| 摘要 |
PURPOSE:To prevent the measuring error due to the defocusing of an image, by detecting the light reflected by an object to be measured by a light detector through a lens, and measuring the interval between the lens and the object to be measured based on the position of the lens, where the amount of the received light becomes the maximum. CONSTITUTION:The image of the light emitted from the small area light source 1 is formed on the surface S of the object to be measured through a beam splitter 5 such as a semitransparent mirror and a lens system means 2. When the surface accuracy of the surface S is high and the surface is a mirror, the reflected light from the surface advances in the reverse direction. The light is inputted into the light detector 4 through the lens system means 2, the beam splitter 5, and an aperture 3. The lens system 2 is scanned by a scanning means 10 in the forward and reverse directions of (x). A reference pulse signal corresponds to the reference position of the lens system 2, which is scanned by a driving signal source 13. When the time between the reference pulse signal and one of peak position pulse signals is measured, the interval between the lens 2 and the surface S can be obtained. |
