Coding unit for e.g. optical rotary encoder, has coding track including coding fields with structured subfields that are structured to deflect impinging beam at different diffraction angle

摘要

The unit has a coding track (104) with a set of structured coding fields (106), where each coding field has a set of structured subfields (106a, 106b). Each of the subfields effects a deflection of impinging beam (110) at a predetermined diffraction angle. The subfields are structured to deflect the impinging beam at different diffraction angles. The subfields have micro-structured risings and hollows to define a phase grid with different grid constants for each subfields.