A Study for Measurement of Thermophysical Properties using Thermal Fluctuations

从本研究中获得的结果总结如下。(1)In为了检测来自热激发表面波（ripplon）的非常弱的散射光，我们已经开发了使用具有100 μ m周期的光栅的外差检测装置。以正戊烷为样品液体，在室温附近，我们发现该装置有足够的能力检测到ripplon的信号。（2）通过实验研究，找到了激光束在液体表面的入射角和光栅衍射光束的阶数的最佳条件。据证实，在原则上，我们能够计算的表面张力和运动粘度的功率谱的波纹。(3)As作为高温熔体测量的第一步，我们设计了一个BN硅熔体槽，并设计了一个使用红外成像炉的高达1600 ℃的高温炉系统。(4)In为了从ripplon获得更强的散射光，我们采用了200 μ m的光栅。通过使用这种光栅，我们能够检测到更好的S/N比信号，并且再现性得到改善：()0.4%和运动粘度（）SY. ±. ()11%.（5）由于再现性的提高，我们能够检测由于液体表面的降解而引起的作为时间函数的表面张力的变化。

The results obtained from the present research are summarized as follows.(1)In order to detect very weak scattered light from thermally excited surface wave (ripplon), we have developed an heterodyne detection apparatus using a grating having a100 mum period. By employing n-pentane as an sample liquid near room temperature, we found that the apparatus has enough ability to detect the signal from ripplon.(2)Through experimental considerations, we have found optimum conditions for the incident angel of laser beam on the liquid surface and the order of diffracted beam from the grating. It was confirmed that, in principle, we are able to calculate the surface tension and the kinematic viscosity from the power spectrum of ripplons.(3)As the first step towards measurement on high temperature melts, we have designed a trough for molten Si using BN.We also have designed a high temperature furnace system up to 1600 ﾟC by using an infrared imaging furnace.(4)In order obtain much stronger scattered light from ripplon, we have employed a 200 mum-optical grating. By using this grating, we were able to detect much better S/N ratio signals and the reproducibility was improved : surface tension (〕SY.+-.〔)0.4% and kinematic viscosity (〕SY.+-.〔)11%.(5)Due to the improvement of reproducibility, we were able to detect the change of surface tension as a function of time because of degradation of liquid surface.