METHOD AND EQUIPMENT FOR MEASUREMENT OF INTACT PULP FIBERS

摘要

The present invention provides a non-destructive method capable of real-time or on-line measurement of a wood or pulp fiber without sample pretreatment for the microfibril angle and the path difference, a parameter proportional to the fiber's cell wall thickness. The method employs a circular polariscope in combination with a line spectral camera with the former generating a micrograph insensitive to the orientation of a fiber and determined only by the fiber's properties related to polarized light and the latter capturing a line image cross the fiber and dispersing it into a spectral image to perform a real-time spectral analysis of the fiber's image. The method further uses the spectrum of a background image part contained in the line image that borders the fiber to normalizing the fiber's spectrum. Therewith the method enables measurement of a fiber or a moving fiber oriented arbitrarily for its microfibril angle and phase retardation by acquiring only one image from the fiber and is capable of over-determining the parameters with the light intensity data created at all wavelengths in the spectral range of the equipment used to avoid possible ambiguous results in signal processing. The method of the invention can be modified for real-time or on-line measurement of other birefringent samples including retardation films and waveplates.