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报道了一种长脉冲泵浦条件下Nd:YAG激光棒热透镜焦距和温度梯度导致的光走离角测量方法。该方法通过高速相机以5 khz的拍摄频率获取TEM00模He-Ne激光的光斑尺寸和位移变化,运用光学矩阵、q参数和ABCD法则,计算得到了动态热透镜焦距和光走离角。经多组测量发现:热透镜在泵浦期间表现为负透镜,泵浦强度越强焦距越短;在这些测量中出现的最短焦距约为-0.33 m;光走离的变化和热透镜焦距的变化几乎同步;光走离的方向限制在一个特定的子午面内;走离角随泵浦增强而增大,最大走离角同样出现在泵浦结束后,大约为3 mrad。
A long distance pulsed Nd:YAG laser rod thermal lens focal length and temperature gradient caused by the light walking away from the angle measurement method. In this method, the spot size and displacement of TEM00-mode He-Ne laser were acquired by a high-speed camera at a shooting frequency of 5 khz. The focal lengths of the dynamic thermal lens and the optical walking distance were calculated by using the optical matrix, q-parameter and ABCD rule. After several sets of measurements, it was found that the thermal lens behaved as a negative lens during pumping, the shorter the focal length was, the stronger the pump intensity was. The shortest focal length appeared in these measurements was about -0.33 m. The change of light divergence and thermal lens focal length The changes are nearly simultaneous; the direction of light travel is confined to a specific meridional plane; the walking away angle increases with increasing pumping, and the maximum walking angle also appears at the end of the pump at about 3 mrad.