Optical: systems and elements – Lens – With variable magnification
Patent
1989-10-25
1991-11-19
Sugarman, Scott J.
Optical: systems and elements
Lens
With variable magnification
354219, 354222, 354225, G02B 1514, G03B 1302, G03B 1310
Patent
active
050661159
ABSTRACT:
A view-finding optical system may be used which is simple in construction, employs inexpensive optical materials, and is capable of eyesight adjustment over a range of -2.5 to +1.5 diopters. A pentaprism is provided closest to the focusing side screen. A negative meniscus lens in provided next to the pentaprism. The surface of the negative meniscus lens closest to the focusing side screen is a convex surface. Additonally, this lens is preferably formed of a polycarbonate resin. A biconvex lens is provided on the other side of the negative meniscus lens. This lens is preferably formed of an acrylic resin. The eyesight is adjusted by moving the biconvex lens along the optical axis while the negative meniscus lens remains in a fixed position.
REFERENCES:
patent: 4217048 (1980-08-01), Egawa
patent: 4707103 (1987-11-01), Ikemori et al.
patent: 4731625 (1988-03-01), Nozawa
patent: 4751539 (1988-06-01), Yamada et al.
patent: 4757336 (1988-07-01), Nakayama et al.
"Symposium on Optical Surface Technology", Ulrich Greis, Gunther Kirchof, Proceedings, vol. 381, Apr. 12-14, 1983.
Asahi Kogaku Kogyo K.K.
Sugarman Scott J.
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