Pro Lite Technology

Laser Safety Frequently Asked Questions

Frequently Asked Questions

Can I Look Directly Into the Laser Beam with my Laser Safety Glasses?

No! Laser safety glasses are designed to protect your eyes against an accidental direct hit of the laser beam. They are not designed for long-term or intra beam laser viewing conditions. A properly selected pair of glasses will protect you under standardised conditions against a direct hit by the laser, but only for minimum 10 seconds or 100 pulses. 

Do You Have Laser Safety Glasses with 'Class 4'?

The term ’class 4’ is the laser safety classification according to EN 60825-1 and ANSI Z136.1. The Class 4 designation means that this is a dangerous laser and emitted radiation is an eye, skin and fire hazard. When you work with this laser, laser protective eyewear is mandatory. This classification, however, does not include any information regarding the wavelengths or the required protection levels that the glasses must protect against. For these and other laser safety questions, please use our enquiry form or call Pro-Lite and our presentative will assist you.

How Long Will My Glasses Protect Me?

There is no simple answer to this question. Some glasses are worn-out after only one year, while others look like new after many years. This depends upon several factors such as careful treatment, proper care as well as environmental factors. A pair of glasses that are treated with care, cleaned according to instructions and used in a laboratory setting will certainly outlast a pair of glasses that are treated carelessly and perhaps even worn by several different people in a tough production environment. Glasses that show any damage whatsoever (e.g. a damaged or scratched filter, colour changes in the filter, damaged metal reinforcement of the frames) should not be used. If you are in doubt, please contact Pro-Lite for technical support and a safety inspection of your glasses.

What is the Difference Between Glasses Offered According to EN 207 and Glasses Offered According to EN 60825?

The difference is in the resistance time of the filter against a direct laser hit. The specified protection level of the filter and the energy or power density of the laser are taken into account in EN 207 which requires that a filter must withstand a direct hit from the laser for which it was designed under defined conditions for 10 seconds (continuous wave mode) or 100 pulses (pulsed mode). If there is no filter available that fulfils these requirements, we will offer a filter based on the reduced requirements of EN 60825 that comes as close as possible to meeting the requirements of EN 207. This means that the optical density (OD) of the filter will always be sufficient, but the resistance time of 10 seconds or 100 pulses cannot be guaranteed. 

Why is the Beam Diameter so Important for the Calculation of the Protection Level?

This has to do with the resistance time that the filter will withstand a direct laser hit. It is necessary to calculate the damage threshold – which is the highest value that the filter material can withstand. The unit is power or energy density, which is the power or energy per square meter. For this calculation, the pulse energy or average power of the laser and the beam area are needed. Without the diameter, it is not possible to calculate the beam area nor the energy or power density. Therefore it would be impossible to know what the filter needs to withstand in the case of a direct laser hit. 

Can I See the Laser Beam Through the Glasses?

The laser beam itself cannot be seen. What might possibly be seen with visible wavelength lasers is the beam spot where the laser beam hits an object or some scattered light from dust in the air. Laser safety eyewear is usually designed as full protection eyewear (per EN 207). Such filters protect against laser radiation at the specified wavelength or wavelengths by absorbing or reflecting the beam completely. For full protection filters, the beam spot even from visible lasers will not be visible. If it is still visible, this would mean that the protection level of the glasses is not high enough, or that secondary radiation (at a different wavelength) is being generated. Please check carefully whether the marking of the laser safety eyewear matches the requirements of the laser. The protection of correctly selected eyewear will remain stable even when directly hit by the laser throughout a minimum period of 10 seconds or 100 pulses (under standardised conditions). Nevertheless, it is extremely important to not look into the beam directly under any circumstances even using appropriate eyewear. 

How Can I Align my Visible Wavelength Laser?

Do I have to put down my glasses? Never put down your laser safety glasses when working with lasers above class 2. There are so-called alignment safety glasses available for this purpose (per EN 208) for the 400-700nm wavelength range only. These filters are suitable for aligning lasers which emit dangerous radiation in the visible spectral range. Alignment filters do not absorb or reflect the laser radiation completely. The radiation is only reduced to values below 1mW for continuous wave lasers (consistent with laser class 2). Care must be taken that the average power of the laser does not exceed the maximum power rating given on the glasses. 

You have Offered Red Filters. Can I Have the Glasses with Different Colour Lenses?

The colour of absorption filters cannot be chosen at random, but depends on the wavelengths the filters protect against. To protect against wavelengths in the UV or blue, a yellow or orange filter is usually offered. A red filter is usually used to protect against wavelengths in the green region. Please take into consideration that you may not select glasses by their colour. Always make sure that the glasses you intend to use match the requirements of your laser. LASERVISION dielectric coated filters (interference coatings on clear substrates) generally do not shift the colour of objects viewed though the glasses and also possess a high daylight transmission. 

I Have a Pair of Glasses (e.g.) for a Nd:YAG Laser. Can I Use Them for my New Laser as Well?

Before this question can be answered, you must determine the specific requirements of your new laser (wavelength, operational parameters, viewing conditions, etc.) and calculate the protection level according to the EN 207/208 standards. When these parameters are known, verify that the marking on your existing pair of glasses matches these requirements. If you are not sure, please call us or use our enquiry form. We will carry out the calculation and Check for you. PLEASE NOTE: The thoughtless use of a pair of laser safety glasses for a different laser (different wavelength or different power/energy density) may mean that your glasses do not offer sufficient protection and can lead to an eye injury or loss of your eyesight.

Why is There No Pair of Glasses Covering All of my Lasers?

The radiation that is visible to the human eye falls between 380-780nm. In order to block all lasers, you would need a material that does not transmit any visible radiation, which means it would be completely black. When you block all visible radiation, the only wavelengths that are left are invisible to the human eye. If you have several lasers in this area, then it is necessary to use several pairs of glasses in order that you can still see through the glasses. However, even if you do not want to completely block all wavelengths or have 'just a few wavelengths' to cover, the glasses may still be too dark. Usually the protection within a material slowly increases spectrally until it reaches the required protection level at a given wavelength. This means that it not only covers the required wavelength but also areas below and above it (with lower optical density). Therefore, if you want to cover several wavelengths in the visible spectrum, the optical density curves will overlap resulting in dark filters or glasses. Bear in mind that coated filters generally offer improve visible light transmission and reduced coloration compared with absorbing glass or plastic filters.

» Back - Calculating Scale Numbers for Protective Eyewear

» Next - Glossary of Terms

Related Products
Case Studies
Knowledge Base
Have a Question?

Why not use our convenient enquiry form?

> Click Here

Buy Online

This product can be ordered via the Pro-Lite on-line shop.

> Click Here

Need a measurement?

Contract measurement services are available from Pro-Lite Photometrics using this product

> Click Here