Eyepiece lens with long eye relief

Details Eyepiece lens with long eye relief Eyepiece lens with long eye relief

1996-09-20

1998-05-05

Nelms, David C.

Optical: systems and elements

Lens

Eyepiece

359643, 359644, 359645, G02B 2500

Patent

active

057483809

ABSTRACT:
An eyepiece lens is disclosed that corrects aberrations over a wide apparent field of view, and has a short overall length and sufficiently long eye relief (typically at least 150% of overall focal length F). The eyepiece lens comprises, in order from the objective lens side, first and second lens groups having negative and positive refractive power, respectively, with a field stop situated therebetween. The first lens group comprises a cemented negative lens including two lens elements cemented together. The second lens group comprises, in order from the objective lens side, a positive meniscus lens element having a concave surface oriented objectivewise; a cemented lens comprising two lens elements cemented together and in which the most objectivewise lens surface is a concave surface oriented objectivewise; and a lens subgroup having positive refractive power and comprising a positive meniscus lens element having a concave surface oriented eyewise. The eyepiece lens satisfies at least the conditions: -4.5.ltoreq.F.sub.1 /F.ltoreq.-2.0, 1.0<F.sub.2 /F.ltoreq.3.0, and 2.5.ltoreq.D/F.ltoreq.5.0, wherein F, F.sub.1, and F.sub.2 are the respective focal lengths of the eyepiece lens overall, the first lens group, and the second lens group G.sub.2 ; and D is the axial air-space distance between the first and second lens groups.

REFERENCES:
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patent: 3352620 (1967-11-01), Scidmore et al.
patent: 3384434 (1968-05-01), Scidmore et al.
patent: 4286844 (1981-09-01), Nagler
patent: 4497546 (1985-02-01), Kobayashi
patent: 4747675 (1988-05-01), Nagler
patent: 5579167 (1996-11-01), Oomura et al.
patent: 5612823 (1997-03-01), Koizumi
patent: 5638213 (1997-06-01), Ueno

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