OPTICAL SYSTEM FOR DEFECT INSPECTION, DEFECT INSPECTION DEVICE, AND METHOD OF DEFECT INSPECTION

摘要

PROBLEM TO BE SOLVED: To provide an optical system for defect detection and a defection device capable of detecting defects with high accuracy substantially without being affected by back surface defects. SOLUTION: Ring-shaped light flux received by a hollow optical member for receiving ring-shaped light flux is focused as a light beam on a surface of a disk. Scattered light coming from the disk surface toward the hollow in the optical member is received by an objective lens. The scattered light is received by a light receiver via the objective lens.