HIGH-RESOLUTION OPTICAL POSITION ENCODER WITH LARGE MOUNTING TOLERANCES

A high-resolution optical position encoder is described that consists of a scale as encountered in a standard moire-based system, a simple i maging system with stabilized magnification and a novel segmented phas e detector integrated circuit. Compared with encoder systems of compar able resolution and accuracy, the encoder presented offers large mecha nical tolerances in the alignment of the reading head to the scale, wh ile an interpolation accuracy of better than 0.1 mu m is preserved. Th e system is especially well suited for high-resolution linear encoders as well as for the cost-effective fabrication of compact high-resolut ion rotary encoders. (C) 1997 Optical Society of America.