THz-TDs Quantitation Nondestructive Testing Technology Based On Optical Parameters Extraction

In recent years,Terahertz technology has been widely used in aerospace,medical,security and other fields.Composite materials as a new type of materials are widely used in various industrial fields,at the same time scientific research and a large number of confirmatory experiments have shown that THz-TDs has important research value in testing composite materials qualitatively and quantitatively as well as in Non-destructive testing.Based on terahertz time-domain spectroscopy theory and optics material parameter extraction theory,this paper completes qualitative and quantitative detection of composite defects.Firstly,Abstract the theory of optical parametric extraction of composite materials based on terahertz time-domain spectroscopy technology,experiments were carried out to extract the optical parameters of the composite materials,it is verified that the composite materials have stable refractive index and absorption characteristics in the specific frequency range of terahertz time-domain.Secondly the thickness detection model of THz-TDs is established based on terahertz imaging technology.A quantitative detection model is established based on super-resolution B-SCAN imaging technology.Finally,I designed the quantitative detection experiment of different kinds of composite materials and different types of composite materials' defect.The results show that the known defects can be detected quantitatively by using the THz-TDs technique: The detection accuracy of the relatively low refractive index composite materials is about 0.1 mm,and the detection accuracy of the composite materials with relatively high refractive index is about 0.06mm;The absorption characteristics of terahertz wave in composite materials affect the thickness and precision of the tested samples;THz-TDs technology can also complete the qualitative and quantitative detection of unknown defect types of composite materials.The results of THz-TDs quantitative experiments show that the THz-TDs technique based on the extraction of optical parameters has a good effect on quantitative and qualitative detection of composite materials defects.