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影栅云纹是物体离面变形和表面形貌测量常用的一种比较简单的方法,用单纯的影栅云纹法即便在最好的光学系统配置情况下测量精度也只有1~100μm左右,在影栅云纹测试方法中引进相移技术是提高测量精度的主要手段。采用液晶投影仪和数字图像处理技术实现数字影栅云纹测量的准确数字相移,避免了在影栅云纹法中使用结构比较复杂或特制的相移机构。由计算机产生相移条纹图经液晶显示投影,应用实时图像灰度算术相减技术得到数字相移影栅云纹条纹图。该方法具有“基准栅”的栅距和相移步长实时可调,配置高速图像采集系统和图像后处理软件,可将相移技术引入动态测量中,从而提高动态测量的精度的优点。最后的悬臂梁实验结果证实了该方法的有效性。
Film grating moiré is a relatively simple method commonly used to measure the out-of-plane deformation and surface topography of an object. With a simple shadow grating moiré measurement accuracy of only about 1 ~ 100μm even in the best optical system configuration, The introduction of phase-shift technique in the film grating moire test method is the main measure to improve the measurement accuracy. Using LCD projector and digital image processing technology to achieve the accurate digital phase shift of the digital shadow grating moire measurement, the phase shift mechanism with complicated structure or special structure is avoided in the shadow grid moire method. The phase shift fringe pattern generated by the computer is projected on the liquid crystal display. The digital phase shift grille moire fringe pattern is obtained by applying the real-time image gray arithmetic subtraction technique. The method has the advantages of real-time adjustable grating pitch and phase-shift step length of the “reference grid”, and the configuration of high-speed image acquisition system and image post-processing software, which can introduce the phase shift technology into the dynamic measurement to improve the precision of the dynamic measurement. The final cantilever experiment results confirm the effectiveness of this method.