F.theta. lens
US5086350A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Aug 28, 1990 |
| Grant date | Feb 4, 1992 |
| Priority date | — |
| Expiry date | Aug 28, 2010 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG02B13/0005
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
An f.theta. lens comprises a first lens set having a positive or negative refracting power and a second lens set having a positive refracting power, which are located in that order from the side of a light deflector. The first lens set is composed of two lenses cemented together, and the second lens set is composed of a single lens. They satisfy the conditions EQU 0.2.ltoreq..PSI.G2/.PSI..ltoreq.1.5 EQU r1, r2<0 EQU 0.3.ltoreq.r3/r1.ltoreq.1.7 EQU vdl>vd2 where .PSI. denotes the reciprocal of the focal length of the whole f.theta. lens; .PSI.G2 denotes the reciprocal of the focal length of the second lens set; r1, r2, and r3 denote the radii of curvature of the first, second, and third lens-surfaces, each radius taking a positive value when the lens surface is convex as viewed from the side of the light deflector; vd1 denotes the Abbe's dispersion number of the first lens of the first lens set; and vd2 denotes the Abbe's dispersion number of the second lens of the first lens set.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.