Device for inspecting an interference filter for a projection television display tube
US4988203A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Mar 28, 1989 |
| Grant date | Jan 29, 1991 |
| Priority date | — |
| Expiry date | Mar 28, 2009 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01M11/00
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
In a device for measuring the cut-off wavelength of an interference filter for a projection television display tube, the interference filter and a bandpass filter are arranged one behind the other. The bandpass filter has a transmission characteristic with a cut-off wavelength which approximately coincides with the desired cut-off wavelength of the interference filter, but with a slope varying in the opposite direction. A white light beam generated in a light source is incident through the two filters. The intensity, which is measured by a detector on the other side of the filters, is a measure of the cut-off wavelength of the interference filter. The device may have a second measuring system for measuring the absorption of the interference filter.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.