Biological Effects

Exposure to lasers can cause harmful biological effects.

Lasers can interact with the tissues of the eye and skin in several negative ways:

• Thermal effects are caused by elevated temperature after absorption of laser energy and can be created across nearly all wavelengths and exposure durations.
• Thermal damage, also known as a burn, is generally associated with lasers operating at exposure times greater than 10 microseconds and in the wavelength region from the near ultraviolet to the far infrared (0.315 µm-103 µm). Thermally induced acoustic waves may cause tissue damage following exposures to sub-microsecond laser exposures.
• Photochemical effects are caused only by lasers with a wavelength less than 0.550 micrometers and can create chemical reactions within body tissue after absorption of laser energy.
• Shockwave, or acoustic, damage from lasers is an explosive effect caused when the retina absorbs short pulses.
• Repetitively pulsed or scanning lasers can cause burns when the pulses compound, creating an additive effect. The principal thermal effects of laser exposure depend on certain factors:
  • The absorption and scattering coefficients of the tissues at the laser wavelength
  • Irradiance or radiant exposure of the laser beam
  • Duration of the exposure and pulse repetition characteristics, where applicable
  • Extent of the local vascular flow
  • Size of the area irradiated

To learn more about Laser Safety visit our Laser Safety Online Training web page.