Diffractive incremental and absolute coding principle for optical rotary sensors

Rotary sensors are an essential component in numerous applications where a rotation movement has to be detected. With optical encoders, a high angular resolution can be achieved. As a disadvantage, the resolution enhancement is associated with increasing cost. To overcome this issue, a coding principle is presented that uses a diffractive solid measure on a microstructured plastic disc. Like a DVD, this encoder disc can be manufactured in a cost effective injection molding process. For this approach, a differential incremental code, as well as an absolute code, has been developed.