Patent ID: 8450689

Claim:
A non-contacting type paint film thickness measuring device comprising: a generator for generating a terahertz pulse light; a predetermined optical path; a detector for detecting the terahertz pulse light generated by the generator, passing through the predetermined optical path, and reaching the detector; a sputtering mirror; measured wave form in time-series obtaining means for obtaining a measured wave form in time-series indicating an electric field intensity in time series of a terahertz echo pulse light that is the terahertz pulse light emitted to an object whose paint film thickness is to be measured, reflected at the object and detected by the detector, the object being positioned on the predetermined optical path; intrinsic wave form in time-series obtaining means for calculating an intrinsic wave form in time-series of the object on the basis of a standard wave form in time-series and the measured wave form in time-series, the standard wave form in time-series indicating an electric field intensity in time-series of a reflected light that is the terahertz pulse light generated at the generator, emitted to the sputtering mirror, reflected at the sputtering mirror, and detected by the detector, the sputtering mirror being positioned on the predetermined optical path instead of the object at the location of the object; and the intrinsic wave form in time-series obtaining means including an intrinsic electric field spectrum calculating means and an intrinsic wave form in time-series calculating means, the intrinsic electric field spectrum calculating means calculating an intrinsic electric field spectrum by multiplying a measured electric field spectrum by a standard electric field spectrum and an Wiener inverse filter, the measured electric field spectrum obtained by applying a Fourier transformation to the measured wave form in time-series, the standard electric field spectrum obtained by applying a Fourier transformation to the standard wave form in time-series and the Wiener inverse filter expressed with a constant number, and the intrinsic wave form in time-series calculating means calculating the intrinsic wave form in time-series by applying an inverse Fourier transformation to the intrinsic electric field spectrum with increasing or decreasing the constant number.