Technology Reserch Of Variable Divergence Of Diode Laser Beam

The beam divergence angle in the fast axis direction can be as large as40°and is usually8°～10°in the slow axis direction due to the dissymmetrical active region of high power diode laser. In order to make the high power laser beam meet the illumination requirement, the beam divergence always need to be changed. The beam shaping technology was studied deeply in this paper.On the base of studying the beam characters of broad area diode laser, a source model was established for astigmatic elliptical beam with different divergences and beam quality in fast axis and slow axis. An aspherical cylindrical lens with high numerical aperture and a plane-convex cylindrical lens with long focal length were used to compact the divergence angles of fast and slow axes respectively. This system can obtain the requisite beam divergence and change it in a certain range by defocusing method. The mathematical model between the amount of cylindrical optical elements’movement and beam divergence was set up.A variable beam divergence shaping system was designed with above method and simulated by commercial optical design software for typical high power diode laser. The simulation results show that this system can reduce the beam divergence and change it continually in a certain range. The transformed beam can illuminate different area objects at faraway distance.