Abstract: An electro-optical position transducer employs an optical mask having a number of parallel channels formed of alternating opaque and transparent sections extending along the direction of motion of a movable member. One channel has opaque and transparent sections, and the section lengths correspond to the smallest measureable increment. This channel generates the least significant bit of the code. A pair of channels, displaced linearly relative to one another, are provided for each of the higher order bits. Pairs of LED's and photo-transistors are provided for each channel and extend in a line normal to the length of the channel. The outputs of the photo-transistors are decoded so that all transitions between binary values in the output signal occur in synchronism with transitions of the least significant digit.

Abstract: A pneumatic powered probe having a rod that extends into contact with the surface of a workpiece to gauge its position includes optics and electronic circuitry for generating a binary signal proportional to the position of the probe end. The circuitry includes a parallel channel optical mask that moves with the rod between a set of light emitting diodes and a set of photo-transistors, both supported on a circuit board. Transistor circuitry supported on the board converts the outputs of the photo-transistors into a binary parallel code which may be transmitted to a remote location upon receipt of an enabling signal by a plurality of gates in the device. The rod is connected to a cylinder which cooperates with a piston fixed to the device housing. Air admitted into the chamber between the piston and cylinder force outward motion of the rod. The optical mask is supported on the cylinder and moves with it relative to the diodes and photo-transistors to generate the position related signal.