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Journal of Biomedical Optics • Open Access

Trends in melanosome microcavitation thresholds for nanosecond pulse exposures in the near infrared

Paper Abstract

Thresholds for microcavitation of bovine and porcine melanosomes were determined using nanosecond laser pulses in the near-infrared (1000 to 1319 nm) wavelength regime. Isolated melanosomes were irradiated by single pulses (10 or 50 ns) using a Q-switched Spectra Physics Nd:YAG laser coupled with an optical parametric oscillator (1000 to 1200 nm) or a continuum laser at 1319 nm. Time-resolved nanosecond strobe photography after the arrival of the irradiation beam allowed imaging of microcavitation events. Average fluence thresholds for microcavitation increased nonlinearly with increasing wavelength from ∼0.5  J/cm 2 at 1000 nm to 2.6  J/cm 2 at 1319 nm. Fluence thresholds were also measured for 10-ns pulses at 532 nm and found to be comparable to visible nanosecond pulse values published in previous reports. Calculated melanosome absorption coefficients decreased from 925  cm1 at 1000 nm to 176  cm 1 at 1319 nm. This trend was found to be comparable to the decrease in retinal pigmented epithelial layer absorption coefficients reported over the same wavelength region. Estimated corneal total intraocular energy retinal damage threshold values were determined in order to compare to current and proposed maximum permissible exposure (MPE) safe levels. Results from this study support recently proposed changes to the MPE levels.

Paper Details

Date Published: 10 March 2014
PDF: 10 pages
J. Biomed. Opt. 19(3) 035003 doi: 10.1117/1.JBO.19.3.035003
Published in: Journal of Biomedical Optics Volume 19, Issue 3
Show Author Affiliations
Morgan S. Schmidt, Air Force Research Lab. (United States)
Paul K. Kennedy, Air Force Research Lab. (United States)
Rebecca L. Vincelette, TASC, Inc. (United States)
Michael L. Denton, TASC, Inc. (United States)
Gary D. Noojin, TASC, Inc. (United States)
Kurt J. Schuster, TASC, Inc. (United States)
Robert J. Thomas, Air Force Research Lab. (United States)
Benjamin A. Rockwell, Air Force Research Lab. (United States)

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