| 摘要 |
<p>PURPOSE:To enable measurement of condition of deformation of a surface to be measured directly with high resolutions even when the surface to be measured exists in a narrow space by forming an image of a grid near the surface to be measured through an optical axis conversion optical system. CONSTITUTION:In a projection optical system, an output light of a light source 9 is made to irradiate a diffusion plate 11 and a control grid 12 is lighted by the light diffused. A real image 14 of the grid 12 is formed near a surface 8 to be measured using a projection lens 13. Then, a reference grid 16 is arranged in an axial symmetry with the control grid 12. The real image on the object surface 8 is formed on the grid 16 using a photo detecting lens 15. When the object surface 8 is planar perfectly, the real image equal in magnification as the grid 12 is formed on the grid 16. According to the optical system, the real image of the grid 12 is formed near the object surface 8 and the real image obtained from the real image of the grid 12 through the lens 15 is over the grid 16 thereby forming a moire fringe.</p> |
