Du Junlin, Luo Xiaopeng, Zhu Jiangping, An Shiyong, Zhou Pei
Appl Opt. 2024 Jan 10;63(2):383-389. doi: 10.1364/AO.507420.
The three-dimensional (3D) measurement task of complex microstructures holds paramount significance in the domains of precision manufacturing and inspection. The calibration of the 3D system heavily determines the final reconstruction accuracy. The widely adopted system calibration method is phase-height mapping (PHM) and stereo vision (SV) based. The former can be applied directly to the calculation without considering the imaging model of the system, but it relies on highly precise and expensive translation stages or standard blocks. The latter's accuracy cannot be guaranteed because it is difficult to accurately calibrate the projector. In this paper, we establish an optically coupled microscopic fringe projection profilometry system that consists of a Scheimpflug pinhole projector and a super-low distortion bi-telecentric camera. We introduce a simplified 3D system calibration approach that combines phase modulation transfer and ray propagation. Our method enables the simultaneous calibration of the system, including the calibration of the projector, camera, and the phase to a 3D coordinates relationship, using only a 2D target. The calibrated projector's external parameters are used to obtain the target's complete poses, and then the direct mapping coefficients of the phase to the 3D coordinates can be obtained through the optical geometry structure and phase labels. Comparable experiments verify the feasibility of the proposed method.
复杂微结构的三维（3D）测量任务在精密制造和检测领域具有至关重要的意义。三维系统的校准在很大程度上决定了最终的重建精度。目前广泛采用的系统校准方法是基于相位 - 高度映射（PHM）和立体视觉（SV）的。前者可以直接应用于计算，无需考虑系统的成像模型，但它依赖于高精度且昂贵的平移台或标准块。后者的精度无法保证，因为投影仪难以精确校准。在本文中，我们建立了一种光学耦合微观条纹投影轮廓测量系统，该系统由一台施密特 - 普吕克针孔投影仪和一台超低失真双远心相机组成。我们引入了一种简化的三维系统校准方法，该方法结合了相位调制传递和光线传播。我们的方法仅使用一个二维目标就能同时校准系统，包括投影仪、相机以及相位与三维坐标关系的校准。校准后的投影仪外部参数用于获取目标的完整姿态，然后通过光学几何结构和相位标签获得相位到三维坐标的直接映射系数。对比实验验证了所提方法的可行性。
