海面大气边界层中聚焦光束漂移各向异性的实验研究
Anisotropy of beam wander of focused beam in atmospheric boundary layer above sea level
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摘要: 利用位置敏感型光电倍增管（PSPMT），设计了测量聚焦光束漂移的实验装置。该装置在80 mm的有效探测面内实现了2维位置信号的直接探测，空间分辨率可达1 mm，明显优于四象限探测器和阵列探测器，最高采样频率可达80 kHz，且动态范围很大，优于一般的成像器件。在近海岸海面上5 m处的大气边界层中进行了距离为1 000 m的聚焦激光传输实验。测量结果表明：聚焦光斑的质心漂移具有各向异性，水平方向光斑漂移幅度一般介于5.61 mm和14.83 mm之间，垂直方向光斑漂移幅度介于3.54 mm和7.3 mm之间，两者之比的平均值为1.69；水平方向和垂直方向的光斑漂移功率谱密度（PSD）在低频段也存在差异，垂直方向光斑漂移的PSD比水平方向光斑漂移的PSD下降速率更快。Abstract: The beam wander of focused laser beam in atmospheric boundary layer was studied experimentally over 1 000 m path at five meters above sea level using a position sensitive photomultiplier tube (PSPMT). A new experimental setup was designed to directly measure two dimensional position variations in the active area of 80 mm diameter. The high spatial resolution of the new setup reaching 1 mm is better than that of the quadrant detector and the detector array system markedly. This system is better than the ordinary imaging systems for its high sampling frequency of 80 kHz and wide dynamic range. The statistic results show that the beam wander is strongly anisotropic. The beam wander in horizontal direction is between 5.61 mm and 14.83 mm and in vertical direction always varies from 3.54 mm to
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Key words:
- light propagation /
- atmospheric turbulence /
- beam wander /
- anisotropy
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