Optics: eye examining – vision testing and correcting – Eye examining or testing instrument – Objective type
Patent
1980-09-26
1983-12-20
Rosenberger, R. A.
Optics: eye examining, vision testing and correcting
Eye examining or testing instrument
Objective type
351237, A61B 310
Patent
active
044213913
ABSTRACT:
An eye-refractometer includes an objective optic having a first optical path, an apertured mirror for dividing the first optical path into a second optical path and a third optical path, a mask disposed in the second optical path and having linear marks orientated in at least three directions, a radiation source for illuminating the mask, a mask disposed in the third optical path and having liner detecting areas orientated in at least three directions and photocells arranged behind the respective areas. Improvements in this eye-refractometer comprise an apertured plate disposed between the apertured mirror and one of above said masks and an annular apertured plate disposed between said apertured mirror and the other mask. Another improvement is found in that the length of the linear detecting area is shorter than the length of optimum focused images of the linear marks.
REFERENCES:
patent: 3594071 (1971-07-01), Okajima
patent: 3883230 (1975-05-01), Guilino
patent: 4132466 (1979-01-01), Matsumura
patent: 4265518 (1981-05-01), Matsumura
patent: 4293198 (1981-10-01), Kohayakawa et al.
Hirano Reiji
Ishikawa Yasuyuki
Kohayakawa Yoshimi
Maruyama Shigeo
Matsumura Isao
Canon Kabushiki Kaisha
Rosenberger R. A.
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