Method and apparatus for analyzing ophthalmic elements and the l

Details Method and apparatus for analyzing ophthalmic elements and the l Method and apparatus for analyzing ophthalmic elements and the l

1982-04-19

1986-09-16

Rosenberger, R. A.

Optics: measuring and testing

Lens or reflective image former testing

Optical center, cylinder axis, or prism measuring or...

356125, G01B 900

Patent

active

046119132

ABSTRACT:
The disclosure concerns the determination of the ophthalmic parameters of a thin astigmatic optical element without requiring initial location of its cylindrical axis. The effective optical power of the eye or other element is measured in three mutually spaced meridians that are selected without regard for the cylindrical axis. The ophthalmic parameters of the element, typically the spherical power, the cylindrical power and the cylindrical axis, are then derived from the measured powers and their selected meridian angles. The power of an astigmatic element in a selected meridian intermediate the principal meridians may be determined in generally conventional manner by adjusting a test optical system to produce a sharp image of a suitable target, preferably with limitation of the image-forming light to rays that traverse the element close to the selected meridian. Also disclosed is a method of establishing correct focus of such a test system in terms of the lateral magnification of the target image rather than its sharpness. For that purpose the test system is typically of Badal type with effective aperture stop axially spaced from the element under test.

REFERENCES:
patent: 1510114 (1924-09-01), Thorner
patent: 3486825 (1969-12-01), Howland
patent: 4275964 (1981-06-01), Vassiliadis

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