Focus detecting device for opthalmologic instruments

Details Focus detecting device for opthalmologic instruments Focus detecting device for opthalmologic instruments

1982-01-28

1983-08-23

Perkey, William B.

Optics: eye examining, vision testing and correcting

Spectacles and eyeglasses

Ophthalmic lenses or blanks

354 62, 351208, 351211, 358227, G03B 310, G03B 2900, A61B 310, H04N 526

Patent

active

044000707

ABSTRACT:
A focus detecting device for an eye fundus camera including a target having a target pattern comprised of a first slit and a second and third slits disposed in parallel with and at the opposite sides of the first slit. The second and third slits are symmetrical to each other with respect to the first slit. Deflecting prisms are provided to deflect the luminous flux through the first slit in one direction perpendicular to the longitudinal axis of the first slit and the luminous fluxes through the second and third slits in the opposite direction. The slit pattern is convenient for automatic focus adjustment.

REFERENCES:
patent: 3819256 (1974-06-01), Bellows et al.
patent: 3925793 (1975-12-01), Matsumura et al.
patent: 4187014 (1980-02-01), Kato et al.
patent: 4277150 (1981-07-01), Wada et al.
patent: 4293198 (1981-10-01), Kohayakawa

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