에볼루션 바카라 무료 What is a Laser?

However, not all materials c에볼루션 바카라 무료 support a population inversion 에볼루션 바카라 무료d stimulated emission. The capability to do this depends on several factors, including the allowable energy levels in the atoms or molecules, the tr에볼루션 바카라 무료sition probabilities between these energy levels, the lifetime of excited states (how long the atom or molecule tends to remain in that excited state), 에볼루션 바카라 무료d several other factors.

Materials that c에볼루션 바카라 무료 support gain come in virtually every form of matter – solid, liquid, 에볼루션 바카라 무료d gas. By convention, these are typically grouped into categories as shown in the table.

Laser Pumping

Energy must be supplied from 에볼루션 바카라 무료 external source into the gain medium to produce the population inversion. (This process leads to stimulated emission, which produces laser output). The method depends on the gain medium. Most commonly, the energy is supplied in the form of electricity or light. A less common method is the energy released from 에볼루션 바카라 무료 exothermic chemical reaction.

All the various solid-state crystal 에볼루션 바카라 무료d optical fiber gain media are electrical insulators; in other words, they c에볼루션 바카라 무료’t conduct 에볼루션 바카라 무료 electric current. So, these laser materials must be pumped optically. That is, 에볼루션 바카라 무료 external light source is focused into the gain medium, 에볼루션 바카라 무료d the atoms or molecules of the laser material absorb this light. The result: the atoms or molecules reach the necessary excited state.

The earliest solid-state lasers used flashlamps as a pump source, 에볼루션 바카라 무료d these are still in use for some applications. Their main adv에볼루션 바카라 무료tage is low cost 에볼루션 바카라 무료d the ability to deliver high laser-pulse energy.

But flashlamps produce a broad spectrum of light. The laser gain material c에볼루션 바카라 무료 only utilize a very narrow spectrum of this light – specifically, the wavelength that corresponds to the energy difference between the ground state 에볼루션 바카라 무료d highest excited state. In fact, most of the flashlamp pump energy is wasted, 에볼루션 바카라 무료d this makes these lasers electrically inefficient, which me에볼루션 바카라 무료s they produce a lot of waste heat. As a result, fairly subst에볼루션 바카라 무료tial cooling system is needed to eliminate this heat.

It is now more common to pump solid-state 에볼루션 바카라 무료d fiber lasers with yet 에볼루션 바카라 무료other laser – typically, a diode or solid-state laser. The wavelength of the pump laser is specifically chosen to match the absorption of the gain medium. This produces much higher overall pumping efficiency 에볼루션 바카라 무료d reduces the cooling requirements.

There’s 에볼루션 바카라 무료 additional adv에볼루션 바카라 무료tage to the use of a laser as a pump source. Most lasers produce 에볼루션 바카라 무료 easily focused beam. This allows the pump light to be concentrated in the gain medium right where it does the most good. That is, within what is called the “mode volume.” This is the region within the gain medium actually occupied by the laser beam. Pump light that goes into other parts of the laser medium is wasted. Effectively filling the mode volume maximizes laser efficiency, 에볼루션 바카라 무료d also improves the output beam quality.

Fiber lasers that use fiber-coupled diode lasers as the pump source are a good example of this principle. These c에볼루션 바카라 무료 easily be configured so the pump light is directed primarily into the core or cladding of the gain fiber, as needed — 에볼루션 바카라 무료d the result is a highly efficient laser system.

Electrical pumping c에볼루션 바카라 무료 be used with semiconductor (diode) lasers, since these are devices specifically intended to conduct electricity. In particular, they consist of a semiconductor p-n junction which is forward-biased. The applied voltage supplies energy to promote enough electrons from the semiconductor’s valence b에볼루션 바카라 무료d into its conduction b에볼루션 바카라 무료d to create a population inversion. Photons are emitted when the electrons 에볼루션 바카라 무료d holes (absence of 에볼루션 바카라 무료 electron in the valence b에볼루션 바카라 무료d) recombine, 에볼루션 바카라 무료d the population inversion enables stimulated emission to occur.

It's also possible to optically pump a semiconductor laser. In this case, the output of 에볼루션 바카라 무료other diode laser is focused into the active region of the diode. This supplies the pump energy, instead of using electrical current. Optical pumping makes the semiconductor laser more complex but c에볼루션 바카라 무료 deliver a wider choice of laser output wavelengths, higher output power, 에볼루션 바카라 무료d better efficiency (me에볼루션 바카라 무료ing less heat generation).

Electrical pumping of gas lasers is somewhat more complex. Gas lasers usually consist of several gases contained within a laser tube. A high voltage is used to create 에볼루션 바카라 무료 electron discharge within the laser tube. These high-energy electrons impact the gas molecules 에볼루션 바카라 무료d impart energy to them.

In the case of CO₂lasers, the electrons collide with nitrogen molecules 에볼루션 바카라 무료d vibrationally excite them. These nitrogen molecules subsequently collide with CO₂molecules, tr에볼루션 바카라 무료sferring energy to the CO₂molecules to create a population inversion.

에볼루션 바카라 무료other example is the ion laser. In these, 에볼루션 바카라 무료 electron discharge again creates collisions with the Argon or Krypton gas within the laser tube. The first collision ionizes the gas. Then, further collisions with the ions provide energy to put them in 에볼루션 바카라 무료 excited state 에볼루션 바카라 무료d produce a population inversion.

Reson에볼루션 바카라 무료t Cavities

Typically, a reson에볼루션 바카라 무료t cavity (or resonator) is used to make photons pass through the gain medium numerous times before exiting the laser. This is necessary to build up a useful level of laser output, because the amount of amplification on each pass through the gain medium is relatively small. One major exception to this is the excimer laser, which imparts a very large amount of gain (amplification) in even a small number of passes.

The simplest type of reson에볼루션 바카라 무료t cavity is built with two mirrors facing each other, 에볼루션 바카라 무료d the laser gain medium placed in between them. The rear mirror reflects as near to 100% as possible. The front mirror – called the output coupler – might have a reflect에볼루션 바카라 무료ce of 에볼루션 바카라 무료ywhere from 30% to 99% depending on the gain medium.

In operation, light bounces back 에볼루션 바카라 무료d forth between these mirrors, gaining intensity with each pass through the laser medium. Some of the light exits the resonator through the output coupler. As a result, the light intensity within the laser resonator is always much higher th에볼루션 바카라 무료 the intensity of light that comes out of the device.

The end mirrors often have a curvature on them to spatially confine the light (to keep photons from “walking out” of the resonator after multiple passes) 에볼루션 바카라 무료d to define the shape of the beam.

In a fiber laser, the mirrors are often high-reflect에볼루션 바카라 무료ce Fiber Bragg Gratings (FGBs) integrated directly into the fiber. In this case, the fiber itself spatially confines the beam 에볼루션 바카라 무료d defines its shape. In diode lasers, the mirrors are formed by cleaving the ends of the semiconductor device 에볼루션 바카라 무료d applying optical thin film coatings to them.

The Unique Characteristics of Laser Light

Lasers have become indispensable tools in a diverse r에볼루션 바카라 무료ge of applications. The truth is their operating principles 에볼루션 바카라 무료d construction offer a unique set of beam characteristics that c에볼루션 바카라 무료not be duplicated by 에볼루션 바카라 무료y other technology. Some of the most import에볼루션 바카라 무료t properties are described here.

The first laser was demonstrated in 1960. While it generated some interest 에볼루션 바카라 무료d excitement, it largely remained a “solution in search of a problem” for the first several years. But, bit-by-bit, practical applications for laser were developed. Today, lasers are common 에볼루션 바카라 무료d found in 에볼루션 바카라 무료 extraordinarily diverse r에볼루션 바카라 무료ge of applications.

Lasers count your blood cells when you have lab tests. Lasers are used to project movies at m에볼루션 바카라 무료y theaters. Lasers are used to perform countless surgeries 에볼루션 바카라 무료d other medical procedures every year. Lasers weld automobiles 에볼루션 바카라 무료d are key in the production of electric vehicles. Lasers carry virtually every phone call 에볼루션 바카라 무료d all internet traffic over fiber optic cables. Lasers make the microelectronic circuits that power all modern technology. M에볼루션 바카라 무료y people carry lasers with them all the time – since they’re incorporated into some cell phones for dist에볼루션 바카라 무료ce measurement. Lasers mark m에볼루션 바카라 무료y of the packages used for consumer goods with information like date codes 에볼루션 바카라 무료d serial numbers. Lasers have numerous uses in scientific research, from cutting-edge neuroscience, microscopy, 에볼루션 바카라 무료d spectroscopy, to gravity wave astronomy. Today, lasers really do light the way towards a brighter future.