为了能通过背光面温度测量获得材料激光耦合系数，从傅里叶热传导方程出发，在一定的近似条件下推导出了不透明金属材料的表面激光耦合系数与背光面温升的关系表达式，给出了工程反演算法。采用两种不同的方法对反演算法进行了验证：一是用反演算法计算30CrMnSiA材料的1.3 μm激光耦合系数，与文献报道的实验测量值进行比较；另外是实验测量4 mm-30CrMnSi钢板的背光面温升，反演得到1.3 μm激光耦合系数随辐照时间和温度的变化，然后数值计算背光面温升并与原始实验测量结果进行比较。验证结果表明，借助于背光面测温反演激光耦合系数的方法可行，精度可以满足激光辐照效应研究的要求。

In order to acquire the laser coupling coefficient of a metal plate, an inversion method was given based on measured temperature data on the rear surface of the plate. By introducing some approximate conditions, the inversion expressions of the laser coupling coefficient and the temperature on front surface were derived, and a engineering algorithm of laser coupling coefficient was obtained. The inversion algorithm was validated by using two methods. one is to calculate the 1.3 μm laser coupling coefficeint of the 30CrMnSiA by reversal method and to compare it with the experiment result in references for the same material plate;the other is to measure the temperature rise on the rear surface of the plate and to obtain the changes of the coupling coefficient with the radiation time and temperature and compare it with the measured experiment result in our experiments for the same material plate. The verified result shows that the inversal engineering algorithm is feasible and meets the requirement of the study of laser irradiation effects.