Hagy H E
Appl Opt. 1973 Jul 1;12(7):1440-6. doi: 10.1364/AO.12.001440.
Photoelastic analysis of a large fused sandwich seal, composed of two glasses with slight composition differences, permits reliable measurement of the thermal expansion difference to 0.0002 ppm/ degrees C. If the expansion of one of the glasses is known, the method becomes absolute. For the titania-silica system, it is shown that for any two compositions with small titania differences the expansion coefficient differential remains constant from -195 degrees C to 925 degrees C. A direct correlation between ultrasonic velocity and thermal expansion has been established for this glass system and has led to successful nondestructive measurements. With an experimentally defined relationship, the measurement of the ultrasonic velocities yields absolute or differential expansions. Excellent agreement with seal testing data is shown to exist with differential data taken by both methods.
对由两种成分略有差异的玻璃组成的大型熔合夹层密封件进行光弹性分析，可实现对热膨胀差的可靠测量，精度可达0.0002 ppm/℃。如果其中一种玻璃的膨胀情况已知，该方法就可成为绝对测量方法。对于二氧化钛-二氧化硅系统，研究表明，对于任何两种二氧化钛含量差异较小的成分，从-195℃到925℃，膨胀系数差保持恒定。已为该玻璃系统建立了超声速度与热膨胀之间的直接关联，并成功实现了无损测量。根据实验确定的关系，超声速度的测量可得出绝对膨胀或膨胀差。两种方法获取的膨胀差数据与密封测试数据显示出极佳的一致性。
