Optical: systems and elements – Lens – Reverse telephoto
Patent
1999-04-20
2000-11-07
Epps, Georgia
Optical: systems and elements
Lens
Reverse telephoto
359663, 359726, 359784, G02B 1304, G02B 1322, G02B 1700, G02B 912
Patent
active
061445037
ABSTRACT:
A projection lens which has a wide angle view, a short projection distance and telecentricity, and in which the projection can be performed with high contrast, various aberrations such as a distortion aberration are reduced and the optical path is converted by providing a first lens group having negative refractive power and second and third lens groups having positive refractive power are arranged from a longer conjugate side. Representing a back focus at a projection distance of an infinite point by BF; the composite focus distance of the entire system by F; a center distance between said first lens group and said second lens group by GD1; the composite focus distance of said first lens group by F1; the composite focus distance of said second lens group and said third lens group by F23; and the center distance between said second lens group and said third lens group by GD2, the following relationships are satisfied:
REFERENCES:
patent: 4526442 (1985-07-01), Betensky et al.
patent: 5278698 (1994-01-01), Iizuka et al.
patent: 5331462 (1994-07-01), Yano
patent: 5760965 (1998-06-01), Kim
patent: 5870228 (1999-02-01), Kreitzer et al.
Epps Georgia
Maioli Jay H.
Sony Corporation
Spector David N.
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