Optical: systems and elements – Lens – Multiple component lenses
Patent
1991-04-18
1992-06-09
Sugarman, Scott J.
Optical: systems and elements
Lens
Multiple component lenses
359771, G02B 934
Patent
active
051212579
ABSTRACT:
A lens for reading an original at a reduced magnification has first to fourth lens groups sequentially arranged from an object side toward an image side, and a diaphragm arranged between the second and third lens groups. The first lens group are constructed by a joining lens having a positive focal length and is composed of positive and negative lenses. The second lens group are constructed by a joining lens having a positive focal length and is composed of a negative meniscus lens having a convex face on the object side and a positive meniscus lens having a convex face on the object side. The third lens group is constructed by a positive meniscus lens having a concave face on the object side. The fourth lens group is constructed by a joining lens composed of negative and positive lenses. A partial dispersion ratio .theta..sub.gF defined as (n.sub.g -n.sub.F)/(n.sub.F -n.sub.C) using refractive indexes n.sub.g, n.sub.F and n.sub.C of a lens material with respect to lines g, F and C, and an Abbe number .nu..sub.e with respect to a line e satisfy the following conditions,
REFERENCES:
patent: 3941457 (1976-03-01), Kawakami
patent: 4319810 (1982-03-01), Mori
patent: 4560243 (1985-12-01), Terasawa
patent: 4784480 (1988-11-01), Yokota et al.
Ricoh & Company, Ltd.
Sugarman Scott J.
LandOfFree
Lens for reading original does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Lens for reading original, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Lens for reading original will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1809373