Mehta J M, Black W Z
Appl Opt. 1977 Jun 1;16(6):1720-6. doi: 10.1364/AO.16.001720.
Errors caused by refraction and end effects in interferometric systems are studied analytically. Both errors are estimated for Mach-Zehnder and differential interferometers when these instruments were used to measure convective heat transfer coefficients in air and water. Both errors were found to be larger for the Mach- Zehnder interferometer than for the differential interferometer. This result suggests that the differential interferometer is potentially a more suitable and accurate device than the Mach-Zehnder interferometer, if one wishes to measure heat transfer coefficients. Convective heat transfer coefficients measured with a differential interferometer are presented. The experimental study used a specially designed test section, which was inserted into the interferometer. The test involved heat dissipated from a vertical plate by free convection to water. The measured results were found to compare satisfactorily with published results at Rayleigh numbers less than 10(4). At higher Rayleigh numbers, refraction caused sufficient bending of the light rays that a zone of no information next to the heated surface resulted in significant errors.
对干涉测量系统中由折射和端部效应引起的误差进行了分析研究。当马赫曾德尔干涉仪和差动干涉仪用于测量空气和水中的对流传热系数时，对这两种误差进行了估算。结果发现，马赫曾德尔干涉仪的这两种误差都比差动干涉仪的大。这一结果表明，如果想要测量传热系数，差动干涉仪可能比马赫曾德尔干涉仪更合适、更精确。给出了用差动干涉仪测量的对流传热系数。实验研究使用了一个专门设计的测试段，将其插入干涉仪中。该测试涉及垂直平板通过自然对流向水散热的情况。发现在瑞利数小于10⁴时，测量结果与已发表的结果比较令人满意。在较高的瑞利数下，折射导致光线发生足够的弯曲，使得加热表面附近出现无信息区域，从而产生显著误差。
