Investigation of a new modulated aperture using speckle techniques

Abstract

Abstract Background A design of equally spaced eight-circles placed at equal distances from the origin is suggested. Three models corresponding to the eight-circle design considering conic, linear, and quadratic distributions are investigated. This arrangement is considered for the sake of improving both microscope resolution and image contrast as compared with the pure annular aperture. This design is different compared with other recent work on aperture modulation. Results and discussions The point spread function (PSF) is computed in all the models using the fast Fourier transform (FFT) algorithm that computes the discrete Fourier transform (DFT) corresponding to the models and compared with the corresponding PSF in the case of uniform circular aperture. In addition, the autocorrelation images for the apertures are shown differently. It is shown smooth pattern for the circular arrangement as compared with the deformation and shrinking appeared in the central peak in case of conic model. Finally, the speckle images corresponding to the considered apertures are investigated. Reconstructed apertures are obtained from the speckle images using the FFT algorithm. Conclusions The PSF is computed for the described models, and the autocorrelation corresponding to the apertures showed difference. The reconstructed apertures from the speckle images can be improved using filtering techniques. It is noted that MATLAB codes are constructed in the computations of all images and plots.