Thermal damage thresholds for multiple-pulse porcine skin laser exposures at 1070 nm.

As solid-state laser technology continues to mature, high-energy lasers operating in the near-infrared (NIR) band have seen increased utilization in manufacturing, medical, and military applications. Formulations of maximum permissible exposure limits establish guidelines for the safe use of these systems for a given set of laser parameters, based on past experimental and analytical studies of exposure thresholds causing injury to the skin and eyes. The purpose of our study is to characterize the skin response to multiple-pulsed laser exposures at the NIR wavelength of 1070 nm, at a constant beam diameter of 1 cm, using anesthetized Yucatan mini-pig subjects.

Suprathreshold laser injuries in excised porcine skin for millisecond exposures at 1070 nm.

Skin injury response to near-infrared (NIR) laser radiation between the minimum visible lesion threshold and ablation onset is not well understood. This study utilizes a 1070-nm diode-pumped Yb-fiber laser to explore the response of excised porcine skin to high-energy exposures in the suprathreshold injury region without inducing ablation. Concurrent high-speed videography is employed to determine a dichotomous response for three progressive damage categories: observable surface distortion, surface bubble formation due to contained intracutaneous water vaporization, and surface bubble rupture during exposure.

Infrared skin damage thresholds from 1319-nm continuous-wave laser exposures.

A series of experiments were conducted in vivo using Yucatan miniature pigs (Sus scrofa domestica) to determine thermal damage thresholds to the skin from 1319-nm continuous-wave Nd:YAG laser irradiation. Experiments employed exposure durations of 0.25, 1.

Infrared skin damage thresholds from 1940-nm continuous-wave laser exposures.

A series of experiments are conducted in vivo using Yucatan mini-pigs (Sus scrofa domestica) to determine thermal damage thresholds to the skin from 1940-nm continuous-wave thulium fiber laser irradiation. Experiments employ exposure durations from 10 ms to 10 s and beam diameters of approximately 4.8 to 18 mm.

Damage Thresholds for Exposure to NIR and Blue Lasers in an In Vitro RPE Cell System.

Purpose: Until reliable nonanimal systems of analysis are available, animal models will be necessary for ocular laser hazard analysis and for evaluating clinical applications. The purpose of this work was to demonstrate the utility of an in vitro system for laser bioeffects by identifying photothermal and photochemical cytotoxicity thresholds for continuous-wave (cw) and mode-locked (ml) laser exposures.

Methods: Exogenous melanosomes were added to hTERT-RPE1 cells in exposure wells 1 day before laser exposure.

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

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-microm wavelength occurred mainly in the cornea where light from this wavelength is highly absorbed.

ED50 study of femtosecond terawatt laser pulses on porcine skin.

Background And Objectives: Terawatt (TW) lasers have become commonplace since the development of the chirped-pulse amplification method using Ti:sapphire and Nd:glass laser rods. We have measured the minimum visible lesion (MVL) thresholds for porcine1The animals involved in this study were procured, maintained, and used in accordance with the Federal Animal Welfare Act and the "Guide for the Care and Use of Laboratory Animals" prepared by the Institute of Laboratory Animal Resources-National Research Council. Brooks City-Base, TX has been fully accredited by the Association for Assessment and Accreditation of Laboratory Animal Care, International (AAALAC) since 1967.

Sub-50-fs laser retinal damage thresholds in primate eyes with group velocity dispersion, self-focusing and low-density plasmas.

Background: In vivo retinal injury studies using sub-50-femtosecond laser pulses in the near-infrared must consider nonlinear effects such as group velocity dispersion (GVD), self-focusing, laser-induced breakdown (LIB) and low-density plasmas (LDPs). In this paper we present the results of our theoretical calculations of nonlinear effects and our experimental measurements for the visible lesion thresholds in live eyes. We compare these values with the measured LIB and LDP thresholds in an artificial eye.

A comparative study of retinal effects from continuous wave and femtosecond mode-locked lasers.

Background And Objectives: In order to provide a direct comparison of the effects of mode-locked systems to those with continuous-wave (CW) or nonpulsed output, we have performed an experiment with lasers possessing otherwise identical output characteristics. This in vivo minimum visible lesion study compares retinal effects of mode-locked and CW lasers complete with histopathology of the treated areas.

Study Design/materials And Methods: Titanium:Sapphire lasers produced 800-nm output for either mode-locked (76 MHz repetition rate, 120 femtoseconds) or CW exposures.

Thresholds for retinal injury from multiple near-infrared ultrashort laser pulses.

Multiple-pulse lasers are routinely used in the laboratory for research, manufacturing, medical procedures, and in military applications. In order to provide a safe work environment for personnel using these lasers, safety standards have been established and have been in use for many years. These safety standards have addressed laser pulses of nanosecond duration and longer.