LASER means Light Amplification from Stimulated Emission of Radiation. Laser is created by specific process within the laser device to cause the controlled emission of radiation in form of light. Laser usually comes in one color and it comes in a thin beam. Lasers were first invented by physicist Gordon Gould in 1958 and first working model was built in 1960.They have been used in Europe and America for more than forty years and have been used in fields of dermatology, surgery. ophthalmology and physical medicine and rehabilitation. Laser is used by physiotherapists for relief of pain, to accelerate healing and decrease inflammation.

Difference between Low Level Laser Therapy and High Power Laser Therapy

An output power of less than 0.5 Watts is classed as Low Level Laser Therapy LLLT ( class III in the USA) whereas lasers with an output powers greater than 500mW or 0.5 Watts are termed High Power Laser Therapy HPLT (Class IV lasers in the USA). HPLT creates heat on the surface of the skin due to their higher power density (irradiance). LLLT is often referred to as “Cold Lasers” since they do not create a heating sensation during treatment

Laser device is made up of an optical cavity or chamber that contains active medium for which laser is named. The chamber has mirrors on either end that are perfectly parallel to each other within a single wavelength of light. One of the mirror is partially open. Electricity or energy is added to the medium which excites it. The active medium atoms are reflected back and forth across the mirrors within the chambers. This cause more excitation of atoms within the medium. Laser light is then emitted through the partially reflective end of mirror. The light production occurs in the following steps:

1.Electron is pumped to a higher energy level.

2.Pumping level is unstable so the electron quickly jumps to a slightly lower energy level.

3.Electron relaxes to a lower energy state and releases a photon.

4.Light and an electron in an excited energy level produces two photons of same wavelength and phase.

5.Mirror reflects the photons or laser light is emitted.