| 摘要 |
PROBLEM TO BE SOLVED: To detect and measure a tilt angle θ between a first measuring surface and a second measuring surface of an object installed in an optical system unit, which is not more than Rayleigh limit. SOLUTION: A luminous flux from a laser light source 1 is converted to a parallel luminous flux through a collimator lens 3 and travelled to the two test objects 4, 7. The luminous fluxes reflected on the measuring surfaces 5, 8 of the test objects 4, 7 are returned to an outward path and are converged as spots on a first imaging surface 6 from the collimator lens 3. These light converging positions are the position p1, p2 to be determined by an angle θA based on the tilt angle θ between the measuring surfaces 5, 8 of the test objects, which is not more than Rayleigh limit. These are projected without forming an image to a light receiving part 6 such as CCD by a light receiving lens 10 with an optional magnification. When projected, the 2 spots include an angle θB to generate interference fringes on the overlapping part of the spots. By counting the number of the interference fringes, the tilt angle θ between the measuring surfaces 5, 8 of the test object is obtained. COPYRIGHT: (C)2009,JPO&INPIT
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