Tangari Larrategui Martin, Zhang Yanqi, Brown Thomas G, Ellis Jonathan D
Opt Lett. 2021 Oct 1;46(19):4960-4963. doi: 10.1364/OL.432891.
The pixel modulation transfer function response degrades the contrast of non-null interferometric surface figure measurements. We experimentally quantify this effect for spatial frequencies ranging from 0 to 363 lp/mm (≈3.33 times the Nyquist limit). Our results show a low SNR spatial frequency band that behaves like a low-pass filter for sub-Nyquist interferometry and a stop-band filter for multiple-wavelength phase-shifting interferometry. We also introduce a multiple-mode, multiple-wavelength interferometry approach to measure optical surfaces with slope departure angles mapping to spatial frequencies in this low SNR band. The extended measurement range of this approach is achieved without using a sparse-array detector.
像素调制传递函数响应会降低非零干涉表面形貌测量的对比度。我们通过实验对0至363 lp/mm（约为奈奎斯特极限的3.33倍）范围内的空间频率的这种效应进行了量化。我们的结果显示了一个低信噪比空间频段，对于亚奈奎斯特干涉测量，它的行为类似于低通滤波器，而对于多波长相移干涉测量，它的行为类似于阻带滤波器。我们还引入了一种多模式、多波长干涉测量方法，用于测量光学表面，其斜率偏离角映射到这个低信噪比频段的空间频率。该方法在不使用稀疏阵列探测器的情况下实现了扩展的测量范围。
