Laser-induced heating, phase-shift, and damage : measurements and simulations

This research was a collaborative effort between the Air Force Research Laboratory (AFRL) and the University of Texas at Austin to study laser induced thermal lensing. Analysis with a high-frame rate thermal camera system in an optical cuvette determined rates of heating and cooling in water exposed to 1200, 1310 and 1318-nm wavelengths. Thermal modeling software (BTEC) developed at AFRL was used to simulate the beam parameters that were used experimentally. The simulation was also used to compute axial temperature for various power levels, beam diameters, and pulse durations. Laser-induced optical pathlength modulation or phase-shift was computed to study the thermal lensing effect. Power and irradiance damage thresholds were calculated for collimated and focused geometries to study the effect in a focusing eye on retinal damage thresholds.