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Laser Classifications
Science & education · Laser classifications
Class is about the eye, not the outcome.
Lasers have been classified by wavelength and maximum output power into four classes and a few subclasses since the early 1970s. The classes describe hazard — how much the beam can hurt an eye or skin — and nothing about how well a laser treats.
Classification runs from Class 1, safe under all conditions of normal use, to Class 4, a severe hazard to eye and skin. It rests on accessible emission limits (AEL): the maximum power or energy that can be emitted at a given wavelength and exposure time. It is the manufacturer’s responsibility to classify the laser correctly and to fit it with the warning labels and safety measures the regulations prescribe — key controls, warning lights, beam stops, emergency shutoffs. Two systems are in use: the pre-2002 U.S. FDA regulations and the international IEC 60825 standard. Erchonia labels its devices under both so they can be used worldwide.
- Erchonia lasers: Class 2
- Visible light, 400–700 nm
- ≤ 1 mW per diode class limit
- Blink-reflex safe
- FDA + IEC 60825
Built at Class 2 on purposeErchonia’s handhelds and scanners use Class 2 line-generating diodes: visible light the blink reflex protects against, at the low-power end where photochemistry — not heat — does the work.
4
classes, from inherently safe (Class 1) to severe hazard (Class 4)
2
the class Erchonia builds at — visible light, blink-reflex safe, no goggles for the patient
0.25 s
the human blink reflex that makes a Class 2 laser safe by design
> 500 mW
where Class 4 begins — a laser that can burn skin and ignite material
U.S. system (pre-2002 FDA)
Classes 1 to 4.
The FDA classes, with their limits for visible, continuous-wave lasers.
| Class | What it means | Protection |
|---|---|---|
| Class 1 | Safe under all conditions of normal use; the maximum permissible exposure cannot be exceeded. Includes high-power lasers that are fully enclosed. A continuous 600 nm laser emits at most 0.39 mW. | None |
| Class 1M | Safe except when viewed through magnifying optics. Large-diameter or divergent beams that refocusing could raise to a higher class. | None without optics |
| Class 2 | Safe because the blink reflex limits exposure to 0.25 s. Visible light only (400–700 nm), limited to 1 mW continuous wave. Erchonia’s lasers. | Blink reflex |
| Class 2M | Safe by the blink reflex if not viewed through optical instruments; large-diameter or highly divergent beams. | Blink reflex |
| Class 3R | Safe if handled carefully with restricted viewing; the MPE can be exceeded with a low risk of injury. Visible continuous lasers limited to 5 mW. | Care |
| Class 3B | Hazardous with direct eye exposure; diffuse reflections are harmless. Continuous output (315 nm to far infrared) limited to 0.5 W; pulsed 400–700 nm limited to 30 mJ. Protective eyewear is typically required where direct viewing may occur. | Eyewear, key switch, interlock |
| Class 4 | Every laser above Class 3B. By definition a Class 4 laser can burn the skin, cause devastating and permanent eye damage from direct or diffuse viewing, and ignite combustible materials. | Eyewear, key switch, interlock, controlled area |
International system (IEC 60825)
Classes I to IV.
The same hazard ladder, as the international standard draws it.
| Class | What it means |
|---|---|
| Class I | Inherently safe; no eye damage is possible, whether from low output or because the beam is enclosed. CD players, laser printers. |
| Class II | The aversion response prevents damage unless a person deliberately stares into the beam. Output to 1 mW; visible light only. |
| Class IIa | A low-power Class II that would need more than 1,000 seconds of continuous viewing to burn the retina. Supermarket scanners. |
| Class IIIa | Dangerous with optical instruments; output to 5 mW and beam density to 2.5 mW/cm². Firearm sights and pointers. |
| Class IIIb | Direct beam entry causes damage — 5 to 500 mW. Can cause permanent eye damage with exposures of 1/100th of a second or less; protective eyewear recommended; high-power units may burn skin or present a fire hazard. |
| Class IV | Output above 500 mW. Causes severe, permanent eye or skin damage without optical magnification; diffuse reflections are hazardous within the nominal hazard zone. |
Why it matters in the clinic
Hazard rating, not a treatment rating.
Classification describes the possible risk for eye injury and has nothing to do with efficiency in treatment.
01
No goggles, no restraint
A Class 2 laser is safe by the blink reflex. Patients — and animals — stay comfortable and unrestrained, and staff work without eyewear.
02
No burns, no cooldown
Class 4 devices work by heating; the same energy that warms can burn, which is why they need scanning, cooldown and controlled areas. Class 2 photochemistry needs none of it.
03
Cleared on the evidence
Every Erchonia indication was earned on a double-blind, placebo-controlled trial of a Class 2 device. Power was never the variable that mattered.
Read more: the power and penetration myth and the FDA clearances.
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