Multifocal multiphoton microscopy

TLDR

The study introduces a real‑time, direct‑view multiphoton excitation fluorescence microscope enabling high‑resolution 3‑D imaging. The system uses a rotating microlens disk to split a mode‑locked Ti:sapphire laser into an array of high‑aperture foci, scanning at 225 fps and capturing fluorescence with a video‑rate camera. The microscope achieves axial resolutions of 0.84 µm (oil) and 1.4 µm (water), matching single‑beam two‑photon performance while providing a 40–100× faster imaging speed and enabling real‑time visual inspection of live samples.

Abstract

We present a real-time, direct-view multiphoton excitation fluorescence microscope that provides three-dimensional imaging at high resolution. Using a rotating microlens disk, we split the near-infrared light of a mode-locked titanium:sapphire laser into an array of beams that are transformed into an array of high-aperture foci at the object. We typically scan at 225 frames per second and image the fluorescence with a camera that reads out the images at video rate. For 1.4 aperture oil and 1.2 water immersion lenses at 780-nm excitation we obtained axial resolutions of 0.84 and 1.4 µm, respectively, which are similar to that of a single-beam two-photon microscope. Compared with the latter setup, our system represents a 40–100-fold increase in efficiency, or imaging speed. Moreover, it permits the observation with the eye of high-resolution two-photon images of (live) samples.