Paper area density measurement from forward transmitted scattered light
US6229612A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Oct 7, 1999 |
| Grant date | May 8, 2001 |
| Priority date | — |
| Expiry date | Oct 7, 2019 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10S162/06
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A method whereby the average paper fiber area density (weight per unit area) can be directly calculated from the intensity of transmitted, scattered light at two different wavelengths, one being a non-absorpted wavelength. Also, the method makes it possible to derive the water percentage per fiber area density from a two-wavelength measurement. In the optical measuring technique optical transmitted intensity, for example, at 2.1 microns cellulose absorption line is measured and compared with another scattered, optical transmitted intensity reference in the nearby spectrum region, such as 1.68 microns, where there is no absorption. From the ratio of these two intensities, one can calculate the scattering absorption coefficient at 2.1 microns. This absorption coefficient at this wavelength is, then, experimentally correlated to the paper fiber area density. The water percentage per fiber area density can be derived from this two-wavelength measurement approach.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.