adminLASER
The word LASER is an acronym for “light amplification by simulated emission of radiation”. Laser is a device that provides an intense directional beam by amplifying light through simulated emission.
Compare with ordinary light, laser light is monochromatic since it consists of only a single wavelength. Laser is non-divergent, because it travels in a single direction. The intensity of laser light is higher because concentration of photons is higher. Laser light is highly coherent. Due to its high intensity the brightness of laser light is high.
There are various types of lasers and they are; gas lasers, solid state laser, semiconductor laser and fiber laser. The component of a laser are; active medium, pumping energy source, excitation mechanism and the resonance cavity.
The active medium is the material the laser action takes place. The active medium may be solid crystals such as liquid dyes, gases like co2 or helium, neon or semiconductors such as GaAs. This medium decides the wavelength of laser radiation. Active mediums contain atoms which can produce more stimulated emission than spontaneous emission and cause amplification; they are called ‘active centers’.
The pumping energy source or the excitation mechanisms pumps the active centers from ground state to excited state to achieve population inversion. The pumping by energy source can be optical, electrical or chemical depending on the active medium.
In the resonance cavity, the optical resonator contains a pair of reflecting surfaces of which one is fully reflecting and the other partially reflecting. The active material is kept in between the two reflecting surfaces. Photons (light) emitted due to transitions between the energy states of the active material are bounced back and forth between the two reflecting surfaces, so the intensity of the light is increased. Finally the intense amplified beam called LASER comes out through the partial mirror.
GAS LASER uses ages ages as the active or gain medium such as helium-neon (He-Ne) or carbon dioxide (Co2).
SOLID STATE LASER uses a solid as active or gain medium such as neodymium (Nd) or yttrim-aluminium-garnet(YAG).
Semiconductor LASER uses a semiconductor as the active or gain medium such as gallium arsenide (GaAs) or indium phosphide (InP).
FIBER LASER uses a fiber optic as an active or gain medium.
The advantages of laser are; lasers produce intense beam of light, which can be focused to a very small area. LASERs produce a single colour beam of light, which can be used for specific applications. LASERs produce a coherent beam of light which can be used for various applications such as holography etc.
The disadvantages of LASERs are lasers can be hazardous to the eyes and skin and require proper safety precaution. LASERs can be expensive especially high powered LASERs. LASERs require regular maintenance to ensure proper operation. LASER has a limited lifespan.
LASERs have found widespread applications in the following; material processing for cutting, welding and surface treatment. Medicine, for surgical procedures or skin treatment and eye surgery. LASERs are used for spectroscopy, interferometry and other scientific applications. LASERs are used for military applications such as target designation and missile guidance.
The future of LASERs is predicated on the trends, advances and development in the following technologies; advanced materials, increase use in medicine for medical procedures and treatments. New applications, such as quantum computing and space exploration. Also improved safety measures will encourage it to be adopted in many other applications.
SOURCES:
- Principles of LASERs by Orazio Svelto.
- LASERS: fundamentals and applications by Kumar, Gupta and Sharma.
- LASER TECHNOLOGY by J.Wilson and J.F.B Hawkes.
- LASER handbook by Frederick J. Duarte.
- LASERs and optoelectronics: fundamentals and applications by G.H.C New and J.M Dawson.
