用电子散斑干涉法测量材料热膨胀系数
Measurement of atmospheric coherence length in daytime and at night
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摘要: 利用双光束电子散斑干涉法（ESPI）对试件受热变形进行了实时观测，针对一次实验过程中得到的图片较多（300～500幅）的特点，在图像处理时摒弃了以往的手动识别等位移线的办法，用MATLAB语言编写了批处理程序，能够在采集的大量散斑图片中自动快速准确地标定等位移线，得到相应的位移和应变，并结合实时测量的温度值，获得了45钢和LY12铝合金在不同温升率下的热膨胀系数及其随温度的变化。实验结果表明，在涉及的温升率范围内，温升率的改变对材料热膨胀系数的影响不明显，材料的热膨胀系数随温度的升高略有上升。Abstract: The principle of atmospheric coherence length measurement via differential image motion measure of the optical wave's angle-of-arrival fluctuation is introduced. An instrument for the measurement of atmospheric coherence length both in the daytime and at night were described. The statistical characteristics of the atmospheric coherence length in the daytime and at night were analyzed from some primary observation results. It shows that the refractive index structure constant varies with the time in total layer, and the time-varying behavior is basically in accordance with that of the boundary layer, that is, the atmospheric coherence length during the period of sunrise and sundown is much larger than that in the other periods.
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