CE / EN207 / EN208 is a standard for laser protective glasses formulated by the European Union. All laser protective glasses legally sold in Europe must pass EN207 or EN208 certification. They must bear the CE mark. It is illegal to sell non-CE certified laser protective glasses. .
Before the introduction of the CE / EN207 / EN208 standard, laser protective glasses are usually expressed in optical density (OD), especially in the United States using the ANSI Z136 standard. The characteristics of the ANSI Z136.1 standard are simple and intuitive, measured by optical density (OD, Optical Density), and intuitively reflect the blocking effect of the laser. OD6 means that the radiation at this wavelength is attenuated by 106 (1000000) times.
However, the limitation of optical density is that it does not take into account the damage threshold of the material used to protect us from laser radiation, that is, the power or energy density (W / m2 or J / m2) that the glasses themselves can withstand. The European Union CE / EN207 / EN208 standardizes this part of the damage threshold, and the optical density and damage threshold of laser protective glasses must be considered at the same time.
The method is to calculate the maximum achievable emission of the laser, divided by the maximum allowable exposure (MPE) of the laser radiation. It is assumed that the wavelength 1 type can reach a polycarbonate laser goggle with an emission limit of 10 mW and an optical density of OD6. Under all exposure conditions, this power is safe. In theory, we hope that the protective glasses can withstand laser damage of 1000000x10mW = 10kW. But in fact, we put the laser protective glasses themselves (polycarbonate material) in a laser of up to 20W or hundreds of watts, which will be damaged instantly. Optical density OD does not consider how much laser power the glasses material itself can withstand.
Therefore, the choice of laser protective glasses is not only to determine the protection wavelength range, protection level (optical density OD value), visible light transmittance (if it is too low, it needs a well-lit environment), and frame style, etc. The certification of protective glasses can be divided into CE certified laser protective glasses and non-CE certified laser glasses according to the certification. Herne recommends the use of CE certified NOIR laser protective glasses.
After the NOIR laser protective glasses are CE EN207 certified, NOIR laser goggles will be marked with various symbol parameters. The EN 207 standard first classifies the laser into four categories according to the pulse width: continuous laser, pulse mode, giant pulse mode and mode locking laser. For different laser modes, the lens and frame must reach a nominal protection level of 10 seconds or more than 100 pulses. 'LB number' refers to the L level. The higher the protection effect, the better the maximum energy density it bears. The specific value needs to be found in the EN207 standard.