Zhou Rongjing, Shen Dongran, Huang Peng, Kong Lingbao, Zhu Zhiwei
Opt Express. 2021 Oct 11;29(21):33512-33526. doi: 10.1364/OE.440654.
The noncontact optical probe-based surface scanning is promising for the measurement of complex-shaped optical surfaces. In this study, by combining a chromatic confocal sensor and a planar nano-positioning stage, a sub-aperture scanning and stitching method is developed for the noncontact measurement of the microstructured optical surfaces, with the measured form accuracy being irrespective of the accuracy of the global scanning stage. After the scanning, the Gaussian process-based denoising is employed to remove the measurement noises, and a hybrid registration algorithm is proposed to achieve a 6-DOF alignment of any neighbored sub-apertures. For the registration, the differential evolution-based minimization is implemented to find a coarse transformation which then serves as the initial value for the iterative closest point-based fine registration. The hybrid method is beneficial in finding an optimal registration with a greatly reduced computation burden. Finally, the effectiveness of the developed measurement system, as well as the stitching algorithm, is comprehensively demonstrated through practically measuring a sinusoidal micro-grid surface.
基于非接触光学探头的表面扫描技术在复杂形状光学表面测量方面具有广阔前景。在本研究中，通过将彩色共焦传感器与平面纳米定位台相结合，开发了一种用于微结构光学表面非接触测量的子孔径扫描与拼接方法，所测形状精度与全局扫描台的精度无关。扫描后，采用基于高斯过程的去噪方法去除测量噪声，并提出一种混合配准算法以实现任意相邻子孔径的六自由度对准。对于配准，实施基于差分进化的最小化以找到粗变换，然后将其用作基于迭代最近点的精细配准的初始值。该混合方法有利于找到具有大大降低计算负担的最优配准。最后，通过实际测量正弦微网格表面全面证明了所开发测量系统以及拼接算法的有效性。
