Two-photon photopolymerization (TPP) has emerged as a popular method for three-dimensional (3D) printing of micro-/nano-structures. On the other hand, optical diffraction tomography (ODT) has become attractive for label-free cell imaging by reconstructing the 3D refractive index (RI) distributions. We propose a high-speed ODT method to fully characterize the TPP-printed structures. Compared with traditional methods like scanning electron microscopy and atomic force microscopy, our ODT-based characterization method offers many advantages, such as revealing both the internal and external morphological features, mapping the 3D RI distributions, and quantifying the surface and side-wall roughness.
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