부산대학교 도서관

A fringe visibility method for sizing particles 10 mm and larger has been developed. As the image of a particle scans across a variable frequency grid, the transmitted light signal oscillates with varying visibility. The visibility goes through a null at a well-defined point where the particle diameter approximates the local grid spacing. Several optical arrangements implementing the variable frequency grid technique have been tested. Using classified alumina and pulverized coal particles we obtained good agreement between size distributions measured by this technique and those from a commercial off-line analyzer. However, our optical arrangement and signal processing techniques require further development to reduce them to practice.