The most commonly used lasers in physical medicine are:

• semiconductor
• to He-Ne (Helium-Neon)
• a CO2

The semiconductor laser is a small, low-power solid laser with a wavelength of 904 nm. The He-Ne laser is a gas laser that emits red light on the visible of about 632nm, with powers ranging from 1 to 50 mW. The CO2 laser is a large gas laser whose active material is carbon dioxide, producing invisible light in the infrared with a wavelength of 10600 nm.

The powers that can be achieved are very high, up to a few hundred watts; the CO2 laser can be equipped with a mechanical arm with reflective mirrors inside, which, by directing the light onto a defocusing lens, allow the power to be reduced, making the beam linear and allowing a scanner effect similar to that of low-power (He-Ne) lasers. The passage of light energy produces, by the Joule effect, tissue heating.

In particular, the CO2-IR laser is capable of producing considerable output power as a function of high efficiency (about 30 percent compared with 0.1 percent for most helium-neon lasers).The new infrared diodes, which are equipped with high emission power, thus enable particularly high energy density to be transmitted in depth. All this in extremely short times.

Biological effects

Laser therapy produces an antalgic, antiphlogistic (anti-edema) and biostimulating effect on the substrate. The analgesic and antiphlogistic action is attributed to both the temperature-induced increase in the tissues and a direct action of the laser beam on the tissues (increased pain threshold with increased circulating endorphins, etc.). In vitro, biostimulatory action occurs at the molecular level (increased ATP production, etc.), at the cellular level with modification of phagocytosis, proliferation, immune response and motility.