Shifted sequence pseudo random coded reticle correlation apparatus

Claim 1

An optical radiant energy encoding apparatus comprising an encoding member with a plurality of continuous loop tracks each having the same pseudo random code formed thereon, a portion of each track in combination with a portion of the other tracks constituting a section thereby establishing a plurality of sections and the code in each track being shifted relative to the adjacent tracks by an amount equal to the width of the section with a sufficient number of tracks being provided so that each section contains a complete code, input means for focusing the optical radiant energy on the encoding member, a field stop having an aperture therein and positioned in the path of the optical radiant energy to form the field of view of said encoding apparatus such that it corresponds to the periphery of a section on said encoding member, means for driving the encoding member so that successive segments of the pseudo random code intercept the radiant energy incident thereon, and a photodetector positioned to receive the modulated light transmitted through the encoding member and produce a correspondingly modulated electrical signal.