Abstract A problem present in the wood boards industry is the lack of knowledge of its roughness. The roughness causes the formation of voids between the board and the protective cover commonly used to give a special finish to the board. This leads to poor adhesion between the adhesive and the cover which affects the quality of the final product. Thus, a precise and fast way to measure the roughness that allows characterization in line and across the board is required. Speckle interferometry is a widely used technique to perform non-invasive measurements, mainly by illuminating objects under study with coherent light. In this study, laser speckle interferometry is used to determinate surface roughness in different wood boards. The proposed method uses an optical system and an image processor that correlates a series of successive images of intensity speckle pattern. These images are obtained varying the illumination angle. In order to obtain the roughness parameters of the boards, the measured correlations were adjusted to a theoretical function by using a numerical regression algorithm. The obtained values of roughness for different boards varied between 1.55 µm and 12.69 µm. Our results show a good agreement with the measurements obtained using conventional methods. Finally, we present a discussion of how laser speckle interferometry can be adapted to characterize roughness during production in real time and in wide area boards.

中文翻译：

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使用散斑干涉法估计木板的表面粗糙度

摘要 木板行业存在的一个问题是对其粗糙度缺乏了解。粗糙度会导致板和通常用于对板进行特殊处理的保护层之间形成空隙。这会导致粘合剂和覆盖物之间的粘合性较差，从而影响最终产品的质量。因此，需要一种精确且快速的粗糙度测量方法，以便在线和全面进行表征。散斑干涉测量法是一种广泛使用的非侵入性测量技术，主要通过用相干光照射研究对象。在这项研究中，激光散斑干涉测量法用于确定不同木板的表面粗糙度。所提出的方法使用光学系统和图像处理器来关联强度散斑图案的一系列连续图像。这些图像是通过改变照明角度获得的。为了获得板的粗糙度参数，通过使用数值回归算法将测量的相关性调整为理论函数。获得的不同板的粗糙度值在 1.55 µm 和 12.69 µm 之间变化。我们的结果与使用传统方法获得的测量结果非常吻合。最后，我们讨论了如何采用激光散斑干涉测量法来实时表征大面积板生产过程中的粗糙度。通过使用数值回归算法将测量的相关性调整为理论函数。获得的不同板的粗糙度值在 1.55 µm 和 12.69 µm 之间变化。我们的结果与使用传统方法获得的测量结果非常吻合。最后，我们讨论了如何采用激光散斑干涉测量法来实时表征大面积板生产过程中的粗糙度。通过使用数值回归算法将测量的相关性调整为理论函数。获得的不同板的粗糙度值在 1.55 µm 和 12.69 µm 之间变化。我们的结果与使用传统方法获得的测量结果非常吻合。最后，我们讨论了如何采用激光散斑干涉测量法来实时表征大面积板生产过程中的粗糙度。