Design method of a binary optical element for collimation of high power LD beams with astigmatism

摘要

Owing to its compactness, lightness, and low cost, laser diodes (LD) play an important role as a coherent source in various fields of technology. Because of the waveguide properties of their active areas, laser diodes generate large divergence-angle beams with elliptically shaped intensity profiles. And the beam of LD has astigmatism. So it is difficult to collimate LD beams effectively. The binary optical elements are small, light, easy to be copied and able to realize multi-purpose integrated, especially suits for the beam shaping of laser diode array. Based on accurate far-field model of high-power laser diode, a design method of binary optical element for laser diode beams, which can correct the astigmatism of the laser beam, has been developed, and the principle and process has been given in detail. The method is simple and practical. The relief surface of the element is of multiphase structure. And its theoretical diffraction efficiency is as high as 95%.