Geckeler Ralf D, Křen Petr, Just Andreas, Schumann Matthias, Krause Michael, Lacey Ian, Yashchuk Valeriy V
Physikalisch-Technische Bundesanstalt, Bundesallee 100, 38116 Braunschweig, Germany.
Czech Metrology Institute, Okružní 31, 63800 Brno, Czech Republic.
Rev Sci Instrum. 2019 Feb;90(2):021705. doi: 10.1063/1.5057402.
Deflectometric profilometers are indispensable tools for the precision form measurement of beam-shaping optics of synchrotrons and x-ray free electron lasers. They are used in metrology labs for x-ray optics worldwide and are crucial for providing measurement accuracy dictated by the form tolerances for modern state-of-the-art x-ray optics. Deflectometric profilometers use surface slope (angle) to assess form, and they utilize commercial autocollimators for the contactless slope measurement. In this contribution, we discuss the influences of environmental parameters, such as temperature and air pressure, including their gradients, on high-accuracy metrology with autocollimators in profilometers. They can cause substantial systematic errors in form measurement, especially in the case of large and strongly curved optical surfaces of high dynamic range. Relative angle and form measuring errors of the order of 10 are to be expected. We characterize environmental influences by extended theoretical and experimental investigations and derive strategies for correcting them. We also discuss the possibility to minimize the contributions of some errors by the application of sophisticated experimental arrangements and methods. This work aims at approaching fundamental limits in autocollimator-based slope and form metrology.
偏折轮廓仪是同步加速器和X射线自由电子激光束整形光学元件精密形状测量中不可或缺的工具。它们在全球范围内的X射线光学计量实验室中得到应用，对于提供现代先进X射线光学元件形状公差所要求的测量精度至关重要。偏折轮廓仪利用表面斜率（角度）来评估形状，并使用商用自准直仪进行非接触式斜率测量。在本论文中，我们讨论了环境参数（如温度和气压，包括它们的梯度）对轮廓仪中使用自准直仪进行高精度计量的影响。它们会在形状测量中导致显著的系统误差，特别是在具有高动态范围的大型且强烈弯曲的光学表面的情况下。预计相对角度和形状测量误差会达到10的量级。我们通过广泛的理论和实验研究来表征环境影响，并推导校正这些影响的策略。我们还讨论了通过应用复杂的实验装置和方法来最小化某些误差影响的可能性。这项工作旨在接近基于自准直仪的斜率和形状计量的基本极限。
