| 摘要 |
PURPOSE:To measure accurately a fine shape with less driving energy by moving a part of an in-focus state discriminating optical system provided with an internal light source while holding an optical path near its object lens and providing a movement extent measuring means of this moving part. CONSTITUTION:The luminous flux emitted from a light source 4 of an in-focus state discriminating optical system 2, whose parts except an object lens 12 are attached to a casing 22, and converged by a lens 12 after passing a collimator lens 6, etc. is projected to the surface of an object 20 to be measured, and the reflected light is led to a sensor 16, and the lens 12 is moved along an optical axis X so that the output of the sensor 16 is zero, thus performing auto-focusing. The extent of movement of the lens 12 is measured by a length measuring means consisting of a length measuring means body 24 using the wave number reading system of a laser interferometer and a corner cube 26 to measure the position of the surface of the object 20 to be measured. This position measurement is performed for the whole of the surface of the object 20 to be measured. |
