| 摘要 |
PURPOSE:To obtain a checking device for pregroove disk which can measure easily and accurately the depth and width of a pregroove as well as the size variance, by making use of the diffracted light of the laser light. CONSTITUTION:A pregroove disk 2 to be checked is supported rotatably on a spindle 1, and this spindle 1 can move in the radius direction (arrow A) of the disk 2 by a shift device 3. A laser light source 4 is provided, and the laser light transmitted through the disk 2 is diffracted by the pregroove to be turned into the primary and secondary diffracted light 7 and 8. The detection signal of a detector 10 for the light 7 is extracted as an output signal (a) corresponding to the depth of the pregroove via an amplifier 13. This signal (a) is supplied to a divider 15. The detection signal of a detector 11 for the light 8 is supplied to the divider 15 via an amplifier 14. From an output of the divider 15, the (primary diffracted light intensity/secondary diffracted light intensity) is calculated, and the detection signal is extracted as an output signal (b) corresponding to the width of the pregroove. |
