Peterhänsel S, Pruss C, Osten W
Institute of Applied Optics and Research Center SCoPE, University of Stuttgart, 70569 Stuttgart, Germany.
Opt Express. 2013 May 20;21(10):11638-51. doi: 10.1364/OE.21.011638.
One common way to measure asphere and freeform surfaces is the interferometric Null test, where a computer generated hologram (CGH) is placed in the object path of the interferometer. If undetected phase errors are present in the CGH, the measurement will show systematic errors. Therefore the absolute phase of this element has to be known. This phase is often calculated using scalar diffraction theory. In this paper we discuss the limitations of this theory for the prediction of the absolute phase generated by different implementations of CGH. Furthermore, for regions where scalar approximation is no longer valid, rigorous simulations are performed to identify phase sensitive structure parameters and evaluate fabrication tolerances for typical gratings.
测量非球面和自由曲面的一种常见方法是干涉零位测试，即在干涉仪的物光路中放置一个计算机生成全息图（CGH）。如果CGH中存在未检测到的相位误差，测量将显示系统误差。因此，必须知道该元件的绝对相位。这个相位通常使用标量衍射理论来计算。在本文中，我们讨论了该理论在预测不同CGH实现方式所产生的绝对相位方面的局限性。此外，对于标量近似不再有效的区域，进行了严格的模拟，以识别相位敏感结构参数并评估典型光栅的制造公差。
