Absolute Exposure Limit

Description

Learned of Absolute Exposure Limit (AEL) in Laser and Radiation Safety

The term of Absolute Exposure Limit, or just AEL, is crucial in the field of laser safety, optical instruments, and devices in the industrial or medical field for safety regulations. You will find it helpful to know what AEL means if you’re working in an industry related to medical equipment, laser manufacturing, photography, telecommunications, or scientific research so as to ensure the safety of people and things.

What is the Absolute Exposure Limit?

AEL or Absolute Exposure Limit is the maximal exposure to radiation or energy from a laser or optical source considered safe over a specified time. This is in essence, a protective cap from receiving injuries from lasers or other intense radiation that may harm the eye or skin. We use AEL as an arbitrary lumping of laser products into classes. Normally operating safely implies that a laser is safe if it does not emit energy higher than the AEL for its class; otherwise, it should be appropriately labeled or enclosed. There is the analogy of having the sun out on a bright day. Minimal exposure shouldn’t be bad, and it might as well be good for you. Directly looking at the sun or remaining in it will have hurt your skin or eyes. AEL also marks that particular level at which exposure to artificial light or radiation becomes harmful.

Who Determines AEL Values?

AEL values are not arbitrary, as internationally and nationally recognized safety organizations define them. The most notable of these organizations is the International Electrotechnical Commission (IEC). In the United States, a major contributor to the establishment of these rules is the American National Standards Institute (ANSI). These organizations conduct studies and determine AEL values for various classes of lasers on parameters like:

• Wavelength of the laser
• Duration of exposure
• What kind of exposure is it for the eyes or skin?
• Beam size and power output

AEL’s Units

• Power in watts or milliwatts
• Joules for power
• For area, square centimetres

For example, a laser of a certain type may be rated at an AEL of one milliwatt per square centimetre for one second. Any higher output is dangerous therefore likely to cause harm to a person.

Classification of Lasers and AEL

Lasers are categorized into five classes defined by the potential for hazards including Class One, Class Two, Class Three A, Class Three B, and Class Four. Each class has its AEL benchmark:

• Class 1 lasers are lower than the AEL. Normally safe to use without protection.
• Class 2 lasers can be viewed for a short time when their output is below the AEL. It is believed the eye blink response serves in a protective capacity.
• Grade Three B and Grade Four exceed the AEL limits. Safety precautions should include the wearing of safety glasses, confinement within an enclosure, and the displaying of caution signs.

Therefore, AEL is the demarcation line between safe and dangerous laser handling.

Why AEL is Important

There are numerous reasons why it becomes important to know and follow AEL criteria:

• Safety of Human Beings
  Exposure to lasers is capable of causing skin damage, damaging the eye’s retina, and others. AEL ensures that a device does not overly consume energy.
• Following the Rules and Laws
  To get safety certifications and comply with the law, manufacturers need to adhere to AEL rules. Failure to do so can lead to legal action and products’ prohibition.
• Making Things Safe to Use
  AELs added to the engineers’ and designers’ device-making trade that works yet fairly safe to be used.
• Safety and Training Procedures
  Employees in laboratories and manufacturing facilities should be familiar with AEL so that they can comply with proper usage rules and wear appropriate safety attire.

Examples from the Real World

• Surgical lasers for skin treatments
  The surgical laser for skin treatment must emit energy at an AEL over short periods of time to avoid damaging deeper tissues.
• Barcode readers
  These are devices that use lasers but at a very low AEL for short periods, so they are safe to be used in public places.
• Laser Pointers
  To ensure safety, it is advisable that the AEL of consumer laser pointers should not go beyond the Class Two or Class Three level – as injury could be caused when one inadvertently shines the laser into their eye for just a moment.
• Gadgets meant for industrial or military application in the field
  Some lasers go beyond the AEL because of their very high power. Such lasers will require very stringent safety systems and user training.

Conclusion

The Accessible Emission Limit is the vital concept in ensuring use of lasers and other optical radiation devices, most importantly safely. Concerning science and law, it lays a boundary between safe exposure and exposure which would be termed potentially dangerous. AEL would allow mature use of advanced technologies, either by technicians, designers, doctors, or just ordinary people. Lasers, among strong sources of energy, require precaution. This begins with understanding one’s limits and not exceeding them.