Desing And Implementation Of System For Handheld Raman Spectrometer

Raman spectroscopy is a kind of scattering spectrum,which is very sensitive to the structure of molecules.Each molecule or sample has a unique "fingerprint" spectrum through Raman detection,which can be quickly identified by matching with the "fingerprint" in the database.In recent years,the increasing spread and rapid updating of new-type drugs have brought great challenges to the rapid detection of drugs by law enforcement department.Compared with traditional detection technology,Raman spectroscopy has a series of advantages such as real-time,fast,non-destructive,non-contact,small sample size and no pretreatment of samples,it has been widely used in the field of drug detection.Traditional Raman spectrometer is generally large and expensive,and only suitable for scientific research.Handheld Raman spectrometer is ideal for rapid on-site detection of drugs due to its small size,portability,and ease of operation.However,at present,the handheld Raman spectrometer produced by domestic manufacturers has poor performance and accuracy,and there is no complete drug Raman database,the handheld Raman spectrometer market is mainly monopolized by foreign companies.Therefore,it is of great practical significance to develop a handheld Raman spectrometer with superior performance,independent intellectual property rights and supporting drug Raman database.In this thesis,Raman detection of methamphetamine,ketamine,magu andcaffeine was carried out for the purpose of establishing a drug-based Raman signature database,and the Raman spectra of the above drugs were calculated theoretically according to the density functional theory through the Gaussian software.By comparison,we found: the theoretical calculations were basically consistent with the experimental results,which proved the correctness of the experimental results.Then,the experimentally Raman characteristic peaks of each drug were assigned in detail,this prepared for the next step to identify the sample by characteristic Raman peaks.At the same time,in this thesis,the principle machine of the handheld Raman spectroscopy detection device was also constructed.The laser module control circuit was designed to make the laser output stably,and the USB circuit between the spectrometer and the host computer was designed to realize the data communication.Morover,the human-computer interaction interface of the handheld Raman spectroscopy detection device was designed by the Qt development framework,which realized a series of functions such as spectral display and spectral matching.Finally,the whole system was tested by caffeine and alcohol.The results indicated that the Raman spectra of caffeine and alcohol were basically similar to those obtained by the portable Raman spectrometer,and the spectral display on the LCD screen was the same as that on the PC;For high purity caffeine and alcohol,the results calculated by similarity coefficient algorithm were above 0.95,indicated that the algorithm could achieve fast matching of high purity samples.The above research work had laid a great foundation for the future development of a commercial,independent intellectual property rights hand-held Raman spectrometer.