Hu Yan, Chen Qian, Zhang Yuzhen, Feng Shijie, Tao Tianyang, Li Hui, Yin Wei, Zuo Chao
Appl Opt. 2018 Feb 1;57(4):772-780. doi: 10.1364/AO.57.000772.
In recent years, the fringe projection profilometry (FPP) technique has shown great prospects in the field of dynamic 3D measurement of microscopic surface shape. However, under dynamic conditions, it is desirable to use fewer projected patterns to minimize the sensitivity to motion. The commonly used phase-shifting method needs at least three fringe patterns to retrieve the wrapped phase, which depends heavily on the high-speed hardware to alleviate the effect of motion. Besides, to achieve an unambiguous measurement, at least two wrapped phase maps are required to obtain the absolute phase map, resulting in six pattern projections. In this paper, we propose the marker-embedded Fourier transform profilometry (MEFTP), which extends the modified Fourier transform profilometry with two embedded markers suited to assist the phase-unwrapping process. Combining the embedded markers with temporal phase difference information, the absolute phase can be reliably reconstructed with only two projected patterns. Furthermore, since the phase information is only encoded within a single high-frequency fringe, MEFTP is more suitable for measuring fast-moving or surface-changing objects compared with the phase-shifting method. Experiments on both static and dynamic scenes are performed, verifying that our method can achieve an accurate and robust measurement of a vibrating diaphragm at the speed of 200 frames per second.
近年来，条纹投影轮廓术（FPP）技术在微观表面形状的动态三维测量领域展现出了巨大的前景。然而，在动态条件下，希望使用更少的投影图案以最小化对运动的敏感性。常用的相移法至少需要三个条纹图案来检索包裹相位，这在很大程度上依赖于高速硬件来减轻运动的影响。此外，为了实现无歧义测量，至少需要两个包裹相位图来获得绝对相位图，这导致需要六个图案投影。在本文中，我们提出了嵌入标记的傅里叶变换轮廓术（MEFTP），它通过两个适合辅助相位解包裹过程的嵌入标记扩展了改进的傅里叶变换轮廓术。将嵌入标记与时间相位差信息相结合，仅用两个投影图案就可以可靠地重建绝对相位。此外，由于相位信息仅编码在单个高频条纹内，与相移法相比，MEFTP更适合于测量快速移动或表面变化的物体。我们对静态和动态场景都进行了实验，验证了我们的方法能够以每秒200帧的速度对振动膜片进行准确且稳健的测量。
