To rapidly detect foreign objects, without misdetecting the edge of a disk, when inspecting the foreign objects on the disk by rotating the disk to be inspected, and at the same time applying laser beams to the inspection surface, capturing the reflected light and scattered light for generating images, and performing image recognition processing.
Image generation and image recognition processing are executed and foreign objects are detected on images, and at the same time the position of the edge section of a disk 2 is measured; the amount of eccentricity at the center of disk rotation is calculated from the measurement value, the calculated amount of eccentricity is added to foreign object detection data obtained by the image recognition processing, the foreign object detection data where the amount of eccentricity is added is compared with a data region, corresponding to the inspection surface; the foreign object detection data that do not agree with the data region are excluded; and the detection data at the edge section that has been misdetected as foreign objects are masked, thus maximizing the inspection region and speedily completing inspection, even if measurement of the amount of eccentricity is conducted.
NAGASAKI TATSUO
NAKAJIMA SHINYA
