Patent ID: 9541377
Date: 2017-01-10
CPC Classifications: G01B,G01S

Claim:
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 λ a wavelength-swept laser generating second laser light having a second wavelength λ 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 f 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.