Application of nanoimprint technology to diffraction grating scale for microrotary encoder

Using nanoimprint technology, we developed a rotary diffraction grating scale, which is used for microrotary encoding. The off-center error between the center of the throughhole for inserting a rotational axis and the center of the high-precision micropattern on the periphery of the scale is less than 3 μm because we are able to shape the through-hole and the grating pattern simultaneously. The rotary grating is of sufficient accuracy to use as the scale in a microrotary encoder. The use of nanoimprinting is groundbreaking, in view of the traditionally poor centering precision of grating scale through-holes fabricated by conventional photolithography coupled with the machining of throughholes.