根据基尔霍夫衍射理论,对其衍射公式数值进行积分计算，推导出负折射平板折射率偏离-1时像点附近的光强分布，并用MATLAB画出了相应的光强分布图。研究表明，当折射率偏离-1时，像点附近的光强分布在z方向不再对称，但在x方向依然保持对称，不对称随折射率偏差增大而增大，像点光强变得较分散，且存在伴峰。如果把物点放在对应半径曲面的齐明点处，可以很好地消除球差，但像点位置与n′=-1时有所不同。

Based on the Kirchholf diffraction theory, the slab imaging performances are studied for different negative refractive index deviating from -1, and the field patterns are drawn with MATLAB. The results show that when refractive index deviates from -1, the light-intensity distribution around the image point becomes asymmetric along z-axis, the fields are irregular and the satellite peaks occur. In addition, the aplanatic curvature radius r was found. The results show if the object point is put at the aplanatic point corresponding to the radius curved surface, the spherical aberration can be eliminated but the location of the image point is different from that of n′=-1.