By John O’Hagan
Laser technology and applications sometimes march ahead of laser safety standards. Lasers have been used in the aesthetic industry for many years. The availability of low-cost 808 nm laser diodes has triggered a whole industry of home-use devices for various treatments, such as hair removal (or more correctly hair “management”) and skin rejuvenation. The lasers used are typically Class 3B, but the device is intended to be used in contact with the skin, or at least in very close proximity.
The accessible emission limits (AELs) for the laser classes are intended for eye and skin exposure. However, a number of the manufacturers of the home-use devices have interpreted the AELs as only applying to the eye. Therefore, there are several devices on the market that are considered (incorrectly) to be Class 1.
In order to carry out the process required, it is clear that the maximum permissible exposure for the skin is likely to be exceeded. However, the person receiving the treatment, which is usually self-applied, clearly expects the treatment to work.
In order to “catch up” with the technology that is already widely available in many countries across the world, the International Electrotechnical Commission (IEC) Technical Committee (TC) 76 “Optical Radiation Safety and Laser Equipment” is proposing a new laser class for the next edition of IEC 60825-1 – Class 1C. This class is intended for products used essentially in contact with the skin, but also incorporates appropriate control measures to ensure that the eyes of users and others are not at risk. As such, the AEL for Class 1 should not be exceeded if the applicator is removed from the skin or from leakage to the side of the applicator. It should also not be possible to place the applicator over the eye!
The members of TC76 are not experts in control systems for products used by the public. Therefore, joint work is in progress with IEC TC 61 Safety of Household and Similar Electrical Appliances. The proposed amendments to IEC 60825-1 state that a product may only be assigned to Class 1C if it complies with the requirements of an appropriate vertical (i.e. product-specific) standard. Such a standard is likely to be published in the IEC 60335-2-XX series.
There has been a great deal of discussion on whether Class 1C should be permitted for laser products used in contact with surfaces other than on people. Such as extension presents challenges – not least that Class 1C would mean different things depending on the application. It can also be argued that a hand-held materials processing laser used in contact with the material to be processed could be made Class 1, if the appropriate controls are incorporated. The challenge for manufacturers is how to ensure that the laser beam will be terminated quickly enough if the applicator is removed from the surface (or moves off the edge of a workpiece) and how to check that the surface is not transparent to the laser beam.