Differential fiber optic proximity sensor

Abstract

Proximity sensor for determining the distance between a reflective surface and the sensor utilizes two output light guides positioned with the receiving end of one guide closer to the reflective surface than that of the other. When the surface is close to the guide ends a relatively greater intensity of light will be reflected to the second guide; when the surface is further away a relatively greater intensity of light will be reflected to the first guide. At a predetermined intermediate null position the reflected light intensities will be equal. The device has uses, inter alia, in accurately positioning objects without wear-producing contact, e.g. in numerically controlled machine tool operations; thickness sensing or thickness controlling using single or dual sensors; force sensing; liquid level indication; meter relay actuation; rotational limitation, and the like.

Dependencies are inferred from the claim text.