晶体球法是近年来在国际上发展起来的一种测量非线性系数的新方法。根据聚焦高斯光束二次谐波产生的孔径方程理论 ,分析了晶体球中的第 类非相位匹配二次谐波产生过程 ,讨论了晶体球中第 类非相位匹配二次谐波最佳聚焦参数的选择。报道了 L i Nb O3晶体球中皮秒激光脉冲抽运的非相位匹配二次谐波实验。所得结果与理论预计相符 Crystal ball method is developed internationally in recent years, a new method of measuring nonlinear coefficients. According to the aperture equation theory of the second harmonic of the focused Gaussian beam, the generation of the second-order non-phase-matched second harmonic in the crystal sphere is analyzed. The optimal focusing parameters of the second non-phase-matching second harmonic in the crystal sphere s Choice. Reported the second-phase non-phase harmonic experiment of picosecond laser pulse pumping in L i Nb O3 crystal sphere. The result is consistent with the theoretical prediction