en اپتیک فوریه، هولوگرافی، سیستم‌های تصویر برداری Fourier Optics, Holography, Imaging systems پژوهشي Research <span style="font-size:11pt"><span new="" roman="" style="font-family:" times=""><span style="font-weight:bold">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.</span></span></span> diffraction grating, Fresnel diffraction, Fresnel-Kirchhoff integral, radial grating, self-focusing 195 204 http://ijop.ir/browse.php?a_code=A-10-304-1&slc_lang=en&sid=1 Ali Mohammad Khazaei khazaei.am@lu.ac.ir 10031947532846005206 10031947532846005206 No Department of Physics, Lorestan University, Khorramabad, Iran Fatemeh Afsharipour fatemeh98afshari@phy.uk.ac.ir 10031947532846005207 10031947532846005207 No Department of Interdisciplinary Physics and Technology, Faculty of Advanced science and technology, Shahid Bahonar University of Kerman, Kerman, Iran Hamid Reza Mashayekhi mashhr@uk.ac.ir 10031947532846005208 10031947532846005208 No Department of Interdisciplinary Physics and Technology, Faculty of Advanced science and technology, Shahid Bahonar University of Kerman, Kerman, Iran Mohammad Yeganeh m.yeghaneh@cfu.ac.ir 10031947532846005209 10031947532846005209 Yes Department of Physics Education, Farhangian University, P.O. Box 14665-889, Tehran, Iran