Abstract

Forward light scattering is important but is difficult to measure because of the large unscattered background beam. Photorefraction in a barium titanate crystal is used in this experiment to separate the scattered beam from the unscattered background beam. As a result of beam fanning due to photorefraction in the crystal, greater than 99% extinction of the background beam is achieved. The time dependence, which is essential for taking advantage of this novelty filter, is introduced to the scattered beam by moving the fiber in and out of the laser beam in a time interval that is short compared to the response time of the crystal. Light scattered by the moving fiber then passes through the crystal undisturbed. The light scattering from fibers with radii from 15 μm to 33 μm have been measured in the angular range of 0° to 0.3°. The data is in excellent agreement with theoretical calculations.

© 1992 Optical Society of America