotate independent of and relative to the subassembly.