Schweickhardt León, Tausendfreund Andreas, Stöbener Dirk, Fischer Andreas
Opt Express. 2022 Apr 11;30(8):12615-12629. doi: 10.1364/OE.454741.
With well-known speckle measurement techniques, the root mean square height as well as the autocorrelation length of isotropic surfaces can be determined quickly and over a large area of interest. Beyond that, the present article studies the speckle-based measurement of anisotropic surfaces. For this purpose, a measurement setup and evaluation algorithm are presented that enable the characterization of unidirectionally anisotropic surfaces machined by grinding. As a result, four measurands are obtained from one speckle image: the machining direction, the autocorrelation length perpendicular to the machining direction, as well as two root mean square roughness parameters parallel and perpendicular to the machining direction. The first two measurands are obtained from a two-dimensional fast Fourier transform of the diffraction pattern resulting from the unidirectional tool marks and the latter two by a bidirectional evaluation of the speckle contrast. In addition to measurements on physical reference samples, a spatial light modulator is used to create a large number of surface topographies with known model parameters in order to quantify the measurement uncertainty.
利用众所周知的散斑测量技术，可以在较大的感兴趣区域内快速确定各向同性表面的均方根高度以及自相关长度。除此之外，本文研究基于散斑的各向异性表面测量。为此，提出了一种测量装置和评估算法，能够对通过磨削加工的单向各向异性表面进行表征。结果，从一幅散斑图像中获得了四个测量值：加工方向、垂直于加工方向的自相关长度，以及平行和垂直于加工方向的两个均方根粗糙度参数。前两个测量值是从单向刀具痕迹产生的衍射图案的二维快速傅里叶变换中获得的，后两个测量值是通过对散斑对比度的双向评估获得的。除了对物理参考样品进行测量外，还使用空间光调制器创建大量具有已知模型参数的表面形貌，以量化测量不确定度。
