Laser protective eyewear must comply with the Personal Protective Equipment Directive and associated National Regulations. Such PPE must be CE marked, conforming either to EN207 or EN 208. These standards indicate a level of protection at a specified wavelength by means of a ‘scale number’, a figure that implies a minimum optical density of the filter and its stability to a direct laser exposure. The standards provide tables that allow the selection of a suitable scale number between L1 (least protection) and L10 for blocking filters (EN207) and R1 to R5 for alignment filters (EN208).

For blocking filters, the minimum optical density (D) to provide eye protection under reasonably foreseeable worst-case laser exposure (E) is given by the equation: D = log10 (E÷MPE) where the maximum permissible exposure (MPE) is the value corresponding to the maximum reasonably foreseeable exposure time.

The reasonably foreseeable worst-case laser exposure is also required to assess the stability to laser radiation. Clearly, the eyewear must be capable of withstanding the maximum exposure for a sufficient time (taken as 10s) to allow the wearer to take evasive action. The tests for stability vary depending on whether the laser is continuous wave (CW), pulsed, giant pulsed or mode-locked, but the small test diameter (0.5 to 2 mm) specified in EN207 and EN208 implies that the 10s test time would not be achieved in practice, since laser beam diameters are generally much greater than 2 mm.

In addition to its optical protective properties it is vital that safety eyewear is comfortable to wear in the prevailing work environment. The eyewear should therefore fit properly (over spectacles if necessary) and not unduly restrict normal vision. Poorly fitting eyewear not only performs badly but the likelihood of it being used is diminished. The same is true of eyewear that is too tight, too heavy and prone to fogging. The visible light transmission should be as high as possible and must be sufficient for safe working under the prevailing ambient lighting conditions. The laser protective eyewear should be properly stored when not in use to provide protection against damage and dust. We suggest that regular and documented inspection and maintenance of the eyewear be carried out to assess and repair damage and defects due to misuse, abuse and everyday wear and tear.Laser protective eyewear must comply with the Personal Protective Equipment Directive and associated National Regulations. Such PPE must be CE marked, conforming either to EN207 or EN 208. These standards indicate a level of protection at a specified wavelength by means of a ‘scale number’, a figure that implies a minimum optical density of the filter and its stability to a direct laser exposure. The standards provide tables that allow the selection of a suitable scale number between L1 (least protection) and L10 for blocking filters (EN207) and R1 to R5 for alignment filters (EN208).

For blocking filters, the minimum optical density (D) to provide eye protection under reasonably foreseeable worst-case laser exposure (E) is given by the equation: D = log10 (E÷MPE) where the maximum permissible exposure (MPE) is the value corresponding to the maximum reasonably foreseeable exposure time.

The reasonably foreseeable worst-case laser exposure is also required to assess the stability to laser radiation. Clearly, the eyewear must be capable of withstanding the maximum exposure for a sufficient time (taken as 10s) to allow the wearer to take evasive action. The tests for stability vary depending on whether the laser is continuous wave (CW), pulsed, giant pulsed or mode-locked, but the small test diameter (0.5 to 2 mm) specified in EN207 and EN208 implies that the 10s test time would not be achieved in practice, since laser beam diameters are generally much greater than 2 mm.

In addition to its optical protective properties it is vital that safety eyewear is comfortable to wear in the prevailing work environment. The eyewear should therefore fit properly (over spectacles if necessary) and not unduly restrict normal vision. Poorly fitting eyewear not only performs badly but the likelihood of it being used is diminished. The same is true of eyewear that is too tight, too heavy and prone to fogging. The visible light transmission should be as high as possible and must be sufficient for safe working under the prevailing ambient lighting conditions. The laser protective eyewear should be properly stored when not in use to provide protection against damage and dust. We suggest that regular and documented inspection and maintenance of the eyewear be carried out to assess and repair damage and defects due to misuse, abuse and everyday wear and tear.