Recently, much attention has been paid to optical components with complex surfaces because they can significantly optimize the aberrations of optical systems. However, a complex surface introduces several difficulties for precise measurement. To address this challenge, we propose tilted-wave point diffraction interferometer (TPDI) for measurements of complex surfaces. TPDI combines the advantages of tilted-wave interferometry and point diffraction interferometry, thus enabling high-precision measurements of complex surfaces; moreover, this method has demonstrated good efficiency and versatility. We adopt a fiber array (FA) to generate diffractive tilted waves to compensate for the local gradient of the test specimen. Unlike the classical PDI, which focuses more on the beam quality of the on-axis diffractive wave, the proposed system requires better quality for both the on-axis and off-axis diffractive waves. Therefore, the main parameters of the FA that may introduce measurement errors are analyzed, including the end face roughness of the array, the quality of diffractive wavefronts, and the initial optical path differences. Finally, the measurement result of the high-order hyperboloid verifies that our TPDI is effective and its precision of testing a complex surface is better than λ / 37 (rms, λ = 632.8 nm).

中文翻译：

---

带倾斜波的点衍射干涉仪，用于测量复杂表面

最近，由于具有复杂表面的光学组件可以极大地优化光学系统的像差，因此引起了人们的极大关注。然而，复杂的表面为精确测量带来了一些困难。为了应对这一挑战，我们提出了用于测量复杂表面的倾斜波点衍射干涉仪（TPDI）。TPDI结合了倾斜波干涉测量法和点衍射干涉测量法的优势，从而可以对复杂表面进行高精度测量；此外，该方法已经证明了良好的效率和通用性。我们采用光纤阵列（FA）来产生衍射倾斜波，以补偿试样的局部梯度。不像传统的PDI那样，它更多地关注同轴衍射波的光束质量，对于同轴和离轴衍射波，提出的系统都需要更好的质量。因此，分析了可能引入测量误差的FA的主要参数，包括阵列的端面粗糙度，衍射波阵面的质量以及初始光程差。最后，高阶双曲面的测量结果验证了我们的TPDI是有效的，并且其测试复杂表面的精度优于λ/ 37（rms，λ= 632.8 nm）。