Study On High-Power Diode Laser Beam Collimation

Since the high-power diode laser has small volume, light weight, high electro-optical conversion efficiency, small size, long service life and other characteristics that it has wide application prospects in the industry, military and other fields. However, due to current high-power diode lasers own waveguide structure limits, the output beam in fast axis and slow axis is astigmatic beam, In the fast axis the beam divergence angle reached 80 degree or so, the slow axis beam divergence angle also achieve about 10 degree, which severely limits the high power diode lasers in many fields.In this thesis, On the basis of current collimation methods in domestic and foreign, according to the high power diode laser beam characteristics and evaluation method of laser beam quality, an aspherical plane-convex cylindrical lens and a plane-convex cylindrical lens have been used in collimating the fast and slow axis divergence angle of the laser bar respectively. Using the q parameter and ABCD transfer matrix to analysis of Gaussian beam collimation condition, according to the imaging conditions of geometric optics, calculate the fast axis aspheric surface, fulfilled the fast axial divergence angle is 1.7 mrad after collimation by software simulation. analysis of the slow-axis collimator restrictions, and Zemax optimize the initial model, getting a better result of 1.12 mrad with collimator parameters. At the same time, A fast axis collimation experiment with aspherical cylindrical lens has been carried out, getting a result of 4.7 mrad. It gives a direction of technology realization and process parameter to install micro-lens for diode laser.According to the engineering application needs: to achieve the target that in the range of 0.5 ~5 meters the beam spot of a single emitter was less than 5 millimeters in fast and slow axis respectively. Since micro-lens collimation requires high-precision installation and testing equipment, so the experimental study carry out using traditional spherical lenses to collimate the fast axis and slow axis beam divergence. Adopting three pieces of spherical plan convex cylindrical lens realized the fast axis beam collimation; Using a piece of spherical plan convex cylindrical lens and optical aperture realize slow axis beam collimation. Finally, in this thesis, analyze of the main factors impacting micro-lens collimation, such as installation position of the micro-lens, laser wavelength, temperature, lens materials, which laid a foundation for designing, manufacturing, assembly and adjustment micro-lens for laser bar.