Objective lens for endoscopes and endoscope
US9709796B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Apr 15, 2016 |
| Grant date | Jul 18, 2017 |
| Priority date | — |
| Expiry date | Apr 15, 2036 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG02B13/06
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
An objective lens for endoscopes includes, in order from the object side: a front group; an aperture stop; and a positive rear group. The front group includes, in order from the object side, a negative first lens, in which the absolute value of the radius of curvature of the surface toward the image side is less than that of the surface toward the object side, and at least one plane parallel plate. The rear group includes, in order from the object side, a positive second lens, and a cemented lens formed by a positive third lens and a negative fourth lens. The coupling surface of the cemented lens is convex toward the image side. Conditional Formulae (1) through (3) concerning the plane parallel plates within the front group, the focal length of the first lens, the radius of curvature of the coupling surface of the cemented lens, etc., are satisfied.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.