Ocular Tissue Damage Due to Ultrashort 1060-nm Light Pulses from a Mode-Locked Nd-Glass Laser.

摘要

A study is reported of the ocular tissue damage effects of short trains of 1060 nm wavelength ultrashort laser radiation pulses. The macular sites of 46 retinae of anesthetized rhesus primates (Macaca mulatta) were exposed to single trains of picosecond pulses. The ultrashort pulse trains were obtained from a Nd-glass laser simultaneously Q-switched and mode-locked by means of an intracavity saturable absorber. The mode-locked laser parameters were controlled to yield a single reproducible pulse train containing approximately 13 ultrashort (approximately or equal to 5 ps) pulses of intervals of 6.9 ns. Damage to the retinal tissue was studied by means of a fundus camera. One hour postexposure observations were made to detect the presence or absence of lesions. Results indicate an unusually low value of 2 x 10 to the minus 5th power joules as the total pulse train energy necessary for 50% probability of minimum detectable damage to the macular area in the retina. The energy value is significantly below the energy required to cause damage characterized by the thermal processes as seen at exposure times greater than 1 ns.