Circularly polarized light method and device for determining wall thickness and orientations of fibrils of cellulosic fibres
US7289210B2 · kind B2 · utility
Assignee
Inventor
Key dates
| Filing date | Nov 26, 2004 |
| Grant date | Oct 30, 2007 |
| Priority date | — |
| Expiry date | Aug 31, 2025 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01N2021/8681
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
This invention provides a novel, rapid method and device for determining the relative phase retardation of different layers of a multi-layered specimen, which is related to the thicknesses of its layers and walls, and the orientations of its optical axes. An intact wood pulp fibre is a typical multi-layered birefringent specimen. This new method is based on the change of polarization of polarized light that passes through a specimen composed of birefringent layers with different optical axis orientations, such as directions of cellulosic microfibrils oriented differently in various layers of wood fibres. In particular, a novel solution is found to relate the emerging light intensity from an intact wood fibre to the incident light intensity, the wavelength of the light, and the relative phase retardations of various layers and orientations of their cellulosic microfibrils, such as fibril angle, in a circularly polarized light system. This new method evaluates the transmitted light intensities of multiple predetermined wavelengths simultaneously to determine the optical and physical properties of a multi-layered specimen being measured. A device for determining the relative phase ret…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.