Ocular Hazards of Picosecond and Repetitive-Pulsed Lasers. Volume II. Argon-Ion Laser (514.5 nm).
Abstract
Retinal damage thresholds were determined for exposures of the maculae of rhesus monkeys to CW and repetitive-pulse trains of argon-ion laser radiation at 514.5 nm in the TEMoo mode. Single-pulse exposures were made at pulsewidths of 2, 10, 40, and 100 microsec and 1, 10, 100, and 500 msec. Repetitive-pulse exposures were made for 27 different combinations: train durations of 0.05, 0.5, 5, and 30 sec; pulse repetition frequencies from 0.10 Hz to 10 kHz and pulsewidths of 10, 40, and 100 microsec and 1 msec. Damage thresholds for mode-locked argon laser pulses at 104 MHz and 250 psec pulsewidth for pulse trains of 9.9-sec, 10-msec, and 10-microsec duration were also measured. For pulsewidths of 10 microsec, there is an apparent cumulative effect provided the repetition frequencies are in the range of approximately 0.1 to approximately 10 Hz. The retina is more sensitive to double-pulse exposures, by a factor of 2 to 3 relative to single-pulse thresholds, when the interpulse spacing is approximately 2.5 sec. Nonthermal damage mechanisms, involving a two-step, two-threshold process, may explain our results. Specifically, for double-pulse configurations, the first acts as a reversible photo-trigger which sensitizes the retina in preparation for the subsequent pulse. The elements of an empirical model have been assembled and appear to account satisfactorily for the observed double-pulse threshold data. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Apr 01, 1978
- Accession Number
- ADA053766
Entities
People
- D. E. Egbert
- H. W. Hemstreet Jr.
- J. S. Connolly