Optics: measuring and testing – By light interference – For dimensional measurement
Reexamination Certificate
2005-12-06
2005-12-06
Turner, Samuel A. (Department: 2877)
Optics: measuring and testing
By light interference
For dimensional measurement
Reexamination Certificate
active
06972849
ABSTRACT:
Interferometric scanning method(s) and apparatus for measuring rotationally and non-rotationally symmetric test optics having spherical, mildly aspherical and multiple, mildly aspherical surfaces. At least a partial spherical wavefront is generated from a known origin along a scanning axis through the use of a spherical reference surface positioned along the scanning axis upstream of the known origin. A test optic is aligned with respect to the scanning axis and selectively moved along said scanning axis relative to the known origin so that the spherical wavefront intersects the test optic at the apex of the aspherical surface and at one or more radial positions where the spherical wavefront and the aspheric surface intersect at points of common tangency to generate interferograms containing phase information about the differences in optical path length between the center of the test optic and the one or more radial positions. The interferogram is imaged onto a detector to provide an electronic signal carrying the phase information. The axial distance, ν, by which said test optic is moved with respect to said origin is interferometrically measured and the optical path length differences, p, between the center of test optic and the one or more radial positions is calculated based on the phase differences contained in the electronic signal. The coordinates, z and h, of the aspherical surface are calculated wherever the circles of curvature have intersected the aspherical surface at common points of tangency and in correspondence with the interferometrically measured distance, ν and calculated optical path lengths, p. The shape of the aspheric surface is then determined based on the coordinate values and the optical path length differences.
REFERENCES:
patent: 4697927 (1987-10-01), Ono
patent: 5004346 (1991-04-01), Kühel
patent: 5187539 (1993-02-01), Adachi et al.
patent: 5416586 (1995-05-01), Tronolone et al.
patent: 5625454 (1997-04-01), Huang et al.
patent: 5844670 (1998-12-01), Morita et al.
patent: 6222621 (2001-04-01), Taguchi
patent: 6312373 (2001-11-01), Ichihara
patent: 6456382 (2002-09-01), Ichihara et al.
patent: 6707616 (2004-03-01), Takahashi et al.
patent: 6714308 (2004-03-01), Evans et al.
patent: 2003/0002049 (2003-01-01), Kuchel
patent: 2003/0103215 (2003-06-01), Kuchel
Lin, Ding-tin, and Wang, Der-Shen. “Profile Measurement Of An Asperic Cyllndrical Surface From Retroreflection.” Applied Optics, vol. 30, No. 22 (Aug. 1, 1991): pp. 3200-3204.
Dörband, B. et al. “High Precision Interferometric Measurements of Lens Elements.” Fringe 97: Proceedings of the 3rd International Workshop on Automatic Processing of Fringe Patterns Held in Bremen, Germany, Sep. 15-17, 1997. pp. 473-480.
International Search Report From PCT/EP02/07378 mailed on Nov. 15, 2002.
Caufield Francis J.
Lyons Michael A.
Turner Samuel A.
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