The Application Of Terahertz Radiation In The Field Of Identify Of Chinese Traditional Medicines And Security Inspection

The THz technology developed with the development of ultra-fast laser in resent years . THz radiation is the gap between microwave and far-infrared region . THz time-domain spectroscopy is a powerful tool developed in 1990s for spectroscopy measurement. This technique can record the amplitude of the wave by electro-optical or photoconductive sampling. After fast Fourier transform , the amplitude and phase of the THz pulse wave is given, then the refractive index and absorption of the material in THz region is extracted.The estimate and criterion of the quality of Chinese traditional medicine include 3 content: security, authenticity and quality estimate. As well known that the curative effect of the Chinese traditional medicine is the result of its chemic component. Because of the complex chemic component, the quality estimate and control of Chinese traditional medicine is a difficult problem. The only way to resolve the problem is using external standard of quality estimate and date of experiment to prove the validity, stability and controllable of Chinese traditional medicine. Many people have studied and explored the method of quality estimate of Chinese traditional medicine. The spectrum technology distinguish Chinese traditional medicine according to its effective component, which can avoid the subjectivity and unilateralism. Now the spectrum technology has been regarded. Among the spectrum technology, the infrared spectrum has been rapid developed.Applied in Chinese traditional medicine's identification, THz radiation has both advantages and difficulties. l)Some vibrational and rotational modes of Chinese traditional medicine's biomoleculars are in THz region.2)Dispersion spectroscope of Chinese traditional medicine is available in THz region ,while not in infrared region.3) With the pulse width of picosecond and femtosecond, THz radiation can be used to measure the time-domain spectroscope and transient characteristic of Chinese traditional medicine.In this paper, THz Time-Domain Spectroscope is used to study Chinese traditional medicine. The following is a brief summary of the works conducted in this thesis and the experimental results achieved.Using the THz-TDS, we measured the time-domain spectrum of three sort of Panax and obtain the absorption coefficient curves and refractive index curves. Through comparing their absorption spectrums, we find that all the Panax have some same peaks, but their spectrums are different.We measured the THz time-domain spectrum of two different grade Cordyceps sinensis (Berk) Sacc and obtain their absorption coefficient curves and refractive index curves. We find that the two samples have week peaks in the range of 0-2THz. And their spectrums are approximate.We measured the THz time-domain spectrum of crude bezoar and artificial bezoar and obtain their absorption coefficient curves and refractive index curves. We find that the absorption spectrums of the two sort of bozoars have difference. And we can differentiate the two sort of bezoars by comparing their absorption spectrum.Some suggestions are put forward for the further study of Chinese traditional medicine's THz spectroscopy in the paper.THz radiation has strong penetrability to dielectric and wrapper such as plastic and wrapping paper. It can be used to imaging the matters which have been packed. In this paper, we measure the spectrums of a series of materials. The results show that the THz radiation can pass through these materials. And we obtain a few images of matters which have been packed. The experiment shows that the THz imaging has a good future in the field of security inspection.