At present, the main safety grades of laser protective glasses in the world are the ANSI Z136 standard of the United States and the EN207 standard of the EU CE certification.
American ANSI Z136.1
The ANSI Z136.1 standard is relatively simple and intuitive to express the transmittance of the laser, which is measured by optical density (OD, Optical Density). Optical density indicates the ability of laser protective glasses to withstand laser radiation, which is inversely proportional to the logarithm of transmittance. Taking the light transmittance as 1% as an example, the optical density D is OD2+.
European EN 207
The European EN 207 standard requires the CE mark on the protective glasses, and the LB grade specification must be printed on the lens. The LB level consists of 3 parts: wavelength range, laser mode name and scale number. The wavelength range engraved on laser safety glasses is in nanometers.
The laser mode is divided into four modes: D, I, R and M according to the pulse time.
When selecting laser safety glasses, users need to judge whether the laser safety glasses meet the minimum protection level requirements for a given laser according to the ratio (Ln), wavelength range, and laser mode name, as shown in the following table EN207 laser safety level and standards. If the L-level of the laser goggles is segmented, it needs to be confirmed in combination with its own use. In addition, a wavelength range preceded by a greater than symbol indicates that the mode and ratio apply to light having wavelengths greater than the minimum wavelength of the range and less than or equal to the maximum wavelength of the range. For example, if a lens is rated 530-570 D L5 plus >570-700 D L6, it will be D L5 at 570 nm and D L6 at wavelengths greater than 570 nm and less than or equal to 700 nm.
For example, 180-315 D L5 means that the glasses are suitable for protecting the wavelength band 180-315nm, and the applicable laser is a laser with a pulse time greater than 0.25s. The maximum power density (maximum power/spot area) or energy density (maximum pulse energy/spot area) of the laser output is 1*10^2 W/m^2.
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