Two-dimensional reflective optical encoder based on point source illuminated grating imaging

A novel two-dimensional reflective grating encoder is introduced. The optical encoder is developed by a binary amplitude reflective scale grating and a two-dimensional slit displacement sensor, which is fabricated by MEMS technology. Based on Talbot effort, the proposed method can achieve millimetric measurement with high accuracy, where the displacement difference within 0.1% and 0.2% for 1 mm and 20 mm measurement, respectively. By using the eight-segment data division program, the proposed method can easily distinguish 1 μm displacement measurement. Furthermore, in measurement speed tests, the proposed method can reach the movement speed about 5000 μm/s. The experimental results showed the proposed method can achieve high resolution, high speed and long-range measurement, which is potential in the industries and workshops application.