Search results
Results from the WOW.Com Content Network
Helium–neon laser at the University of Chemnitz, Germany. A helium–neon laser or He–Ne laser is a type of gas laser whose high energetic gain medium consists of a mixture of helium and neon (ratio between 5:1 and 20:1) at a total pressure of approximately 1 Torr (133 Pa) inside a small electrical discharge.
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).
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 ...
The type of pump source used principally depends on the gain medium, and this also determines how the energy is transmitted to the medium. A helium–neon (HeNe) laser uses an electrical discharge in the helium-neon gas mixture, a Nd:YAG laser uses either light focused from a xenon flash lamp or diode lasers, and excimer lasers use a chemical ...
A four-level laser energy diagram. Here, there are four energy levels, energies E 1, E 2, E 3, E 4, and populations N 1, N 2, N 3, N 4, respectively. The energies of each level are such that E 1 < E 2 < E 3 < E 4. In this system, the pumping transition P excites the atoms in the ground state (level 1) into the pump band (level 4).
The energy difference is lost to heat, which may carry away the excess entropy delivered by the multimode incoherent pump. The quantum defect of a laser can be defined as the part of the energy of the pumping photon which is lost (not turned into photons at the lasing wavelength) in the gain medium during lasing. [1]
where U p is the ponderomotive energy from the laser field and I p is the ionization potential. This cut-off energy is derived from a semi-classical calculation, often called the three-step model. The electron is initially treated quantum mechanically as it tunnel ionizes from the parent atom, but its subsequent dynamics are treated classically.
If it is at a higher energy level, it is said to be excited, or any electrons that have higher energy than the ground state are excited. Such a species can be excited to a higher energy level by absorbing a photon whose energy is equal to the energy difference between the levels. Conversely, an excited species can go to a lower energy level by ...