Zoom lens system
US5923478A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Jun 13, 1997 |
| Grant date | Jul 13, 1999 |
| Priority date | — |
| Expiry date | Jun 13, 2017 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG02B15/144113
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
The object of the present invention is to provide a high-performance zoom lens system that has a small number of lens elements and can also be used for wide-angle purpose. In order to achieve the object, said zoom lens system has, from the object side, a first lens unit having positive refractive power, a second lens unit having negative refractive power, a third lens unit having positive refractive power and a fourth lens unit having positive refractive power, wherein said zoom lens system varies magnification by changing a distance between at least said first and second lens units, wherein at least one of said lens units includes a gradient index lens, said gradient index lens having at least one aspherical surface.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.