Li Hongmei, Cao Yiping, Wan Yingying, Li Chengmeng, Xu Cai, Zhang Hechen, An Haihua
Department of Optical Electronics, Sichuan University, Chengdu, 610064, China.
College of Physics and Engineering, Chengdu Normal University, Chengdu, 611130, China.
Sci Rep. 2021 Oct 6;11(1):19882. doi: 10.1038/s41598-021-99420-8.
By using the time-division multiplexing characteristics of the projector and the integral exposure characteristics of the charge coupled device (CCD) camera, a super-grayscale and real-time computer-generated Moiré profilometry based on video grating projection is proposed. The traditional digital static grating is of 256-grayscale at most. If an expected super-grayscale grating with a maximum grayscale of 766 is designed and divided into three 256-grayscale fringe patterns with balanced grayscale as far as possible, they can be synthesized into a repeated playing video grating instead of the traditional static grating. When the video grating is projected onto the measured object, as long as the exposure time is set to three times the refresh cycle of the video grating, the super-grayscale deformed patterns in the 766-grayscale can be captured with a 10-bit CCD camera, so that the deformed patterns are realistic. The digital error in computer-generated Moiré profilometry is effectively reduced. In addition, this method can expand the linear range of the deformed pattern by 20% in computer Moiré profilometry. Therefore, the proposed method has the perspectives of high accuracy and real-time measurement. Theoretical analysis and experimental results demonstrate the validity and capability of the proposed method.
利用投影仪的时分复用特性和电荷耦合器件（CCD）相机的积分曝光特性，提出了一种基于视频光栅投影的超灰度实时计算机生成莫尔轮廓术。传统的数字静态光栅最多为256灰度级。如果设计一个最大灰度级为766的预期超灰度光栅，并将其尽可能均衡地分为三个256灰度级的条纹图案，则可以将它们合成为一个重复播放的视频光栅，而不是传统的静态光栅。当视频光栅投影到被测物体上时，只要将曝光时间设置为视频光栅刷新周期的三倍，就可以用10位CCD相机捕获766灰度级的超灰度变形图案，从而使变形图案更加逼真。有效降低了计算机生成莫尔轮廓术中的数字误差。此外，该方法在计算机莫尔轮廓术中可将变形图案的线性范围扩大20%。因此，该方法具有高精度和实时测量的前景。理论分析和实验结果验证了该方法的有效性和性能。
