THICKNESS AND MOISTURE MEASURING METHOD AND THICKNESS AND MOISTURE MEASURING DEVICE

摘要

PROBLEM TO BE SOLVED: To provide a thickness and moisture measuring device capable of measuring thickness and moisture or the like by using a single device having a single optical system and a single detector. SOLUTION: Spectral separation of light from a light source 1 is made by a diffraction grating 6, and its spectrum is detected by a PDA (photodiod array) 8. A transmittance characteristic of a sample is acquired by detecting the spectrum in both states of inserting the sample between a slit 4 and a lens 2 and not inserting the sample and comparing spectrums acquired in both states. Absorbance of the sample is determined from the transmittance characteristic. The thickness is measured by subjecting a measurement spectrum including an interference component due to multiple reflection to fast Fourier transform, and the moisture is measured by subjecting an absorbance change of an absorption spectrum freed of the interference component due to the multiple reflection to a multivariate analysis.