Scanning interferometer for aspheric surfaces and wavefronts

US6972849B2 · kind B2 · utility

Inventor

• Michael Kuchel · Oberkochen, DE

Key dates

• Filing date: Jun 26, 2002
• Grant date: Dec 6, 2005
• Expiry date: Jul 6, 2023

Classification

• Technology area (CPC G): Physics
• CPC primary: G01B2290/65
• WIPO field: Measurement
• WIPO sector: Instruments

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 differ…