Research On Infrared Imaging Technology Based On Nonlinear Frequency Upconversion

Infrared imaging technology based on nonlinear frequency upconversion is a method that uses laser to interact with matter to achieve frequency conversion.It converts lowfrequency infrared images and other information into near-infrared or visible-light bands,and then converts them through high-performance near-infrared or visible-light cameras.The information is detected,and the low-frequency infrared image information can be indirectly detected.Compared with traditional high-cost infrared imaging cameras,infrared imaging technology based on nonlinear frequency upconversion has high-speed response and no need for cooling,low inherent noise,and has a good research prospect,and with the development of laser technology and improving in the research of nonlinear crystal materials,nonlinear frequency upconversion imaging technology has also been an opportunity for development.At present,the overall conversion efficiency and imaging quality of nonlinear frequency upconversion infrared imaging technology are not high.In order to explore the high conversion efficiency of infrared upconversion imaging,this thesis designs infrared imaging experiments under different light source pumping conditions to analyze infrared on different conditions.Conversion efficiency and imaging quality.In this thesis,the experimental research on infrared upconversion imaging based on pulsed light and continuous light is carried out.In the pulsed-pumped infrared upconversion imaging study,the nonlinear frequency upconversion efficiency,input spectral bandwidth,parametric light tolerance angle and PPLN nonlinear crystal material properties are simulated and the nonlinear frequency upconversion detection technology is applied.The experimental research was carried out.Then the nonlinear frequency upconversion imaging process and characteristics were simulated and analyzed.The midinfrared frequency upconversion imaging was experimentally studied,and the imaging information and resolution of the mid-infrared signal image were obtained.In the study of continuous optical pump infrared upconversion imaging,two continuous optical pumping schemes,internal cavity structure and external cavity structure,were designed.In the nonlinear frequency upconversion experiment of the internal cavity structure,nonlinear frequency upconversion spectrum was measured.In the nonlinear frequency upconversion experiment of the external cavity structure,the upconversion imaging of the mid-infrared image information under low input power conditions is realized,and the nonlinear frequency upconversion imaging information under different pump power conditions is analyzed.