Briefly describe the conditions under which light radiation is generated and what is the difference between spontaneous emission and the process of stimulated radiation
E1 up, this radiation is called stimulated radiation.
the difference:
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Unlike spontaneous radiation, the stimulated radiation must occur under the action of external light and emit an external photon
Exactly the same photon. The stimulated light is coherent light. Stimulated radiation plus the original foreign light, so that light in the pass
The sowing direction is magnified.
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Spontaneous radiation is a spontaneous process that is not affected by external radiation fields. Each atom is in the process of spontaneous transition.
This unrelated, spontaneous emission of light from different atoms in the frequency, phase, polarization direction and propagation direction
There is a certain degree of arbitrariness.
Try to summarize the principle of laser, features
The conditions of light radiation, in the final analysis, are energy. The energy (or frequency) is high, such as gamma rays, decay from the nucleus. And blackbody radiation can come from any object with a temperature higher than 0K, such as the background radiation of 3K microwave radiation, warm objects can launch infrared, higher temperature, such as burning red iron, glass or incandescent light began to launch visible light , The temperature reaches the surface of the sun 6000K black body radiation, including both infrared, visible and ultraviolet light. Discharge phenomena can emit ultraviolet light (such as mercury lamps, hollow cathode lamps) and / or visible light (such as neon lights is the discharge of rare gases). Some substances have fluorescence, phosphorescence properties, that is, absorb a certain wavelength of photons, the energy through another specific, longer than the wavelength of wavelength absorption wavelength of light emitted and released.
The difference between spontaneous emission and stimulated radiation
Spontaneous radiation:
In the excited state of the atom, the electrons in the excited state energy level can only stay for a short period of time, spontaneously jump to the lower energy level, while radiating a photon, this radiation is called spontaneous radiation.
Stimulated radiation: When the atom is in the excited state E2, if the energy is exactly E1 (where E2> E1)
Photons, under the influence of incident photons, the atoms will emit a similar photon and jump to the low level
principle
The laser is the amplification of light-stimulated radiation, which achieves optical amplification by stimulated radiation. Light amplification that is
Is a photon into an atomic system, after leaving the atomic system, became two or more
Photographs with exactly the same characteristics. However, when the photon enters the atomic system and interacts with the atomic system,
The total contains three processes: absorption, spontaneous emission and stimulated radiation. To get the laser must make the stimulated radiation
Better than absorption and spontaneous radiation in the three processes dominate.
Features
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Main features: directional light, high brightness, very pure color, high energy density
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Other features:
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The laser is monochrome or single frequency;
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The laser is coherent light, all its light waves are synchronized, the whole beam is like a wave column;
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Laser is highly concentrated, that is, it takes a long distance will appear scattered or convergence phenomenon.
