• Speckle imaging of annular Hermite Gaussian laser beam

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    • Keywords


      Higher-order laser transverse modes; Hermite–Gaussian annular aperture; autocorrelation of the speckle images; point spread function.

    • Abstract


      Fourier transform (FT) corresponding to the diffuser has a comb function realised from uniform illumination, and hence the speckle image is nearly equal to comb point spread function (PSF). Consequently, the resulted distribution permits computation of the speckle size from the FWHM corresponding to the PSF of the HG$_nm$ annular aperture. In the second method, the numerical autocorrelation of the speckle images using new apertures are computed and the speckle sizes are obtained. The results in both methods are compared with the speckle images obtained using circular aperture. It is noted that, the maximum number of spots produced in the HG$_nm$ modes given by combinations m, n ∈ [0, 5] is (m + 1) (n + 1) = 36 and all images and plots are obtained using Mat-Lab codes.

    • Author Affiliations


      A M HAMED1

      1. Physics Department, Faculty of Science, Ain Shams University, Cairo 11566, Egypt
    • Dates

  • Pramana – Journal of Physics | News

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