Door viewer

Patent

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Details

350286, 350319, 350453, G02B 2504, G02B 2302

Patent

active

048923990

ABSTRACT:
A door viewer includes two prisms of rectangular isosceles triangle shape in cross section whose hypotenuse surfaces abut horizontally, a front convex lens, an intermediate plano-convex lens and a plano-convex eyepiece lens. The front convex lens has a front concave surface and a rear convex surface to correct chromatic aberration. The convex surfaces of the intermediate and eyepiece lenses are positioned face to face with each other to correct barrel distortion. The view casts an image onto a ground glass screen formed on or provided abutting the eyepiece lens.

REFERENCES:
patent: 2424283 (1947-07-01), Miles
patent: 3514188 (1970-05-01), Blosse et al.
patent: 3910676 (1975-10-01), Fojtik et al.
patent: 4082434 (1978-04-01), Hayashi et al.
patent: 4116529 (1978-09-01), Yamaguchi
patent: 4257670 (1981-03-01), Legrand
patent: 4269474 (1981-05-01), Kamimura
patent: 4730911 (1988-03-01), Wood et al.

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