Development and characterization of a temporal dispersive chromatic confocal microscopy for enhancing real-time three-dimensional cornea imaging

Accurate visualization of corneal microstructures with micrometer resolution is critical for diagnosing ocular diseases and guiding treatment strategies. Reflectance confocal microscopy (RCM) was developed for high-resolution three-dimensional (3D) imaging, but its reliance on mechanical scanning limits the 3D imaging speed and may introduce motion artifacts. Here, we demonstrated a time-stretch chromatic confocal microscopy (TSCCM), a single-shot volumetric imaging technique that eliminates mechanical axial scanning by encoding depth information into time-domain swept waveforms. A supercontinuum laser pulse is temporally stretched from picoseconds to 85 ns using free-space angular-chirp-enhanced delay (FACED). FACED enables a low-loss dispersive system that replaces conventional single-mode fiber (SMF), reducing power loss by 1.4-1.8× while achieving a dispersion of 0.55 ns/nm across 650-850 nm. Combined with a chromatic objective, TSCCM enables depth-resolved detection at an A-scan rate of up to 1 MHz. Our system achieves 5 volumes per second with 1-2.2 μm lateral resolution, 346 μm penetration depth in phantoms, and 150 μm in rodent corneas. By decoupling imaging speed from mechanical constraints, TSCCM offers a transformative platform for real-time, high-resolution ophthalmic diagnostics.