用时间域相位解包法测量不连续物体的三维轮廓

针对传统相位解包方法不能测量不连续物体轮廓的问题,提出了一种基于时间域相位解包的傅里叶变换技术.该技术采用先投影一系列间距随时间变化的正弦条纹图到被测物体上,再用电荷耦合器件和图像采集卡来获取由物体面形调制而变形的条纹图,并沿时间轴对这些变形条纹做傅里叶变换、滤波和反变换,然后沿时间轴解包,得到图像上每个时刻每个像素点的相位.由此得到的相位值在像面内是相互独立并且是沿时间轴变化的,这个相位变化率包含有物体的高度信息.实验表明,该技术成功地解决了不连续物体的轮廓测量问题,与传统的空间相位解包方法相比,该技术最大的优点是能够方便、准确地测量不连续和大陡度物体的轮廓.

Three-Dimensional Profile Measurement of Objects with Spatially Isolated Surfaces by Modified Temporal Phase Unwrapping

A three-dimensional profile measurement technique for objects with spatially isolated surfaces is presented, which is combined flexibly with temporal phase unwrapping based on the Fourier fringe analysis. A sequence of sinusoidal fringe patterns with a varying pitch over time is projected onto objects, and the temporal variation of the fringe signal is recorded with charge coupled device(CCD) camera. The phase of the temporal fringe signal is detected at each pixel by Fourier transform method, and is temporally phase unwrapped, independently from other pixels. The temporal frequency of the fringe signal estimated from the time slope of the unwrapped phase provides the information of the absolute surface heights of the objects. The measurement technique of objects with large discontinuities and spatially isolated surfaces is demonstrated by experiment.