| Thermal lensing of crystal has been analyzed theoretically and numerically in this paper, which consists of two parts. The wavefront aberration due to thermal lensing when laser transmits in crystal is studied in the first part. At the beginning, calculation function of optical path difference due to thermal lensing is given, and on the basis of that, the effects on some kinds of crystal are simulated. Furthermore, the image difference forms of wavefront aberration because of thermal lensing were induced, and the method to compensate wavefront aberration because of thermal lensing is presented.Thermal lensing in continuous-wave end-pumped laser rod has been studied in the second part of this paper. First, thermal effects in continuous-wave end-pumped Cr:Nd:GSGG laser rod are studied, and function of temperature distribution is discussed. Stress due to thermal was analysed. The critical pump power causing thermal fracture was presented. By discussing and analysing optics aberration, the calculated formula of difference of optical path is deduced, and the effective focal length of the thermal lens is discussed. Secondly, the temperature field of laser medium by laser diode (LD) end-pumped is simulated using finite element methods. The temperature and its distribution in the medium (e.g. Nd:YAG) are determined. The temperature fields at the conditions of improving the convective heat coefficient of medium's surface, reducing the coolant temperature and cooling the pumped face of rod are simulated and the results have been compared with each other. And last, temperature field of anisotropic laser medium (e.g. Nd:YVO4) by laser diode (LD) end-pumped has been studied by using finite element methods.
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