ON-LINE FIBER ORIENTATION DISTRIBUTION MEASUREMENT

The present invention discloses a method and apparatus for the on-line measurement of fiber orientation in a translucent sheet. To measure the fiber orientation, coherent light is directed onto one surface of the sheet in a pattern of sufficient intensity to produce a second pattern on the other surface of the sheet. The shape of the second pattern is determined, at least in part, by the orientation of the fibers in the sheet. A sensing apparatus including a video camera and frame grabber, views the second pattern and produces a freeze frame image signal. Even though the second pattern may be moving, the sensing apparatus freezes this motion and produces the freeze frame image signal to represent a stationary image of the second pattern. The freeze frame image signal is analyzed to determine the shape of the second pattern and from this shape the orientation of the fibers in the sheet is determined. Also disclosed is an apparatus for using the method and an improved system for making paper using the method.