An optical comparator arranged for rear projection onto a viewing screen combines an optical projector that projects an optical image of a test part under inspection onto the viewing screen with a video projector that projects an optical image of a pixilated template pattern containing illustrated specifications of the test part onto the same viewing screen. The images of the test part and the pixilated template pattern are projected concurrently onto the viewing screen for visually comparing the form of the test part against its specified form.