Objective optical system and endoscope using same
US8902515B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Apr 30, 2014 |
| Grant date | Dec 2, 2014 |
| Priority date | — |
| Expiry date | Apr 30, 2034 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG02B13/04
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
An objective optical system includes: a first lens group having a negative power; an aperture stop; and a second lens group having a positive power, provided in this order from an object side. The first lens group includes a first lens, which is a negative single lens, and a cemented lens formed by a positive lens and a negative lens, provided in this order from the object side. The second lens group includes a fourth lens, which is a positive single lens, and a cemented lens formed by a positive lens and a negative lens, provided in this order from the object side. The objective optical system simultaneously satisfies Conditional Formulae (1) −1.5<f123/f<−0.5 and (2) 1.8<f456/f<2.1, wherein f is the focal length of the entire system, f123 is the combined focal system of the first lens group, and f456 is the combined focal length of the second lens group.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.