Skin Hazards Table - Summary of Pathological Effects Associated with Excessive Exposure to Light 1. General Laser radiation is distinguished from most other known types of radiation by its beam collimation. This, for lasers with an initial high energy content, can result in excessive amounts of energy being transmitted to biological tissues. The primary event in any type of laser radiation damage to a biological system is the absorption of radiation by that system. Without absorption, damage cannot occur.
Absorption occurs at an atomic or molecular level and is a wavelength specific process.
Thus, it is the wavelength that determines which tissue a particular laser is liable to damage. The mechanism by which laser radiation induces damage is similar for all biological systems and may involve interactions of heat, thermo-acoustic transients and photochemical processes. The degree to which any of these mechanisms is responsible for damage may be related to certain physical parameters of the irradiating source, the most important of which are wavelength, pulse duration, image size, irradiance, and radiant exposure. In general terms, in suprathreshold exposures the predominating mechanism is broadly related to the pulse duration of the exposure. For times in excess of 100 s, photochemical processes.