How do laser pointers work

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You can reuse this answer Creative Commons License. Laser pointers are most commonly known to be used during presentations to point out something important on a slide or help follow a diagram being explained from a distance while presenting. That is mainly because smart televisions contain an LCD or LED screen which works by absorbing incoming light, allowing viewers to get a better range of colors visible on the screen, and that they require specialized laser pointers.

While that is one of the most common uses, there are other applications and uses for them, too. Green laser pointers, for instance, can be used for stargazing as they usually have higher power and therefore can be used at night. In order to understand how laser pointers work, it is wise to understand how lasers work first, in general.

Lasers are a small, powerful beam of concentrated light that work to magnify a light source and turn it into a powerful, focused beam. The laser light is different from ordinary light or natural light. The main difference is that natural light generally illuminates a large area by allocating light to that area.

However, when focusing a laser light into one beam, it is so much more powerful than a natural light that is designed to be distributed amongst larger areas, becoming far less powerful. Laser pointers are made up of three parts: lasing medium, energy source and a resonator. The lasing medium is a form of light or electricity that can be powered by a source of energy.

Light mediums, however, can be found used in the form of minerals, gases or even liquids. When powering a laser diode with a form of energy, the laser pointer will emit a beam of light evident to the naked eye. When the laser medium is activated, it will discharge the energy as a monochromatic radiation. Using our ad package , you can display your logo and further below your product description. A laser pointer is a small usually battery-powered laser device designed for pointing at objects by illuminating them with a collimated visible laser beam.

Some significantly more expensive pointers, as shown in Figure 1, emit green or even blue or yellow light and normally contain a small diode-pumped solid-state laser with a nonlinear crystal for frequency doubling.

Here, Nd:YVO 4 is beneficial for a low threshold pump power, and KTP works in a relatively wide temperature range, thus not requiring means for temperature stabilization. Laser pointers should not be confused with lamps containing light-emitting diodes LEDs , which emit a much more diffuse beam with much lower spatial coherence , similar to that of an incandescent lamp and can also emit light with different colors, or white light.

In contrast to that, laser points usually emit quasi- monochromatic light. A typical use of a hand-held laser pointer is to point at some screen or chart during a presentation, e. This is convenient because it can be done from a large distance and requires only a small hand-held device. However, the visibility of the generated spot on the screen is often poor particularly for red laser pointers with relatively long emission wavelength , and a fast-moving light spot can have a somewhat nervous appearance.

Therefore, some people prefer an old-fashioned telescopic pointing device for presentations. Laser pointers can be useful for, e. The apparent brightness of the illuminated spot depends strongly on the wavelength of the emitted light.

Most devices operate in the red spectral region, where the sensitivity of the eye rapidly decreases with increasing wavelength. Devices with nm output appear about twice as bright as those emitting the same power at nm, and nm devices still about two times brighter.

However, the shorter-wavelength laser pointers are typically more expensive. This is particularly true for green lasers , which are significantly brighter than their red counterparts, but are still expensive. They involve a diode-pumped solid-state laser and a frequency doubler. Due to the typically poor conversion efficiency of the frequency doubler at low power levels, hundreds of milliwatts of infrared typically nm light are required for generating a few milliwatts in the green, and the batteries will accordingly not last very long, unless they are comparatively heavy.

Lay persons often ask what is the range of a laser pointer is, and responding to this interest some producers specify some more or less questionable numbers. If the question is meant to be how far the light of a laser pointer can propagate, the correct answer is that there is no limit, provided that the light is not absorbed or scattered away in the atmosphere.