Anderson C S
Appl Opt. 1995 Nov 10;34(32):7474-85. doi: 10.1364/AO.34.007474.
Common-path interferometers have been used to perform phase visualization for over 40 years. A number of techniques have been proposed, including dark central ground, phase contrast (π/2 and π), and field-absorption interferometers. The merits of the interferometers have been judged ad hoc by either tests with a small number of phase objects or by computer simulation. Three standardized criteria, which consolidate the work of others, are proposed to evaluate common-path interferometers: fringe visibility, fringe irradiance, and fringe accuracy. The interferometers can be described as one generic class of Fourier-plane filters and can be analyzed for all input conditions. Closed-form expressions are obtained for visibility and irradiance under the forced condition that little inaccuracy is tolerated. This analysis finds that the π-phase-contrast interferometer is a good choice if the optical phase disturbance is at least 2π; for smaller disturbances, the Π/2 filter selected by Zernike is near optimum. It is shown mathematically that the resulting fringe visibility is highly object dependent, and good results are not ensured. By allowing the optical beam to be 50% larger than the phase object, the interferometer performs well under all conditions. With this approach and a combination π-phase/field-absorption filter, interference fringe visibility is greater than 0.8 for all phase objects.
共光路干涉仪已被用于相位可视化超过40年。人们提出了许多技术，包括暗中心场、相衬（π/2和π）以及场吸收干涉仪。这些干涉仪的优点一直是通过对少量相位物体的测试或计算机模拟临时判断的。本文提出了三个标准化标准，综合了其他人的工作，用于评估共光路干涉仪：条纹可见度、条纹辐照度和条纹精度。这些干涉仪可以被描述为傅里叶平面滤波器的一类通用类型，并且可以针对所有输入条件进行分析。在几乎不容许误差的强制条件下，获得了可见度和辐照度的闭式表达式。该分析发现，如果光学相位扰动至少为2π，则π相衬干涉仪是一个不错的选择；对于较小的扰动，由泽尼克选择的Π/2滤波器接近最优。数学证明，所得条纹可见度高度依赖于物体，不能保证获得良好的结果。通过使光束比相位物体大50%，干涉仪在所有条件下都能良好运行。采用这种方法并结合π相/场吸收滤波器，所有相位物体的干涉条纹可见度均大于0.8。
