Study On The System Of Beam Shaping For High-Power Laser Diode Array

As the time is moving forward, the technology is progressing. It has been over forty years since the invention of the first laser diode in 1962. And nowadays we develop the high-power laser diode array. Owing to its advantages of high-power output, simple structure and high electro-optical conversion efficiency, high-power laser diode array has been widely used in many fields, such as pumping solid-state laser, material processing, illuminating light source and so on. However, because of the poor quality of the output beam, shaping the beams of the high-power laser diode array to meet the requirements of many practical applications becomes a research focus which attracts people's attention.On the basis of summarizing various methods for beam-shaping from lots of reports, we aim to design a laser active imaging illuminator with excellent uniformity and high efficiency in far field. In the thesis we obtain an illuminating light source for an active imaging system by shaping the beams of a high-power laser diode stack (LD Stack).The thesis reviews a variety of domestic and foreign beam-shaping techniques for high-power laser diode. After analyzing each method, we choose the theory of the Multi-tilted Gaussian Beam (MTGB). By adjusting the offset of each cylindrical micro-lens, each output beam gains the different tilted emitting-angle, and then forms a MTGB model.We design a beam-shaping optical system of high-power laser diode stack for uniform illumination by cylindrical micro-lenses. The curvature radius and the thickness of the lenses which affect the beam-shaping are also discussed. The simulation results from ASAP software show that uniform illumination can be obtained in the far-field district. The shaping efficiency reaches to 80%, and the uniformity is beyond 85%. A beam-shaping experiment is also carried out. We set up the instruments and adopt the CCD camera to fix the cylindrical micro-lenses array. After finish the system, we project the illuminator to the far-field and receive the detecting images. To estimate the effect of the system, we analyze the detecting images by MATLAB. The final experimental results is the uniformity is over 80% in the field-angle of 10 degree.