Mikuła Marta, Kozacki Tomasz, Józwik Michał, Kostencka Julianna
Appl Opt. 2018 Jan 1;57(1):A197-A204. doi: 10.1364/AO.57.00A197.
This paper proposes a measurement method of focusing objects with a high gradient shape of a small and large radius of curvature. The measurements are carried out on a Fourier digital holographic microscope with optimized illumination conditions maximizing the usage of the system's numerical aperture. The obtained fringe patterns are the result of interference of deformed spherical object and spherical reference waves. The key elements of the method are the aberration compensation and calibration procedures. They provide accurate reconstruction of the object wave and determination of the focus position of the sample. The shape is calculated in two steps. First, the object wave is reconstructed at the plane of the object focus using single or multiframe phase extraction algorithm and the specialized propagation method. The step includes compensation for spherical aberration. In the second step, the sample shape is computed with the local ray approximation approach. The proposed method is experimentally validated with measurements of challenging, high gradient shapes (convex, concave) of different radiuses of curvature.
本文提出了一种对具有小和大曲率半径的高梯度形状聚焦物体的测量方法。测量是在具有优化照明条件的傅里叶数字全息显微镜上进行的，该条件可最大限度地利用系统的数值孔径。所获得的条纹图案是变形球面物体与球面参考波干涉的结果。该方法的关键要素是像差补偿和校准程序。它们提供了物体波的精确重建以及样品聚焦位置的确定。形状通过两步计算得出。首先，使用单帧或多帧相位提取算法以及专门的传播方法在物体焦点平面重建物体波。该步骤包括对球差的补偿。在第二步中，使用局部光线近似方法计算样品形状。所提出的方法通过对不同曲率半径的具有挑战性的高梯度形状（凸形、凹形）进行测量得到了实验验证。
