Improved methods and apparatus for retroreflective surface inspection and distortion measurement.

摘要

A method of creating retroreflection surface images comprises illuminating the surface (350) with an extended light field from a source (either 340 or 370) and moving a group of retroreflective elements (300) through said light field so as to reilluminate the surface at a succession of locations (380). Camera (360) and illumination axis (371) may be moved in unison with the group of retroreflective elements (300). Another method uses divergent light and a single retroreflector element. The sensitivity may be controlled by selecting the angular distribution of retroreflected light by choosing the wavelength. System calibration is effected by varying the angular distribution under test conditions or by inserting and moving a test surface. Operators may be helped in recreating previous images by alternate display of test and reference images. <IMAGE>