Industrial Laser Safety Calculator
Direct-beam NOHD, diffuse-reflection hazard distance and eyewear OD for industrial cutting and welding lasers, 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.
NOHD of the direct beam
7.13 km
Set by: Retina, thermal
Optical density for the direct beam
OD 6.31
At the exit, set by: Retina, thermal
Reflected power ρP
1200 W
Diffuse hazard distance
2.76 m
Set by: Retina, thermal
Diffuse exposure / limit at 30.0 cm
84.9× (exceeds)
Spot subtends 0.707 mrad
Optical density for the diffuse reflection
OD 1.93
At 30.0 cm
Direct beam, by eye limit
| Limit | Aperture (mm) | H at t (J/m²) | Hazard distance |
|---|---|---|---|
| Retina, thermal | 7.00 | 500 | 7.13 km |
| Anterior eye (skin limit, 2 × in the IR) | 3.50 | 2.00e+5 | 358 m |
A specular (mirror-like) reflection is a direct beam carrying ρP: use the direct-beam values with the reflected power.
The direct-beam NOHD grows the beam as a + rφ (ANSI Z136.1, IEC TR 60825-14). It is the NOHD of the unfocused (collimated, head-off) exit beam, which is conservative; behind a focusing head the beam spreads at about (beam diameter)/f, see the medical laser safety page (lens-on-laser) for that case. A diffuse reflection is Lambertian, ρP/(πr²) beyond a few spot diameters (nearer, the Gaussian spot's exact form), and the spot is an extended source of α = d63/r, which raises the retinal limit through ICNIRP's CE with an open field of view; the retinal limits are assessed no nearer than 10 cm, where the eye stops focusing. Both use the ICNIRP 2013 limits for one exposure of up to t (0.25 s for an unintended view of a visible beam, 10 s in the near infrared, 700–1400 nm; outside 400–1400 nm ICNIRP 2013, p. 285, uses the longest exposure expected). Eyewear OD is log10(exposure / limit); the filter must also survive the beam (EN 207 damage threshold), which this page does not check. Plume, plasma radiation and fumes are separate hazards.
Direct-beam exposure over limit for each eye limit against distance from the exit. The beam is within the limits where every line is below the dashed line; the marker is the NOHD.
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
Direct-beam NOHD (a + rφ) and Lambertian diffuse reflection (extended source, ICNIRP C_E with an open field of view) on the ICNIRP 2013 eye limits, one exposure up to t. Not checked: filter damage, plume.
- 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. Table 2 and eqn 5 (C_E), 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.