为了研究在不同数值孔径情况下振幅调制高斯光束的聚焦特性和焦深,采用基于德拜近似条件的矢量衍射理论进行了计算和数值模拟。模拟结果显示,在低数值孔径的光学系统中,焦平面上的光强分布呈圆形;而在高数值孔径的光学系统中,由于存在去偏振效应,光强的分布呈椭圆形分布。结果表明,可以通过改变几何参量和高斯光束的振幅调制参量的幂指数n调节焦点大小和焦深。

In order to study the focusing property and focal depth of amplitude-modulated Gaussian beam in different numerical-aperture (NA):they were numerically simulated according to the vector diffraction theory based on Debye approximate condition.Simulation results showed that the intensity in the focus plane was in a circular shape in a low NA optical system; while in a high NA optical system,it was in an elliptical shape because of the polarization effect.The focal spot size and focal depth can be adjusted by changing the geometric parameters and the amplitude modulation parameter exponential n of Gaussian beam.