A laser produces a concentrated beam of light, distinct from the scattered light emitted by a conventional light bulb. Not all lasers possess the same power or carry equivalent risks. To help people understand the potential hazards, lasers are categorized into various safety classes. This article specifically examines Class 2 lasers, exploring their characteristics and the safety considerations associated with their use.
What Laser Classifications Mean
Laser classification systems exist to provide a standardized way of communicating the potential hazard level of a laser product. These classifications are based on the laser’s output power or energy and its wavelength. International standards, such as those developed by the International Electrotechnical Commission (IEC 60825-1), guide these categorizations.
The classification system ranges from Class 1, which poses no known hazard during normal operation, through increasingly powerful and potentially dangerous classes like 1M, 2, 2M, 3R, 3B, and 4. Class 2 lasers fit into the lower end of this spectrum, indicating a relatively low power output compared to higher classes.
Class 2 Laser Risks and Protections
Class 2 lasers typically have a maximum output power of less than 1 milliwatt (mW). The primary safety feature for these lasers relies on the human aversion response, specifically the blink reflex. When a bright light, like a Class 2 laser beam, enters the eye, this natural reflex causes the eyelid to close quickly, usually within 0.25 seconds. This rapid closure limits the exposure duration, generally preventing permanent retinal damage from brief, accidental exposure.
Under normal circumstances, the risk of permanent eye damage from a Class 2 laser is considered low due to this protective blink reflex. However, temporary effects can still occur. These might include flash blindness or a startle response. Staring intentionally into the beam or viewing it for prolonged periods can bypass the protection offered by the blink reflex.
Using optical instruments, such as binoculars or telescopes, to view a Class 2 laser beam significantly increases the risk. These devices can concentrate the laser light, delivering a higher power density to the retina than the eye would normally receive, thus overcoming the natural aversion response. Such actions could lead to eye strain, temporary vision disturbances, or, in extreme cases, retinal damage.
Safe Use of Class 2 Lasers
Many common devices incorporate Class 2 lasers due to their relatively low hazard profile. Examples include laser pointers, barcode scanners used in retail, and some laser levels used in construction. These devices are designed with the understanding that the blink reflex provides adequate protection for brief, unintentional exposures.
To ensure safety, certain practices should always be followed when using Class 2 lasers. Never intentionally stare directly into the laser beam, even for a short time. It is also important to avoid aiming the laser at people or animals, particularly their eyes, to prevent accidental exposure and potential startle reactions.
Care should be taken to avoid aiming Class 2 lasers at highly reflective surfaces, as the reflected beam could inadvertently strike someone’s eyes. Additionally, never aim any laser at aircraft. Keep laser devices out of the reach of children, who may not understand the potential risks or instinctively react to bright lights.