Shakiba Mosavat Shahreza, Seyed Ayoob Moosavi, Hossein Saghafifar,
Volume 16, Issue 2 (7-2022)
Abstract
In this paper, Laguerre-Gaussian beams are produced by Computer Generated Hologram (CGH) on Spatial Light Modulator (SLM). The realization of CGH on SLM is simulated by the scalar diffraction theory. At first, Laguerre-Gaussian beam generation process is simulated by diffraction of laser light from phase and amplitude fork gratings in two types: blazed and binary grating and the results are compared. The higher efficiency is obtained for the blazed phase grating in the first order which is more important in our study. Recorded data from the experiment shows a good agreement with simulation results. In order to evaluate the topological charge of the generated Laguerre-Gaussian beam, the Mach-Zehnder interferometer setup is used.
Abolhasan Mobashery, Seyed Ayoob Moosavi, Mojtaba Arjmand,
Volume 18, Issue 1 (10-2024)
Abstract
In the present paper, the design of the laser transmitter section of a LiDAR system is described for autonomous vehicles. The optical system is designed to produce a linear laser beam with uniform intensity. The output beam from the diode laser has a non-uniform Gaussian profile. Conventional methods for converting this profile into a linear one often results in an uneven distribution along the line. In order to address this issue, a Powell lens is used. The Powell lens is an aspheric lens that transforms the incoming parallel beam into a linear beam with a uniform profile. In this type of lens, two parameters—the radius of curvature and the conic constant—must be selected to ensure uniform intensity across the entire laser line. In the present study, the diode laser intensity distribution, collimating lenses, and Powell lens are simulated using Zemax software. The collimating lens transforms the highly divergent laser beam into a nearly parallel beam, after which the Powell lens, with a radius of curvature of r=0.9 mm and a conic constant of -1.7, produces a linear laser profile with a divergence angle of 60 degrees. Experimental results confirm the accuracy of the design and simulation process. In the experimental tests, the power drop of the laser at the start and end of the laser line was measured to be less than 15%.
