基于直接数字频率合成的变频条纹生成方法

针对时间相位重建算法存在的实时性差的缺点，提出了一种可以快速生成并获取二维编码条纹图的方法．该方法利用直接数字合成器驱动的声光偏转器使2束相干光分别发生布喇格衍射，2束衍射光相交后发生干涉，获得干涉条纹．通过调节直接数字合成器的频率控制字改变干涉条纹的空间频率．依据该原理建立的系统可以完成变频条纹图的实时投影与采集，对采集到的变频条纹图进行处理后可以获得物体的三维数字像．实验表明每幅条纹图的投影及采集用时10ms左右，该投影及采集装置可以应用于实时性要求高的三维传感系统中．

Method for Generating Frequency-Varying Fringes Based on Direct Digital Frequency Synthesis

A method for generating and acquiring 2D encoded fringe patterns quickly was presented to overcome the shortcoming of bad real-time for temporal phase unwrapping algorithm. According to this method two laser beams from the same source are Bragg-diffracted respectively by two acousto-optic deflectors driven by one direct digital synthesizer. Interference happens when the two diffraction beams intersect and then interference fringes can be seen. The spatial frequency of interference fringes can be shifted by changing the control word of frequency of direct digital synthesizer. Real-time projection and acquisition of frequency-varying fringes can be achieved through the device developed on the basis of the principle mentioned above. The 3D digital image can be obtained by analyzing time-series frequency varying fringes maps collected by the device. Experiment results show that projection and acquisition of a fringe map costs 10 ms or so. The projection and acquisition device can be applied to real-time 3 D sensing system.