基于二元光栅特征提取的相位展开方法  

Phase Unwrapping Method Based on Feature Extraction of Binary Grating

作　　者：陈劲松 曹益平[1] 吴海涛 CHEN Jin-song;CAO Yi-ping;WU Hai-tao(College of Electronics and Information Engineering,Sichuan University,Chengdu 610065,China)

机构地区：[1]四川大学电子信息学院,四川成都610065

出　　处：《光学与光电技术》2022年第2期17-25,共9页Optics & Optoelectronic Technology

基　　金：国家科技重大专项(2009ZX02204-008)资助项目。

摘　　要：传统基于正弦光栅相位测量轮廓术中,相位因反正切运算而被截断在(-π,π]之间,需要利用菱形等相对相位展开算法进行展开,容易产生相位误差累计,甚至无法展开相位;或者利用投影辅助格雷码等额外结构光场来确定条纹级次,避免相位误差累计,实现相位的展开。提出了一种基于二元光栅特征提取的相位展开方法。通过投影一组相移二元光栅来实现三维测量,既避免了投影仪伽玛非线性对三维测量的影响,又将投影系统的刷新频率提高一个数量级,同时利用二元光栅本身的图像特性,在不增加辅助结构光场投影的前提下,自定条纹级次,从而将自定的条纹级次相位与截断相位相加,实现展开相位,有效避免了相位误差的累计。实验验证了所提方法的可行性和有效性,解相结果与未发生累计误差的菱形算法解相结果具有很好的吻合效果。A phase unwrapping method based on feature extraction of binary grating is proposed in this paper.In traditional phase measuring profilometry based on sinusoidal grating projection,the phase is wrapped between(-π,π]due to the arctangent operation,and it needs to be unwrapped using relative phase unwrapping algorithms such as diamond-type phase unwrapping algorithm in which the accumulation of phase errors is easy to occur or even lead to wrong phase unwrapping;or with the assistance of some additional structured light patterns such as Gray codes,the fringe order may be determined to achieve phase unwrapping without the phase error accumulation.By the proposed method,three-dimensional measurement is achieved by just projecting a set of phase-shifted binary gratings,which can not only avoid the Gamma non-linearity influence of the projector,but also increase the refresh frequency of the projector by more than ten times.At the same time,by using the image characteristics of the binary grating itself,the fringe order can be extracted without increasing any auxiliary structured light pattern.So that the unwrapped phase can be achieved by combining the phase of extracted fringe order with the wrapped phase without the phase error accumulation.The experimental results verify the feasibility and effectiveness of the proposed method,and the solution result is in good agreement with the solution result of the diamond algorithm without cumulative errors.

关 键 词：二元光栅 相位测量轮廓术 不等占空比 相位展开 条纹级次 

分 类 号：O438[机械工程—光学工程]