PURPOSE: To form a groove shape measuring instrument capable of rapidly measuring groove shapes with high accuracy with decreased variations in the photodetecting sensitivity on optical sensor surfaces.
CONSTITUTION: This groove shape measuring instrument has the optical sensors 60 to 62 which detect the respective diffracted light beams K0, K1, K2 of zero order, first order and second order obtd. by irradiating the groove shape measuring point 52A of an optical disk 51 with a laser beam LB and a groove shape calculating section 70 which calculates the groove shapes from these optical sensor outputs (a) to (c) The respective optical sensors 61, 62 of the first order and the second order are equipped with detecting position regulating sections 12, 13 for setting optimum detecting positions and are provided with an optical sensor position control circuit 1 for controlling the respective detecting position adjusting sections 12, 13. This optical sensor position control circuit 1 is provided in combination with a position detecting mechanism for the minus first order diffracted light for capturing the information on the position of the minus first order diffracted light K-1 necessary for calculating the control signal (main part: an elliptic surface mirror 11).
JPH01121708A | 1989-05-15 | |||
JPH02289942A | 1990-11-29 | |||
JPS60166808A | 1985-08-30 |