LiDAR Laser Safety Calculator
Eye safety of a lidar beam (905 or 1550 nm), stationary or scanned across the eye, on the ICNIRP 2013 limits: the repetitive-pulse rule that binds, NOHD, exposure at a viewing distance and eyewear OD.
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.
Average power
2.00 W
Peak power E/τ: 2000 W
NOHD (stationary beam)
146 m
Exposures up to 10.0 s, beam a + rφ
At 10.0 m: pulse / max
172×
Max 58.2 nJ per pulse (Retina, thermal, average power)
Eyewear OD at the window
3.30
Stationary beam 3.00 mm; at 10.0 m it is 33.0 mm
Each rule for an eye at the viewing distance:
| Limit | 1. Single pulse | 2. Pulse groups (average) | 3. C_P × single pulse | Max per pulse | Your pulse / max |
|---|---|---|---|---|---|
| Retina, thermal | 2.30 µJ | 58.2 nJfull train: 2.00e+6 pulses | 306 nJC_P = 0.133, n = 2.00e+6 | 58.2 nJ | 172× (exceeds) |
| Anterior eye (skin limit, 2 × in the IR) | 445 mJ | 21.7 µJfull train: 2.00e+6 pulses | — | 21.7 µJ | 0.460× (within) |
Energies per pulse in the beam (1/e² Gaussian, averaged over each limit's aperture). Rule 3 applies to the retinal thermal limit only; "—" means the rule doesn't apply (rule 2 needs two pulses).
A lidar beam is a pulse train: the ICNIRP 2013 repetitive-pulse rules hold each pulse to the single-pulse limit, every group of pulses (up to the whole exposure) to the limit for the time it spans, and on the retina each pulse to C_P times the single-pulse limit. At 905 nm and hundreds of kHz the average-power rule binds; at 1550 nm the cornea absorbs the beam and its limit (1 mm aperture below 0.35 s, growing to 3.5 mm at 10 s) is far higher, which is why 1550 nm lidars can emit much more. 10 s is ICNIRP's exposure for unintended viewing in the near infrared.
The stationary beam is the worst case (no scanned window carries more), and what a scanner failure leaves. A scanning lidar sweeps the beam across the eye: each pass is a group of pulses, and the passes repeat at the scan rate. The scanned mode holds the pulses three ways: the pulses inside one pass as a short stationary train, each pass as one pulse of the average power (ICNIRP: scanning beams are repetitive-pulse exposures), and on the retina C_P counting the pulses within T₂ whose beam overlaps the pupil. It takes the eye on the centre of the scan line, focused on the scanner (a still retinal image, the most restrictive case), and the scan speed at the viewing distance. Checked against a sum over every window of the actual pulse energies, it is conservative by 1.0–1.6× (up to 2×; more for a narrow beam on the cornea). NOHD is the farthest distance where the beam (1/e² diameter a + rφ) still exceeds a rule, on the averaging apertures (7 mm on the retina). A beam under 1 mm (1/e diameter, d/√2 for the 1/e² d) is held to its peak on the cornea below 0.35 s (ICNIRP 2013 Table 5 note c). Not modelled: several beams (multi-channel lidars) or raster lines crossing the eye, the scan's turning points, optical aids (binoculars lengthen the NOHD), atmospheric attenuation, the IEC 60825-1 class of the product.
Pulse energy over the largest allowed energy per pulse against distance, for each eye limit, as the beam widens. The beam is within the limits where every line is below the dashed line; the NOHD is where the highest crosses it.
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
ICNIRP 2013 repetitive-pulse rules on the eye limits; round Gaussian beam widening as a + rφ, averaged over each aperture (its peak if under 1 mm (1/e) on the cornea below 0.35 s, ICNIRP Table 5 note c). Stationary beam (the worst case, a scanner failure), or scanned: the pulses within a pass (centred), each pass as one pulse of the average power times a worst-phase bound, and C_P over the pulses within T₂ whose 1/e² beam overlaps the pupil; never below the stationary beam's limit; eye on the scan line's centre with a still retinal image. Conservative by 1.0–1.6× against a sum over every window of the pulse energies (up to 2×; more for a narrow beam on the cornea). Not modelled: several beams or raster lines, turning points.
- 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. Repetitive pulse exposures (p. 287), Tables 4, 5 and 8. doi:10.1097/HP.0b013e3182983fd4
- Schulmeister, K. (2025). Extended source AEL analysis of scanned laser emission for IEC 60825-1. White paper, Ed. 2, Seibersdorf Laboratories. Pulse per pass, pass duration and energy (4.2.5, 6.2.3). seibersdorf-laboratories.at