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 four years. This depends on several factors such as careful treatment, proper care, and 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 rough production environment.
Glasses that show any damage whatsoever (e.g. a damaged or scratched filter, colour changes in the filter, damaged metal enforcement of the frames) should not be used. If you are in doubt, please contact our technical support for a safety inspection of your glasses.
Can you repair laser safety glasses?
Of course laservision repairs its own frames and replaces damaged filters. Please contact laservision or one of our customer representatives by phone, fax or mail for details.
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 in relation to the specified protection level and the energy or power density of the laser. The European legislation (EN 207) requires that a filter must withstand a direct hit from the laser for which it was designed for under defined conditions for 10 seconds (continuous wave mode) or 100 pulses (pulsed mode). If there is no filter available that fulfils these requirements, wequote (based on the EN 60825) a filter that comes as close as possible to these requirements. This means that the Optical Density (OD) is always correct, but the resistance time of 10 seconds/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 the filter will withstand a direct hit. It is necessary to calculate the damage threshold – which is the highest value that the material can withstand. The unit is power or energy density, i.e. the power or energy per square metre. For this calculation the pulse energy or average power of the laser and the beam area is needed. Without the diameter it is neither possible to calculate the beam area nor the energy or power density. Therefore it is impossible to know what the filter has to withstand in case of a direct laser hit.
Can I see the laser beam with the glasses?
The laser beam itself cannot be seen; what might be seen by visible laser wavelength is mostly the 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 (EN 207). Such filters protect against laser radiation of the specified wavelength or wavelengths ranges and absorb or reflect the beam completely. So the beam spot even of visible laser radiation is not visible anymore. 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 generated. Please check carefully whether the marking of the lasersafety
eyewear matches the requirements of the laser.
The protection of carefully selected eyewear will remain stable when hit by the laser throughout a minimum period of 10 seconds and 100 pulses under standardised conditions. Nevertheless, it is under no circumstances advisable to look into the beam directly.
What can I do when I have to align my visible laser? Do I have to put down my glasses?
Never put down your laser safety glasses when working with lasers above class II. There are so called alignment glasses available for this purpose, (acc. to EN 208 for 400 – 700 nm 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 (see laser class 2). It must be taken care, that the average power of the laser does not exceed the power (R – protection level) given on the glasses.
Can I look right into the laser beam with my laser safety glasses?
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 look into the laser, but only for minimum 10 seconds/100 pulses.
You have quoted red filters. Can I have the glasses with a different colour?
The colour of absorption filters cannot be chosen at random, but depends on the wavelength the filters protect against. To protect against wavelengths in the UV-region or the lower visible (blue radiation), 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 the colour. Always make sure that the quoted or available pair of glasses matches the requirements of your laser.
Pure coated filters (interference structure on clear substrates), do not affect the colour recognition and possess a high daylight transmission additionally.
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 standard. 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. 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 application (different wavelength or different power/energy than calculated before) may cause the loss of your eyesight.
Why is there no pair of glasses covering all my lasers?
The radiation that is visible to humans lies between 380–780 nm (the exact limits are different in each person). In order to cover all lasers you would need a material that does not transmit any radiation for visible radiation, which means it is completely black. When you block all visible radiation, the only wavelengths 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.
But even if you do not want to completely block all wavelengths or have ’just a few wavelengths‘ to cover, the glasses may 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.
Do you have laser safety glasses with “Class 4”?
The term ’class 4’ is the laser classification according to EN 60825-1 and ANSI Z136.1. 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 call the laser safety help desk and a representative will assist you. The representative can also help you select the proper protective eyewear for your procedures.