Fabrication of a micro-optical lens using femtosecond laser 3D micromachining for two-photon imaging of bio-tissues

We report, for the first time to our knowledge, on the application of a micro-optical lens fabricated by three-dimensional (3D) femtosecond laser direct writing for two-photon fluorescence imaging of biological tissues. We show that the two-photon fluorescence images of a plant leaf tissue acquired with the micro-optical lens are comparable to that of a 5× objective lens. Our result represents an important step towards the application of micro-optical components fabricated by femtosecond laser micromachining in miniaturized nonlinear fluorescence microscopy applications, such as two-photon endoscopy.

Research highlights
► We fabricate high-quality microlens using 3D femtosecond laser micromachining.
► The microlens has a low surface roughness and a resolution comparable to that of a 5× objective lens.
► We perform two-photon imaging of bio-tissues with the laser-fabricated microlens.