Editing Laser (section)

== Safety ==
{{Main|Laser safety}}

{{multiple image |width=155 |image1=DIN 4844-2 Warnung vor Laserstrahl D-W010.svg |alt1=European laser warning symbol |image2=Laser label 2.jpg |alt2=US laser warning label |footer=Left: European laser warning symbol required for Class 2 lasers and higher. Right: US laser warning label, in this case for a Class 3B laser}}

Even the first laser was recognized as being potentially dangerous. [[Theodore Maiman]] characterized the first laser as having the power of one "Gillette", as it could burn through one [[Global Gillette|Gillette]] [[razor]] blade.<ref name="Nast Zurer 2011 e220">{{cite magazine |last=Zurer |first=Rachel |title=Three Smart Things About Lasers |magazine=WIRED |date=December 27, 2011 |url=https://www.wired.com/2011/12/st-3st-lasers/ |access-date=February 16, 2024}}</ref><ref name="Jr 2007 h824">{{cite web |last=Jr |first=John Johnson |title=Theodore Maiman, 79; harnessed light to build the world's first working laser |website=Los Angeles Times |date=May 11, 2007 |url=https://www.latimes.com/archives/la-xpm-2007-may-11-me-maiman11-story.html |access-date=February 16, 2024}}</ref> Today, it is accepted that even low-power lasers with only a few milliwatts of output power can be hazardous to human eyesight when the beam hits the eye directly or after reflection from a shiny surface. At wavelengths which the [[cornea]] and the lens can focus well, the coherence and low divergence of laser light means that it can be focused by the [[human eye|eye]] into an extremely small spot on the [[retina]], resulting in localized burning and permanent damage in seconds or even less time.

Lasers are usually labeled with a safety class number, which identifies how dangerous the laser is:
* Class 1 is inherently safe, usually because the light is contained in an enclosure, for example in CD players
* Class 2 is safe during normal use; the [[blink reflex]] of the eye will prevent damage. Usually up to 1&nbsp;mW power, for example, laser pointers.
* Class 3R (formerly IIIa) lasers are usually up to 5&nbsp;mW and involve a small risk of eye damage within the time of the blink reflex. Staring into such a beam for several seconds is likely to cause damage to a spot on the retina.
* Class 3B lasers (5–499&nbsp;mW) can cause immediate eye damage upon exposure.
* Class 4 lasers (≥ 500&nbsp;mW) can burn skin, and in some cases, even scattered light from these lasers can cause eye and/or skin damage. Many industrial and scientific lasers are in this class.
The indicated powers are for visible-light, continuous-wave lasers. For pulsed lasers and invisible wavelengths, other power limits apply. People working with class 3B and class 4 lasers can protect their eyes with safety goggles which are designed to absorb light of a particular wavelength.

Infrared lasers with wavelengths longer than about 1.4{{nbsp}}micrometers are often referred to as "eye-safe", because the cornea tends to absorb light at these wavelengths, protecting the retina from damage. The label "eye-safe" can be misleading, however, as it applies only to relatively low-power continuous wave beams; a high-power or [[Q-switched]] laser at these wavelengths can burn the cornea, causing severe eye damage, and even moderate-power lasers can injure the eye.

Lasers can be a hazard to both civil and military aviation, due to the potential to temporarily distract or blind pilots. See [[Lasers and aviation safety]] for more on this topic.

Cameras based on [[charge-coupled device]]s may be more sensitive to laser damage than biological eyes.<ref>{{cite news |last1=Hecht |first1=Jeff |title=Can Lidars Zap Camera Chips? |url=https://spectrum.ieee.org/keeping-lidars-from-zapping-camera-chips |access-date=1 February 2019 |work=[[IEEE Spectrum]] |date= January 24, 2018 |archive-date=February 2, 2019 |archive-url=https://web.archive.org/web/20190202041923/https://spectrum.ieee.org/cars-that-think/transportation/sensors/keeping-lidars-from-zapping-camera-chips |url-status=live}}</ref>