Study On Optical Design Of Laser Transient Process Detection

The generation of the plasma will influence the quality of nano-aluminum powder produced by the method of electrical explosion, and it’s necessary for the processing technology to detect the plasma.A better coupling system is proposed, and the optical-to optical conversion efficiency can be 22 %. The parameter requirements that the laser should meet are analyzed. An AO Q-switched laser is built on the test bed, its output power curve and impulse width are measured, the reasons why the laser power decrease when the pulse power passes 17 W are analyzed, and it’s g ood for improvement later. Extras-cavity frequency doubling and intra-cavity frequency doubling are tested, the output power curve and impulse width of intra- cavity frequency doubling laser are measured, and the output power can increase stably when the pulse power is not too high. Then, the Mech-Zehnder interferometer is built on the test bed, continuous light interference and pulsed light interference experiments are done with intra-cavity frequency doubling laser, the interference fringe can be very good after fine adjustments.The whole components of the laser are designed by mechanical design software, a Q-switched frequency doubling laser is made, the output power curve and impulse width of this laser are measured, the optical-to optical conversion efficiency can reach 27 %,and its impulse width is 4.2 ns, the reasons for output power fluctuating are analyzed and the improvement plans are proposed. The divergence angle tested by knife-edge method is 7.2mrad.The laser beam expanding system is studied, an improving plan for the 50 times expanding system is proposed. A 40 times laser beam expanding system with three elements is got with Zemax, its parameters are analyzed and a good effect is expected.The optical imaging system is studied, and the imaging system should meet the requirements: CRA is 7°, formed by several elements with fixed position, the focal length should be 150 mm, small aberration. then, an imaging system with three elements is got designed by Zemax, its parameters are analyzed and a good effect is expected.The whole laser interference device is designed by mechanical design software, the device is built with the components mentioned before. Then spot tested, the process of inert gas aerating is observed on CCD, the fringe disorder caused by airflow disturbance is found. The explosion and diffusion of metal powder are observed, the spreading speed can reach 5 km/s, 50μs are need ed to cover the whole observing field. Besides,the phenomenon of branch cansued by the twisted metal wire is observed. The conclusion that the whole laser interference device can meet the requirements well came.