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Journal of Biomedical Optics

Visible lesion thresholds with pulse duration, spot size dependency, and model predictions for 1.54-µm, near-infrared laser pulses penetrating porcine skin
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Paper Abstract

Er:glass lasers have been in operation with both long pulses (hundreds of microseconds) and Q-switched pulses (50 to 100 ns) for more than 35 yr. The ocular hazards of this laser were reported early, and it was determined that damage to the eye from the 1.54-µm wavelength occurred mainly in the cornea where light from this wavelength is highly absorbed. Research on skin hazards has been reported only in the past few years because of limited pulse energies from these lasers. Currently, however, with pulse energies in the hundreds of joules, these lasers may be hazardous to the skin in addition to being eye hazards. We report our minimum visible lesion (MVL) threshold measurements for two different pulse durations and three different spot sizes for the 1.54-µm wavelength using porcine skin as an in vivo model. We also compare our measurements to results from our model, based on the heat transfer equation and the rate process equation. Our MVL-ED50 thresholds for the long pulse (600 µs) at 24 h postexposure were measured to be 20, 8.1, and 7.4 J cm–2 for spot diameters of 0.7, 1.0, and 5 mm, respectively. Q-switched laser pulses of 31 ns had lower ED50 (estimated dose for a 50% probability of laser-induced damage) thresholds of 6.1 J cm–2 for a 5-mm-diam, top-hat spatial profile laser pulse.

Paper Details

Date Published: 1 March 2006
PDF: 8 pages
J. Biomed. Opt. 11(2) 024001 doi: 10.1117/1.2187987
Published in: Journal of Biomedical Optics Volume 11, Issue 2
Show Author Affiliations
Clarence P. Cain, Northrop Grumman Corp. (United States)
Kurt J. Schuster, Northrop Grumman Corp. (United States)
Justin J. Zohner, Northrop Grumman Corp. (United States)
Kevin Stockton, Northrop Grumman Corp. (United States)
David J. Stolarski, Northrop Grumman Corp. (United States)
Robert J. Thomas, Air Force Research Lab. (United States)
Benjamin A. Rockwell, Air Force Research Lab. (United States)
William P. Roach, Air Force Research Lab. (United States)

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