Radiation Safety Committee
Laser pointer hazard
Some Frequently Asked Questions
- What are Laser Pointers?
- What is LASER radiation?
- What are the categories of lasers?
- What are the hazards with Laser Pointers?
- What precautions are needed?
What are Laser Pointers?
Laser pointers are battery-powered lasers which can produce a small spot of light hundreds of metres away, but which are small enough to be concealed in the closed hand. They were first used by demonstrators to point out features in their visual aids. The latest models can project shapes like stars, circles and squares, in addition to the conventional dot. They are now more widely available, particularly to children, resulting in them becoming a nuisance and an unlikely, but possible, hazard to the eye. There have been numerous reports of people shining the laser beam into the eyes of others with the intention of, at least, distracting them. Laser beams directed at vehicle drivers or machinery operators, while not causing them eye damage, could result in serious accidents.
What is LASER radiation?
Laser devices are sources of light which differ from all other sources of light in both the mechanism of operation and in the quality of the light produced. The word "laser" is an acronym referring to a device that operates by the process of -
Light
Amplification by
Stimulated
Emission of
Radiation
The term "light" is used in the broadest sense to include the entire electromagnetic spectrum - from radiowaves to gamma rays.
Most lasers emit light in the form of a narrow beam of low divergence many times brighter than the sun. The light emitted from a laser differs from that emitted by a light bulb in that it is monochromatic (a pure colour) and it can be readily confined to a narrow beam (typical of a laser pointer) which diverges only slightly with distance. The radiant energy in a narrow laser beam can travel efficiently over large distances and may easily enter the eye and cause damage to it. The colour of light is determined by the wavelength of the light. Most laser pointers emit red light at a wavelength of about 630 nanometres.
What are the categories of Lasers?
Lasers are classified according to the hazard associated with their emissions, as defined in the Australian/New Zealand Standard AS/NZS 2211.1:1997 Laser Safety Part 1: Equipment classification, requirements and user’s guide:
- Class 1 lasers are considered safe under reasonably foreseeable conditions of operation.
- Class 2 lasers emit visible light at higher levels than Class 1, but eye protection is provided by aversion responses such as the human blink reflex.
- Class 3A lasers have higher power levels than Class 2 and the beam has a larger cross section such that the power of the beam entering the eye does not exceed the power of Class 2. This class of laser can be a hazard if optical devices such as binoculars focus the beam onto the retina.
- Class 3B (Restricted) lasers are similar to Class 3A except that the irradiance (power density) limit is increased by a factor of two.
- Class 3B lasers are sufficiently powerful to cause eye damage in a time shorter than the human blink reflex (0.25 seconds). Laser products with power output near the upper range of Class 3B may also cause skin burns.
- Class 4 lasers are high power devices capable of causing both eye and skin burns, and diffuse reflections may also be hazardous.
In 1993, the Radiation Health Committee of Australia’s National Health and Medical Research Council determined that laser pointers (and other consumer laser products) should not exceed Class 2. For visible laser emissions, a Class 2 laser is limited to a maximum power level of 1 milliwatt (mW) continuous wave emission. Unfortunately, there are laser pointers on the market with output powers well above 1 mW (that is, Class 3B). To make matters worse, some of these products are incorrectly labelled and hence their hazard potential is not known to the user. In particular, owing to different classification criteria in the U.S.A. and Australia, some lasers imported into Australia may be labelled as Class 3A when they are actually Class 3B.
What are the hazards with Laser Pointers?
Deliberate staring into a 5 mW beam is potentially damaging to the eye, although most laser pointers are of lesser power. Laser pointers should be kept away from infants and children who do not understand this risk. The natural aversion response of adults will protect their eyes from such lasers, although common sense says not to stare into the beam of any laser.
The most serious hazard from laser pointers is accidents resulting from temporary effects on the eye. Momentary viewing of the beam from a laser pointer may cause temporary flash-blindness, similar in effect to viewing a photographic flash at close range. However, unlike the photographic flash, a laser pointer can cause flash-blindness up to 50 metres or more away. For example, a driver, whose vision is unexpectedly affected, may loose control of their vehicle and have an accident, perhaps involving loss of life.
What precautions are needed?
As with other types of laser products, laser pointers should always be used safely and in accord with relevant user guidelines as specified in AS/NZS 2211.1:1997. Glass surfaces and mirror-like targets should be avoided. Children should not have unsupervised access to these devices - if such access is possible, the batteries should be removed when the pointer is not being used. Adults should be provided with training on the safe use of laser pointers.
In particular, laser pointers should never be intentionally directed towards any person and should not be used outdoors where bystanders may accidentally view the beam. Intentional exposure of another person may be treated as an assault, resulting in serious legal consequences.