| 摘要 |
PURPOSE:To make it possible to perform highly accurate measurement, by changing the length of a light path of reflected light; when the light is irradiated on a reference material and a material to be measured, respectively, the interference light obtained by synthesizing the reflected light beams is utilized, and the displacement is measured. CONSTITUTION:The laser beam emitted from a laser oscillator 1 is reflected by a beam splitter 2 and inputted into a 1/4 wavelength plate which is the reference material. A part of the laser beam is reflected by the surface of the 1/4 wavelength plate, and the other part is reflected by the surface of the material to be measured 13. The respective reflected light beams are inputted into a polarization beam splitter 3 through a beam splitter cube 2. The light beam reflected by the 1/4 wavelength plate passes a 1/4 wavelength plate 6, and is reflected by a mirror surface 10 and also by the polarization beam splitter 3, and then the beam is inputted into a polarizing plate 11. The light beam reflected by the material to be measured 13 passes a 1/4 wavelength plate 5, and is reflected by a mirror surface 9, and then the beam is inputted into the polarizing plate 11. The mirror 9 is controlled so that the interference light which has passed the polarizing plate 11 becomes the maximum or minimum. |
