Viewfinder optical system
US5966244A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Oct 3, 1997 |
| Grant date | Oct 12, 1999 |
| Priority date | — |
| Expiry date | Oct 3, 2017 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG02B25/001
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
An eyepiece lens has a single lens element having a positive optical power, and the single lens element has a refractive power of an aspherical surface and a diffractive power. The eyepiece lens satisfies the following condition: EQU -0.0006<{1 /(fl.multidot..nu.)}+.phi.DOE/.nu.DOE<0.0002 where fl represents the focal length resulting from both refractive effect and diffractive effect of the eyepiece lens, .nu. represents the Abbe number of the eyepiece lens, .phi.DOE represents the power resulting from the diffractive effect of the eyepiece lens, and .nu.DOE represents the Abbe-number-equivalent value resulting from the diffractive effect of the eyepiece lens.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.