Method and apparatus for determining thickness of an OPC layer on a CRT faceplate panel
US5619330A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Dec 22, 1995 |
| Grant date | Apr 8, 1997 |
| Priority date | — |
| Expiry date | Dec 22, 2015 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01B11/0633
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
The invention relates to a method for determining the thickness of an OPC layer 24 that is strongly absorptive to light at a first wavelength and substantially transmissive to light at a second wavelength. According to the method, the OPC layer is illuminated with light from an array 34 of fluorescent lamps 36 and the light transmitted through the layer is incident on a first filter 42 that is transmissive to light of the first wavelength. A first light intensity pattern transmitted through the first filter is sensed and stored in a first memory frame. Then OPC layer is illuminated again with light and the light transmitted through the layer is incident on a second filter 44 transmissive to light of the second wavelength. A second light intensity pattern transmitted through the second filter is sensed and stored in a second memory frame. The ratio of the first light intensity pattern and the second light intensity pattern is determined and utilized to calculate the thickness of the layer. An apparatus for practicing the method utilizes a CCD camera 38 as a light sensor which receives the filtered light. A computer 50 divides the first memory frame by the second memory frame to calc…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.