Laser

The term "laser" (Light Amplification by Stimulated Emission of Radiation) indicates an instrument capable of giving out electromagnetic waves both in the visible and in the infrared and UV fields.
A laser device is essentially made up of three parts:
- an active medium made of solid, liquid or gaseous material (solid, liquid or gas lasers);
- an energy source (pumping system) to excite the active medium's atoms. This source can be represented by a lamp (optical pumping), by electrical systems (electric pumping) and by chemical systems (chemical pumping) or by another laser;
- an optical risonance system (optical cavity) made up of two mirrors that delimit the active medium from the outside, one of which is reflecting and the other partly reflecting.
The laser has some peculiar characteristics:
- it can produce high energy radiations from a low power source
- it can produce unidirectional rays that are propagated in a straight line. In fact it must be remembered that radiations of light produced by a conventional source are propagated in all directions
- it can produce radiations of a single wave length.
- it can concentrate high energy intensity on small areas.
For such characteristics lasers are widely employed in dermatology, eye microsurgery, ENT surgery, gynaecology surgery and surgical endoscopy.
Lasers employed in the medical-surgical field can be divided in three groups according to their action:
- surgical lasers
- photocoagulative lasers
- photodynamic lasers.
The most widely employed surgical lasers are the CO₂laser, the Argon laser and the Nd:YAG (Neodimium Yttrium Aluminum Garnet) laser.
Photocoagulative lasers are mostly employed in Ophthalmology to treat retinal detachment, small haemorrhages and proliferative retinopathy.
Photodynamic lasers are mostly employed in Oncology, although still in the experimental stage. In fact they exploit the property of some cells to fix injected substances and to be photoactivated because of photosensitivity to the employed laser wave length.
Damages, above all to the skin and the eyes, can occur after exposure to laser's radiations because of thermical effect.
Ocular effects depend on the wave length of the radiation:
- visible spectrum radiations are electively absorbed by the pigmented epithelium of the retina and may lead to retinal or choroid burns (this effect is exploited for the treatment of retinal detachment and of lesions of retina and choroid.)
- Infrared and UV radiations are absorbed by the eye adnexa, the cornea, the lens and by the vitreous where they can give rise to opacities.
Skin effects range from erythema to blistering skin to the carbonization of the tissue.



For additional information

• Laser hazards (Occupational Safety & Health Administration)

	Ambulatories
	Diagnostic services
	Laboratories
	Operating theatres

	Ambulatories
	Diagnostic services
	Physical laboratories
	Operating theatres

Laser