Compact absolute shaft angular encoder based on diffractive optical elements

摘要

A compact absolute shaft angular encoder with resolution of 5 arc seconds (18 bits) has been developed. It has the direct readout channel with 14-bit optical code disk and the interpolation channel for obtaining the additional 4 low-order bits by means of analog-to-digital conversion and processing of the quadrature signals from the interpolation track of the code disk. The small sizes of the encoder are achieved by employing special components. Among them are a multiple beam illuminator with diffractive Dammann grating, specialized electronics used for digital data reading and processing and implemented on the base of integrated linear photodetector array, and also a microcontroller with RISC-processor and programmable device.