Transverse and axial resolution of femtosecond laser ablation.

Femtosecond lasers are capable of precise ablation that produces surgical dissections in vivo. The transverse and axial resolutions of the laser damage inside the bulk are important parameters of ablation. The transverse resolution is routinely quantified; but the axial resolution is more difficult to measure and is less commonly performed. Using a 1040-nm, 400-fs pulsed laser, and a 1.4-NA objective, we performed ablation inside agarose and glass, producing clear, and persistent damage spots. Near the ablation threshold of both media, we found that the axial resolution is similar to the transverse resolution. We also ablated neuron cell bodies and fibers in Caenorhabditis elegans and demonstrate submicrometer resolution in both the transverse and axial directions, consistent with our results in agarose and glass. Using simple yet rigorous methods, we define the resolution of laser ablation in transparent media along all directions.