LASERS IN CLINICAL PRACTICE
Today the modern medical science is changing according to the needs of the man to fulfill the dreams of their cosmetic and aesthetic appearance. Cosmetology is fast developing with the introduction of newer laser machines. The word LASER is an acronym for Light Amplification by the Stimulated Emission of Radiation.
LASER consists of an active medium(crystal, gas, dye) that is raised to an excited state by external energy source such as flash lamp or an electric discharge. The resulting process of stimulated emission in the active medium produces abundance of photons of light all of the same wavelength. A pair of mirrors at each end of the active laser medium reflects the light back and forth on itself to increase the probability of stimulated emission. One of the mirrors allows a small fraction of the light to leak through. The resulting beam of light is the output beam of laser.
Sun light has seven different colours, namely Violet, Indigo, Blue, Green, Yellow, Orange and Red with its wavelength measures from 400 to 700 nanometers. Of these 400 nanometer is Violet and 700 nanometer is Red. This visible light is at the at the centre of the electromagnetic spectrum.. On the shorter wavelength side is ultraviolet, and then X-rays, gamma rays and cosmic rays on the extreme short end. Infrared light is adjacent to the visible spectrum on the long wavelength side. Microwaves and radio waves have even longer wavelengths. Lasers used for cosmetic laser applications are in the infrared area of electromagnetic spectrum
Laser light has three unique properties:
1. It is collimated (directional) which means it travels in a single direction with very little divergence even over long distances.
2. It is monochromatic (Single colour/wavelength), consisting of one colour or narrow range of colours.
3. It is coherent (organized), which means all of the light waves move in phase together in both space and time ie. same frequency.
A wide range of lasers are available for medical applications. In general, medical lasers can be divided into four groups.
1. Gas lasers Co2, Argon, He, N2 etc.
2. Solid state lasers Er.YAG, Nd.YAG, KTP etc.
3. Liquid lasers Dye
4. Diode lasers