Fiber Laser Safety Calculator
Output power, NOHD and eyewear OD of a bare fiber end (single-mode or multimode), on the ICNIRP 2013 eye limits.
Educational only — not compliance-grade
These pages implement the published exposure limits for the cases each one states, but they are educational tools: no laser safety officer has signed them off.
- Do not use these results alone for PPE selection, NHZ / NOHD approval, controlled-area sign-off, enclosure/interlock approval, or formal classification.
- Always verify against ANSI Z136.1, IEC 60825-1, your local procedures, and the responsible laser safety officer / CLSO.
100 mm is the closest distance at which the eye focuses (IEC 60825-1 measurement condition 3).
Output power
1000 mW
Fiber loss: 0.00200 dB
NOHD
1.66 m
Governing limit
Retina, thermal
Beam divergence, 1/e² full angle
135.5 mrad
2λ / (π w₀); equivalent NA = 0.0677
Peak irradiance at the fiber end
2.55e+6 W/cm²
Optical density needed at 10.0 cm
OD 2.33
Set by: Retina, thermal
| Limit | Aperture (mm) | H at t (J/m²) | Hazard distance |
|---|---|---|---|
| Retina, thermal | 7.00 | 500 | 1.66 m |
| Anterior eye (skin limit, 2 × in the IR) | 3.50 | 2.00e+5 | 8.00 cm |
A bare fiber end is a Gaussian beam with its waist at the end face, so its diameter at range r is √(d² + (rφ)²). Single-mode: the mode diffracts at the half-angle λ/(πw₀). Multimode: the beam fills the NA (real profiles are not Gaussian, and NA is sometimes quoted at 5 % rather than 1/e²). The limits are ICNIRP 2013 (Health Phys. 105:271) at any wavelength, for one exposure of up to t, averaged over each limit's aperture, for a point source: a core up to 150 µm seen from 100 mm subtends at most 1.5 mrad (a larger core would raise the retinal limit, so this errs safe). Connectors, splices and lensed or collimated outputs change the beam.
Exposure over limit for each eye limit against distance from the fiber end. The beam is within the limits where every line is below the dashed line; the markers are the NOHD and the viewing distance.
Model and references
Textbook approximation. A standard approximation from the literature (for example paraxial, plane-wave or Gaussian-beam), valid within the range the page states. About the tiers
Fiber end as a Gaussian waist: single-mode diffracts at λ/(πw₀), multimode fills the NA; ICNIRP 2013 eye limits averaged over each aperture (its peak if under 1 mm (1/e) on the cornea below 0.35 s, ICNIRP Table 5 note c), one exposure up to t. Real multimode profiles aren't Gaussian.
- ICNIRP (2013). Guidelines on limits of exposure to laser radiation of wavelengths between 180 nm and 1,000 µm. Health Phys. 105(3), 271–295. Tables 5 and 8. doi:10.1097/HP.0b013e3182983fd4
- ANSI Z136.1-2014, American National Standard for Safe Use of Lasers. Appendix B: nominal hazard zone, NOHD and optical density.
- IEC TR 60825-14:2004, Safety of laser products – Part 14: A user's guide. Hazard distances and protective eyewear.