Preview Abstract Provides requirements and specific guidance for the safe operation and maintenance of optical fibre communication systems OFCS. In these systems optical power may be accessible outside the confinements of transmitting equipment or at great distance from the optical source. This Part 2 requires the assessment of hazard levels at accessible locations as a replacement for classification according to IEC It applies to the complete installed end-to-end OFCS, including its components and subassemblies that generate or amplify optical radiation.
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Many scientists involved with lasers agree on the following guidelines:      Everyone who uses a laser should be aware of the risks.
This awareness is not just a matter of time spent with lasers; to the contrary, long-term dealing with invisible risks such as from infrared laser beams tends to reduce risk awareness, rather than to sharpen it, primarily due to complacency. Optical experiments should be carried out on an optical table with all laser beams travelling in the horizontal plane only, and all beams should be stopped at the edges of the table.
Users should never put their eyes at the level of the horizontal plane where the beams are, in case of reflected beams that leave the table. Watches, and other jewelry that might enter the optical plane, should not be allowed in the laboratory.
All non-optical objects that are close to the optical plane should have a matte finish in order to prevent specular reflections. Adequate eye protection should always be required for everyone in the room if there is a significant risk for eye injury.
Alignment of beams and optical components should be performed at a reduced beam power whenever possible. Protective eyewear[ edit ] Laser goggles The use of eye protection when operating lasers of classes 3B and 4 in a manner that may result in eye exposure in excess of the MPE is required in the workplace by the US Occupational Safety and Health Administration.
Eyewear must be selected for the specific type of laser, to block or attenuate in the appropriate wavelength range. If the IR radiation is allowed into the beam, which happens in some green laser pointers, it will in general not be blocked by regular red or orange colored protective eyewear designed for pure green or already IR-filtered beam.
Special YAG laser and dual-frequency eyewear is available for work with frequency-doubled YAG and other IR lasers which have a visible beam, but it is more expensive, and IR-pumped green laser products do not always specify whether such extra protection is needed.
In addition to an optical density sufficient to reduce beam power to below the maximum permissible exposure see above , laser eyewear used where direct beam exposure is possible should be able to withstand a direct hit from the laser beam without breaking.
The protective specifications wavelengths and optical densities are usually printed on the goggles, generally near the top of the unit. In the European Community, manufacturers are required by European standard EN to specify the maximum power rating rather than the optical density. Interlocks and automatic shutdown[ edit ] Interlocks are circuits that stop the laser beam if some condition is not met, such as if the laser casing or a room door is open.
Some systems have electronics that automatically shut down the laser under other conditions. For example, some fiber optic communication systems have circuits that automatically shut down transmission if a fiber is disconnected or broken. The LSO is responsible for ensuring that safety regulations are followed by all other workers in the organization. Van Norren et al. Mainster et al. His eyesight fully recovered within two days, at the time of his eye exam. An intravenous fundus fluorescein angiogram, a technique used by ophthalmologists to visualise the retina of the eye in fine detail, identified subtle discoloration of the fovea.
Thus, it appears that a brief 0. Even if injury occurs, most people will fully recover their vision. Further experienced discomforts than these may be psychological rather than physical.
With regard to green laser pointers the safe exposure time may be less, and with even higher powered lasers instant permanent damage should be expected. These conclusions must be qualified with recent theoretical observations that certain prescription medications may interact with some wavelengths of laser light, causing increased sensitivity phototoxicity.
Beyond the question of physical injury to the eye from a laser pointer, several other undesirable effects are possible. These include short-lived flash blindness if the beam is encountered in darkened surroundings, as when driving at night. This may result in momentary loss of vehicular control. Lasers pointed at aircraft are a hazard to aviation.
A police officer seeing a red dot on his chest may conclude that a sniper is targeting him and take aggressive action. For these and similar reasons, the US Food and Drug Administration has advised that laser pointers are not toys and should not be used by minors except under the direct supervision of an adult.
Fibre optics for communications[ edit ] Fibre optic laser safety is characterised by the fact that in normal operation the light beam is inaccessible, so something has to be unplugged or broken for it to become accessible. The resultant exit beam is quite divergent, so eye safety is highly dependent on distance, and if a magnifying device is used.
However, there are a few significant exceptions. These can create a significant hazard if viewed incorrectly, particularly if they are abnormally high power. High power optical amplifiers are used in long distance systems. They use internal pump lasers with power levels up to a few watts, which is a major hazard. However these power levels are contained within the amplifier module. Any system employing typical optical connectors i.
This tends to reduce the overall risk factor of such systems. Optical microscopes and magnifying devices also present unique safety challenges. If any optical power is present, and a simple magnifying device is used to examine the fiber end, then the user is no longer protected by beam divergence, since the entire beam may be imaged onto the eye.
Therefore, simple magnifying devices should never be used in such situations. Optical connector inspection microscopes are available which incorporate blocking filters, thus greatly improving eye safety. The most recent such design  also incorporates protection against red fault locating lasers. Non-beam hazards — electrical and other[ edit ] For general electrical safety, see High voltage. While most of the danger of lasers comes from the beam itself, there are certain non-beam hazards that are often associated with use of laser systems.
This, coupled with high pressure water for cooling the laser and other associated electrical equipment can create a greater hazard than the laser beam itself. Optical tables, lasers, and other equipment should be well grounded.
Enclosure interlocks should be respected and special precautions taken during troubleshooting. In addition to the electrical hazards, lasers may create chemical, mechanical, and other hazards specific to particular installations. Chemical hazards may include materials intrinsic to the laser, such as beryllium oxide in argon ion laser tubes, halogens in excimer lasers, organic dyes dissolved in toxic or flammable solvents in dye lasers, and heavy metal vapors and asbestos insulation in helium cadmium lasers.
They may also include materials released during laser processing, such as metal fumes from cutting or surface treatments of metals or the complex mix of decomposition products produced in the high energy plasma of a laser cutting plastics. Mechanical hazards may include moving parts in vacuum and pressure pumps; implosion or explosion of flashlamps, plasma tubes, water jackets, and gas handling equipment.
In commercial laser systems, hazard mitigations such as the presence of fusible plugs , thermal interrupters , and pressure relief valves reduce the hazard of, for example, a steam explosion arising from an obstructed water cooling jacket. Interlocks, shutters, and warning lights are often critical elements of modern commercial installations.
In older lasers, experimental and hobby systems, and those removed from other equipment OEM units special care must be taken to anticipate and reduce the consequences of misuse as well as various failure modes.
IEC System of Conformity Assessment Schemes
Safety of laser products - Part 2: Safety of optical fibre communication systems OFCS Abstract Provides requirements and specific guidance for the safe operation and maintenance of optical fibre communication systems OFCS. In these systems optical power may be accessible outside the confinements of transmitting equipment or at great distance from the optical source. This Part 2 requires the assessment of hazard levels at accessible locations as a replacement for classification according to IEC It applies to the complete installed end-to-end OFCS, including its components and subassemblies that generate or amplify optical radiation. Individual components and subassemblies that are sold only to OEM vendors for incorporation into a complete installed end-to-end OFCS need not be assessed to this standard, since the final OFCS should itself be assessed according to this standard. The objective of this Part 2 of IEC is to: - protect people from optical radiation resulting from OFCS; - provide requirements for manufacturers, installation organizations, service organizations and operating organizations in order to establish procedures and supply information so that proper precautions can be adopted; - ensure adequate warnings are provided to individuals regarding the potential hazards associated with OFCS through the use of signs, labels and instructions.