Egan Patrick F
National Institute of Standards and Technology, Gaithersburg, MD 20899, USA.
Int J Thermophys. 2024;45(9). doi: 10.1007/s10765-024-03422-3.
A method is described to measure the thermal expansion coefficient of fused quartz glass. The measurement principle is to monitor the change in resonance frequency of a Fabry-Perot cavity as its temperature changes; the Fabry-Perot cavity is made from fused quartz glass. The standard uncertainty in the measurement was less than 0.6 (nm·m)·K, or 0.15 %. The limit on performance is arguably uncertainty in the reflection phase-shift temperature dependence, because neither thermooptic nor thermal expansion coefficients of thin-film coatings are reliably known. However, several other uncertainty contributors are at the same level of magnitude, and so any improvement in performance would entail significant effort. Furthermore, measurements of three different samples revealed that material inhomogeneity leads to differences in the effective thermal expansion coefficient of fused quartz; inhomogeneity in thermal expansion among samples is 24 times larger than the measurement uncertainty in a single sample.
描述了一种测量熔融石英玻璃热膨胀系数的方法。测量原理是在法布里-珀罗腔温度变化时监测其共振频率的变化；该法布里-珀罗腔由熔融石英玻璃制成。测量的标准不确定度小于0.6（纳米·米）·开尔文，即0.15%。性能的限制可以说是反射相移温度依赖性的不确定性，因为薄膜涂层的热光系数和热膨胀系数都无法可靠得知。然而，其他几个不确定度来源处于相同量级，因此性能的任何改进都需要付出巨大努力。此外，对三个不同样品的测量表明，材料不均匀性导致熔融石英有效热膨胀系数存在差异；样品间热膨胀的不均匀性比单个样品测量不确定度大24倍。
