| 摘要 |
PURPOSE:To obtain a titled device which has a high accuracy and also is inexpensive by providing a focusing controlling circuit for moving a movable lens provided so as to be movable in the optical axis direction between a light source and a focusing lens, in the direction for reducing a spot diameter of a reflected image formed on a photodetecting part. CONSTITUTION:A projecting system 2 converts a light 22 generated from a light source 21 consisting of a semiconductor laser device, to parallel lights by a collimating lens 23, and thereafter, irradiates them to an object to be measured 1 through a movable lens 24 and a focusing lens 26. Also, a photodetecting system 3 is provided at a prescribed angle against the optical axis of the projecting system 2, photodetects a reflected light 31 by a photodetector 33 through an image forming lens 32, and also detects a light quantity distribution of a photodetecting spot. Also, a focusing controlling circuit 4 consists of a spot diameter detecting circuit 41, a CPU42 and a movement controlling circuit 43, and moves the lens 24 in the direction A so that the spot diameter becomes minimum, by driving a moving mechanism 25. |
