Lasers and their effect on health
What is a laser?
Laser stands for Light Amplification by the Stimulated Emission of Radiation. The word is commonly applied to a device that produces a beam of radiation in the optical part of the electromagnetic spectrum. A laser can be described as a variation on the fluorescent light tube by imagining a sealed tube, containing a gas or mixture of gases excited by some form of energy.
Instead of gas, some lasers incorporate a solid material such as ruby, a liquid dye or chemicals. Different substances will produce beams of different wavelengths and colours. Lasers can vary considerably in size from devices that occupy a number of rooms to a tiny semiconductor chip.
What are the safety issues from the use of lasers?
The laser beam may cause eye or skin injury. The damage it causes depends on the power or energy and wavelength of the laser beam, the size of the beam and the part of the body it strikes. However, it is generally possible to contain the laser beam so that people are not exposed. Other hazards, known as non-beam hazards, include high voltages, fumes from materials processing, liquid cooling systems, the weight of the laser and its associated support systems and mechanical hazards. Some lasers use chemicals that may be toxic or carcinogenic.
What is a safe level of laser radiation?
The maximum permissible exposure (MPE) is considered a level at which injury is unlikely to occur. The International Commission on Non-ionizing Radiation Protection (ICNIRP) have reviewed the data from experimental studies and published guidance for exposure limits. Values are expressed as a function of the wavelength of the laser beam and the exposure duration for both the eye and the skin. As an example, the MPE for a single accidental exposure to a laser beam with a wavelength between 400 and 700 nm is 25 watts per square metre. The exposure limits are adopted by the Standards’ bodies as Maximum Permissible Exposure (MPE) values.
Why is it called laser radiation?
The term 'radiation' means that the beam radiates out from the laser. If the beam is in the wavelength range 400 to 700 nm, then the term 'laser light' is often used because the beams are visible to the naked eye. Beams emitted below 400 nm or above 700 nm are invisible. The wavelength range from 100 nm to 1 mm is called optical radiation. Wavelengths less than 100 nm are called x-rays and gamma rays; wavelengths above 1 mm are called radiowaves.
1 nm (nanometre) is 1/1,000,000,000 of a metre.
Does laser radiation make things radioactive?
The use of the term radiation has occasionally led to a misconception that lasers make things radioactive. Normal applications do not have powerful enough beams to exceed the energy threshold for this. Only a few large research lasers have the ability to potentially make target materials slightly radioactive. The term radiation is used because the beam radiates out from the laser.
Why is the Health Protection Agency interested in lasers?
Lasers moved into the “public” arena in the early 1970s when they were first used in barcode scanners in supermarkets. The remit of the National Radiological Protection Board (NRPB) was extended in 1974 to include the so-called non-ionising radiations, including laser beams. NRPB has played an active role in the development of international, European and British Standards since 1974. It has also contributed to the production of a number of application-specific guidance documents. The experience gained by staff who advise a broad laser user community helps to feed back into the development of laser safety standards. NRPB has also provided advice to a number of government departments. NRPB has joined with Loughborough University to produce a series of laser safety training courses. In April 2005 NRPB merged with the Health Protection Agency and now forms the Radiation Protection Division of HPA.
Last reviewed: 4 September 2008
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