Near-Field Ablation Threshold Of Cellular Samples In The Mid-Infrared Wavelength Region

We report the near-field ablation of biological material with spot sizes as small as 1.5 mu m under 3 mu m wavelength radiation. The fluence dependence of the ablation of both cellulose acetate coverslips in water and myoblast cell samples in growth media has been studied. We find that for all near-field experiments, the ablation thresholds are very high compared to far-field experiments. A detailed analysis of the length and time scales of the systems provides support for the identification of a plasma-induced mechanism. Thus, applications of sub-wavelength ablation will require robust near-field techniques with capability for high-power density delivery of light. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4719043]