New high resolution optical incremental rotary encoder

Abstract

At HSG-IMAT a new concept for an incremental encoded optical encoder has been developed. Key element of the sensor concept is a disc with a high precision solid measure, which is fabricated using the manufacturing process for compact discs. Using this process, it is possible to fabricate a high precision solid measure in high quantities and at low manufacturing costs. For detection of the solid measure, a laser beam is focused onto it and the beam is deflected by the diffractive gratings of the solid measure, whereupon two different first orders fall onto separated photodiode elements. Intensive calculations were done to design the solid measure and estimate the signal modulation. To verify the principle of operation, a small size demonstrator device was designed and assembled. The experimental results with this demonstrator device show the large potential of this new sensor concept for different applications.