Design Of Portable Raman Spectrometer And The Automatic Focusing System

In the solid detection of the Raman spectrometer,the laser must be focused on the surface of the sample to collect the correct Raman spectrum signal.However,for the portable Raman spectrometer,due to the limitations of its cost and volume,it is impossible to adopt the focus scheme of large spectrometer.Therefore,this paper designs a portable Raman spectrometer automatic focusing system,which has the advantages of convenient focusing,compact size and visual detection.The experimental results show that the system can meet the focus requirement of the portable Raman spectrometer,and the surface visualization of the sample is realized,and the details of the sample surface can be seen at the same time.The main work of this paper includes the following points:(1)Based on the spectrometer detection of optical path,a compact optical path system was designed,which realized the automatic focus of Raman laser.The system uses the image definition to determine the focus position,and on the basis of the traditional mountain climbing algorithm,the focus search algorithm is improved to reduce the situation of falling into the local maximum point.The system also realizes the visualization of the surface of the sample,amplifies the collection image by more than 8 times,and can see the details of the sample surface at the same time.(2)Design and implement the hardware structure of the spectrometer,including the main controller,spectral collection module,focusing mechanism,image acquisition module and power supply,etc.The focusing mechanism is driven by micro-stepping motor,and the minimum step distance is 10 ?m,which achieves the purpose of high precision focusing.(3)Spectrometer was designed and implemented the software modules and software based on Windows 10 whole platform design,adopt the separation of front and back side B/S architecture,the server based on Qt framework development,focusing algorithm is realized by using OpenCV library.The specific functions of the software include spectral signal acquisition,laser autofocus,sample surface visualization,test record uploading and spectral data export,etc.(4)The actual test of the system designed in this paper proves that the system can meet the design requirements.The system focus accuracy is about 15?m,the average time is about 5s,and the focus success rate is over 95%.In addition,the measurement and modification of offset is also carried out for the focus migration problem in the spectrometer.