A laser pointer or laser pen is a (typically battery-powered) handheld device that uses a laser diode to emit a narrow low-power visible laser beam (i.e. coherent light) to highlight something of interest with a small bright colored spot.
The small width of the beam and the low power of typical laser pointers make the beam itself invisible in a clean atmosphere, only showing a point of light when striking an opaque surface. Laser pointers can project a visible beam via scattering from dust particles or water droplets along the beam path. 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. The intensity of such scattering increases when these beams are viewed from angles near the beam axis. Such pointers, particularly in the green-light output range, are used as astronomical object pointers for teaching purposes.
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.
There are significant safety concerns with the use of laser pointers. Most jurisdictions have restrictions on lasers above 5 Milliwatt. If aimed at a person's eyes, laser pointers can cause temporary visual disturbances or even severe damage to vision. There are reports in the medical literature documenting permanent injury to the macula and the subsequent permanent loss of vision after laser light from a laser pointer was shone at a human's eyes. In rare cases, a dot of light from a red laser pointer may be thought to be due to a Laser sight. When pointed at aircraft at night, laser pointers may dazzle and distract pilots, and increasingly strict laws have been passed to ban this.
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. Because the invisible IR component in the beams of these visible lasers is difficult to filter out, and also because filtering it contributes extra heat which is difficult to dissipate in a small pocket "laser pointer" package, it is often left as a beam component in cheaper high-power pointers. This invisible IR component causes a degree of extra potential hazard in these devices when pointed at nearby objects and people.
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. For the same optical power, green laser light will seem brighter than other colors, because the human eye is most sensitive at low light levels in the green region of the spectrum (wavelength 520–570 nm). Sensitivity decreases for longer (redder) and shorter (bluer) wavelengths. Additionally, the beam's brightness can be influenced by Rayleigh scattering, as shorter wavelengths such as blue and violet light are scattered more readily in the atmosphere making the beam more visible in the air. Laser Beam and Dot Relative Brightness Comparison by Wavelength. 405nm.com. Retrieved on 8 April 2023.
The output power of a laser pointer is usually stated in milliwatts (mW). In the U.S., lasers are classified by the American National Standards Institute ANSI classification scheme (ANSI Z136.1–1993, American National Standard for Safe Use of Lasers). and Food and Drug Administration (FDA)—see Laser safety#Classification for details. Visible laser pointers (400–700 nm) operating at less than 1 mW power are Class 2 or II, and visible laser pointers operating with 1–5 mW power are Class 3A or IIIa. Class 3B or IIIb lasers generate between 5 and 500 mW; Class 4 or IV lasers generate more than 500 mW. The US FDA Code of Federal Regulations stipulates that "demonstration laser products" such as pointers must comply with applicable requirements for Class I, II, IIIA, IIIB, or IV devices. FDA Code of Federal Regulations Title 21, Subchapter J: Radiological Health, PART 1040 – PERFORMANCE STANDARDS FOR LIGHT-EMITTING PRODUCTS. Accessdata.fda.gov. Retrieved on 15 October 2011.
The first red laser pointers released in the early 1980s were large, unwieldy devices that sold for hundreds of dollars. Today, they are much smaller and less expensive. The most common wavelengths are ca. 638 and 650 nm.
Some green lasers operate in pulse or quasi-continuous wave (QCW) mode to reduce cooling problems and prolong battery life.
An announcement in 2009 Green diode lasers a big breakthrough for laser-display tech (i-micronews.com via arstechnica.com). of a direct green laser (which does not require doubling) promises much higher efficiencies and could foster the development of new color video projectors.
In 2012, Nichia LASER Diode-NICHIA CORPORATION. nichia.co.jp and OSRAM Green Laser, Visible Laser – OSRAM Opto Semiconductors. osram-os.com developed and manufactured merchant high-power green laser diodes (515/520 nm), which can emit green laser directly.
Because even a low-powered green laser is visible at night through Rayleigh scattering from air molecules, this type of pointer is used by astronomers to easily point out stars and constellations. Green laser pointers can come in a variety of different output powers. The 5 mW green laser pointers (classes II and IIIa) are the safest to use, and anything more powerful is usually not necessary for pointing purposes, since the beam is still visible in dark lighting conditions.
Some vendors are now selling collimated diode blue laser pointers with measured powers exceeding 1,500 mW. However, since the claimed power of "laser pointer" products also includes the IR power (in DPSS technology only) still present in the beam (for reasons discussed below), comparisons on the basis of strictly visual-blue components from DPSS-type lasers remain problematic, and the information is often not available. Because of the higher neodymium harmonic used, and the lower efficiency of frequency-doubling conversion, the fraction of IR power converted to 473 nm blue laser light in optimally configured DPSS modules is typically 10–13%, about half that typical for green lasers (20–30%).
Lasers emitting a violet light beam at 405 nm may be constructed with GaN (gallium nitride) semiconductors. This is close to ultraviolet, bordering on the very extreme of human vision, and can cause bright blue fluorescence, and thus a blue rather than violet spot, on many white surfaces, including white clothing, white paper, and projection screens, due to the widespread use of optical brighteners in the manufacture of products intended to appear brilliantly the brighteners are chemical compounds that absorb light in the violet (and ultraviolet) region of the electromagnetic spectrum and re-emit light in the blue region by fluorescence. On ordinary non-fluorescent materials, and also on fog or dust, the color appears as a shade of deep violet that cannot be reproduced on monitors and print. A GaN laser emits 405 nm directly without a frequency doubler, eliminating the possibility of accidental dangerous infrared emission. These laser diodes are mass-produced for the reading and writing of data in Blu-ray drives (although the light emitted by the diodes is not blue, but distinctly violet). In mid-to-late 2011, 405 nm blue-violet laser diode modules with an optical power of 250 mW, based on GaN violet laser diodes made for Blu-ray disc readers, had reached the market from Chinese sources for prices of about US$60 including delivery.In September 2011, GaN diode laser modules capable of operating at 250mW (or 300mW pulse) with a heatsink were offered on eBay in the Industrial Lasers category at around US$60.
Red laser pointers can be used in almost any indoor or low-light situation where pointing out details by hand may be inconvenient, such as in construction work or interior decorating. Green laser pointers can be used for similar purposes as well as outdoors in daylight or for longer distances.
Laser pointers are used in a wide range of applications. Green laser pointers can also be used for amateur astronomy. Green lasers are visible at night due to Rayleigh scattering and airborne dust, allowing someone to point out individual stars to others nearby. Also, these green laser pointers are commonly used by astronomers worldwide at Star party or for conducting lectures in astronomy. Astronomy laser pointers are also commonly mounted on telescopes in order to align the telescope to a specific star or location. Laser alignment is much easier than aligning through using the eyepiece.
They may also be helpful in scientific research in fields such as photonics, chemistry, physics, and medicine.
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. This intuitive interface simplifies directing the robot while visual feedback improves the positioning accuracy and allows for implicit localization.
Laser pointers are a popular plaything for pets (e.g. cats, ferrets and dogs) whose natural predatory instincts are triggered by the moving laser and will chase it and/or unsuccessfully try to catch it as much as possible, providing entertainment for the pet owner as well.
However, laser pointers have few applications beyond actual pointing in the wider entertainment industry, and many venues ban entry to those in possession of pointers as a potential hazard. Very occasionally laser gloves, which are sometimes mistaken for pointers, are seen being worn by professional dancers on stage at shows. Unlike pointers, these usually produce low-power highly divergent beams to ensure eye safety. Laser pointers have been used as props by magicians during magic shows.
As an example of the potential dangers of laser pointers brought in by audience members, at the Tomorrow Land Festival in Belgium in 2009, laser pointers brought in by members of the audience of 200 mW or greater were found to be the cause of eye damage suffered by several other members of the audience according to reports about the incident filed on the ILDA (International Laser Display Association's) Web site. laserist.org. laserist.org. Retrieved on 15 October 2011. The report says that the incident was investigated by several independent authorities, including the Belgium police, and that those authorities concluded that pointers brought in by the audience were the cause of the injuries.
Laser pointers can be used in hiking or outdoor activities. It can be used as a rescue signal in emergencies which is visible to aircraft and other parties, during both day and night conditions, at extreme distances. For example, during the night in August 2010 two men and a boy were rescued from marshland after their red laser pen was spotted by rescue teams. UK Marine and Coastguard Agency . Nds.coi.gov.uk. Retrieved on 15 October 2011.
According to an MSNBC report there were over 2,836 incidents logged in the US by the FAA in 2010. Illumination by handheld green lasers is particularly serious, as the wavelength (532 nm) is near peak sensitivity of the dark-adapted eye and may appear to be 35 times brighter than a red laser of identical power output.
Irresponsible use of laser pointers is often frowned upon by members of the laser projector community who fear that their misuse may result in legislation affecting lasers designed to be placed within projectors and used within the entertainment industry. Others involved in activities where dazzling or distraction are dangerous are also a concern.
Another distressing and potentially dangerous misuse of laser pointers is to use them when the dot may reasonably be mistaken for that of a laser gun sight. Armed police have drawn their weapons in such circumstances.
Studies have found that even low-power laser beams of not more than 5 mW can cause permanent retinal damage if gazed at for several seconds; however, the eye's blink reflex must be intentionally overcome to make this occur. Such laser pointers have reportedly caused , flash blindness and glare, Princeton University: Safety Recommendations for Laser Pointers. Web.princeton.edu. Retrieved on 15 October 2011. but not permanent damage, and are generally laser safety when used as intended.
A high-powered green laser pointer bought over the Internet was reported in 2010 to have caused a decrease of visual acuity from 6/6 to 6/12 (20/20 to 20/40); after two months acuity recovered to 6/6, but some retinal damage remained. The US FDA issued a warning after two it received of eye injury from laser pointers.
Laser pointers available for purchase online can be capable of significantly higher power output than the pointers typically available in stores. Dubbed "Burning Lasers", these are designed to burn through light plastics and paper, and can have very similar external appearances to their low-power counterparts.Gordon, Serena (8 September 2010) Kids Playing With Laser Pointers May Be Aiming for Eye Trouble; Teen boy damages retina with Internet-purchased 'toy,' doctors say . Bloomberg BusinessWeek Because of their high power, many online retailers have warned high-power laser pointer users not to point them at humans or animals.
Studies in the early twenty-first century found that the risk to the human eye from accidental exposure to light from commercially available class IIIa laser pointers having powers up to 5 mW seemed rather small; however, prolonged viewing, such as deliberate staring into the beam for 10 or more seconds, can cause damage.
The UK Health Protection Agency warns against the higher-power typically green laser pointers available over the Internet, with power output of up to a few hundred milliwatts, as "extremely dangerous and not suitable for sale to the public." UK Health Protection Agency Information Sheet on Laser Pointers . Hpa.org.uk (21 May 2010). Retrieved on 2011-10-15.
Though the IR from a DPSS laser is less collimated, the typical neodymium laser in such lasers do produce a true IR laser beam. The eye will usually react to the higher-powered visible light; however, in higher power DPSS lasers the IR laser output can be significant. What poses a special hazard for this unfiltered IR output is its presence in conjunction with laser safety goggles designed to only block the visible wavelengths of the laser. Red goggles, for example, will block most green light from entering the eyes, but will pass IR light. The reduced light behind the goggles may also cause the pupils to dilate, increasing the hazard to the invisible IR light. Dual-frequency so-called YAG laser eyewear is significantly more expensive than single frequency laser eyewear, and is often not supplied with unfiltered DPSS pointer style lasers, which output 1064 nm IR laser light as well. These potentially hazardous lasers produce little or no visible beam when shone through the eyewear supplied with them, yet their IR-laser output can still be easily seen when viewed with an IR-sensitive video camera.
In addition to the safety hazards of unfiltered IR from DPSS lasers, the IR component may be inclusive of total output figures in some laser pointers.
Though green (532 nm) lasers are most common, IR filtering problems may also exist in other DPSS lasers, such as DPSS red (671 nm), yellow (589 nm) and blue (473 nm) lasers. These DPSS laser wavelengths are usually more exotic, more expensive, and generally manufactured with higher quality components, including filters, unless they are put into laser pointer style pocket-pen packages. Most red (635 nm, 660 nm), violet (405 nm) and darker blue (445 nm) lasers are generally built using dedicated laser diodes at the output frequency, not as DPSS lasers. These diode-based visible lasers do not produce IR light.
In 1998, an audience member shone a laser at Kiss drummer Peter Criss's eyes while the band was performing "Beth". After performing the song, Criss nearly stormed off the stage, and lead singer Paul Stanley ripped into whoever had been manipulating the laser light:
According to FIFA stadium safety and security regulations, laser pointers are prohibited items at stadiums during FIFA football tournaments and matches. FIFA Stadium Safety and Security Regulations — see page 96, "g" They are also prohibited in matches and competitions organised by UEFA. UEFA Disciplinatory Regulations — see page 9, "2.d" In 2008 laser pointers were aimed at players' eyes in a number of sport matches worldwide. Olympique Lyonnais was fined by UEFA because of a laser pointer beam aimed by a Lyon fan at Cristiano Ronaldo. – Laser Zap Leads to Soccer Fine. Blog.wired.com (22 March 2008). Retrieved on 2011-10-15. In a World Cup final qualifier match held in Riyadh, Saudi Arabia between the home team and the team, South Korean goalkeeper Lee Woon-Jae was hit in the eye with a green laser beam. kfa.or.kr/sportalkorea – 사우디 관중, 이운재에 레이저 포인터 공격 (includes a photograph showing a laser beam shining upon the goalkeeper's face) 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 Swiss franc50,000 (approx. Pound sterling33,000/Euro41,100/US$56,200) by FIFA for the use of lasers and other violations of the rules by Algerian fans at the stadium. During a football match in Athens between Greece and Ireland on 16 June 2023, Greek supporters were asked repeatedly over the public address system to stop shining laser beams at the Irish footballers. Ireland's Greek odyssey ends in disappointing defeat RTÉ Sport, 23-06-16.
In 2009 police in the United Kingdom began tracking the sources of lasers being shone at helicopters at night, logging the source using GPS, using thermal imaging cameras to see the suspect, and even the warm pointer if discarded, and calling in police dog teams. As of 2010 the penalty could be five years' imprisonment.
Despite legislation limiting the output of laser pointers in some countries, higher-power devices are currently produced in other regions and are frequently imported by customers who purchase them directly via Internet mail order. The legality of such transactions is not always clear; typically, the lasers are sold as research or OEM devices (which are not subject to the same power restrictions), with a disclaimer that they are not to be used as pointers. DIY videos are also often posted on Internet video sharing sites like YouTube which explain how to make a high-power laser pointer using the diode from an optical disc burner. As the popularity of these devices increased, manufacturers began manufacturing similar high-powered pointers. Warnings have been published on the dangers of such high-powered lasers. US FDA: Consumer Safety Alert: Internet Sales of Laser Products. Fda.gov (6 September 2011). Retrieved on 2011-10-15. Despite the disclaimers, such lasers are frequently sold in packaging resembling that for laser pointers. Lasers of this type may not include Laser safety sometimes found on laser modules sold for research purposes.
There have been many incidents regarding, in particular, aircraft, and the authorities in many countries take them extremely seriously. Many people have been convicted and sentenced, sometimes to several years' imprisonment. News of aviation-related incidents, arrests, etc. Laser Pointer Safety. Retrieved on 15 October 2011.
In November 2015 a 14-year-old Tasmanian boy damaged both his eyes after shining a laser pen "... in his eyes for a very brief period of time". He burned his retinas near the macula, the area where most of a person's central vision is located. As a result, the boy has almost immediately lost 75% of his vision, with little hope of recovery.
During the 2019–20 Hong Kong protests, laser pointers were used by protesters to confuse police officers and scramble facial recognition cameras. On August 6, 5 off-duty police officers arrested Baptist University student union president Keith Fong Chung-yin after he purchased 10 laser pointers in Sham Shui Po for possession of "offensive weapons". Fong said he would use the pointers for stargazing, but police described them as “laser guns” whose beams could cause eye injuries. In defence of the arrest, police said that under Hong Kong law the pointers can be deemed “weapons” if they are used in or intended for use in an attack. The incident led to a public outcry. Human rights activist Icarus Wong Ho-yin said that going by the police explanation, “a kitchen worker who buys a few knives can be arrested for being in possession of offensive weapons”. Democratic Party lawmaker and lawyer James To Kun-sun criticized the police for abuse of power. Hundreds of protesters gathered outside the dome of Hong Kong's Space Museum to put on a “laser show” to denounce police's claims that these laser pointers were offensive weapons. Fong was released unconditionally two days later.
Since 2010, it is an offence in the UK to shine a light at an aircraft in flight so as to dazzle the pilot, strict liability, with a maximum penalty of a level 4 fine (currently £2500). It is also an offence to negligently or recklessly endanger an aircraft, with a maximum penalty of five years imprisonment and/or an unlimited fine. Air Navigation Order 2009. For the strict liability offence, see paragraphs 222 and 241(6) and part B of schedule 13 of the Order. For reckless endangerment, see paragraphs 137 and 241(8) and part D of schedule 13 of the Order.
To assist with enforcement, police helicopters use GPS and thermal imaging camera, together with dog teams on the ground, to help locate the offender; the discarded warm laser pointer is often visible on the thermal camera, and its wavelength can be matched to that recorded by an event recorder in the helicopter.
All laser products offered in commerce in the US must be registered with the FDA, regardless of output power.
Public act 328 of 1931 makes it a felony for a person to "sell, offer for sale, or possess" a "portable device or weapon from which an electric current, impulse, wave, or beam may be directed" and is designed "to incapacitate temporarily, injure, or kill". "Michigan Legislature - Section 750.224a". Legislature.mi.gov. Retrieved 27 March 2013.
Colors and wavelengths
Red 638 nm, 650 nm, 670 nm Orange 593 nm Yellow 589 nm, 593 nm Green 532 nm, 515/520 nm Blue 450 nm, 473 nm, 488 nm Violet 405 nm
Red
Green
Blue
Applications
Pointing
Industrial and research use
Leisure and entertainment
Weapons systems
Hazards and risks
Incorrect power rating
Malicious use
Eye injury
Infrared hazards of DPSS laser pointers
Regulations and misuse
Australia
Canada
Colombia
Hong Kong
Netherlands
Sweden
Switzerland
United Kingdom
United States
Arizona
Michigan
Maine
Massachusetts
Utah
See also
Further reading
External links
Laserbook247
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