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Graphical abstractA novel noncontact dual laser triangulation measuring device based on the Scheimpflug principle to measure petal thickness is presented. The actual petal thickness is precisely calculated from the normal direction of the petal surface.Display Omitted A noncontact, dual laser triangulation measuring device is presented.A cubic spline method was used to fit multipoints of irregular petal surfaces.Actual petal thickness is found from normal equations of petal surface. The growth and health status of plants can be evaluated by their petal or leaf thickness. However, the thickness of these sections is difficult to measure because of the irregular curvature of petal and leaf surfaces and their soft nature. The petal surface is easily damaged when traditional contact mechanical apparatus is used to measure it. In this research, we developed a novel noncontact measuring device that uses dual laser triangulation based on the Scheimpflug principle to measure petal thickness. A cubic spline method is employed to curve fit the multipoints of the petal surface after dual laser triangulation module measurement. The actual petal thickness can be calculated precisely from the normal equations of curvatures of the petal surface. The measuring range and the resolution of the petal thickness measuring device are ?2mm and 2µm/pixel, respectively. The total measurement uncertainty (comprising measurement repeatability, different surface slopes, and colors) of the dual laser triangulation system is less than 16µm. Using Phalaenopsis as a sample case, we make various compensations according to the different surface curvatures of its petal. |
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