Marginal changes in geometrical dimensions due to temperature changes affect the performance of optical instruments. Highly dimensionally stable materials can minimize these effects since they offer low coefficients of thermal expansion (CTE). Our dilatometer, based on heterodyne interferometry, is able to determine the CTE in $10^{-8} {\mathrm{K}}^{-1}$ range. Here, we present the improved interferometer performance using angular measurements via differential wavefront sensing to correct for tilt-to-length coupling. The setup was tested by measuring the CTE of a single-crystal silicon at 285 K. Results are in good agreement with the reported values and show a bias of less than 1%.

由于温度变化而引起的几何尺寸的边际变化会影响光学仪器的性能。尺寸稳定的材料可提供低的热膨胀系数（CTE），因此可将这些影响降至最低。我们的膨胀计基于外差式干涉仪，能够确定$\mathrm{1个}{0}^{-8} {\mathrm{ķ}}^{-\mathrm{1个}}$范围。在这里，我们提出了通过差分波前传感进行角度测量以校正倾斜长度耦合的干涉仪性能。通过在285 K下测量单晶硅的CTE来测试设置。结果与报告的值高度吻合，并且偏差小于1％。