Detection of Small Convex and Concave Defects on Optical Films by Patterned Illumination (3rd Report)

—Optimum Designing of Optical System based on the “Reaching Range of the Ray”—

Abstract

This paper describes an optimum designing method of optical system for convex and concave defect detection, which uses patterned illumination. “Reaching Range of the Ray(RRR)”, which is calculated numerically based on the defect shape, is defined. RRR indicates width of effective area on the patterned illumination that contributes to observation of the defect. It is used as guidance for sensitivity of defect detection. Determination method of illumination pattern and optical alignment by using detection sensitivity based on RRR is shown. This paper also described an estimation method of observation images of defects and a selection method of defect detection algorithm for various shapes of defects.