论文标题
用于测量流体表面较小偏转的总内部反射挠度测定法
Total-internal-reflection deflectometry for measuring small deflections of a fluid surface
论文作者
论文摘要
我们描述了一种方法，该方法在大型透明罐内的水上接口处使用总内部反射来测量界面的偏转。使用这种配置，我们获得了一个光学设置，其中液体表面充当可变形镜。该设置被证明对反射水面非常小的干扰非常敏感，这些干扰通过可视化参考模式的反射而检测到。当水面变形时，它反映了参考模式的扭曲图像，类似于合成的Schlieren设置。使用合适的图像相关方法分析了模式的失真。因此获得的位移场与水面的局部空间梯度相关。梯度场以最小二乘的意义集成，以获得水面的完整瞬时重建。当将固体物体放置在水面上方时，该方法特别有用，该物体的存在使液体表面原本无法通过光学上的访问。
We describe a method that uses total internal reflection at the water-air interface inside a large, transparent tank, to measure the interface's deflections. Using this configuration, we obtain an optical set-up where the liquid surface acts as a deformable mirror. The set-up is shown to be extremely sensitive to very small disturbances of the reflecting water surface, which are detected by means of visualising the reflections of a reference pattern. When the water surface is deformed, it reflects a distorted image of the reference pattern, similar to a synthetic Schlieren set-up. The distortions of the pattern are analysed using a suitable image correlation method. The displacement fields thus obtained correlate to the local spatial gradients of the water surface. The gradient fields are integrated in a least-squares sense to obtain a full instantaneous reconstruction of the water surface. This method is particularly useful when a solid object is placed just above water surface, whose presence makes the liquid surface otherwise optically inaccessible.
