双光纤点衍射干涉投影系统误差校正及优化

条纹投影测量技术为复杂曲面提供了一种大动态范围的非接触式三维形貌检测方式。在基于双光纤点衍射干涉的条纹投影检测系统中，系统结构参数对最终面形检测精度影响较大。通过建立系统结构几何分析模型，对系统结构参数进行了优化。针对双光纤点衍射探头投射角标定误差的影响，传统基于零级亮条纹定位的投射端投射角标定方法由于临近级次条纹光强较为接近难以区分而导致存在较大误差，为此提出了一种基于基准平面的投射角迭代校正方法，在原标定方法的基础上进一步提高了其标定精度，进而有效提高了面形检测精度。为验证所提出方法的可行性，搭建实验系统对不同斜率动态范围的待测物测量比对，结果表明校正前后的测量系统与三坐标测量机的测量结果偏差从0.418 2 mm减小至0.021 1 mm，实现了微米级的检测精度，为各类复杂曲面的高精度检测提供了一种可行的方法。

Optimization and error correction of dual-path fiber point-diffraction interference projection system

The fringe projection testing technology provides a non-contact three-dimensional profile measurement method with large dynamic range for various complex surfaces. In the dual-path point-diffraction interference projection testing system, the system structure parameters could significantly influence the surface testing accuracy. The system structural parameters were optimized based on the geometric model of testing system. In view of the projection angle calibration error in dual-fiber point-diffraction probe, the traditional method based on location of zero-order bright fringe could lead to obvious measurement error, due to the fact that the light intensity of the neighboring-order fringes was too close to distinguish from each other. To address this issue, an iterative correction method based on reference plane was proposed for the projection angel calibration, and it could effectively improve the testing accuracy. To demonstrate the feasibility of the proposed method, an experimental testing system was built to test the samples with various slopes dynamic ranges. The results show that the measurement deviation between the testing system after error correction and high-precision coordinate measuring machine is reduced from 0.418 2 mm to 0.021 1 mm, and the testing accuracy in the order of microns is achieved, providing a feasible way for the high-precision testing of various complex surfaces.