Lasers - Types of Lasers and Its Applications

Laser stands for " Light Amplification by Stimulated Emission of Radiation", which is an optical source that emits photons in a coherent beam. Laser means "to produce laser light" or possibly "to apply laser light to".

Laser is a monochromatic light, which consist of wavelength or color, and emitted in a narrow beam. This is in contrast to common light sources, such as the incandescent light bulb, which emit incoherent photons in almost all directions, usually over a wide spectrum of wavelengths.

Types of Lasers:-

There are many different types of lasers. The laser medium can be a solid, gas, liquid or semiconductor.

• Solid-state lasers:- The ruby laser, ND:YAG laser are comes under solid state laser. The neodymium-Yag laser emits infrared light at 1,064 nanometers (nm). These lasers are most alike to the "ideal laser". They are pumped with flashlights, which either give off flashes of light and makes the laser give one pulse, or give continuous light. The lasing substance is doped into a host material in a suitable concentration. The host material is chosen to be transparent, a good heat conductor, even quality etc.

• Gas lasers: The helium and helium-neon, HeNe, are the most common gas lasers, which have a primary output of visible red light. CO 2 lasers emit energy in the far-infrared, and are used for cutting hard materials.

• Dye lasers:- The gain medium in a dye laser is an organic dye molecule that is dissolved in a solvent. The dye and solvent are circulated through a cell or a jet, and the dye molecules are excited by flashlamps or other lasers. The organic dye molecules have broad fluorescence bands and dye lasers are typically tunable over 30 to 80 nm. Dyes exist to cover the near-uv to near-infrared spectral region: 330 - 1020 nm.

• Semiconductor lasers : It is sometimes called diode lasers, are not solid-state lasers. These electronic devices are generally very small and use low power. Semiconductor lasers are light-emitting diodes within a resonator cavity that is formed either on the surfaces of the diode or externally. An electric current passing through the diode produces light emission when electrons and holes recombine at the p-n junction.

Applications of Lasers:-

The main applications of lasers are as:-

• Lasers have been used in industry for cutting and boring metals and other materials, and for inspecting optical equipment.

• In medicine, they have been used in surgical operations. Lasers have been used in several kinds of scientific research.

• Lasers have opened a new field of scientific research, nonlinear optics, which is concerned with the study of such phenomena as the frequency doubling of coherent light by certain crystals.

• Lasers have also been used in plasma physics and chemistry.