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Schematic diagram of a typical 2-3 mW red (633 nm) helium–neon laser tube Commercial He-Ne lasers are relatively small devices compared to other gas lasers, having cavity lengths usually ranging from 15 to 50 cm (but sometimes up to about 1 meter to achieve the highest powers), and optical output power levels ranging from 0.5 to 50 m W .
Schematic diagram of a typical laser, showing the three major parts. A laser is constructed from three principal parts: An energy source (usually referred to as the pump or pump source), A gain medium or laser medium, and; Two or more mirrors that form an optical resonator.
Laser types with distinct laser lines are shown above the wavelength bar, while below are shown lasers that can emit in a wavelength range. The height of the lines and bars gives an indication of the maximal power/pulse energy commercially available, while the color codifies the type of laser material (see the figure description for details).
A laser normally produces a very narrow beam of light in a single wavelength, in this case, green. Photons, the quanta of electromagnetic radiation, are released and absorbed from energy levels in atoms and molecules. In a lightbulb or a star, the energy is emitted from many different levels giving photons with a broad range of energies.
The gas laser was the first continuous-light laser and the first laser to operate on the principle of converting electrical energy to a laser light output. The first gas laser, the Helium–neon laser (HeNe), was co-invented by Iranian engineer and scientist Ali Javan and American physicist William R. Bennett, Jr., in 1960. It produced a ...
Centered at 550 nm, the left photo shows its high reflectance to yellow light and its high transmittance to red and blue light. The right photo shows it reflecting 75% of a laser beam and transmitting 25%, although the beam appears brighter when moving toward the observer than when moving away. Output coupler of a 594 nm Helium−Neon laser
Q-switching, sometimes known as giant pulse formation or Q-spoiling, [1] is a technique by which a laser can be made to produce a pulsed output beam. The technique allows the production of light pulses with extremely high peak power, much higher than would be produced by the same laser if it were operating in a continuous wave (constant output) mode.
This means that, if the laser is optically pumped, the frequency of the pumping light must be greater than that of the resulting laser light. In other words, the pump wavelength is shorter than the laser wavelength. It is possible in some media to use multiple photon absorptions between multiple lower-energy transitions to reach the pump level ...