Laser therapy has its origins in the 1960s. Laser radiation does not occur in nature. Laser light is an electromegnetic wave with some unique characteristics.
History of laser therapy
Laser therapy has its origins in the second half of the twentieth century. The first laser was constructed in 1960 by TH Maiman in aviation company. A few years later, E. Mester, a Hungarian physicist and pioneer of laser therapy applied a low level laser to difficult-to-heal wounds and boils.
Laser construction
Each laser consists of three main components
- Active laser medium such as gas, liquid, solid or semiconductor.
- Pumping system.
- Optical cavity—a pair of mirrors, one ordinary and one semipermeable.
Characteristics of laser light
Monochromaticity means that the radiation emitted by the laser has mostly one wavelength (small spectral width). Monochromaticity may be achieved by splitting white light on a prism. A similar phenomenon occurs in the rainbow emerging in the sky when the sun’s rays refract through the air filled with water droplets.
Coherence of the laser means that the waves occurring in the laser light are in phase. Coherence of the laser as well as monochromaticity result from the method of producing laser light in an optical resonator. Only strictly defined wave frequency in a particular phase leaves semipermeable mirror.
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| Waves are coherent | Waves are incoherent |
Polarization – the laser light is polarized. From a physics point of view, light is an electromagnetic wave which has both magnetic and electric components. The polarization of such wave is that the electric and magnetic components are subjected to changes in selected plains, while the light such as sunlight is “chaotic” and its components vary randomly in all plains. Polarized sunglasses are perfect example of polarization, which are used to suppress e.g. glare from the water or they may be dedicated for night driving. Ordinary light can be polarized either through a polarizing filter or through the polarizing mirror.
These three characteristics: monochromaticity, coherence and polarization cause that the laser light has a unique impact on the human body tissue which can not be compared with any naturally occurring effects of light.
