OPTICAL DISPLACEMENT SENSING APPARATUS

摘要

An optical displacement sensing apparatus comprises a confocal Fabry-Perot interferometer (1) in which one of the confocal mirrors (6) is mounted on a resilient diaphragm (8), which is attached to a housing (2) supporting the other mirror (3), so that the mirrors are relatively movable in response to an external stimulus applied to the interferometer. The position of the mirror (3) is variable by a piezoelectric element (4), and a servo unit (16) is responsive to the optical output from the interferometer (1) to apply a voltage signal to the piezoelectric element which opposes relative displacement of the mirrors by an external stimulus and tends to maintain the spacing between the mirrors constant. Hence, the servo unit produces a signal corresponding to the stimulus. Both the input light signal for illuminating the interferometer (1) and the output light signal may be transmitted via optical fibers (12, 15).