The beam characteristic of Nd:YAG frequency doubling in a KTP crystal by the resonant external ring cavity

In laser sintering we adopt the method of Nd: YAG frequency doubling to acquire short wave laser in order to obtain fine focus. The paper describes and discusses the method as well as the beam quality of the laser. Based on experiments and theories, we studied frequency doubling in a KTP crystal on Nd:YAG laser by the resonant external ring cavity. The Nd:YAG laser average power is 50w with Q-switch and its frequency is 1005Hz. In the experiment the wavelength of 0.532μm green light output was obtained with 31.4% light conversion efficiency when 1.064μm input average power is 35w. In the green light the proportion of TEM00 model is about 95%. The method is proved to be an effective way to solve the problem of how to get a mini-focus. It is especially useful in the application of laser rapid prototyping. The experimental results for the characteristics of ring cavity frequency doubling were analyzed. The two lasers of 1.064μm and 0.532μm on the beam quality were compared in this paper. The thesis provides the pictures of beam focuses tested with CCD and compares some experimental results with those pictures. A theory of the ring cavity frequency doubling has been put forward in this paper. The sintering effect of the 0.532μm laser was showed in contrast with the 1.064μm laser. The experimental results show that the short wave laser is better for the micro fabrication.