Long focal length microlens system
US5831775A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Feb 2, 1996 |
| Grant date | Nov 3, 1998 |
| Priority date | — |
| Expiry date | Feb 2, 2016 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG02B27/0068
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
A long focal length microlens system that controls the variation of the aberration from the infinite object distance to shooting at equal magnification. The long focal length microlens system includes a first lens group G1 of positive refractive power a second lens group G2 of positive refractive power and a third lens group G3 of negative refractive power. When focusing from a infinite object distance to a close shooting distance, a value of D1 is reduced while a value of D2 is increased and a condition of 0.16<.vertline..DELTA.D1 .vertline./.DELTA.D2<0.5 is satisfied where D1 is a gap of lens apexes between said first group G1 and the second group G2. D2 is a gap of lens apexes between said second group G2 and the third group G3, .DELTA.D1 is (D1 at any object distance)-(D1 in the infinite object distance) and .DELTA.D2 is (D2 at any shooting distance)-(D2 in the infinite object distance).
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.