Friedman G, Gasser G
Appl Opt. 1972 Dec 1;11(12):2768-77. doi: 10.1364/AO.11.002768.
Interferometric texts were performed on a 1.8-m ULE lightweight mirror at different uniform temperature conditions to determine figure changes due to expansion coefficient inhomogeneity. The conclusions of the experiment were: (1) The rms value of surface figure changes due to material inhomogeneities were found to be 0.036lambda over a 42 degrees C soak range at 6328 A. (2) Time variations of surface figure change were found to be insignificant over periods of up to 6 days. (3) No hysteresis remained after returning to figuring temperature (the measurement uncertainty was less than 0.023lambda rms at lambda = 6328 A). (4) Analytical predictions of surface figure change based on alpha inhomogeneity data were in close agreement with measurements.
在不同的均匀温度条件下，对一面1.8米的超低膨胀（ULE）轻质镜进行了干涉测量，以确定由于膨胀系数不均匀性导致的面形变化。实验结论如下：（1）在6328埃波长下，42摄氏度的浸泡范围内，由于材料不均匀性导致的表面面形变化的均方根（rms）值为0.036λ。（2）在长达6天的时间内，表面面形变化的时间变化不显著。（3）回到定形温度后没有滞后现象（在λ = 6328埃时，测量不确定度小于0.023λ rms）。（4）基于α不均匀性数据的表面面形变化的分析预测与测量结果密切吻合。
