Dispersion extension method for ultrasmall fiber probes in the chromatic confocal system

This study proposes a method for extending the dispersion range using combined gradient refractive index (GRIN) lenses. The imaging model of the probe was established based on the self-focusing characteristics of GRIN lens. The dispersion extension of the probe can be achieved using the model to optimize the probe structure while ensuring high resolution and small size. Experiments indicated that the probe achieved a dispersion range of 3 mm and an axial resolution of 0.2 µm. Compared to existing GRIN probes with similar axial resolutions, the designed probe was 60.7% shorter with double the dispersion range.