一种新的形貌检测系统标定技术

A Novel Calibration Technology in Profilometry

形貌检测中,经相位解调和相位展开后,所求得的只是待测物体表面与参考面的相对相位分布,而三维形貌检测要测的是高度分布 在分析一般测试系统的基础上,推导出了相位与高度分布的非线性函数映射关系 设计了标定测试系统的实验方案 通过平移实物参考面,测得其上的相位分布,由平移距离与相位增量之间的关系,用最小二乘迭代法计算相位差与物体高度映射关系最后,对一个实际测试系统进行了标定,并与Hung的标定方法进行了分析比较.理论和实验都表明,新方法精度高,操作方便,降低了标定复杂度。

It is only the relative phase distribution between the tested object and reference plane that is attained after phase demodulation and phase unwrapping in profilometry. However, the objective of 3D shape measurement is to obtain the object′s height distribution .The nonlinear mapping relationship of both phase and height is analysed and deduced in a general experimental setup. The calibration scheme is designed. When the reference plane is shifted, its corresponding phases have been measured. According to the shifted distance and the phase increment ,the mapping relationship between phase difference and depth of the object can determined by the least square interactive method. Finally, a practical experimental system is calibrated and compared with Hung′s method. The experimental results and theoretical analysis show that the new method is characterized by the high accuracy, easy to handle ,lower the complexity of calibration .