Product Code: ILSC2011_802

Characterizing Temperature-Dependent Photo-Oxidation to Explain the Abrupt Transition from Thermal to Non-Thermal Laser Damage Mechanisms at 413 nm
Authors:
Michael Denton, TASC, Inc.; San Antonio TX
C.D. Clark, TASC, Inc.; Brooks City-Base TX USA
Gary Noojin, TASC, Inc.; Brooks City-Base TX
Kurt Schuster, TASC, Inc.; Brooks City-Base TX
Curtis Burney, Air Force Research Laboratory; Brooks City-Base TX
Benjamin Rockwell, Air Force Research Laboratory; Brooks City-Base TX USA
Robert Thomas, Air Force Research Laboratory; Brooks City-Base TX USA
Presented at ILSC 2011

Laser exposure duration dictates whether tissues subjected to short visible wavelengths ( 514 nm) are damaged by thermal (e.g. 0.1 s) or non-thermal ( 100 s) mechanisms. Somewhere between these extremes, an abrupt transition between the two damage mechanisms has been found for both in vitro and animal retinal models. Non-thermal (photochemical) damage is characterized by an inverse relationship between damage threshold irradiance and exposure duration (irradiance reciprocity). We have found that exposures of 60 90 s in an in vitro retinal model require radiant exposures well above the expected requirement for non-thermal damage, which thus led to damage by thermal mechanisms. Here we characterize and describe with computational modeling the temperature dependence of photo-oxidative processes between 37- 45 °C.