Polarimetric linear absolute position encoder

Abstract Optical encoders based on measurement of the axis-angle of linear polarizers offer high resolution and moderate accuracy, but are usually restricted to rotary measurement. We show that annular polymer sheet polarizer materials can be sheared into rectangular tapes, with a polarizing axis that varies linearly along the tape. This makes possible the construction of polarimetric linear absolute position encoders. We demonstrate also sheared polymer birefringent retarders, which function similarly, potentially with cost and size-flexibility advantages.