| 摘要 |
PROBLEM TO BE SOLVED: To correctly position a pinhole on an optical axis. SOLUTION: An information area 15 on which a cross pattern having positional information on an X axis and a Y axis for positioning the pinhole 11 is marked by etching, printing or the like is provided in a pinhole plate 10, and a reflection type photodetector 16 which emits light and detects return light is provided in the information area 15. The detection of positional information on the X axis and the Y axis from the information area 15 or the like is controlled by a control circuit 17 by driving a semiconductor laser 3, detecting data from a PD 12 and driving/detecting the reflection type photodetector 16. The pinhole plate 10 is movable to the X axis and the Y axis orthogonal to it by an X actuator 13 and a Y axis actuator 14. |
