A Novel High-Resolution Optical Displacement Encoder Design Based on Double-Concave Lens
A novel optical displacement encoder was proposed in this paper. An optical mechanism was designed by the equations of thick lens to change and modify the paths of light, and then to get a more visible position change in the optical detector to improve the measurement accuracy. The simulation results indicated that the optical mechanism with 5 mm stroke, which the lens radii of curvature of the incident and the exit surface on the lens were -0.625 cm and 1.25 cm, respectively, and the magnification was 50 times in imaging distance of 38 cm, could make the 1 nm movement intervals of light source to be about 50 nm movement intervals in the detecting surface. Thus we can combine the optical mechanism and a photo-detector array with 50 nm resolution and 25 cm total detecting length to form the optical displacement encoder with 1 nm measuring accuracy.
Jianhong Zhao, Masanori Kunieda, Guilin Yang and Xue-Ming Yuan
Y. H. Fan et al., "A Novel High-Resolution Optical Displacement Encoder Design Based on Double-Concave Lens", Key Engineering Materials, Vols. 447-448, pp. 579-583, 2010