| 主权项 |
1. An optical encoder comprising:
a light source that emits light; a scale including two or more scale gratings each having a predetermined pitch; a light source grating disposed between the light source and the scale and having a predetermined pitch; and an interference fringe detector that detects an interference fringe generated by the light source grating and the scale, wherein the two or more scale gratings are disposed side by side, and any adjacent pair of the scale gratings are displaced from each other by a ½ period; the interference fringe detector comprises a light-receiving grating that includes light-transmitting portions and light-blocking portions alternately arranged with the same pitch as the predetermined pitch of the light source grating; and a gap between the light source grating and the scale is the same as a gap between the scale and the light-receiving grating. |
