Appl Opt. 2023 May 1;62(13):3347-3356. doi: 10.1364/AO.483985.
The coefficient of thermal expansion (CTE) of ultra-low-expansion (ULE) glass is critical to the development of precision optical systems. Herein, an ultrasonic immersion pulse-reflection method is proposed to characterize the CTE of ULE glass. The ultrasonic longitudinal wave velocity of ULE-glass samples with significantly different CTE values was measured using a correlation algorithm combined with moving-average filtering, which can achieve 0.2 m/s precision with a contribution to the ultrasonic CTE measurement uncertainty of 0.47 ppb/°C. Furthermore, the established ultrasonic CTE measurement model predicted the 5°C-35°C mean CTE with a root-mean-square error of 0.9 ppb/°C. Notably, a complete uncertainty analysis methodology was established in this paper, which can provide directional guidance for the subsequent development of higher-performance measurement devices and the improvement of relevant signal processing procedures.
超低膨胀（ULE）玻璃的热膨胀系数（CTE）对于精密光学系统的发展至关重要。在此，提出了一种超声浸脉冲反射法来表征 ULE 玻璃的 CTE。使用相关算法结合移动平均滤波测量了 CTE 值差异显著的 ULE 玻璃样品的超声纵波速度，该方法的精度可达 0.2 m/s，对超声 CTE 测量不确定度的贡献为 0.47 ppb/°C。此外，所建立的超声 CTE 测量模型预测了 5°C-35°C 的平均 CTE，均方根误差为 0.9 ppb/°C。值得注意的是，本文建立了完整的不确定度分析方法，可为后续开发更高性能的测量设备和改进相关信号处理程序提供指导方向。
