Band-limited angular spectrum numerical propagation method with selective scaling of observation window size and sample number

Band-limited angular spectrum (BLAS) methods can be used for simulating the diffractional propagation in the near field, the far field, the tilted system, and the nonparaxial system. However, it does not allow free sample interval on the output calculation window. In this paper, an improved BLAS method is proposed. This new algorithm permits a selective scaling of observation window size and sample number on the observation plane. The method is based on the linear convolution, which can be calculated by fast Fourier transform effectively.