METHOD AND APPARATUS FOR MEASURING DISPLACEMENT QUANTITY, AND DISPLACEMENT VELOCITY OF MOVABLE BODY

摘要

PROBLEM TO BE SOLVED: To measure a displacement quantity or a displacement velocity, for each region of a body moving at a high-speed with simple constitution, in a method and an apparatus for measuring the displacement quantity and the displacement velocity, in which the displacement quantity and the displacement velocity of the movable body, such as a polygon mirror for use in an electrophotographic image forming apparatus or the like, are measured.;SOLUTION: An interference fringe 22, by a reflected light from the movable object to be measured, for example the rotating polygon mirror 100, and by a reference light, is measured with a CCD camera 16. The contrast of the imaged interference fringe 22 is detected by a computer 6, and the displacement velocity and the displacement quantity for each spot of the mirror surface of the polygon mirror 100 are measured, by comparing the contrast of the detected interference fringe 22, with correlation data of the displacement quantity and the displacement velocity with the contrast of the interference fringe, acquired in advance. Thus, the displacement velocity and the displacement quantity for each spot can be measured, over the whole surface to be measured, without two-dimensionally scanning the object to be measured with a laser light. Because a speckle pattern is not used for the measurement, the displacement velocity and the displacement quantity can be measured, even if the surface to be measured is a mirror surface.;COPYRIGHT: (C)2005,JPO&NCIPI