Proceedings Article | 14 August 2023
KEYWORDS: Nondestructive evaluation, Tomography, Signal detection, Phase shift keying, Reconstruction algorithms, Imaging systems, Fourier transforms, Terahertz radiation, Frequency modulation
In recent years, with the development and progress of society, the demand for non-destructive testing in the fields of safety testing, biomedicine, cultural heritage, and material science is becoming more and more urgent. Now, conventional testing methods such as radiographic testing, ultrasonic testing and infrared testing gradually fail to meet people's needs. Terahertz wave, with its low photon energy and high penetration to many non-metallic and non-polar materials, can be used in nondestructive testing, filling the vacancy in the field of nondestructive testing. In this paper, we study the terahertz nondestructive testing technology in depth. Firstly, we conduct experiments on terahertz tomographic imaging, and use point-by-point scanning method to image the samples composed of rubber and resin, which can realize two-dimensional and three-dimensional images of the samples. Secondly, we design a set of terahertz nondestructive detectors, including terahertz transceiver module, data acquisition module, imaging system. The terahertz transceiver module adopts the large-bandwidth frequency modulated continuous wave and, based on the superheterodyne detection structure, converts the echo signal down frequency into the intermediate frequency signal we need. The intermediate frequency signal then realizes the three-dimensional reconstruction of the sample through the data acquisition module and the imaging system. The dynamic range of the system is large, the action distance can reach about 1m, and the range resolution and directional resolution can reach millimeter level, which will fill the vacancy in the field of nondestructive testing and lay a solid foundation for the following quantum terahertz detection.
