Laser pointer

laser pointerslaser lightLaser pengreen laser lightsgreen laser pointerpointertargeted by laser beams
A laser pointer or laser pen is a small handheld device with a power source (usually a battery) and a laser diode emitting a very narrow coherent low-powered laser beam of visible light, intended to be used to highlight something of interest by illuminating it with a small bright spot of colored light.wikipedia
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Laser diode

semiconductor laserdiode laserlaser diodes
A laser pointer or laser pen is a small handheld device with a power source (usually a battery) and a laser diode emitting a very narrow coherent low-powered laser beam of visible light, intended to be used to highlight something of interest by illuminating it with a small bright spot of colored light. The least expensive laser pointers use a deep-red laser diode near the 650 nm wavelength.
Laser diodes are the most common type of lasers produced, with a wide range of uses that include fiber optic communications, barcode readers, laser pointers, CD/DVD/Blu-ray disc reading/recording, laser printing, laser scanning and light beam illumination.

Laser

laserslaser beamlaser light
A laser pointer or laser pen is a small handheld device with a power source (usually a battery) and a laser diode emitting a very narrow coherent low-powered laser beam of visible light, intended to be used to highlight something of interest by illuminating it with a small bright spot of colored light.
Spatial coherence also allows a laser beam to stay narrow over great distances (collimation), enabling applications such as laser pointers and lidar.

Survival kit

emergency kitsurvival gearsurvival pack
Laser pointers make a potent signaling tool, even in daylight, and are able to produce a bright signal for potential search and rescue vehicles using an inexpensive, small and lightweight device of the type that could be routinely carried in an emergency kit.

List of laser applications

laser sightlaser sightslaser aiming module
In rare cases a dot of light from a red laser pointer may be thought to be due to a laser gunsight.
This is a low-power laser pointer used to indicate a target for a precision-guided munition, typically launched from an aircraft.

Second-harmonic generation

second harmonic generationfrequency doublingfrequency doubled
The low-cost availability of infrared (IR) diode laser modules of up to 1000 mW (1 watt) output has created a generation of IR-pumped, frequency doubled, green, blue, and violet diode-pumped solid-state laser pointers with visible power up to 300 mW.
Nevertheless, some "green laser pointer" products have become available on the market which omit the expensive infrared filter, often without warning.

Laser guidance

laser-guidedSemi-active laser homingsemi-active laser
Laser pointers are used in robotics, for example, for laser guidance to direct the robot to a goal position by means of a laser beam, i.e. showing goal positions to the robot optically instead of communicating them numerically.
Examples of proof-of-concept experiments of directing a robot by a laser pointer are shown on video.

Laser safety

Laser ClassANSI Z136class 1
In the U.S. lasers are classified by the American National Standards Institute and Food and Drug Administration (FDA)—see Laser safety#Classification for details. Such laser pointers have reportedly caused afterimages, flash blindness and glare, but not permanent damage, and are generally safe when used as intended.
Some laser pointers and measuring instruments are class 2.

Potassium titanyl phosphate

KTPKTP periodically poled KTP
The crystal is mounted on a copper block, acting as a heat sink; its 1064 nm output is fed into a nonlinear crystal (often potassium titanyl phosphate (KTP)), mounted on a heat sink in the laser cavity resonator.
KTP crystals coupled with Nd:YAG or Nd:YVO 4 crystals are commonly found in green laser pointers.

Flash blindness

flashblindnessblind from the flash of the nuclear detonationflash-blind
Such laser pointers have reportedly caused afterimages, flash blindness and glare, but not permanent damage, and are generally safe when used as intended.
Flash blindness is an either temporary or permanent visual impairment during and following exposure of a varying length of time to a light flash of extremely high intensity, such as a nuclear explosion, flash photograph, or extremely bright light, i.e. a searchlight or laser pointer or ultraviolet light.

Neodymium

Ndneodymium glassNd:glass
This lasing action is due to an electronic transition in the fluorescent neodymium ion, Nd(III), which is present in all of these crystals.
Neodymium-doped crystals (typically Nd:YVO 4 ) generate high-powered infrared laser beams which are converted to green laser light in commercial DPSS hand-held lasers and laser pointers.

Diode-pumped solid-state laser

DPSSdiode-pumpeddiode-pumped solid state lasers
The low-cost availability of infrared (IR) diode laser modules of up to 1000 mW (1 watt) output has created a generation of IR-pumped, frequency doubled, green, blue, and violet diode-pumped solid-state laser pointers with visible power up to 300 mW.
DPSSLs have advantages in compactness and efficiency over other types, and high power DPSSLs have replaced ion lasers and flashlamp-pumped lasers in many scientific applications, and are now appearing commonly in green and other color laser pointers.

2014 FIFA World Cup Group H

Group H2014 FIFA World Cupgroup stage match
At the 2014 World Cup during the final group stage match between Algeria and Russia a green laser beam was directed on the face of Russian goalkeeper Igor Akinfeev.
After the match the Algerian Football Federation was fined 50,000 CHF by FIFA for the use of laser pointers, a prohibited item in the stadium according to FIFA Stadium Safety and Security Regulations, and other violations of the rules by Algerian fans.

Coherence (physics)

coherentcoherenceincoherent
A laser pointer or laser pen is a small handheld device with a power source (usually a battery) and a laser diode emitting a very narrow coherent low-powered laser beam of visible light, intended to be used to highlight something of interest by illuminating it with a small bright spot of colored light.

Rayleigh scattering

Rayleighscatteredscattering
Higher-power and higher-frequency green or blue lasers may produce a beam visible even in clean air because of Rayleigh scattering from air molecules, especially when viewed in moderately-to-dimly lit conditions.

Infrared

IRnear-infraredinfra-red
The low-cost availability of infrared (IR) diode laser modules of up to 1000 mW (1 watt) output has created a generation of IR-pumped, frequency doubled, green, blue, and violet diode-pumped solid-state laser pointers with visible power up to 300 mW.

Helium–neon laser

HeNe laserHe-Ne laserHe-Ne
Early laser pointers were helium–neon (HeNe) gas lasers and generated laser radiation at 633 nanometers (nm), usually designed to produce a laser beam with an output power under 1 milliwatt (mW).

Nanometre

nmnanometernanometers
Early laser pointers were helium–neon (HeNe) gas lasers and generated laser radiation at 633 nanometers (nm), usually designed to produce a laser beam with an output power under 1 milliwatt (mW).

Wavelength

wavelengthswave lengthsubwavelength
The least expensive laser pointers use a deep-red laser diode near the 650 nm wavelength.

Eye

eyesoculareyeball
Slightly more expensive ones use a red-orange 635 nm diode, more easily visible because of the greater sensitivity of the human eye at 635 nm.

Blu-ray

Blu-ray DiscBDBlu-ray 3D
In early 2010 "Blu-ray" (actually violet) laser pointers at 405 nm went on sale.

Human eye

eyeeyeseyeball
The apparent brightness of a spot from a laser beam depends on the optical power of the laser, the reflectivity of the surface, and the chromatic response of the human eye.

American National Standards Institute

ANSIAmerican Standards AssociationAmerican National Standard
In the U.S. lasers are classified by the American National Standards Institute and Food and Drug Administration (FDA)—see Laser safety#Classification for details.

Code of Federal Regulations

CFRC.F.R.federal regulation
The US FDA Code of Federal Regulations stipulates that "demonstration laser products" such as pointers must comply with applicable requirements for Class I, IIa, II, or IIIa devices.

Active cooling

actively
That is because such a complex process may require temperature stabilizers and active cooling, which can't be mounted into a small-sized host.

Laser guide star

laser guide star (LGS)guide star laserlaser guide stars
Astronomical observatories use a specially tuned dye laser at 589.2 nm (yellow) to create a laser guide star for use with astronomical adaptive optics.