| 摘要 |
PURPOSE:To obtain a shear amount at high accuracy by shifting a reference flat plate, which is disposed so that it can intersect orthogonally with the optical axis of a lens in terms of the light condensing point of a converter lens, by a micro distance in the optical axis direction and measuring fringes of interruption fringes arising in an area sensor. CONSTITUTION:A laser light source 10 is light-emitted, and the light beam is reflected by the reference plane 50 intersecting orthogonally with the optical axis through an expander lens 12, a beam splitter 14 and the converter lens 18 to obtain a measurement light beam. Then it is made incident on a beam splitter 26 through the lens 18 and the splitter 14, is branched by corner cubes 28 and 30. The branched light beams are made incident on the area sensor 34. While an operator is viewing the area sensor 34, the moves the reference flat plate 50 and obtains a point P (light condensing point of the lens 18) where the interruption fringe disappears. Then the flat plate 50 is shifted by the known micro distance (d) to measure the number N of the interruption fringes arising in the area sensor 34. The shear amount S, the number N and the moving distance (d) have a certain relationship S=f(N,d). Thus the shear amount S can be obtained easily and precisely. |
