Diffraction integral computation using sinc approximation

We propose a method based on sinc series approximations for computing the Rayleigh-Sommerfeld and Fresnel diffraction integrals of optics. The are given in terms convolution, our proposed numerical approach is not only super-algebraically convergent, but it also satisfies an important property convolution—namely, preservation bandwidth. Furthermore, accuracy depends how well source field approximated; independent wavelength, propagation distance, observation plane discretization. In contrast, methods fast Fourier transform (FFT), such as angular spectrum (ASM) its variants, approximate optical fields planes using series. will show that ASM introduces artificial periodic boundary conditions violates bandwidth property, resulting limited which decreases longer distances. sinc-based avoids both these problems. Numerical results presented Gaussian beam circular aperture to demonstrate high-order short-range long-range propagation. For comparison, we present obtained with method.