Characterization of two-photon photopolymerization fabrication using high-speed optical diffraction tomography

Two-photon photopolymerization (TPP) has recently become a popular method for the fabrication of three-dimensional (3D) micro- and nanostructures. The reproduction fidelity designed nanostructures is influenced by experimental writing conditions, including laser power, exposure time, etc. To determine appropriate parameters, characterization morphological features surface roughness during experiment needed. Traditional methods TPP, e.g., scanning electron microscopy atomic force microscopy, have limited speed cannot study internal structures without invasive approaches. Optical diffraction tomography (ODT) an emerging label-free 3D imaging technique based on reconstructing object’s refractive index (RI) distribution with diffraction-limited resolution. Here, we propose non-invasive solution to fully characterize TPP-fabricated using high-speed ODT technique, which can eliminate need complex sample preparation, such as fluorescence labelling or metal-coating, achieve full measurement time 6 ms. By visualizing studying different structures, embedded spirals cubes, via system, quality, features, levels, roughness, be examined quantitatively. results suggest our effectively improve quality reproducibility generating impacts nanofabrication community.