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Proceedings Paper

Corneal epithelial injury thresholds for multiple-pulse exposures to erbium fiber laser radiation at 1.54 μm
Author(s): Russell L. McCally; Jennifer Bonney-Ray
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Paper Abstract

Corneal epithelial damage thresholds for exposures to sequences of pulses of 1.54 μm infrared radiation produced by an Er fiber laser were investigated. Thresholds were determined for sequences of 8 to 128 pulses at a repetition frequency of 10 Hz and 8 to 256 pulses at 20 Hz. The duration of the individual pulses was 0.025 sec and the 1/e diameter of the laser beam was 0.1 cm. The results show that threshold damage is correlated by an empirical power law of the form Hth = CN, where Hth is the threshold radiant exposure per pulse, and N is the number of pulses. The constant C is different for the 10 Hz and 20 Hz exposures and, for both cases, is greater than the estimated threshold for a single 0.025 sec pulse. Thus the empirical power law breaks down for small numbers of pulses (viz., N< 8), where it overestimates the damage thresholds. Temperature calculations for the threshold exposure conditions show that a critical temperature model also correlates the multiple-pulse injury thresholds.

Paper Details

Date Published: 18 April 2005
PDF: 6 pages
Proc. SPIE 5688, Ophthalmic Technologies XV, (18 April 2005); doi: 10.1117/12.596444
Show Author Affiliations
Russell L. McCally, Johns Hopkins Univ. (United States)
Wilmer Eye Institute, Johns Hopkins Medicine (United States)
Jennifer Bonney-Ray, Johns Hopkins Univ. (United States)


Published in SPIE Proceedings Vol. 5688:
Ophthalmic Technologies XV
Fabrice Manns; Bruce E. Stuck; Michael Belkin; Per G. Söderberg; Arthur Ho, Editor(s)

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