LASER light amplification by stimulated emission

LASER, light amplification by stimulated emission of radiation... 

Since the field of spectroscopic laser applications is so vast and the number of published papers exceedingly large, this review cannot be complete. However, the author has tried to give a reasonable survey of what has been done and to offer some ideas about what can be done in modem spectroscopy with such an interesting and stimulating invention as the laser (Light Amplification by Stimulated Emission of Radiation). 

Stimulated emission of photons. This process consists of electronic transitions from the excited energy level to the lower one stimulated by an external radiation of the appropriate frequency ( 2 - E fh and constitutes the basis of the laser (light amplification by stimulated emission of radiation) phenomenon. 

Laser—Light Amplification by Stimulated Emission of Radiation... 

In principle, a laser (light amplification by stimulated emission of radiation) is not limited to wavelengths normally associated with light, that is, the visible wavelength range of approximately 380-780 nm (see Fig. 1). 

Lasers (Light Amplification by Stimulated Emission of Radiation) are devices which amplify light and produce beams of light which are very intense, directional, and pure in colour. They can be solid state, gas, semiconductor, or liquid. 

The idea of amplification of EM radiation by stimulated emission was first realized for microwaves. The MASER (microwave amplification by stimulated emission of radiation) was developed in the Soviet Union in the early part of the 1950s, particularly by N. Basov and A. Prokhorov. At the same time, it was developed by C. H. Townes, A. L. Schawlow, and others in the United States. Originally, the laser was called light-maser, but the name was changed to LASER (light amplification by stimulated emission of radiation). 

A pulsed beam of coherent monochromatic light of high power density, commonly known as a laser (Light Amplification by Stimulated Emission of Radiation), is focused on to the workpiece surface causing it to vaporize locally. The material then leaves the surface in the vaporized or liquid state at high velocity (see 5.4F). 

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