| In the context of the signing of the Comprehensive Nuclear-Test-Ban Treaty,inertial confinement fusion is an extremely important direction in the field of national security and basic science,and has become a major frontier scientific research field that the major economic powers in the world are scrambling to study.The large laser driver,as its key equipment,is the object that countries have invested a lot of resources to study.The complex optical path of a large laser driver contains a large number of optical elements,including optical elements of quartz,KDP,DKDP and other materials.These elements are extremely vulnerable to damage when working in the high-energy 351 nm pulsed laser environment for a long time,and thus endanger the safe operation of the laser driver.Therefore,it is necessary to test the optical elements.By measuring the optical loss of the optical elements,ensure the uniformity of the elements,eliminate defects and pollution,control the initial damage of the optical elements,and ensure the long-term safe and stable operation of large and ultra-large laser driver systems.For this reason,the optical loss measurement technology of optical elements based on 355 nm pulse optical cavity ring-down is proposed,and the 355 nm pulse optical cavity ring-down system is designed and built to realize the single-point loss measurement and two-dimensional scanning of optical elements.In this experiment,based on the theory of optical cavity ring-down technology,the optical loss measurement system of optical elements based on 355 nm pulse optical cavity ring-down is built to study the optical loss distribution of optical elements of various materials.It includes the following contents:1.Research background and significance.Aiming at the application background of confinement fusion and large laser driver and the detection requirements of optical elements,a measurement technology of optical loss of optical elements based on 355 nm pulse cavity ring-down is proposed.According to the theoretical mode,the expressions of the pulse ring-down time and the loss of the optical elements to be measured are derived,and the stability conditions of the resonator,the mode theory of the resonator,and the factors causing the experimental error are analyzed.2.Design and build a pulse optical cavity ring-down loss measurement system,and debug the system.Test the stability of the initial cavity,and the standard deviation of the repeated measurement of the initial cavity ringdown time is 0.011 us;Analyzed the change in average reflectivity of the initial cavity with a change in cavity length;The response time of the instrument was measured through experiments,and whether it affects the measured loss results was analyzed.3.The loss measurement system of 355 nm pulse optical cavity ring-down loss is used to measure the loss of quartz element at single point and two-dimensional scanning,and the results can be measured accurately.The 1064 nm optical feedback system is used to measure the loss of quartz element at a single point and conduct two-dimensional scanning for comparative analysis.The 355 nm pulsed optical cavity ring-down loss measurement system is used to measure the loss of KDP and DKDP components at a single point and two-dimensional scanning,and accurate and repeatable measurement results are obtained. |
