Optics: measuring and testing – By configuration comparison – With photosensitive film or plate
Patent
1990-05-30
1994-05-31
Turner, Samuel A.
Optics: measuring and testing
By configuration comparison
With photosensitive film or plate
356359, 356360, 351211, 385 43, G01B 1106
Patent
active
053173899
ABSTRACT:
An novel interferometric apparatus and method for measuring the topography of aspheric surfaces, without requiring any form of scanning or phase shifting. The apparatus and method of the present invention utilize a white-light interferometer, such as a white-light Twyman-Green interferometer, combined with a means for dispersing a polychromatic interference pattern, using a fiber-optic bundle and a disperser such as a prism for determining the monochromatic spectral intensities of the polychromatic interference pattern which intensities uniquely define the optical path differences or OPD between the surface under test and a reference surface such as a reference sphere. Consequently, the present invention comprises a "snapshot" approach to measuring aspheric surface topographies such as the human cornea, thereby obviating vibration sensitive scanning which would otherwise reduce the accuracy of the measurement. The invention utilizes a polychromatic interference pattern in the pupil image plane, which is dispersed on a point-wise basis, by using a special area-to-line fiber-optic manifold, onto a CCD or other type detector comprising a plurality of columns of pixels. Each such column is dedicated to a single point of the fringe pattern for enabling determination of the spectral content of the pattern. The auto-correlation of the dispersed spectrum of the fringe pattern is uniquely characteristic of a particular optical path difference between the surface under test and a reference surface.
REFERENCES:
patent: 3781096 (1973-12-01), Townsley
patent: 5071251 (1991-12-01), Hochberg et al.
PCT Publication, WO90/12534, Publication Date Nov. 1, 1990, Glynn et al.; title: Device for Monitoring Body Functions.
Baroth Edmund C.
Hochberg Eric B.
California Institute of Technology
Keesee, II LaCharles P.
Tachner Leonard
Turner Samuel A.
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