  Endoscopic optical coherence tomography (OCT) is a valuable tool for
providing diagnostic images of internal organs and guiding interventions in
real time. Miniaturized OCT endoscopes are essential for imaging small and
convoluted luminal organs while minimizing invasiveness. However, current
methods for fabricating miniature fiber probes have limited ability to correct
optical aberrations, leading to suboptimal imaging performance. In this study,
we introduce a new paradigm of liquid shaping technique for the rapid and
scalable fabrication of ultrathin and high-performance OCT microendoscopes
suitable for minimally invasive clinical applications. This technique enables
the flexible customization of freeform microlenses with sub-nanometer optical
surface roughness by regulating the minimum energy state of curable optical
liquid on a wettability-modified substrate and precisely controlling the liquid
volume and physical boundary on a substrate. Using this technique, we
simultaneously fabricated 800-nm OCT microendoscopes with a diameter of
approximately 0.6 mm and evaluated their ultrahigh-resolution imaging
performance in the esophagus of rats and the aorta and brain of mice.
