METHOD AND APPARATUS FOR MEASURING REFLECTING POINT OF OPTICAL PART

摘要

PURPOSE:To measure with a high sensitivity position of the reflecting point of a low reflectivity in an optical part and the reflectivity. CONSTITUTION:The light of an incoherent light source 1 is split. One light beam is cast on an optical part. The reflected light is made to be the reflecting- point measuring light, and the other is cast on a movable mirror. The reflected light is made to be the first reference light. Both light beams are made to interfere. The signal is detected as the optical-part-reflecting-point measuring signal. The light of a coherent light source 2 having the same wavelength as the central wavelength of the incoherent light source is split. One is cast on the movable mirror and made to be the mirror-speed measuring light (b), and the other is cast on a fixed mirror and the reflected light is made to be the second reference light. Both light beams are made to interfere, and the signal is detected as the mirror-speed measuring signal. The AC component in the mirror-speed measuring signal is extracted from the reflecting-point measuring signal of the optical part.