APPARATUS FOR REAL-TIME NON-CONTACT NON-DESTRUCTIVE THICKNESS MEASUREMENT USING TERAHERTZ WAVE

摘要

Provided is an apparatus for real-time non-contact non-destructive thickness measurement using a terahertz wave, and more particularly, an apparatus for real-time non-contact non-destructive thickness measurement using a terahertz wave, which is capable of measuring a thickness of a sample by irradiating a terahertz continuous wave, which is generated from a wavelength-fixed laser and a wavelength-swept laser and of which the frequency is changed at a high speed, to the sample and measuring the terahertz wave transmitting or reflected from the sample.

主权项

1. An apparatus for real-time non-contact non-destructive thickness measurement using a terahertz wave, comprising:
a wavelength-fixed laser generating first laser light having a first fixed wavelength λ1; a wavelength-swept laser generating second laser light having a second wavelength λ2 changed from a preset minimum wavelength to a preset maximum wavelength at a high speed for one period; a driver applying a voltage modulated at the same frequency as a wavelength sweep rate to the wavelength-swept laser to change the second wavelength from the minimum wavelength to the maximum wavelength for the one period; a coupler coupling the first laser light with the second laser light to form mixed light and splitting the mixed light into first mixed light and second mixed light; an emitter receiving the first mixed light split from the coupler to output a terahertz wave having a frequency fTHz=|f1−f2| corresponding to a difference between a frequency f1=c/λ1 (c is the speed of light in vacuum) corresponding to the first wavelength λ1 and a frequency f2=c/λ2 corresponding to the second wavelength λ2; a sample irradiated with the terahertz wave output from the emitter; a detector receiving the second mixed light split from the coupler and the terahertz wave transmitting or reflected from a sample to generate a photocurrent; a data acquisition unit converting the photocurrent into digital data to acquire and output the digital data; and a calculator generating frequency-domain data from the output digital data, performing fast Fourier transform on the frequency-domain data to generate time-domain data, and calculating a thickness of the sample on the basis of the time-domain data.