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利用误差扩散方法产生二元编码正弦光栅可以消除数字投影仪的非线性对投影光栅正弦性的影响,且能充分利用基于数字光处理技术(DLP)投影仪中数字微镜的二元高速开关特性,高速投影二元编码正弦光栅。投影仪分辨率不足会导致电子二元编码正弦光栅正弦性下降,从而影响测量精度。先对比了两种典型误差扩散编码算法:Floyd-Steinberg距离加权和Sierra Lite“蛇”形扫描获得的光栅的正弦性。然后针对目前DLP投影仪产生频率较高的二元编码正弦光栅时,二元编码正弦光栅的正弦性较差的问题,提出了两种改善方法:1)利用柱透镜卷积作用,在栅线方向上对二元编码正弦光栅进行平滑;2)组合多帧具有不同微结构的二元编码正弦光栅,来减小二元编码正弦光栅的误差,保证相位测量轮廓术(PMP)方法的测量精度。所提方法充分利用了DLP投影二值图像的高速特性,又明显改善了由于DLP分辨率有限导致的二元编码正弦光栅的正弦性较差的问题,实验验证了这两种方法的有效性。
The use of an error diffusion method to generate a binary coded sinusoidal grating eliminates the effects of the digital projector’s nonlinearity on the sinusoidality of the projection grating and takes full advantage of the binary high speed switching characteristics of digital micromirrors based on digital light processing (DLP) projectors , High-speed projection binary coded sinusoidal grating. Projector resolution will result in a sinusoidal sinusoidal electronic binary coding decline, thus affecting the measurement accuracy. First, we compare two typical error diffusion coding algorithms: Floyd-Steinberg distance weighted and Sierra Lite “snake ” shaped scan grating obtained sinusoidal. Then for the current DLP projector to produce a higher frequency binary coded sinusoidal grating, binary sinusoidal encoder sinusoidal poor problem, proposed two improved methods: 1) the use of cylindrical lens convolution, the gate line Direction of the binary code sinusoidal smoothing; 2) combination of multiple frames with different microstructures of binary coded sinusoidal grating to reduce the error of binary coded sinusoidal grating, phase measurement profilometry (PMP) method to ensure the accuracy of measurement . The proposed method makes full use of the high speed of DLP projection binary image and obviously improves the poor sinusoidity of binary coded sinusoidal grating due to the limited resolution of DLP. Experiments show the effectiveness of these two methods.