计算和分析了红外聚焦光探测系统中光限制材料的几何排布对光限制效应的影响 ,给出了优化的几何分布 .结果显示 ,近场条件下的光限制效应与远场条件下的完全不同 ,在某些情况下 ,具有正光学非线性系数的材料不能被用作光限制之用 ,这与远场情况不同 .分析也表明 ,聚焦几何排布可用于非线性折射系数的测量 ,并具有比常规 Z扫描方法更高的灵敏度 . The influence of optical confinement geometry on the optical confinement effect in infrared focused optical detection system is calculated and analyzed, and the optimized geometric distribution is given. The results show that the optical confinement effect in near-field is similar to that in far-field , In some cases, materials with positive optical nonlinearities can not be used as optical confinement, which is different from the far-field case.The analysis also shows that the focusing geometry can be used to measure the nonlinear refractive index and Has a higher sensitivity than the conventional Z-scan method.