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 imaging system with stabilized magnification and a novel segmented phase detector integrated circuit. Compared with encoder systems of comparable resolution and accuracy, the encoder presented offers large mechanical tolerances in the alignment of the reading head to the scale, while an interpolation accuracy of better than 0.1 µm is preserved. The system is especially well suited for high-resolution linear encoders as well as for the cost-effective fabrication of compact high-resolution rotary encoders.