Apparatus for measuring the refractive power of an optical syste

Details Apparatus for measuring the refractive power of an optical syste Apparatus for measuring the refractive power of an optical syste

1993-11-30

1995-06-27

Sikes, William L.

Optics: eye examining, vision testing and correcting

Eye examining or testing instrument

Objective type

351211, 356124, A61B 310

Patent

active

054284147

ABSTRACT:
A compact, low-cost apparatus for measuring the refractive index of an eye utilizes a chopper which forms and scans two orthogonal fringes. In a light-receiving unit, at least three light-receiving elements are arranged not to be aligned in a line. With these light-receiving elements, time differences when the fringes pass light-receiving elements in each of two pairs are measured. A control & arithmetic unit calculates the spherical power, the cylindrical power, and the cylindrical axis degree by performing predetermined calculations using the measurement data. The apparatus requires no image rotator, and hence, a compact, low-cost apparatus can be realized. Also, the measurement time can be shortened.

REFERENCES:
patent: 4199816 (1980-04-01), Humphrey
patent: 4353625 (1982-10-01), Nohda et al.
patent: 4526451 (1985-07-01), Nohda
patent: 5148231 (1992-09-01), Ishiguro et al.
patent: 5210555 (1993-05-01), Ishikura et al.
Patent Abstracts of Japan, vol. 11, No. 173 (P-582) 4 Jun. 1987 (JP-A-62 005 147).

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