Objective with large aperture ratio
US5299065A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Feb 22, 1993 |
| Grant date | Mar 29, 1994 |
| Priority date | — |
| Expiry date | Feb 22, 2013 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG02B13/16
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
An objective lens comprising, respectively from the object: a first element of a positive lens, at the object end thereof, having a convex surface; a second element of a positive meniscus lens, at the object end thereof, having a convex surface; a third element of a negative lens, at the image end thereof, having a concave surface; a fourth element of a single lens or a cemented lens, at the object end thereof, having a convex surface, wherein the cemented lens includes two or three lenses; a fifth element of a negative lens, at the object end thereof, having a concave surface; and a sixth element of a positive lens, at the object end thereof, having a convex surface. The objective lens satisfies the following three conditional equations, assuming that "f" designates the focal distance of the entire lens system: EQU 0.44f<R II<0.65f (1) EQU 0.63f<R IV<1.00f (2) EQU 0.55f<S III+D IV<0.70f (3) where R II is the curvature radius of the object-end surface of the second lens element; R IV, the curvature radius of the object-end surface of the fourth lens element; S III, a distance between the third and the fourth lens elements; and D IV, the thickness of the fourth lens element.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.