Research On Design And Data Processing Of Spectral Acquisition System Based On CCD

With the development of the times,spectral measurement plays a very important role in science and technology.It is widely used in agronomy,chemistry,material analysis,space exploration and other fields,and is an important means of material analysis.Although the traditional spectrometer can perform spectrum detection,and the result is very accurate,due to its complicated operation,high price,large size and other factors,it has great limitations,can not be on-site real-time detection,and can not be well popularized.Sex.Therefore,it is especially important to develop a miniaturized,inexpensive,and popular spectrometer.In this paper,the structure of portable spectrometer is studied in detail.Based on this,a linear array CCD is used as the detector and FPGA as the core chip.A portable spectrometer acquisition system is built.The hardware part of the system consists of four modules,including: the main control module,with EP4CE6F17C8 as the main chip,generating drive signals for controlling CCD work,A/D conversion and USB communication;CCD detector module,the system uses linear array CCD1304 AP The image detector;the signal processing module,the module includes signal preprocessing and A/D conversion,the signal preprocessing is used to adjust the CCD output signal,and the A/D conversion circuit converts the CCD output analog signal into a digital signal;USB A communication module for transmitting the collected data to the host computer.The host computer module uses C++ to build with MFC in the Visual Studio software environment,and completes the basic functions of image data display,spectral image preservation and spectral data storage.The hardware part of the final acquisition system is only 65mm(length)* 50mm(width)* 25mm(height),which further meets the needs of portable.The experimental results show that the system can perform spectrum acquisition normally.Based on the detailed research of the image sensor,a large-area photosensitive device is used to improve the resolution of the acquisition system.Finally,the transmission rate of the acquisition system is improved and the spectrum is improved.The data can be displayed in real time on the host computer.In the data processing part,firstly,the noise of the acquisition system when the spectral signal is collected is analyzed in detail.For the Gaussian white noise and impulse noise contained in the spectral signal data,a fusion wavelet filtering method based on stationary wavelet is proposed.The results show that when the stationary wavelet is used instead of the traditional wavelet transform and the median filtering method is added to the stationary wavelet layer decomposition,the Gaussian white noise and impulse noise in the spectral signal can be effectively removed,and the measurement of the spectral data can be changed.More accurate;secondly,Direct peak finding and Gaussian fitting are used to find the characteristic peaks of the collected mercury lamp spectrum,and the wavelength calibration is performed by least squares method;finally,the collected potassium permanganate is obtained by using Lange-Beer law.According to the actual application and experimental results of Lange-Beer's law,the mathematical model was improved,and the mathematical model with higher fitting times was used to fit the concentration curve,and better concentration calibration results were obtained.