Speckle patterns offer valuable insights into the surface characteristics or the characteristics of the light generating the speckle. One possible way to extract this information is via spectral speckle correlation (SSC). The cross-correlation between two speckle fields, generated at different wavelengths, can be used for example to determine the roughness of the illuminated surface. Taking defocused measurements of the surface or measuring on a tilted surface leads to a displacement between the speckle, which in turn affects the cross-correlation and leads to errors in the calculated roughness. In this work we present a model to determine the lateral speckle displacement for a change in wavelength in the case of subjective speckle and defocused, tilted objects. This model is therefore applicable to a wide range of applications and allows to estimate and correct for this speckle displacement. Experimental results show sub-pixel accuracy for object tilts up to ±7° and defocus distances up to ±25 mm.

中文翻译：

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散焦和倾斜成像系统中的光谱散斑位移

散斑图案为了解表面特征或产生散斑的光的特征提供了有价值的见解。提取此信息的一种可能方法是通过光谱散斑相关 (SSC)。例如，可以使用在不同波长处生成的两个散斑场之间的互相关来确定照射表面的粗糙度。对表面进行散焦测量或在倾斜表面上进行测量会导致散斑之间的位移，进而影响互相关并导致计算的粗糙度出现误差。在这项工作中，我们提出了一个模型，用于在主观散斑和散焦、倾斜物体的情况下确定波长变化的横向散斑位移。因此，该模型适用于广泛的应用，并允许估计和校正这种散斑位移。实验结果表明，物体倾斜的亚像素精度高达 ±7°，散焦距离高达 ±25 mm。