EN 207
EN 207 is a European norm for laser safety eyewear (now superseded, together with the EN 208, by the ISO 19818:2021 standard ).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. According to this standard, laser safety glasses should not only absorb laser light of a given wavelength, but they should also be able to withstand a direct hit from the laser without breaking or melting, both the filter and the frame. In this respect, the European norm is more strict than the American norm (ANSI Z 136) that  only regulates the required optical density. More precisely, the safety glasses should be able to withstand a continuous wave 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. 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 formula_1, 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. From the scale it can be inferred that the power densities that correspond to formula_3 are considered safe without protective eyewear.