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

摘要

The present invention relates to a non-contact and non-destructive real-time thickness measuring apparatus using terahertz waves. More specifically, the apparatus projects a laser beam with a fixated wavelength and continuous terahertz waves generated by wavelength sweep laser to have a frequency changing at high speeds into a specimen unit, and measures a transmitted or reflected terahertz waves; thereby measuring a thickness of the specimen unit. According to a preferred embodiment of the present invention, the non-contact and non-destructive real-time thickness measuring apparatus using the terahertz waves is able to include the wavelength fixing laser, wavelength sweep laser, coupler, generator, detector, data obtaining unit, a computation unit, and a driving unit. The wavelength fixing laser and the wavelength sweep laser are inputted to a coupler to form mixed light. The mixed light is inputted to the generator generating the terahertz waves. The terahertz waves discharged from the generator and passing through or being reflected from a sample is inputted to a detector. Photocarriers excited by the mixed light are biased by the electrical field of the terahertz waves to generate a photocurrent in the detector. The data obtaining unit obtains the photocurrent in a form of digital data to output the photocurrent to the computation unit. The computation unit converts the data outputted by the data obtaining unit to frequency area data, generates time area data through fast Fourier conversion of the frequency area data, and computes the thickness of the sample based on the time area data.