Objective lens system for endoscopes having an image transfer optical fiber bundle
US5777797A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Sep 5, 1996 |
| Grant date | Jul 7, 1998 |
| Priority date | — |
| Expiry date | Sep 5, 2016 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG02B23/243
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
An objective lens system for an endoscope having an image transfer optical fiber bundle comprises from the object end a first lens of negative power having a concave image side surface, a second lens of positive power having a radius of curvature greater on an image side than on an object side, a third lens of positive power having a radius of curvature greater on the object side than on the image side, a doublet lens of positive power which comprises a forth lens element and a fifth lens element, and an aperture diaphragm interposed between the second and third lenses and satisfies the following relations: EQU .vertline.d.multidot.f/f.sub.R.sup.2 .vertline.<0.11 EQU v2<45.0 where f is the equivalent focal length of the entire objective lens system, f.sub.R is the equivalent focal length of the rear lens group including the third, fourth and fifth lens elements, d is the axial distance between the aperture diaphragm and the front focal point of the rear lens group, and v2 is the Abbe number of glass for the second lens.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.