| The invention and development of laser diode, its application and expectation, as well as several methods for evaluating beam quality are discussed. Furthermore, a new method for evaluating beam quality of laser diode is given.The main work of this dissertation is summarized as follows1. Several methods such as focused spot size, far-field divergence angle, times diffraction limited factorβ, Strehl rate, energy circle rate and M~2 factor are summarized. The application range, strongpoint and shortcoming of them especially used in evaluating beam quality of laser diode are also analyzed.2. The main factors to influence collimating the beam of laser diode with lenses are analyzed. A new quality parameter L*θ_y~7* As(L is the size of the emitter in the direction parallel to the junction plane,θ_y is the angle of the beam in the perpendicular direction, As is the astigmatism parameter of a semiconductor laser )for evaluating beam quality of laser diode is given. The difficulty of collimation is well expressed by this mean. The smaller the value of Lθ_y~7* As is, the more easily the beam is collimated. |
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