Compact objective lens
US5327291A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Mar 30, 1992 |
| Grant date | Jul 5, 1994 |
| Priority date | — |
| Expiry date | Mar 30, 2012 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG02B13/18
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
A lens system for a folding reflex camera is provided. The system includes: (a) a first group on the object side of the system's stop which (i) has a positive dioptric power, (ii) includes an aspheric surface, and (iii) has a concave surface adjacent to the stop; and (b) a second group on the image side of the stop consisting of either a single positive component or the combination of a single positive component and one or more focusing elements. The system includes at least two elements made of materials differing in dispersive powers where at least one of the elements is of plastic. The system can comprise just two plastic elements and even with such a simple configuration achieves excellent optical performance including a relatively flat field, relatively low distortion, and at least partial correction for lateral chromatic aberration.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.