Laser safety is the safe design, use and application of lasers to minimize the risk of laser accidents, especially those involving eye injuries. Because even laser light in relatively small amounts can cause permanent eye injury, laser sales and use are usually subject to government regulations.
Medium and high-power lasers are potentially dangerous because they can burn the eye's retina, or even the skin. To control the risk of injury, specifications, such as 21 Section 1040 of the Federal Regulations (CFR) Section 1040 in the US and IEC 60825 internationally, determine the laser "class" depending on their strength and wavelength. This rule imposes on the manufacturer the necessary security measures, such as labeling lasers with special warnings, and wearing laser safety glasses when operating the laser. Consensus standards, such as the American National Standards Institute (ANSI) Z136, provide users with laser hazard control measures, as well as various tables helping in calculating the maximum permissible limits (MPE) and accessible access limits (AEL).
Video Laser safety
Bahaya radiasi laser
Thermal effects are a major cause of laser radiation injury, but photo-chemical effects can also be of concern for certain wavelengths of laser radiation. Even a laser that is driven enough can cause eye injury. High-power lasers can also burn the skin. Some lasers are so strong that even the diffuse reflections from the surface can be harmful to the eye.
Coherence and low divergence angles of laser light, aided by the focus of the eyepiece, can cause laser radiation to be concentrated to a very small area of ​​the retina. A temporary increase of only 10 Â ° C can destroy retinal photoreceptor cells. If the laser is strong enough, permanent damage can occur in a fraction of a second, literally faster than the blink of an eye. A strong laser in near-infrared range (400-1400 nm) will penetrate the eyeball and may cause retinal heating, whereas laser radiation exposure with wavelengths less than 400 nm and greater than 1400 nm is largely absorbed by the cornea. and lenses, leading to the development of cataracts or burns.
Infrared lasers are very dangerous, because the rejection response of body glare, also referred to as "blink reflex," is only triggered by visible light. For example, some people who are exposed to high power Nd: YAG lasers that emit an invisible 1064 nm radiation may not feel pain or see direct damage to their eyesight. The pop or click sounds coming from the eyeballs may be the only indication that retinal damage has occurred that the retina is heated to over 100 ° C which causes localized explosive explosives accompanied by direct creation from a permanent blind spot.
Mechanism of damage
Lasers can cause damage to biological tissue, either on the eyes or on the skin, due to several mechanisms. Thermal damage, or burning, occurs when the network is heated to the point where protein denaturation occurs. Another mechanism is photochemical damage, in which light triggers chemical reactions in tissues. Photochemical damage occurs mostly with short wavelengths (blue and ultra-violet) and can accumulate for several hours. The laser pulses shorter than about 1 can cause rapid temperature rise, resulting in a boiling water explosion. The shock wave from the explosion can cause damage relatively far from the point of impact. Ultrashort pulses can also show self-focusing on the transparent eye, leading to an increased potential for damage compared to longer pulses with the same energy. Photoionization has proven to be a major mechanism of radiation damage in the use of sapphire titanium lasers.
The eyes focus the visible and near-infrared light to the retina. The laser beam can be focused on the intensity of the retina that may be up to 200,000 times higher than at the point where the laser light enters the eye. Much of the light is absorbed by the melanin pigment in the pigment epithelium just behind the photoreceptor, and causes burns in the retina. Ultraviolet light with wavelengths shorter than 400 nm tends to be absorbed by the lens and 300 nm in the cornea, where it can produce wounds at relatively low strength due to photochemical damage. Infrared light primarily causes thermal damage to the retina at near-infrared wavelengths and more front of the eye at longer wavelengths. The table below summarizes the various medical conditions caused by the laser at different wavelengths, excluding pulsed laser injuries.
The skin is usually much more sensitive to laser beams than the eyes, but excessive exposure to ultraviolet light from various sources (laser or non-laser) can cause short and long-term effects similar to sunburn, while visible and infrared wavelengths are especially dangerous because of damage thermal.
Laser and flight security
FAA researchers collected a database of more than 400 reported incidents between 1990 and 2004 in which pilots have been surprised, disturbed, while blind, or disoriented by laser exposure. This information led to an investigation in the US Congress. Exposure to hand-held laser light in such circumstances may seem trivial given the shortness of exposure, the large distances involved and the spreading of light up to several meters. However, laser exposure can create dangerous conditions such as flash blindness. If this happens during a critical moment in an aircraft's operation, the aircraft may be in danger. In addition, about 18% to 35% of the population has an autosomal dominant genetic trait, sneezing photic, causing the affected individual to experience unintended maternal joints when exposed to a sudden flash of light.
Maps Laser safety
Maximum allowed exposure
The maximum permissible exposure (MPE) is the highest power or energy density (in W/cm 2 or J/cm 2 ) from the source light which is considered safe, that is, which has a negligible probability of creating damage. Usually about 10% of doses that have 50% chance of creating damage in the worst conditions. MPE is measured in the cornea of ​​the human eye or on the skin, for certain wavelengths and exposure times.
Calculation of MPE for ocular exposure takes into account the various ways light can act on the eye. For example, deep ultraviolet light causes accumulated damage, even at very low strengths. Infrared light with a wavelength longer than about 1400 nm is absorbed by the transparent portion of the eye before it reaches the retina, which means that the MPE for this wavelength is higher than visible light. In addition to wavelength and lighting time, MPE takes into account the spatial distribution of light (from lasers or other). Wraping the laser beam from visible and near-infrared light is very dangerous at relatively low strength because the lens focuses light onto a small place in the retina. Light sources with smaller levels of spatial coherence than well-elaborated laser beams, such as high-power LEDs, cause the distribution of light over a larger area of ​​the retina. For such sources, MPE is higher than collimated laser light. In the MPE calculation, the worst-case scenario is assumed, in which the lens focuses the light to the smallest possible size of place on the retina for a certain wavelength and full open pupil. Although MPE is defined as power or energy per unit surface, it is based on the strength or energy that can pass through the fully open pupil (0.39 cm 2 ) for visible and near-infrared wavelengths. This is relevant for a laser beam that has a cross section smaller than 0.39 cm 2 . Standard IEC-60825-1 and ANSIÃ, Z136.1 include methods of calculating MPE.
Rule
In various jurisdictions, standards bodies, laws, and government regulations define the laser class according to the risks associated with them, and determine the safety measures required for those people who may be affected by the laser.
In the European Community (EC), the eye protection requirements are specified in the European standard EN 207. In addition to EN 207, the EN 208 European standard specifies requirements for eyeglasses for use during beam alignment. It transmits a portion of the laser beam, enabling the operator to see where it is, and does not provide complete protection against direct laser light. Finally, European standard EN 60825 determines optical density in extreme situations.
In the US, guidelines for the use of protective eyewear, and other elements of safe laser use, are provided in the standard ANSI Z136 series. This consensus standard is intended for laser users, and full copies can be purchased directly from ANSI or the secretariat and publisher of this standard, the American Laser Institute. The standards are as follows:
- ANSI Z136.1 - Safe Use of Lasers
- As the master document of the Z136 series of laser security standards, Z136.1 is the foundation of laser safety programs for industry, military, research and development (laboratory), and higher education (universities).
- ANSI Z136.2 - Secure Use of Fiber Optic Communication Systems Utilizing Laser Diodes and LED Sources
- This standard provides guidance for the safe use, maintenance, service and installation of optical communication systems using laser diodes or light-emitting diodes operating at wavelengths between 0.6 Ã,Âμm and 1 mm. Optical communications systems include end-to-edge fiber-based optical links, point-to-point terrestrial-free spaces, or a combination of both.
- ANSI Z136.3 - Safe Use of Lasers in Health Care
- Provides guidance for laser-working individuals High-grade 3B and Class 4 lasers and laser systems in health care (including, but not limited to: Operating room personnel designated as Laser Safety Officers )
- ANSI Z136.4 - Recommended Exercises for Laser Safety Measurements for Hazard Evaluation
- Provides guidance for the measurement procedures required for optical radiation hazard classification and evaluation.
- ANSI Z136.5 - Safe Use of Laser at Educational Institution
- This standard addresses the issue of laser security in educational settings.
- ANSI Z136.6 - Use of Outdoor Laser Safe
- This standard provides guidance for the safe use of lasers in outdoor environments, for example, construction, display/laser lightshows, scientific/astronomical research, and military (DoE/DoD).
- ANSI Z136.7 - Testing and Labeling of Laser Protector
- The objective of this standard is to provide reasonable and adequate guidance on the testing methods and protocols used to provide eye protection from lasers and laser systems.
- ANSI Z136.8 - Safe Use of Lasers in Research, Development, or Testing
- The objective of this standard is to provide guidelines for the safe use of lasers and laser systems found in a research, development or testing environment, where general safety controls for commercial lasers may be lost or disabled..
- ANSI Z136.9 - Safe Use of Lasers in the Manufacturing Environment
- Intended to protect individuals with potential laser exposure when lasers are used in manufacturing environments, these standards include policies and procedures to ensure laser safety in both public and private industries as well as product development along with testing.
Through 21 CFR 1040, the US Food and Drug Administration (FDA) regulates laser products entering the trade and requires all grade III and class IV lasers offered in US trades to have five standard safety features: lock buttons, interlock safety dongles, indicators power, aperture, and emission delays (usually two to three seconds). OEM lasers, designed to be part of other components (such as DVD burners), are excluded from these requirements. Some non-portable lasers may not have safety dongles or emission delays, but have emergency stop buttons and/or switches remotely.
Classification
Lasers have been classified by wavelength and maximum output power into four classes and several subclasses since the early 1970s. Classification categorizes lasers according to their ability to produce damage to exposed persons, from grade 1 (no harm during normal use) to grade 4 (serious harm to the eyes and skin). There are two classification systems, the "old system" used before 2002, and the "revised system" is being phased since 2002. The latter reflects the larger laser knowledge that has accumulated since the original classification system was created, and allows the type of laser to be recognized as having a hazard lower than implied by its placement in the original classification system. The revised system is part of the revised IEC 60825 standard. From 2007, the revised system was also incorporated into the US-oriented ANSI Laser Safety Standard (ANSI Z136.1). Since 2007, labeling in accordance with the revised system was accepted by the FDA on laser products imported into the US. The old and revised systems can be distinguished by the 1M, 2M, and 3R classes that are only used in the revised system and the 2A and 3A classes that are only used in the old system. The class numbers are assigned using Roman numerals (I-IV) in the US under the old system and Arabic numerals (1-4) in the European Union. The system is revised using Arabic numerals (1-4) in all jurisdictions.
The laser classification is based on the concept of accessible emission limits (AEL) defined for each laser class. This is usually the maximum power (in W) or energy (in J) that can be emitted within a certain wavelength range and the exposure time passing through a particular aperture stop at a specified distance. For infrared wavelengths above 4 m, this is determined as the maximum power density (in W/m 2 ). It is the manufacturer's responsibility to provide the right laser classification, and to equip the laser with appropriate warning labels and security measures as specified by the regulations. Security measures used with stronger lasers include key-controlled operations, warning lights to show laser light emissions, light stops or attenuators, and electrical contacts that the user can contact to stop emergency or interlock.
Revised system
Below, the main characteristics and requirements for the classification system as determined by the registered IEC 60825-1 standard, together with the required special warning labels. In addition, classes 2 and higher must have a triangular warning label shown here and other labels required in certain cases that show laser emissions, laser holes, skin hazards, and invisible wavelengths. For classes I to IV, see the old system section below.
Class 1
Class 1 laser is safe under all normal usage conditions. This means the maximum permissible exposure (MPE) can not be exceeded when viewing a laser with the naked eye or with the help of a typical magnifying optic (eg a telescope or microscope). To verify compliance, the standard specifies the aperture and the distance corresponding to the naked eye, a typical telescope that sees collimated light, and a distinctive microscope that sees different rays. It is important to realize that certain lasers classified as Class 1 can still be dangerous when viewed with a telescope or microscope with a large aperture. For example, high power lasers with very large collimation rays or very different beams can be classified as Class 1 if power passing through a hole defined in the standard is less than AEL for Class 1; However, unsafe power levels can be collected by magnifying optics with larger openings. -
Class 1M
1M Class Lasers are safe for all use conditions except when passing through optical enlargements such as microscopes and telescopes. 1M Class Lasers produce large diameter beams, or different beams. MPE for Class 1M lasers can usually not be exceeded unless focus or optical imaging is used to narrow down the file. If the rays are refocused, the dangers of 1M Class lasers can be improved and product classes can be changed. The laser may be classified as Class 1M if the force that can pass through the naked pupil is less than AEL for Class 1, but the strength that can be collected into the eye by typical magnifying optics (as defined in the standard) is higher than AEL for Class 1 and lower than AEL for Class 3B.
Class 2
Class 2 lasers are considered safe because blink reflexes (glare rejection response to bright light) will limit the exposure to no more than 0.25 seconds. This only applies to visible laser rays (400-700 Â ° nm). Laser Class-2 is limited to a continuous wave of 1 mW, or more if emission time is less than 0.25 seconds or if the light is not spatially coherent. A deliberate emphasis on blink reflexes can cause eye injury. Some laser pointers and measuring instruments are class 2.
Class 2M
Class 2M lasers are safe because of the blink reflex if not seen through optical instruments. Like the 1M class, this applies to laser beams with large diameter or large divergences, where the amount of light passing through the pupil can not exceed the limit for class 2.
Class 3R
Class 3R lasers are considered safe if handled with care, with limited light viewing. With a 3R class laser, the MPE can be exceeded, but with a low risk of injury. Continuous lasers seen in Class 3R are limited to 5 mW. For other wavelengths and for pulsed lasers, other limits apply.
Class 3B
Class 3B laser is harmful if the eye is exposed directly, but spreading reflections such as from paper or other matte surfaces are harmless. AEL for continuous laser in the wavelength range from 315m to far infrared is 0.5 W. For laser beats between 400 and 700nm, the limit is 30 mJ. Another limit applies to other wavelengths and pulsed ultrasort lasers. Eyeglass protectors are usually required where a direct view of 3B class laser beams can occur. Laser Class-3B must be equipped with a lock switch and security lock. Class 3B lasers are used in CD and DVD writers, although the author's unit itself is class 1 because the laser beam can not leave the unit.
Class 4
Class 4 is the highest and most dangerous laser class, including all lasers that exceed Class AEL 3B. By definition, a grade 4 laser can burn the skin, or cause permanent and permanent eye damage as a result of direct, spreading or indirect viewing of light. These lasers can ignite flammable materials, and thus represent the risk of fire. These dangers may also apply to indirect or non-specular reflections of light, even from surfaces that appear to be matte - which means to be very careful to control the emission path. Class 4 lasers should be equipped with keylock switch and interlock protection. Most industrial, scientific, military, and medical lasers fall into this category. Medical lasers can have different emissions and require awareness of occlusive ocular hazard distance (NOHD) and nominal ocular hazard areas (NOHA).
Old system
Safety classes in the "old system" classification are established in the United States through consensus standards (ANSIZ136.1) and federal and state regulations. The international classifications described in consensus standards such as IEC 825 (then IEC 60825) are based on the same concept but are presented with a slightly different name from the US classification.
This classification system was only slightly altered from the original system developed in the early 1970s. It's still used by US laser product safety regulations. The mentioned laser strengths are typical values. Classification also depends on the wavelength and whether the laser is pulsed or continuous. For laser classes 1 through 4, see the section on the revised system above.
Class I
Safe inherently; there is no possibility of eye damage. This can be caused by low output power (in which case eye damage is not possible even after hours of exposure), or due to enclosures that block the user's access to laser light during normal operation, such as on a CD player or laser printer.
Class II
Reflexes of the human eye (aversion responses) will prevent eye damage, unless the person is deliberately staring at the light for long periods of time. Output power may be up to 1 mW. This class only includes lasers that emit visible light. Some laser pointers are in this category.
Class IIa
A region at the low end of Class II power where the laser takes more than 1000 seconds continuously to produce burns to the retina. Commercial laser scanners are in this subclass.
Class IIIa
Lasers in this class are mostly harmful in combination with optical instruments that change the diameter of light or power density, although even without additional optical devices direct contact with the eyes for more than two minutes can cause serious damage to the retina. Output power not exceeding 5 mW. The beam power density should not exceed 2.5 mW/cm 2 if the device is not labeled "warning" warning labels otherwise warning labels of "hazards" are required. Many laser sights for firearms and laser pointers commonly used for presentations fall into this category.
Class IIIb
Lasers in this class can cause damage if the jets get into the eye directly. This usually applies to lasers that are powered from 5-500 mW. Lasers in this category can cause permanent eye damage with exposures of 1/100 of a second or more depending on laser strength. Diffuse reflections are generally harmless but specular reflections can be just as dangerous as direct exposure. Eyeglass protectors are recommended when seeing a direct beam of Class IIIb lasers can occur. Lasers at the high power end of this class can also cause a fire hazard and may burn light skin.
Class IV
Laser in this class has an output power of over 500 mW in the beam and can cause permanent damage to the eyes or the skin is severe without being enlarged by optical eyes or instrumentation. Reflection of laser light reflections can be harmful to the skin or eyes within the Nominal Hazard Zone. (The Nominal Hazard Zone is an area around the laser where applicable MPE is exceeded.) Many industrial, scientific, military and medical lasers fall into this category. Many laser pointers ("laser pointers") at this level of output are also now available in this category.
Security measure
General precautions
Many scientists involved with lasers agree on the following guidelines:
- Anyone using a laser should be aware of the risks. This awareness is not just a matter of time spent with lasers; Conversely, long-term transactions with invisible risk (such as from infrared laser light) tend to reduce risk awareness primarily due to complacency, rather than sharpening it.
- An optical experiment should be performed on an optical table with all laser beams moving in the horizontal plane only, and all the beams must stop at the edge of the table. Users should not focus on the level of the horizontal plane where the beam is in the case of the reflected block leaving the table.
- Watches and other jewelry that may enter the optical field should not be allowed in the laboratory. All non-optical objects close to the optical plane must have a matte finish to prevent specular reflections.
- Adequate eye protection should always be necessary for everyone in the room if there is a significant risk of eye injury.
- High-intensity rays that can cause fire or skin damage (especially from class 4 and ultraviolet lasers) and which are not often modified should be guided through an opaque tube.
- Beam alignment and optical components should be made at reduced light power whenever possible.
Protective goggles
Use of eye protection when operating class 3B and 4 lasers in a way that may result in more eye exposure than MPE is required in the workplace by the US Occupational Safety and Health Administration.
Protective goggles in the form of precise optical filtering can protect the eyes from reflected or scattered laser beams with the power of harmful rays, as well as from direct exposure to laser light. Glasses should be selected for special laser types, to block or thicken in the appropriate wavelength range. For example, glasses absorbing 532 nm usually have an orange look (though it should not depend solely on the color of the lens when choosing a laser eye shield), transmitting wavelengths greater than 550 nm. Such glasses will be useless as protection against lasers that emit at 800nm. In addition, some lasers emit more than one wavelength of light, and this may be a special problem with some low-frequency laser frequencies, such as 532 "nm" green laser pointers "that are generally pumped by infrared diode 808 nm lasers, as well produces a base 1064Ã ¢ Â Â Â Â Â laser light used to produce a final output of 532,, nm.If IR radiation is allowed into the light, which occurs in some green laser pointers, it will generally not be blocked by red or orange protective goggles designed for rays green or IR filtered YAG lasers and dual-frequency glasses are available to work with double-frequency YAG and other IR lasers that have visible, but more expensive, rays and IR laser-pumped green laser products do not always determine whether extra protection is required.
Glasses are assessed for optical density (OD), which is the base-10 logarithm of the attenuation factor in which the optical filter reduces the emission power. For example, glasses with OD 3 will reduce the emission power within a given wavelength range by a factor of 1000. In addition to the optical density sufficient to reduce the emission to below the maximum permissible exposure (see above), laser glasses are used where direct exposure to light may must be able to withstand the direct blow of laser light without breaking. The protective specifications (wavelength and optical density) are usually printed on eyeglasses, generally near the top of the unit. In the European Community, producers are required by European EN 207 standards to determine maximum power ratings rather than optical density.
Interlock and auto-shutdown
Interlock is a circuit that stops the laser beam if some conditions are not met, such as if the laser casing or door of the room is open. Lasers Class 3B and 4 usually provide connections for external interlock circuits. Many lasers are considered class 1 simply because of the light contained in interlocked cages, such as DVD drives or portable CD players.
Some systems have electronics that automatically turn off the laser under other conditions. For example, some fiber optic communication systems have circuits that automatically shut off transmission if a fiber is broken or damaged.
Laser security
In many jurisdictions, an organization operating a laser shall appoint a laser safety officer (LSO). The LSO is responsible for ensuring that safety rules are followed by all other workers within the organization.
Laser pointer
In the period 1999 to 2016, increased attention has been paid to the risks posed by so-called laser pointers and laser pens. Typically, laser pointer sales are limited to grade 3A (& lt; 5 mW) or grade 2 (& lt; 1 mW), depending on local regulations. For example, in the US, Canada and the UK, Class 3A is the maximum permitted, unless key-driven controls or other safety features are provided. In Australia, class 2 is the maximum allowed class. However, because enforcement is often not too tight, class 2 laser pointers and above are often available for sale even in countries where they are not allowed.
Van Norren et al. (1998) can not find an example in the medical literature of a class III laser that causes vision impairment. Mainster et al. (2003) gave one case, an 11-year-old boy who temporarily damaged his vision by holding about 5 mW of red laser pointer close to his eyes and staring into the light for 10 seconds; he had a scotoma (blind spot) but recovered completely after three months. Luttrull & amp; Hallisey (1999) described a similar case, a 34-year-old male staring at a red laser grade IIIa 5 mW for 30 to 60 seconds, causing temporary central scotoma and visual field loss. His eyesight fully recovered within two days, at the time of his eye examination. An intravenous fundus fluorescein angiogram, a technique used by ophthalmologists to visualize the retina of the eye in fine detail, identifies subtle color changes of the fovea.
Thus, it appears that a short 0.25 second exposure to suchMW lasers as found in red laser pointers poses no threat to eye health. On the other hand, there is the potential for injury if a person deliberately stares into a class IIIa laser beam for a few seconds or more from close range. Even if an injury occurs, most people will fully recover their vision. The discomfort experienced more deeply than this may be psychological rather than physical. With regard to green laser pointer the time of safe exposure may be less, and with higher laser laser-powered permanent damage should be expected. This conclusion must be qualified by recent theoretical observations that certain prescription drugs may interact with some wavelengths of laser light, leading to increased sensitivity (phototoxicity).
In addition to physical eye injury problems from laser pointers, some other undesirable effects may occur. These include short-lived flash blindness if the beam is encountered in dark environments, such as when driving at night. This can cause a loss of vehicle control for a moment. Laser pointing to an aircraft is a danger to the flight. A police officer sees a red dot on his chest can conclude that snipers aim at him and take aggressive action. In addition, the shock reflex shown by some people exposed unexpectedly to such laser beams has been reported to have resulted in cases of self-injury or loss of control. For this and similar reasons, the US Food and Drug Administration has suggested that laser pointers are not toys and should not be used by minors except under the adult direct supervision.
Fiber optics for communication
Optical fiber laser security is characterized by the fact that in normal operation light beam is inaccessible, so something must be removed or damaged in order to be accessible. The resulting beam output is quite different, so the safety of the eye is highly dependent on distance, and if the magnifying device is used.
In practice, unintentional exposure to most installed systems is unlikely to have a health impact, as power levels are usually below 1 mW and wavelengths in infra-red, ie. Class 1. However, there are some notable exceptions.
Most single mode/multi mode fiber systems actually use infra-red light, not visible to the human eye. In this case, there is no 'eye response. â € A special case is a system that operates at 670-1000m, where the rays may appear dull red, even if the beam of light is very intense. Technicians can also use red lasers for error discovery around 628-670 nm. This can create significant harm if viewed improperly, especially if they are abnormal high strengths. Such seemingly visible mistakes are usually classified as Class 2 to 1 mW, and Class 2M to 10 mW.
High-power optical amplifiers are used in remote systems. They use an internal pump laser with a power level of up to several watts, which is a big danger. However this power level is contained in the amplifier module. Any system that uses a typical optical connector (ie, not an expanded beam) usually can not exceed 100 mW, above that the single level power mode connector becomes unreliable, so if there is a single mode connector in the system, the design power level will always below this. level, even if no other details are known. An additional factor with this system is that light around the wavelength of 1550m (common for optical amplifiers) is considered a relatively low risk, since eye fluids absorb light before it is focused on the retina. This tends to reduce the overall risk factor of the system.
Optical microscopes and magnifying devices also present unique security challenges. If optical power exists, and a simple magnifying device is used to check the fiber ends, the user is no longer protected by light irregularities, since all rays can be imaged to the eye. Therefore, a simple magnifying device should not be used in such situations. An inspection microscope optical connector is available which incorporates a blocking filter, which greatly improves eye safety. The latest design also incorporates protection against lasers looking for red errors.
Danger non-beam - electricity and others
While most laser hazards originate from the light itself, there are certain non-beam hazards that are often associated with the use of laser systems. Many lasers are high voltage devices, usually 400 V upwards for small 5 mJ pulsed lasers, and exceed many kilovolts in high powered lasers. This, coupled with high-pressure water to cool the laser and other associated electrical equipment can create a greater danger than the laser beam itself.
Electrical equipment should generally be installed at least 250 mm (10 inches) above the floor to reduce the risk of electricity in case of flooding. Optical tables, lasers, and other equipment should be properly grounded. Interlock covers should be respected and special precautions taken during troubleshooting.
In addition to electrical hazards, lasers may pose a chemical, mechanical, and other hazard specific to a particular installation. Chemical hazards may include intrinsic materials in lasers, such as beryllium oxide in argon laser laser tubes, halogens in excimer lasers, organic dyes dissolved in toxic or combustible solvents in dye lasers, and heavy metal vapors and asbestos insulation in helium cadmium lasers. They may also include materials that are removed during laser processing, such as metal fumes from cutting or surface metal treatment or complex mixtures of decomposition products produced in high energy plasma from laser cutting plastics.
Mechanical hazards may include moving parts in vacuum and pressure pumps; explosion or explosion flashlamps, plasma tubes, water jackets, and gas handling equipment.
High temperatures and fire hazards can also occur due to the operation of Class IIIB or Class IV Laser high power.
In commercial laser systems, hazard mitigation such as the presence of mixed plugs, heat breakers, and pressure relief valves reduces the danger, for example, the steam explosion arising from an unobstructed water cooling jacket. Interlocks, window coverings, and warning lights are often an essential element of modern commercial installations. In older lasers, experimental and hobby systems, and removed from other equipment (OEM units) special care must be taken to anticipate and reduce the consequences of abuse as well as various modes of failure.
See also
- Laser and flight safety
- Audience scanning - the use of lasers in light shows, where they are purposely directed to the audience to create special effects
References
External links
- Laser safety fact sheet (University of Kentucky)
- US Navy Laser Security Website
- OSHA Technical Manual Part III, Chapter 6, Laser Security
- Laser safety resources (Vanderbilt Environmental Health & Safety)
- OSHA Web page on Laser Hazard
- "ANSI Z136 Standard: The Foundation of a Successful Laser Safety Program". American Laser Institute .
- "The Truth About Lasers in Skin Care". Women's Health and Fitness .
Source of the article : Wikipedia
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