Design Of Line Laser Microscopic Raman Spectroscopy Imaging System

By combining Raman spectroscopy technology with microscopic imaging technology,target spectra and image information can be collected to obtain the composition and distribution of substances.The confocal micro Raman spectroscopy imaging system has a complex structure and strict requirements for the working environment,making it difficult to apply in the field;However,portable Raman spectroscopy collection devices generally do not have spectral imaging capabilities.The study of portable micro Raman spectroscopy imaging system technology is of great significance for meeting the needs of in situ analysis.The thesis first analyzed the typical structure of the spectral imaging system,and based on the characteristics of Raman signals and detection requirements,the overall design of the line laser micro Raman spectral imaging system was carried out.The feasibility of the overall design was verified through optical path simulation.Starting from the high-resolution requirements of micro area detection and the characteristics of Raman spectral signals,the thesis selects KAF16803,which has high resolution,large pixel size,high dynamic range,and can be cooled,as the spectral imaging detector.Based on the characteristics of KAF 16803,the circuit design of an imaging electronics system has been completed,including a power module,voltage bias module,level conversion module,temperature control module,etc.Based on the Xilinx XCZ7020 device,firmware programs were designed for CCD timing logic,temperature control logic,data cache logic,SD card read/write logic,SPI bus interface logic,and other functions,including CCD data output,data acquisition data cache,and storage.Preliminary testing was conducted using a C-port industrial camera lens with a focal length of 12-120mm and a continuously adjustable aperture of F1.8-F16 as the imaging mirror of KAF 16803.The results showed that the core circuits such as the KAF 16803 driver and AD9826 acquisition conversion were functioning properly,and the entire imaging electronics system could achieve image acquisition.In order to facilitate the adjustment of the distance between the imaging focusing mirror and KAF 16803 and ensure its perpendicularity to the CCD target surface,a preliminary imaging electronics system shell structure was designed;This structure simultaneously achieves the sealing of the CCD,providing necessary conditions for CCD refrigeration.Temperature control performance testing was conducted to evaluate the impact of temperature on CCD noise,and the results showed that temperature control has a significant effect on suppressing CCD noise.The experimental optical path of a linear laser micro Raman spectral imaging system consisting of a 532nm laser,a tunable magnification beam expander,a DOE homogenizer,a 532nm dichroic mirror,a 532nm notch filter,a 40mm focal length cylindrical mirror,a 1200 line/mm Blazed grating and a 200mm focal length imaging focusing lens was set up.The experimental samples were made using a laboratory tablet press and calcite powder The fluorescence image of calcite sample was obtained at 4MHz readout rate,which preliminarily proved the rationality of the principle optical path of the line laser micro Raman spectral imaging system.However,from the perspective of imaging quality,there is significant room for optimization in the performance of core optical components such as gratings,linear laser focusing lenses(cylindrical mirrors),optical path structure,and temperature control performance of the system.