Abstract: A high resolution optical position sensor for measuring the linear displacement of a reciprocating device with a long stroke, includes a code plate having a substrate comprised of a fiber optic faceplate having a plurality of parallel optical waveguides which are fused together and aligned perpendicular to each of two major surfaces of the faceplate, and an optical mask with serial transparent and opaque regions encoded in each of a plurality of bit channels disposed on one of the two major surfaces of the faceplate, a portion of the plurality of optical waveguides being in registration with the transparent regions of each bit channel.