| The more and more critical food security problems damage people’s health andalso propose new requirement, real time detection, to the food security detectionequipments. Infrared spectrum technology has incomparable superiority because of itscharacteristic of convenience operation, rapid detection and accuracy. Due to thefeature of high spectrum definition, great SNR (Signal to Noise Ratio) and widespectrum detection range, Fourier transform infrared spectrometer has become theprimary instrument used in infrared spectrum analysis. However, in face of thecomplexity of food security problems and the requirement of real time detection, thetraditional Fourier transform infrared spectrometers couldn’t be applied in fielddetection out of laboratory because of the huge size, poor portability and the high price.In order to expand application directions of Fourier transform infrared spectrometers inthe field of food security detection, this paper aims to develop a novel low cost andportable Fourier transform infrared spectrometer which can achieve field rapidaccurate detection and online detection.Firstly, this paper proposed a new instrument structure based on MEMSmicro-mirror and slipped reflector. In this structure, slipped reflector replaces themoving reflector system to achieve interference modulation of incident light, whichreduces the size of instrument. Using the optical switch effect of MEMS micro-mirror,this structure can achieve sampling intensity signal of spatial interference light withsingle photonic detector, which decreases the instrument cost. This paper builttheoretical model of Fourier transform infrared spectrometers based on this novelstructure and analyses its spectrum definition, SNR and spectrum detection range. Inorder to overcome system’s inherent defect of low luminous flux and improve SNR,this paper raised an innovative solution which uses hadamard modulation template tosample interference signal and uses hadamard transform algorithm to demodulate.Secondly, according to theoretical model of system, this paper designedminiaturized static interferometer based on cube beamlitter and tested its property,selected light source and detector according to system demand, proposed instrumentcontrol system framework which combine data acquisition system and instrument maincontrol system.Thirdly, in order to achieve portability and intelligentization of system, this paper also developed embedded instrument main control system based in ARM-Linux. Thiswork contains hardware circuit design and test, customizing and transplantingBootLoader and embedded Linux kernel, building operation environment of embeddedapplication software, and developing human-computer interaction program ofspectrum detection system.Last, this paper seted up experimental system and conducted test item whichcontains recovering spectrum, SNR improvement based on hadamard transform andsystem stability to verify the design of spectrum detection system comprehensively.The test result of recovering spectrum indicated that our system can recover spectrumnormally, and the degree of accuracy during near infrared wavelength range preceded4nm, the spectrum definition reached on10nm. The test result of SNR improvementindicated that our innovative solution based on hadamard modulation template andhadamard transform algorithm can promote system SNR effectively. The test result ofsystem stability indicated that the deviation of characteristic peaks and intensity ofthem are all less than0.4%, which means our system has great working stability. |
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