Numerical speckle images formed by diffusers using modulated conical and linear apertures

Abstract

The use of three types of modified apertures is considered in the formation of speckle images. The first assumes amplitude modulation of conical shape for the illumination of a numerical object having a randomly distributed function. The second assumes a linear variation of the amplitude inside the circular aperture. The third aperture has 1=2 distribution. The modulated numerical speckle images are obtained in all cases, using the MATLAB program, and compared with that obtained in the case of a uniform circular aperture for the illumination. We have considered coherent illumination obtained from a laser beam in order to facilitate the computation of the Fourier transform of the computed speckle intensity corresponding to these apertures. Secondly, the autocorrelation intensity of the randomly distributed object is calculated in all cases. Finally, the point spread function (PSF) is calculated for all apertures and compared with the corresponding value obtained in the case of a uniform circular aperture.