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液体的可流动性为液体激光器热管理提供便利,研究液体流动状态对激光光束质量的影响对液体激光器研制具有一定的现实意义。采用Fluent软件,模拟了激光系统增益区液体介质横向流动状态。结果表明,介质流速较为均匀稳定,对于激光光束质量不会产生大的影响。实验测量了液体介质流速分别为0.48,1.51和5.39 L/min时,通过增益区的信标光(He-Ne光)相位分布,信标光的斯垂耳(Strehl)比为0.9964,0.9960及0.9936。在纵向均匀抽运条件下,粘性流动的非均匀性使得信标光的光束质量与理想流动相比略有下降,抽运功率密度为46.9 W/cm2,流速分别为0.48和5.39 L/min时信标光的Strehl比为0.9484和0.9995。当抽运功率密度升高至100 W/cm2,两种流速状态下的信标光的Strehl比为0.1051和0.9978。加快液体的流动速度可以减少因介质流速的不均匀而引起的波前畸变。
The fluidity of the liquid facilitates the thermal management of the liquid laser. It is of practical significance to study the effect of liquid flow on the quality of the laser beam. Fluent software is used to simulate the lateral flow of liquid medium in the gain region of laser system. The results show that the medium flow rate is more uniform and stable, which will not have a big impact on the laser beam quality. The phase distributions of beacon light (He-Ne light) passing through the gain region were measured experimentally at a liquid medium flow rates of 0.48, 1.51 and 5.39 L / min, respectively. The Strehl ratios of the beacon light were 0.9964, 0.9960 and 0.9936. Under the condition of longitudinal uniform pumping, the nonuniformity of the viscous flow makes the beam quality of the beacon light slightly decrease compared with the ideal flow. The pumping power density is 46.9 W / cm2 and the flow rates are 0.48 and 5.39 L / min respectively Strehl ratios for beacon light are 0.9484 and 0.9995. When the pump power density was increased to 100 W / cm2, the Strehl ratios of beacon light at both flow rates were 0.1051 and 0.9978. To speed up the liquid flow rate can reduce the wavefront distortion caused by the non-uniform flow velocity of the medium.