Objective optical system and endoscope using same
US8896940B2 · kind B2 · utility
Assignee
Inventor
Key dates
| Filing date | Apr 28, 2014 |
| Grant date | Nov 25, 2014 |
| Priority date | — |
| Expiry date | Apr 28, 2034 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG02B23/243
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
The angle of view of an objective optical system is widened, while suppressing generation of lateral chromatic aberration. 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, in this order from an object side. The first lens group includes a negative single first lens, and a cemented lens formed by cementing a positive lens and a negative lens together, provided in this order from the object side. The second lens group includes a positive single fourth lens, and a cemented lens formed by cementing a positive lens and a negative lens together, provided in this order from the object side. The objective optical system satisfies Conditional Formula (1): 15.0<νd(RN)<18.6, wherein νd(RN) is the Abbe's number of the negative lens in the cemented lens within the second lens group with respect to the d line.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.