Laguerre-Gaussian beam shaping by binary phase plates as illumination sources in micro-optics

The lack of intensity in the central region of Laguerre-Gaussian beams reduces their applicability as illumination sources. For this reason, it is usual to shape a Laguerre-Gaussian beam to a nearly Gaussian beam using a binary phase mask. The behavior of this rectified Laguerre-Gaussian beam is analyzed in this work in the Fresnel regime. A comparison between diverse Laguerre-Gaussian beams with rectified Laguerre-Gaussian beams shows that there appear two different regions along the propagation axis: first is a transition region (for lower distances) with a flat intensity distribution, and next is a second region (for longer distances) where the rectified Laguerre-Gaussian tends to a Gaussian shape. The results of this work are very valuable for the use of this kind of beam in micro-optical applications. (C) 2014 Optical Society of America