THICKNESS MEASURING DEVICE AND THICKNESS MEASURING METHOD FOR TRANSPARENT BODY, AND THICKNESS DERIVATION DEVICE, THICKNESS DERIVATION METHOD AND THICKNESS DERIVATION PROGRAM FOR TRANSPARENT BODY

摘要

PROBLEM TO BE SOLVED: To measure accurately the thickness of even a transparent body comprising a plurality of layers having different refractive indexes.;SOLUTION: A light source 2 of this thickness measuring device 1 for the transparent body projects a beam at a prescribed incident angle from a fixed position in the oblique direction to the surface of the transparent body 50 comprising a plurality of layers. A camera 3 detects two reflected beams reflected by both faces of a thickness measuring object layer of the transparent body 50. The thickness measuring device 1 is equipped with this thickness derivation device 9, and the thickness derivation device 9 includes a distance derivation part 4, a refractive index storage part 5, an incident angle storage part 6 and a thickness calculation part 7. The distance derivation part 4 derives the distance between the two reflected beams detected by the camera 3, and the refractive index storage part 5 stores the refractive index of the thickness measuring object layer, and the incident angle storage part 6 stores the incident angle of the projected beam. The thickness calculation part 7 calculates the thickness d_i of the thickness measuring object layer from the formula (1) by using the distance L_i between the two reflected beams, the refractive index n_i of the thickness measuring object layer, the incident angle ₀ of the projected beam, or the like.;COPYRIGHT: (C)2003,JPO