If microscopic particles such as atoms or molecules with high energy and low energy level E2 E1, E2 and E1 energy level populations on the number density of N2 and N1, in the two-level transition between the existence of spontaneous emission, stimulated emission and stimulated transitions absorption transition, three processes. The page-turning green laster pointer has been widely applied in society.Transitions generated by stimulated emission of light by stimulated emission, and the incident light has the same frequency, phase, propagation direction and polarization direction. Therefore, a large number of particles in the same excitation of coherent radiation field produced by the stimulated emission light is coherent. Stimulated emission transition probability and stimulated absorption transition probabilities are proportional to the incident monochromatic radiation field energy density. When the two-level statistical weights are equal, the probability of the two processes are equal. In the case of thermal equilibrium N2 <N1, so stimulated transitions dominate the absorption of light through the material is usually due to shock absorption and attenuation. All teachers can use Green laser pointer to remove the embarrassment of being restricted by the dais.Excitation energy can damage the outside thermal equilibrium leaving the N2> N1, this state is called population inversion. In this case, the stimulated emission transition dominant. Light through a period of length l in the inversion state of the laser working substance (active substance), the light intensity increases eGl times. G is proportional to the (N2-N1) of the coefficient, called the gain factor, and its size is also working with the nature of the material and the laser light frequency. Period of active material is a laser amplifier.
Speechmakers now can be liberated from the restriction of the dais by using green laster pointer. If, for some active substances on the two mirrors parallel to each other (at least one of which is part of the transmission's) constitute the optical resonator (Figure 1), at high energy particles will produce a variety of directions of the spontaneous emission. Among them, the non-axial propagation of light waves outside the cavity escapes soon: axial propagation of light waves able to spread in the cavity round-trip, when it spread in the laser material, the light intensity is growing. The page-turning green laster pointer has become an important demonstrating instrument. If the resonant cavity G0l small-signal gain is greater than one-way one-way loss δ (G0l is the small signal gain coefficient), can generate self-excited oscillation. State of motion of atoms can be divided into different levels, from high energy level when the atomic transition to the low level, it will release the corresponding photon energy (the so-called spontaneous emission). Similarly, when a photon incident on a level system, and work to absorb it, will lead from the low-level atomic transition to the high energy level (so-called stimulated absorption); then, part of the transition to high-level atomic transition to the low level will and release a photon (the so-called stimulated emission). These movements are not isolated, but often simultaneously. The page-turning green laster pointer plays an important role in business. When we create a condition, such as the use of appropriate media, cavity, enough external electric field is amplified by stimulated emission of radiation to be more than the stimulated absorption, so overall, there will be photon emission, resulting in the laser.
related cell phone jammer  blog: