INSIDE DIAMETER MEASUREMENT APPARATUS OF DISK SUBSTRATE, INSIDE DIAMETER MEASUREMENT METHOD, MANUFACTURING METHOD OF DISK SUBSTRATE AND MANUFACTURING METHOD OF MAGNETIC DISK

摘要

PROBLEM TO BE SOLVED: To provide a noncontact disk substrate inside diameter measurement apparatus for enabling an accurate measurement, and preventing a to-be-measured object from being damaged during the measurement. SOLUTION: A laser displacement gauge 100 for measuring an inside diameter of a disk substrate 200 with a circular hole 210 formed in the center includes: a line laser light source 110 for irradiating a main surface of the disk substrate with a line laser 112; a substrate holder 130 for supporting the disk substrate 200; a lifting section 140 for lifting the substrate holder 130 or the line laser light source 110 so as to pass the line laser 112 through the circular hole 210 of the disk substrate 200; a light receiving section 120 for receiving the line laser 112 reflected by or passing through the disk substrate 200, and obtaining a distribution of the light quantity while the substrate holder 130 or the line laser light source 110 is lifted; and an inside diameter measuring section 150 for measuring the inside diameter of the circular hole 210 from the distribution of the light quantity obtained by the light receiving section 120. The substrate holder 130 supports the disk substrate 200 at three supporting points 220A-220C. COPYRIGHT: (C)2009,JPO&INPIT