Properties of Holographic Relief Phase Gratings with Conic Section Profile

Abstract

In many applications, it is necessary to divide a single laser beam into N beams of similar intensity with a high coupling efficiency. This is the case for robotic vision systems, coherent summation of laser beams, multiple imaging, security systems or coherent addition of detector signals in heterodyne detection. Binary phase gratings have been employed with success for such applications when the number of beams (N) is relatively small (≤9). But as N is increasing the fabrication of these gratings becomes impractical and costly. Fiber gratings, made with optical fibers placed side by side and embedded in epoxy, also give interesting performances for large N (≥25). However fiber gratings cannot be custom made with a specified pitch since they depend on the fiber’s diameters available.