Abstract We experimentally demonstrate the shape measurement of micro objects by means of phase retrieval under spatially partially coherent illumination. This approach offers an extended depth of focus, vibration insensitivity, short measurement time and precise shape measurements, enables the use of spatially extended light sources such as LEDs and thus significantly improves the eye safety of the method. The employed setup is based on a telecentric 4 f -imaging system with a tunable lens across the common Fourier plane. Based on the theoretical investigation presented in Part I, we verify that 4 f -based phase retrieval is feasible if the radius of the point spread function of the imaging system is smaller than that of the correlation (spatial coherence) area across the object plane. In this case, a light field with a defined complex amplitude can be assigned to the measured intensity distributions. As a proof of principle towards industrial applications, the 3D shape of a cold-formed micro-cup is reconstructed by combining phase retrieval with two-wavelength contouring. A depth of focus in the range of few millimeters and the measurement time and uncertainty of 0.4 s, and 2 μ m, respectively, can be achieved.

中文翻译：

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在空间部分相干照明下基于透镜的相位恢复 - 第二部分：形状测量

摘要 我们通过空间部分相干照明下的相位检索实验证明了微观物体的形状测量。这种方法提供了扩展的焦深、振动不敏感、较短的测量时间和精确的形状测量，允许使用空间扩展的光源，例如 LED，从而显着提高了该方法的眼睛安全性。所采用的设置基于远心 4 f 成像系统，具有跨公共傅立叶平面的可调镜头。基于第一部分中提出的理论研究，我们验证了基于 4 f 的相位检索是可行的，如果成像系统的点扩散函数的半径小于整个物平面的相关（空间相干）区域的半径。在这种情况下，可以将具有定义的复振幅的光场分配给测量的强度分布。作为工业应用的原理证明，冷成型微型杯的 3D 形状是通过将相位检索与双波长轮廓相结合来重建的。可以实现几毫米范围内的焦深以及 0.4 秒和 2 μ m 的测量时间和不确定度。