莫尔条纹测量扭转变形角的方案研究

Measurement of torsion angular distortion based on Moiré fringe

提出了一种基于双光栅干涉产生莫尔条纹测量扭转角的高精度光学测角方法。为了验证莫尔条纹测量设备间扭转变形精度的有效性，进行了方案设计及实验分析。采用平行光管模拟设备，通过微调机械结构调节平行光管的扭转角来模拟三维物体的扭转变形，在独立的地基平台上进行了方案设计测量实验，并通过实验比较了不同的设计方案。选择的实验方案首先使CCD靶面在平行光管内像面处安装固定，然后采用滤波细化等图像处理方法得到采集到的莫尔条纹的宽度，进而根据条纹宽度变化通过数学模型计算出扭转变形量。实验结果表明，当微调机构使平行光管在±7’的视场内旋转时，该方案可以得到较为清晰的莫尔条纹图像，经过算法处理后，当莫尔条纹宽度为1615～1712μm时，扭转角的测量精度为4．3”（3σ）。该方法满足了设备间扭转角高精度测量的要求，为提高光电测量设备的测量精度奠定了基础。

A high-precision optical angular measurement method is proposed to measure the torsion angle based on the Moire fringe produced by double diffraction grating interference. In order to validate the validity of measurement equipment by Moire fringe, the schematic design and experimental analysis are carried out. The torsional flexibility of a three-dimensional object is simulated by collimator simulation equipment adjusted by a fine-tuning mechanical structure. The measurement experiments are carried out on the independent foundation platform. By comparing different design proposals with experiments, a scheme of CCD target surface installed in the image surface of parallel light is selected to use in this measurement. In this scheme, the image processing technology of filtering thinning is used to obtain the stripe width by treating the collected Moire fringe,and the torsional flexibility value is calculated by the mathematical model and the changes of stripes width. The experimental results show that the clearer Moire fringe image can be gotten in the scheme when the collimator is circumgy- rated by fine-tuning institution in the field of view of ±7＇. And the measuring accuracy of torsion angle is 4.3＂（3σ） by the algorithms process when the Moire fringe width is 1 615-1 712 μm. This method meets the measurement requirements of high-accuracy of torsion angle between equipments, and it lays the foundation to enhance the photoelectric precision of measurement equipment.