发明名称 |
Interferometric apparatus and methods for measuring surface topography of a test surface |
摘要 |
Apparatus and methods are disclosed for measuring the surface topography of a test surface, such as a spherical or aspherical surface of a refractive or reflective optical element. The test surface is measured by detecting the state of interference fringes generated by interference of a reference light beam and a measurement light beam that interacts (e.g., reflects from) the test surface. The reference and measurement beams are produced by a point light source having a reflective surface. The point light source is disposed between a source of input light and the test surface. The measurement beam (after interacting with the test surface) and the reference beam are caused to interfere with each other to produce a first interference-fringe state. The distance between the point light source and the test surface can be changed between production of the first interference-fringe state and production of a second interference-fringe state. The profile of the test surface is determined by analyzing the resulting interference fringes. A null element can be used to convert a spherical wavefront of the measurement beam into an aspherical wavefront corresponding to the aspherical test surface, or to convert an aspherical wavefront generated by reflection of a spherical wavefront from an aspherical test surface into a spherical or planar wavefront.
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申请公布号 |
US6344898(B1) |
申请公布日期 |
2002.02.05 |
申请号 |
US19990396491 |
申请日期 |
1999.09.14 |
申请人 |
NIKON CORPORATION |
发明人 |
GEMMA TAKASHI;ICHIHARA HIROSHI;ICHIKAWA HAJIME;NAKAYAMA SHIGERU;JACOBSEN BRUCE |
分类号 |
G01B11/255;G01J9/02;(IPC1-7):G01B9/02 |
主分类号 |
G01B11/255 |
代理机构 |
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