Research Lab Laser Safety Calculator
Class, NOHD, eyewear OD and diffuse-reflection hazard of a CW laser in a lab, and whether the direct beam is still hazardous at the walls (IEC 60825-1:2014 class, 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.
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.
Class (IEC 60825-1:2014)
Class 3B
NOHD, direct beam
152 m
Retina, thermal
Eyewear optical density
OD 2.73
for the 1.50 mm beam; round up
Direct beam across the room
Hazardous at every wall
room diagonal 6.40 m; beam 11.1 mm, 0.620 W/cm² peak there
Diffuse reflection hazard, white wall
4.04 mm
viewing the spot closer than this exceeds the limit
Direct-beam exposure over each eye limit against distance (log scales); above 1 the limit is exceeded.
Class: IEC 60825-1:2014 for a CW beam (naked eye and binoculars). NOHD: the distance beyond which the direct beam stays within the ICNIRP 2013 eye limits for the exposure time, averaged over each limit's aperture, with the beam spreading as d + rφ (ANSI Z136.1, IEC TR 60825-14). If it exceeds the room diagonal, the nominal hazard zone is the whole room wherever the beam can go, including after a specular reflection (mirrors, windows, optics), which keeps the beam's hazard.
The optical density brings the whole output beam within every limit (OD = log₁₀ of the exposure over the limit); the filter must also survive the beam (EN 207). The diffuse reflection is a white (Lambertian, ρ = 1) surface lit by the beam at its output size: a larger spot is a larger, safer extended source. Class 3B and 4 lasers need a laser safety officer, controlled area, interlocks and eyewear (IEC TR 60825-14, ANSI Z136.1). Not modelled: pulses, several beams at once (each beam has its own NOHD; they add only where they overlap), the skin.
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
Class: IEC 60825-1:2014 CW AELs. NOHD (d + rφ), eyewear OD and white-wall diffuse reflection on the ICNIRP 2013 eye limits for the exposure time. Not modelled: pulses, specular paths, skin, several beams.
- 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 2–5 and 8. doi:10.1097/HP.0b013e3182983fd4
- IEC 60825-1:2014. Safety of laser products – Part 1: Equipment classification and requirements. Tables 3–8 (AELs). webstore.iec.ch
- IEC TR 60825-14:2004, Safety of laser products – Part 14: A user's guide. Hazard distances, protective eyewear, controls.