Wuhan National Laboratory for Optoelectronics, School of Optical and Electronic Information, and National Engineering Research Center for Laser Processing, Huazhong University of Science and Technology, Wuhan, Hubei, China.
Opt Lett. 2012 Dec 1;37(23):4943-5. doi: 10.1364/OL.37.004943.
A novel method is proposed for simulating free-space diffraction propagation. This method is an improvement of the angular spectrum (AS) method and the band-limited angular spectrum (BLAS) method. Due to the sampling problem about the transfer function, AS is not suited for the long-distance propagation. For BLAS, the calculation accuracy would decrease when the propagation distance is relatively large. Using a wide calculation window can largely reduce the numerical error of AS and BLAS. However, a wide calculation window generally causes a huge calculation burden in the simulation. For the proposed method, the calculation window size is chosen to make sure all the sampling points in the frequency domain are effective in the sense of Nyquist theorem. The calculation complexity is independent of the calculation window size because of the use of the linear convolution. The linear convolution can be evaluated effectively by fast Fourier transform. This method can produce simulation results with high accuracy for far and near field propagation.
提出了一种新的自由空间衍射传播模拟方法。该方法是对角谱（AS）方法和带限角谱（BLAS）方法的改进。由于传递函数的采样问题，AS 不适合远距离传播。对于 BLAS，当传播距离较大时，计算精度会降低。使用宽计算窗口可以大大减少 AS 和 BLAS 的数值误差。然而，宽计算窗口通常会在模拟中带来巨大的计算负担。对于所提出的方法，选择计算窗口大小以确保频域中的所有采样点在奈奎斯特定理意义上都是有效的。由于使用了线性卷积，计算复杂度与计算窗口大小无关。线性卷积可以通过快速傅里叶变换有效地评估。该方法可以为远场和近场传播产生高精度的模拟结果。
