Fast label-free point-scanning super-resolution imaging for endoscopy

Optical endoscopy plays a crucial role in minimally invasive medical diagnostics and therapeutic procedures. Nonetheless, state-of-the-art endoscopic zoom objectives are bulky, requiring multi-element lens actuation, which can limit continued miniaturization. Point-scanning super-resolution approaches improve spatial resolution by illuminating the scene with a reduced-width focused spot, yet mechanical scanning requirements limit applicability in clinical settings. Here, we experimentally demonstrate a Fast label-free point-scanning super-resolution (Flaps) microscopy system, which exploits a multi-level phase-only diffractive optical element (DOE) to generate super-resolution spot(s) and uses a high-speed digital micromirror device (DMD) to deliver the illumination without mechanical scanning. Two imaging architectures are explored: a single super-resolution spot (0.47 Airy spot) or a 5 times 5 super-resolution spot array (0.52 Airy spot) in the far-field; the DMD scans the spot or spot array in the object plane at kHz rates. To demonstrate super-resolution imaging with high-speed acquisition using optical elements suitable for future deployment in endoscopy, we image a label-free resolution test target and fluorescently labelled cells.