Ali Mohammad Khazaei, Fatemeh Afsharipour, Hamid Reza Mashayekhi, Mohammad Yeganeh,
Volume 17, Issue 2 (6-2023)
Abstract
A new class of gratings is produced by combining the radial grating (RG) with the Fresnel zone plate (FZP). Besides having an azimuthal periodicity, these gratings focus the incident beam at a specific distance. This paper investigated the diffraction from modified Fresnel zone gratings (MFZGs) theoretically and experimentally. Our approach was to solve the Fresnel-Kirchhoff integral in the cylindrical coordinate system for a plane beam on an MFZG. The experimental results of diffraction patterns of a laser beam from the amplitude type of MFZGs confirmed the theoretical predictions well. The near-field diffraction patterns agreed with the patterns obtained from theoretical calculations.
