300px, EN207-compliant laser goggles. The user has added yellow stickers summarizing the complicated EN207 specifications shown in the inset.
EN 207 is a European norm for
laser safety eyewear (now superseded, together with the EN 208, by the ISO 19818:2021 standard ). Any laser eye protection sold within the European Community must be certified and labeled with the
CE mark
The presence of the logo on Product (business), commercial products indicates that the Manufacturing, manufacturer or importer affirms the goods' conformity with European Environment, health and safety, health, safety, and environmental prote ...
. According to this standard, laser safety glasses should absorb laser light of a given wavelength, and their filters and frames should be able to withstand a direct hit from the laser without breaking or melting. In this respect, the European norm is more strict than the American norm (ANSI Z 136), which regulates only the required
optical density
Absorbance is defined as "the logarithm of the ratio of incident to transmitted radiant power through a sample (excluding the effects on cell walls)". Alternatively, for samples which scatter light, absorbance may be defined as "the negative log ...
. More precisely, the safety glasses should be able to withstand a
continuous wave
A continuous wave or continuous waveform (CW) is an electromagnetic wave of constant amplitude and frequency, typically a sine wave, that for mathematical analysis is considered to be of infinite duration. It may refer to e.g. a laser or particl ...
laser for 5 seconds, or 50 pulses for a pulsed laser (EN 207:2017).
An EN 207 specification might read ''IR 315–532 LB6''. Here, the letters ''IR'' indicate the laser working mode, in this case a ''pulsed'' mode. The range ''315–532'' indicates the wavelength range in nanometers. Finally, the scale number ''LB6'' indicates a lower limit for the optical density, i.e. the transmittance within this wavelength range is less than 10
−6.
Laser working modes
EN 207 specifies four laser working modes:
Scale numbers
The scale numbers range from LB1 to LB10, where the number is a lower
limit for the optical density, i.e. LB''n'' means that OD > ''n'', or
, where ''T'' is the transmittance. The
minimum scale number for a given laser with a beam diameter of 1 mm
depends on the working mode and the wavelength as follows (EN 207:2017):
If the beam diameter differs from 1 mm a correction factor, depending on the material of the filter and frame, must be applied.
Another correction factor must be used for pulsed lasers in case of repeated pulses for wavelengths above 400 nm.
;Examples
# the laser operates at 1064 nm and has a pulse duration of 10 ns, 100 mJ/cm
2 (or 10
3 J/m
2). You have goggles that are specified as ''DIR 1064 LB5''. The pulse duration indicates that we should look at the ''R'' specification, with scale number ''n''=5, which gives an upper limit of 5×10
2 J/m
2, which means that these goggles do not offer suitable protection for this particular laser.
# the laser operates at 780 nm, is continuous wave with an intensity of 50 mW/cm
2 (''P'' = 500 W/m
2). This means you need a ''D'' protection level of
, which is rounded up to 2. In other words, the safety goggles should be at least ''D 780 LB2''.
# such example can be found too ''900 - 1070 D LB7 + IR LB8 + M LB8Y''.
The symbols have the same meaning as in the previous examples, just note on marking with Y:
if the eye protection device has not been tested with low repetition frequencies (≤ 25 Hz), the protection level must be extended by the letter Y .
From the scale it can be inferred that the power densities that correspond to
are considered safe without protective eyewear.
References
{{List of EN standards, state=autocollapse
#00207
Laser safety and standards