A noninterferometric optical probe

A noninterferometric optical probe has been designed and built on the basis of simple geometric principles. It may be used to sense the motion of unprepared and/or inaccessible targets of virtually any material with an accuracy of ±0.1 mm at a distance of 1550 mm. Experimental results are presented, which include the determination of the distortion of a target object in an electric furnance operating at 800°C.