LASER SELECTIVE CUTTING BY IMPULSIVE HEAT DEPOSITION IN THE IR WAVELENGTH RANGE FOR DIRECT-DRIVE ABLATION

摘要

The present invention relates to an apparatus for laser processing a biological material, comprising: a laser source (1) for generating laser pulses (6) with wavelengths lying between about 1.5 and about 20 microns and wherein said laser source (1) is configured such that each laser pulse (6) has: i) wavelengths selected for exciting a vibrational state of at least one component said biological tissue upon absorption of the pulse; ii) an energy sufficient to produce superheated temperatures above a vaporization point of the at least one component of the biological material when the pulse is absorbed in a laser irradiated volume (8) of the biological material, iii) a pulse duration time and wavelength that meets requirements for impulsive heat deposition such that the pulse duration time of the laser pulse (6) is shorter than a time required for thermal diffusion out of the laser irradiated volume (8) of biological material and shorter than a time required for a thermally driven expansion of the laser irradiated volume (8) of biological material, and iv) the pulse duration time is long enough and the pulse energy low enough so that a peak intensity of the laser pulse (6) is below a threshold for ionization and plasma formation to occur in the biological material; and wherein said laser source (1) is further configured such that a time delay between laser pulses is longer the time required for thermal diffusion from the irradiated volume of biological material.