| 摘要 |
PROBLEM TO BE SOLVED: To measure the surface shape, if nonspherical, at a high accuracy by providing means for changing the spacing between a spot light source generating means having a reflective surface and a test surface and means for analyzing an interference fringe, emitting a reference flux from the spot light source forming means and reflecting a measuring light by the reflective surface to form the interference fringe as a reflected flux. SOLUTION: A reflection mirror pin hole mirror 3 having a pin hole as a spot light source generating means is disposed between a laser light source 1 and a spherical test surface 4. A light from the light source 1 passes through the mirror 3 to irradiate the aspherical test surface 4 as a measuring flux and reflected lights are again collected to the mirror 3. The light reflected from the mirror 3 passes through an image forming lens 6 to form an image on a light receiving face of a CCD 7. On the light receiving face an interference fringe is formed by the interference of a reference flux with a measuring flux from the test surface. A computer 8 computes the shape of the aspherical test surface 4. If the aspherical test surface 4 is geatly deviated from a spherical surface, a stepping motor 9 moves the mirror 3 to measure once again.
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