大功率CO_2混合模光束输出窗的热效应研究

Thermal Effect of Output Window in High-power CO_2 Laser of Blending-mode Beams

为了解决大功率CO2激光器输出窗热效应问题,以解析分析为基础,研究了混合模式振荡下输出窗的温度场以及热形变分布情况。通过CO2激光器大功率运转时腔内振荡模分布特点的分析,给出了腔内混合模光束光强分布解析表达式。并依据输出窗工作特点分析,建立了热分析模型,利用热传导方程推导出了温度场的一般通解表达式,然后分析了腔内激光功率对输出窗温度场的影响。同时定量计算了不同材料输出窗的温度场以及热形变情况。研究结果表明:若CO2激光器腔内混合模光束功率为4500W,腰斑半径为450μm时,Zn Se窗的最高温升为53.9℃,最大热形变量为2.1μm。研究方法和所得结论具有普适性,可用于其他激光器腔内混合模式振荡状态下的热问题研究中。

In order to solve the thermal effect problem of output-coupler window in high-power CO2 lasers,the temperature field and thermal deformation of infrared output-coupler window under blending-mode oscillation state of cavity have been obtained by analytic solution. According to analysis the characteristics of oscillation mode distribution in cavity at high-power CO2 lasers working,the general analytical expression of the blending-mode beam distribution in cavity is given. And through the working characteristic analysis of the output-coupler window,to build the thermal analysis model of output-coupler window. By the heat conduction equation,the general solution expression of the temperature filed of output-coupler window is derived,when blending-mode output. Then,analyzed the influence of the output-coupler window by reason of the laser power. Simultaneously contrasted of the thermal deformation of the output-coupler window using different infrared materials. The results show that: if the blending- mode resonant power is4500 W in the CO2 laser cavity,maximum temperature rise of the Zn Se window was 53. 9℃,and the max thermal distortion is 2. 1μm. Research methods and the findings have universal relevance,which can be applied to other thermal effects research work with blending-mode oscillation state in laser cavity.