Testing Aspheric Lenses: New Approaches
Wolfgang Osten, Bernd Dorband, Eugenio Garbusi, Christof Pruss, Lars Seifert
Keywords: optical metrology, asphere testing, dynamic wavefront adaption, dynamic wavelength adaption
Pages: 40-53
Abstract
Optical metrology provides a unique approach to measuring surfaces, both technical and optical, over a wide measurement range from macro to nano. We present two new approaches to measuring aspheric lenses with increased flexibility. The first is based on a modified Twyman -Green interferometer where multiple sources for the illumination of the aspheric surface with different angles are adopted to achieve a local compensation of the gradient and consequently a reduction of interference fringes. The second is based on a chromatic Fizeau interferometer with a diffractive element as null-optic for the measurement of extreme ultraviolet aspheres.
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