| 摘要 |
PURPOSE:To prevent an error from being generated in measuring a clear paint film thickness due to the surface reflection of the film and the like by using the contrast value of the reflectance of the clear paint film coated with a known thickness. CONSTITUTION:A wavelength wave absorbed by a specific wavelength electromagnetic wave absorbent contained in a clear paint film to be measured and a wavelength wave that is not absorbed by the absorbent are irradiated 1 on the clear paint film under the same condition and values compared with reflectances for both waves are calculated 7. Then, from a relationship between the values compared with the reflectances for both the wavelength waves and a film thickness when those two wavelength waves are irradiated 1 on the clear paint film with the known thickness, the thickness of the clear paint film to be measured is measured 7. Thus, a calibration curve is made which determines a relationship between the film thickness and a voltage level corresponding to the intensity ratio of the reflected light with two wavelengths from the clear paint film with the known thickness irradiated 1 under the same condition. When the voltage level corresponding to the intensity ratio between reflected light with two wavelengths from the clear paint film to be inspected with an unknown thickness is referred to the calibration line, errors due to the scattering of light on the surface of the clear paint film and the like are reduced and the film thickness can be easily measured with a high accuracy.
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