Research On Control Logic And Signal Acquisition System Of Raman Spectrometer

Raman spectroscopy is a non-destructive spectroscopy analysis technique,containing information on molecular vibration or rotation,so it is also called "fingerprint spectroscopy".Raman spectroscopy is less interfered by water molecules and is widely used in biotechnology,medicine,mineralogy,materials science,environmental monitoring and many other fields.But the Raman scattering signal is extremely weak and easily submerged in the noise,which causes the signal to noise ratio is very low and puts forward higher requirements for the detection and acquisition of Raman spectral signal.CCD detector is a wide range of spectral detection,suitable for low light detection of the photoelectron.Therefore,how to suppress the CCD noise to improve the signal to noise ratio effectively is the key to achieve high quality acquisition of Raman spectroscopy.In this paper,for high-quality Raman spectral signal acquisition needs,the research on CCD signal acquisition and processing system is carried out,spectral signal acquisition and noise suppression method,full data frame capture algorithm,the host computer software noise reduction,etc.are studied emphatically,the high performance Raman spectrum acquisition system is developed.The main contents of the paper are as follows:(1)This paper reviews the current situation of CCD detector signal acquisition,processing system and Raman spectroscopy data processing.It analyzes the advantages and disadvantages of various signal processing methods.And the main content of the paper is elaborated.(2)The basic principle of Raman spectroscopy and the characteristics of CCD detector are analyzed.Based on the characteristics of Raman spectroscopy and CCD detector output signal,the general scheme of Raman spectrum acquisition is established.(3)The digital correlation oversampling algorithm is studied,which realizes the elimination of the reset noise of the CCD output signal and the effective suppression of the random noise.Full data frame capture algorithm is studied,and the complete acquisition of the effective spectral data is realized.The logic design of each module of digital circuit is completed,and the function simulation of each module and the whole acquisition system control logic is verified based on Modelsim.(4)The design method of spectrum acquisition software and the technique of spectral data processing are studied.USB firmware programming and host computer spectrum acquisition software design is completed.Three algorithms of Multi-frame Averaging,Moving Window Averaging and Gaussian Filtering are studied emphatically.(5)An experimental test platform is built to test the control logic of the spectral acquisition system and signal collection software,with mercury lamp as the test object.The test results show that the system accurately captures and collects the complete frame spectral signal,compared with Correlated Double Sampling,the signal variance of the Digital Correlation Oversampling algorithm is reduced by 51%-63% and the signal-tonoise ratio is significantly improved.Compared with the three software denoising algorithms,the Multi-frame Average achieves the best denoising effect,and has the least effect on spectral peak height.In this paper,the Raman spectra of various biological samples are obtained successfully.