Safety goggles calculator for CW lasers
following European norm EN 207
This calculator is for a single wavelength, continuous wave (CW) laser and cannot calculate safety requirements for pulsed lasers or multiple laser wavelengths. The information is provided for educational purpose only.
Safety goggles that follow the EN 207 norm are labelled with the CE logo.
A short introduction to laser safety goggles can be found on this page.
Laser safety goggle rating calculator (CW)
USE AT YOUR OWN RISK!
Test
| λ | Wavelength | — | nm | |
| P | Power | — | mW | |
| d | 1/e Laser beam diameter | — | mm | |
| I | Intensity | 4P/(πd2) | W/m2 | |
| A | Limiting aperture 1 | f(λ) | mm | |
| t | Exposure duration 2 | Visible light: 0.25 s Invisible light: 100 s |
s | |
| Ieff | Effective intensity | 4P/(π.max(A2, d2)) | W/m2 | |
| MPE | Maximum permissible exposure 3 | g(λ,t) | W/m2 | |
| OD | Optical density required | log10(Ieff/MPE) | ||
| LB | Minimum EN207 scale number 4 | h(λ, I) |
1 f is a function given by the IEC 60825-14 (see table on p. 25 of the 60825-14)
2 values recommended by the IEC 60825-14 for direct accidental exposure (see p. 28 of the 60825-14)
3 g is a function given by the IEC 60825-14 (see table on p. 49 of the 60825-14)
4 h is a function given by the EN 207 norm (see this table)
Author: Réouven Assouly.