Optical: systems and elements – Lens – Eyepiece
Patent
1997-02-04
1998-05-26
Nelms, David C.
Optical: systems and elements
Lens
Eyepiece
359758, 359761, 359764, G02B 2500
Patent
active
057575533
ABSTRACT:
Eyepiece lenses of wide visual field, one of which has a field angle of 75.degree. or wider, and another one of which has a field angle of 60.degree. with a smaller number of constituent lenses than the former has. One of these eyepiece lenses comprises, in the order from the light incidence side, a first lens unit of negative refractive power, a second lens unit of positive refractive power in the meniscus form concave toward the light incidence side, a third lens unit of meniscus form concave toward the light incidence side, a fourth lens unit of positive refractive power, and a fifth lens unit of positive refractive power in the meniscus form convex toward the light incidence side. A middle image plane lies within the second lens unit, or in a space between the second and third lens units.
REFERENCES:
patent: 2899862 (1959-08-01), Baker
patent: 4720183 (1988-01-01), Dilworth
patent: 4747675 (1988-05-01), Nagler
patent: 5255121 (1993-10-01), Suzuki
Bey Dawn-Marie
Canon Kabushiki Kaisha
Nelms David C.
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