| 摘要 |
PURPOSE:To make it possible to measure displacement of the surface by use of a regular photodetecting element, by making a light beam irradiate the surface of an object, forming an image by the reflected ray, and detecting the displacement of the image, which is accompanied by that of the surface, by means of a regularly rotating douser. CONSTITUTION:An image Q is formed by a reflected ray of the light spot which is formed by making a light beam irradiate an object to be measured A. A dousing disk 18 which has a slit 17 and rotates at a constant speed is provided so as to conform with a moving locus of the image Q. The photodetector 21 detects a light beam of the image Q which moves through the slit 17, and a reference light beam is detected by the photodetector 24. In this constitution, a rotation reference position signal is output by the reference position signal generating circuit 25. A detection signal of the moving image Q is output from the output of the photodetector 21. As for both these signals, count signals corresponding to the angle of rotation of the image Q are output by the rotation angle detection circuit 24. Since displacement of the image Q is in porportion to the angle of rotation, displacement of the image Q, namely, displacement of the surface of an object can be grasped by knowing the angle of rotation. In this way, displacement can be measured by use of a regular photodetecting element. |
