| 摘要 |
PURPOSE:To obtain high resolution by a compact device by constituting a reflection type device which utilizes reflected light from a code plate and using laser light as a light source. CONSTITUTION:The code plate 2 is rotated and laser light is emitted from a laser oscillation part 7. This laser light is reflected by the total reflection right- angle mirror 14 and half-mirrors 16a, 16b, and 16c and projected upon the code plate 2 through a condenser lens. The reflected light of the laser light projected upon the code plate 2 is passed through the condenser lens 7 and half-mirrors 16a, 16b, and 16c of a laser photodetection part 8. The relative positions of the devices such as the reflecting means 12 and laser oscillation part 7 are preset so that the laser light has the largest quantity of light when the laser light is convergent to the surface 2a of the code plate where none of pits 2a, 2b, 3b... is present. |
