| 摘要 |
PURPOSE:To take a measurement which is not affected by variation in the transmissivity of an optical disk substrate, variation in the quantity of laser light, etc., by rotating a polarizer and an analyzer provided on both sides of a body to be measured in a crossed nicols and a parallel nicols state. CONSTITUTION:Linear polarized laser light from a light source 1 is converted by a (1/4)lambda plate 2 into circular polarized light. The polarizer 3 and analyzer 5 which are rotated by pulse motors 7 and 8 respectively are provided on both sides of the body 4 to be measured and a photodetecting element 6 is provided behind the analyzer 5. Then, the polarizer 3 and analyzer 5 are rotated by the pulse motors 7 and 8 in the crossed nicols and parallel nicols states under the control of a microcomputer 10, a signal obtained by the photodetecting element 6 is A/D-converted 9 and inputted to the microcomputer 10, and variation of the signal is analyzed by using a specific expression.
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