Self measuring illumination device
US4654521A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Sep 16, 1985 |
| Grant date | Mar 31, 1987 |
| Priority date | — |
| Expiry date | Sep 16, 2005 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01J1/4214
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
An illumination device is disclosed which includes a lamp for producing light. Light from the lamp enters the input end of a cuboidal integrating bar formed of material having a refractive index greater than .sqroot.2. The edges of the output end of the bar are rendered imperfect by blunting. Light escaping the bar, other than through the output end of the bar, by virtue of the imperfections, is detected by a photosensitive device in a space within a housing around the bar. The housing has inlet and outlet apertures such that light cannot enter the space in the housing other than through the bar. The imperfections are masked so that light cannot enter the bar through the imperfections. The photosensitive device produces a signal indicative of the useful light output of the bar, which signal is not influenced by light entering the output end of the bar.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.