ABSORPTION OF LASER RADIATION
USER MANUAL
107
ABSORPTION OF LASER RADIATION
Human tissues absorbs electromagnetic radiation in different ways depending on tissue
characteristics and the wavelength of the radiation. Certain wavelengths may be trans-
mitted or absorbed, in different levels, by the human tissue. In the specific case of the
eye, the Cornea and Crystalline lens allows most of the radiation within the wavelength
range of 400nm to 1400nm to pass a reach the retina (where are the vision sensors).
This range includes the visible light as wells a s near-infrared. The Arex™ 400 laser mark-
ers emit in the 1060nm range and thus can be focalized by the eye lens at retina with
serious risk of causing irreversible damage do vision sensors.
Regarding human skin, the tissue abortion level is higher for the same wavelength range
but the maximum exposure tolerance level, before there is a damage, is different com-
pared to eye.
Retina
Vitreus Body
Cornea
Optical Nerve
Crystalline Lens
Crystalline Humor
Figure 1: Eyeball section.
The damage mechanism, that absorbed laser radiation can cause, depends on the radia-
tion wavelength. Radiation on the short wavelength range (UV 180-400nm) generally
cause photochemical effects such as:
•
cataract, or opacification of the crystalline lens
•
melanin coloring, or reddening of the skin
Radiation at longer wavelength range (IR 780nm to 10µm), generally cause thermal
effects such as:
•
detachment or photocoagulation of the retina
•
burning of the tissue
The degree of injury depends on the amount of absorbed radiation; the power, energy
and peak power of the radiation source, as well as the time exposed to such radiation.
