High-precision miniaturized low-cost reflective grating laser encoder with nanometric accuracy.

This paper presents a novel optical encoder, M-encoder, which can be used within high-precision metrology systems based on the technology of customized prism and homodyne detection. The M-encoder is an exposed encoder measuring reflective glass and metal scale, which is targeting the biggest area of the encoder market, 20 µm pitch, and has a resolution under 100 nm. The error of 23 nm for 100 mm traveling distance has been measured. The applied technology has successfully improved alignment tolerances, in which the tolerance of installation achieved to ±0.5