Liquid-crystal image director for single-lens-reflex camera
US5337106A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jun 9, 1993 |
| Grant date | Aug 9, 1994 |
| Priority date | — |
| Expiry date | Jun 9, 2013 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG03B19/12
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
The mirror in a single-lens-reflex (SLR) camera is eliminated by employing a liquid crystal cell and a polarizing beam splitter. The light from an illuminating lamp (32) is linearly polarized in a horizontal direction by a polarizer (58). The polarized illuminating light is totally reflected by a polarizing beam splitter (PBS) (54) and passes through a quarterwave plate (QWP) (56) and an objective lens (36). After passing through QWP (56) for the second time, the light is vertically polarized and totally passes through PBS (54). A focusing lens (40) focuses the image onto a film (30). A voltage supply (46) is connected to a liquid-crystal (LC) cell (44) by an electric switch (52) that can turn LC cell (44) on or off. When LC cell (44) is off, the polarization of the light is rotated by 90.degree. to be horizontally polarized. Thus the light is reflected by another PBS (48) to a prism (24) for viewing by a user (26). When the LC cell (44) is on, the light polarization is not rotated, and the light is transmitted through the PBS (48) to a mechanical shutter (28). During the shutter's (28) open period, an intense light pulse from a strobe lamp (42) illuminates a patient's eye (38) and…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.