Zhou Guocheng, Li Tong, Zhang Shaohui, Hao Qun
School of Optics and Photonics, Beijing Institute of Technology, Beijing 100081, China.
Biomed Opt Express. 2023 Jul 17;14(8):4156-4169. doi: 10.1364/BOE.497711. eCollection 2023 Aug 1.
As a typical computational method, Fourier ptychographic microscopy (FPM) can realize high spatial resolution and quantitative phase imaging while preserving the large field of view with a low numerical aperture (NA) objective. A programmable light-emitting diode (LED) array is used as a typical illuminator in an FPM system, and the illumination parameters of each LED element are crucial to the success of the FPM reconstruction algorithm. Compared with LED arrays arranged in rectangular arrays, LED arrays with special structures such as domes or rings can effectively improve FPM imaging results and imaging efficiency. As a trade-off, their calibration difficulty is greatly increased due to the lack of geometric constraints of rectangular arrays. In this paper, we propose an effective hybrid full-pose parameter calibration method for freeform LED array illuminators, combining stereoscopic 3D imaging techniques and the geometric constraints of the microscopic platform. First, a stereovision system is used to obtain the accurate 3D position of each LED element of the freeform illuminator and to construct a rigid 3D coordinate LED array system. Then, calibration between the coordinate system of the LED array and that of the optical imaging component is realized according to the geometric features of the brightfield-to-darkfield edges. Finally, we verify the feasibility and effectiveness of the proposed method through full-pose parameter calibration of LED arrays with different arrangement rules.
作为一种典型的计算方法，傅里叶叠层显微镜（FPM）可以在使用低数值孔径（NA）物镜保持大视场的同时实现高空间分辨率和定量相位成像。在FPM系统中，可编程发光二极管（LED）阵列用作典型的照明器，每个LED元件的照明参数对于FPM重建算法的成功至关重要。与矩形阵列排列的LED阵列相比，具有特殊结构（如圆顶或环形）的LED阵列可以有效提高FPM成像结果和成像效率。作为权衡，由于缺乏矩形阵列的几何约束，它们的校准难度大大增加。在本文中，我们提出了一种针对自由形式LED阵列照明器的有效混合全姿态参数校准方法，结合了立体3D成像技术和微观平台的几何约束。首先，使用立体视觉系统获取自由形式照明器每个LED元件的精确3D位置，并构建一个刚性的3D坐标LED阵列系统。然后，根据明场到暗场边缘的几何特征实现LED阵列坐标系与光学成像组件坐标系之间的校准。最后，我们通过对具有不同排列规则的LED阵列进行全姿态参数校准，验证了所提方法的可行性和有效性。
