Three-group zoom lens
US6654180B2 · kind B2 · utility
Assignee
Inventor
Key dates
| Filing date | Jan 10, 2003 |
| Grant date | Nov 25, 2003 |
| Priority date | — |
| Expiry date | Jan 10, 2023 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG02B15/143507
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
A three-group zoom lens includes, in order from the object side, a first lens group of negative refractive power, and second and third lens groups, each of positive refractive power. The first and second lens groups include negative and positive components and the third lens group is a single lens component. All the lens components may be single lens elements. When zooming from the wide-angle end to the telephoto end, the second and third lens groups move toward the object side and all three lens groups move such that the group spacings decrease. The second lens group includes a diaphragm on its object side. A constant axial spacing between the second and third lens groups is maintained when zooming while the zoom lens is focused at infinity, and the third lens group is moved toward the object side when focusing from infinity to a near point.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.