Contactless diffraction grating position angle measurement system has angled retroreflector and aperture stop with exact openings providing optical system focal plane scale

摘要

A contactless diffraction grating angle measurement system has an angled retroreflector (5) with angle invariant in one or two planes and aperture stop (4) with exact openings (4-1, 4-2) providing measurement (7) of the optical system focal plane (6) scale for distance determination.