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چکیده
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In this paper, a simple method is reported for the design and preparation of fork-shaped diffraction gratings with different topological charges. First, the diffraction gratings were prepared using the computer-generated holography technique. Using the image processing methods in the MATLAB environment, the images of the generated holograms were first prepared in the gray level format, then converted into binary, and finally saved in the vector form. The vector images prepared from the holograms were printed on transparent sheets using a semi-industrial printer. By optimizing the groove distance of the gratings through experimental tests, the groove distance equal to 175 micrometers has been chosen as the optimal line distance for making the gratings. By designing and setting up a suitable optical arrangement, the prepared fork-shaped gratings were exposed to laser beams and Laguerre-Gaussian beams were generated. The results showed the desired generation of these types of beams with the simple method presented for making the gratings. In the following, by setting up a Mach-Zehnder interferometric setup, the topological charges of the generated Laguerre-Gaussian beams were also measured. The results indicated that the number of fork branches formed in the interference patterns was equal to the topological charge of the Laguerre-Gaussian beams. Using computer simulations, the experimental results obtained in this work have also been examined and tested.
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