Micro-thruster Ignition Shaping Optical System With High Power Density Ld

With the invention of Laser Diode(LD), it has been widely used in diode pumped solid-state laser(DPSSL), fiber laser, material processing etc. The single emitter LD's output power is about several hundreds mili-watt to several watt which is widely used in communication, distance surveying, medicine etc. In these fields high intensity, high brightness, high collimation laser output is required, but the LD's special characteristics such as large divergence and great astigmatism make it difficult to realize. At the same time the small size of the LD increases the difficulties of the work of beam shaping by macro optics, which affects its direct application. The work in this dissertation focuses on diode laser in high intensity by using beam transformation. The research has an instructive significance for high-power LD development and applications.The laser plasma thruster(LPT) is a new microthruster for small satellites, which require small size, long work distance and enough intensity laser system. Based on the detailed investigation on the special optical system and the structure and output characteristics of high-power LD, firstly the demand for imaging quality of the focusing subsystem was analyzed. Secondly, the method of decreasing astigmatism and enhancing intensity of the output beam by using beam transformation theory was analyzed. Thirdly, several sub-systems with different functions, such as collimating, shaping and focusing were investigated. The optical system was simulated and traced by optical software. Experiment was done with 1.13W power output, efficiency approximating 61%, maximum intensity reaching 7×10~4W/(cm~2) and N.A. about 0.346. At the end of this presentation, the experimental result was analyzed.