用于强反射表面形貌测量的投影栅相位法

为了实现强反射表面三维形貌的光学非接触测量,提出一种改进的投影栅相位法。分析了强反射表面的反射光特点及其对相位解算的影响,指出了反射光亮度范围与相机动态范围的不一致是导致传统投影栅相位法测量失效的主要原因;提出了亮暗条纹投射、多曝光时间采集图像和图像合成等技术,使相机亮度测量范围与强反射表面的反射光亮度范围相一致,并分析了此方法的可行性和适应范围。最后,给出了改进投影栅相位法的条纹投射与图像采集步骤。实验结果表明,改进的投影栅相位法克服了强反射表面引起的条纹图像饱和或过暗问题,能够成功测量出99.6%以上的三维点云,有效解决了测量点云缺失问题,能够实现强反射表面三维形貌光学非接触测量。

Projected fringe profilometry for profile measurement of high reflective surface

An improved non-contact optical measuring method, projected fringe profilometry, is proposed to realize the 3-D structure measurement of high reflective surfaces. The reflection characteristics of high reflective surfaces and their effects on phase computation are analyzed, and it is pointed out that the failure reason of the traditional projected fringe profilometry is the mismatch of the range of reflection intensity with the dynamic range of the measuring camera. Then, the techniques of light-dark fringe projection,multi-exposure time image acquisition and image synthesis are introduced to match the measuring range of intensity of camera with the range of reflection intensity. The feasibility and useable range of the method are analyzed. Finally, the processes of fringe projection and image acquisition in the improved profilometry are given. Experimental results indicate that the improved profilometry is able to handle the problems of fringe image saturation and dark images.Moreover,it has obtained 3-D data cloud more than 99.6%, and solve the problem of loss of 3-D data. In conclusions, the improved method can measure the 3-D profiles of high reflective surfaces with non-contact methods.