Effect of apertures on the speckle size from rough surfaces

Based on the scattering theory from rough surfaces and Gaussian moment theorem, the relationship between the apertures and the three-dimensional size of the speckle in the far field are discussed. The results show that the three-dimensional dimension of the speckle is closely dependent on the shape of and the size of the apertures. The lateral speckle size is positive proportional to the ratio of the wavelength and the distance to the size of the apertures, while the longitudinal speckle size is positive proportional to the wavelength and the square of the ratio of the distance to the size of the aperture size. The different the shape of the aperture, the different the proportion factor.