| 摘要 |
PURPOSE:To minimize the influence of the unevenness of the ink surface of a substrate by measuring the spread of an image or the shape of a brightness distribution, etc., with data from a detector and calculating the thickness of an ink film from the measured value. CONSTITUTION:This device consists of a laser light emission device 2, a lens 4, a detector 5, and a computing element 6 and the detector 5 measures the spread of plural projection light beams. At this time, glass which has a refractive index distribution periodically in two directions is regarded as a flat plate 9 which has many small lenses 8 and many convergent light beams 11 obtained by projecting parallel light 10 thereupon are projected on the ink film. Then, the spread of plural projection light beams on the ink surface is measured by a detector 5 and analyzed by the computing element 6. Consequently, as the spread of images becomes larger and larger, relative dispersion becomes lower and lower and the gradient of a graph increases, so that an analytical value of good quality is obtained. Therefore, even if the substrate of the ink surface has unevenness, its influence is minimized, so a decrease in measurement accuracy is eliminated and the ink film thickness is easily measured.
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