Showing 2 results for Yeganeh
Dr. Saifollah Rasouli, Mr. Mohammad Yeganeh,
Volume 7, Issue 2 (International Journal of Optics and Photonics (IJOP) Vol 7, No 2, Summer-Fall 2013)
Abstract
One of the solutions of the Helmholtz equation is the vortex beams. In the recent decades, production and applications of these types of beams have found serious attentions. Determination of the vortex beam topological charge and its sign are very important issues. Odd number of reflections of the vortex beam changes its vorticity. In this paper, we have used a q-plate to generate a vortex beam from a plane wave of a He-Ne laser beam and a two-channel moiré based wavefront sensor is used to measure wavefront gradient of the vortex beam. In two different arrangements the vortex beam experience odd and even number of reflections, respectively, and from the moiré pattern deformations the topological charge of the vortex beam and its sign are determined.
Ali Mohammad Khazaei, Fatemeh Afsharipour, Hamid Reza Mashayekhi, Mohammad Yeganeh,
Volume 17, Issue 2 (Summer-Fall 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.
