Comparative analysis of spot size dependence for lesions produced by infrared laser pulses

Abstract

The current laser safety standard for skin exposures, ANSI Z136.1, was based on a limited number of data points for various beam sizes at a few specific wavelengths. To help refine this standard, we explore the existence of a relationship between beam spot size and the ED 50 lesion threshold values. In the first phase of this study we analyzed the spot size dependence of the skin lesion thresholds from previously documented experiments. We utilized the thermal skin model to predict damage thresholds and compared these with those presented in this paper. We report the results of this analysis , which we used to design an experiment to determine the true spot-size dependency of skin laser damage thresholds. The data collected in this first phase is discussed and compared to the existing ANSI Z136.1 (2000) laser safety standard.

Measured skin damage thresholds for 1314-nm laser exposures

“…When compared to other work near this wavelength, this study's preliminary results are within a reasonable expected range as predicted by various models as well as the data listed in Table 3. These models and the issue of spot size dependency are discussed in detail in Roach et al 7 and Thomas et al 8 Final results are not expected to differ significantly from these preliminary measurements with the additional two animals. Supra-threshold sites were characterized by distinctive wedge-shaped necrosis within the dermis, with the base at the epithelial surface.…”