基于条纹反射的类镜面三维面形测量方法

Three-Dimensional Shape Measurement for Specular Surface Based on Fringe Reflection

提出了一种基于条纹反射和相移技术的类镜面三维面形测量的新方法。首先在平板显示器上显示正弦条纹,然后用CCD相机分别记录由待测面和标准面反射的正弦条纹像,通过相移得到各自的相位分布,与标准面相位分布相比较得到待测表面起伏引起的相位变化。推导了相位变化量与待测表面梯度的对应关系,分别对待测面进行水平和垂直两个方向光栅相位测量,通过计算可得到梯度分布并由梯度分布恢复待测表面面形。同时初步分析了影响条纹反射技术测量精度的因素。测量中,光栅由计算机产生,可以实现精确的相移,而且可以方便地调节光栅的周期及方向,通过预设标记点来引导相位展开有效地解决待测面和标准面的条纹对应问题。实测了建筑用釉面瓷砖表面起伏,验证了该方法的可行性。

A novel three-deimensional shape measurement method for specular surface, based on fringe reflection and phase shift is presented. A sinusoidal fringe is displayed on a plane monitor, and then the images will be recorded by a CCD camera after reflected by the tested and standard surfaces, respectively. The difference between the tested surface and standard surface is obtained as soon as the phase distributions are worked out by phase shift. Then the shape of the tested surface will be restored from the surface gradients, which is calculated by the relations between the tested gradients and phase difference of horizontal and vertical fringes. The measurement resolution of this method has also been discussed. Notablely, the computer-generated fringe will bring a no-error phase shift and make the shift of periods and directions more easily. A marked point is used to guide the phase unwrapping procedure. The experimental results of a tile surface are presented and prove its validity.