The EN 208:2009 standard applies to laser conditioning filters and safety goggles. These filters and goggles are used for adjustment work on lasers and laser systems where harmful radiation occurs in the visible spectral range from 400 nm to 700 nm, as defined in EN 60825-1:2007. The filters specified in this European Standard reduce this radiation to the values defined for class 2 lasers (<= 1 mW for CW (continuous wave) lasers). This European Standard defines requirements, test methods and marking. Annex B provides selection and usage guidance. EN 207 applies to eye protection against accidental exposure to laser radiation.
EN 208 applies only to visible lasers (i.e. 400 – 700 nm wavelength range).
EN208 will adopt EN166 part, EN167 part, EN170 and other test requirements.
Standard protective eyewear typically has a high optical density (OD), such as OD 6 or higher is common, with an attenuation factor of 1,000,000 or higher. The result is that even the visible laser beam becomes invisible, and we cannot see where the beam lands.
From a safety point of view, it would be better if we could know where the beam is, as we are less likely to be exposed to it. Sometimes it is also necessary to be able to see the position of the beam for alignment purposes.
· Balances optical density between beam protection and visibility
·Protects the light beam in case of accidental direct eye contact
· Allows the wearer to see spots from the beam
· Reduce the power of the laser beam below the Class 2 limit (i.e. 1 mW for CW lasers)
· Not designed for intentional direct observation of the beam
EN 208 (Personal goggles. Goggles for adjustment work using lasers and laser systems (laser adjustment goggles)) specifies the testing and marking of laser alignment eyewear. To calculate the specs of glasses needed for laser calibration glasses, do the following:
Suitable for CW lasers (and pulsed lasers with pulse duration > 0.2 MS)
Take the CW (or average) power of the laser (if the beam is larger than 7mm, only take the power that can pass through the 7mm diameter aperture)
Find specifications from Table B1.
For pulsed lasers (pulse duration between 1 NS and 0.2 MS)
Capture energy per pulse (for beams longer than 7mm, capture energy through 7mm diameter aperture)
Multiply by the correction factor N1/4 (where N is the number of pulses in 10 seconds)
Find specifications from Table B1 below.
|scale number||Maximum power (duration > 2 x 10-4 seconds) W||Maximum energy (pulse 10-9 to 2 x 10-4 s) J|
|R1||0.01||2 x 10-6|
|R2||0.1||2 x 10-5|
|R3||1||2 x 10-4|
|R4||10||2 x 10-3|
|R5||100||2 x 10-2|
Therefore, the glasses are marked as follows:
For example. 532 0,1 W 2 x 10-5 J R2
It is important not to confuse the R2 EN208 marking with the R L2 EN207 marking etc.
The optical density of glasses with EN208 mark at the specified wavelength is shown in the table below:
|scale number||Optical density|
|R1||1 >outer diameter < 2|
|R2||2 >outer diameter< 3|
|R3||3 > outer diameter< 4|
|R4||4 > outer diameter < 5|
|R5||5 >outer diameter < 6|
Contact Person: Mrs. Nica Chow