Lasers come in different power levels and types, and each carries unique safety risks. To help people use lasers safely, international standards like IEC 608251 and the US ANSI Z136.1 divide them into four main classes, with certain sub-classifications. These indicate how much protection someone needs when using or encountering a laser.
1. Why Laser Classifications Exist
Lasers can harm people—especially through the eyes or skin. To minimize risks, standards define:
Accessible Emission Limit (AEL): The maximum radiation a laser can emit for its class.
Maximum Permissible Exposure (MPE): The safe daily exposure level for eyes or skin.
Natural Aversion Response: The blink or turn-away reflex when exposed to bright visible light (~0.25 s).
If a laser’s beam could exceed safe limits, it’s placed in a higher class requiring more safety controls.
2. Class 1: Safe Under Normal Use
Definition: This class includes lasers that cannot harm a person during normal use—even with long exposure or certain failures .
Why it’s safe: The beam is either very low power or enclosed so that no radiation escapes to the user .
Common devices: DVD drives, laser printers, optical disc players.
No laser safety glasses or special controls are needed.
3. Class 1C: For Skin-Contact Medical Devices
Definition: A newer subclass from IEC 608251:2014. These lasers may exceed skin-safe exposure but are engineered so that eye safety is guaranteed.
Where used: Medical treatments (e.g., skin therapy).
Why special: They rely on design controls to prevent eye exposure while treating skin.
They don’t appear in ANSI Z136.1 but are recognized in IEC standards.
4. Class 1M: Safe Without Magnifying Tools
Definition: Safe to view with the naked eye, but may be dangerous when viewed through magnification (telescopes, binoculars, magnifying lenses) .
Why it matters: Magnifiers gather more light and can focus it into the eye above safe levels.
Devices such as wide-beam fiber-optic equipment and telecom lasers fall under this class.
5. Class 2: Low-Power, Blink Response Protects
Definition: Visible lasers (400−700 nm) that don’t exceed 1 mW in continuous power—safe if you don’t stare at them.
Protection: Natural blink reflex (<0.25 s) typically protects you.
Examples: Laser pointers, low-power alignment tools.
No magnifiers required, and safety glasses are optional; just don’t look long.
6. Class 2M: Safe to Blink, Risky with Magnifiers
Definition: Like Class 2, but it becomes hazardous if magnified—risk exists even without staring.
Why: Magnifiers concentrate beam power, reducing the blink protection.
Examples: Laser markers or pointers with wide beams.
Same visual appearance as Class 2, but with extra caution about magnifying lenses.
7. Class 3R: Low Risk, But Caution Required
Definition: Lasers that are up to 5× the safe limit, typically ≤5 mW for visible beams .
Danger level: Could harm eyes under close or steady viewing, but injury probability is low if handled correctly.
Control requirements: Basic safety measures like warning labels.
Applications: Laser sighting devices, some alignment tools.
Diffuse (scattered) beams are not considered dangerous.
8. Class 3B: Medium-Power, Potentially Dangerous
Definition: Lasers more powerful than 3R, up to 0.5 W continuous or equivalent energy in pulses.
Hazard: Direct or mirror-like/“specular” viewing is dangerous. Even reflections can injure.
Diffuse reflection: Usually safe unless power is very high.
Uses: Lab equipment, medical devices, industrial applications.
Safety glasses, interlocks, warning signs, and restricted areas are typical controls.
9. Class 4: High-Power, Serious Risks
Definition: Any laser above 0.5 W, with risks of eye damage, skin burns, fire, and even airborne contaminants from vaporized materials.
Hazards: Direct beam, reflections—both mirror-like and scattered—are dangerous.
Common uses: Industrial cutting/welding, high-power medical lasers, military/defense systems.
Controls required: Full safety protocols—enclosed areas, goggles, interlocks, exhaust systems.
10. Quick Summary of All Classes
|
Class |
Power/Exposure |
Eye Hazard |
Controls Needed |
|
1 |
≤ AEL under all conditions |
None |
Minimal; caution label |
|
1C |
AEL safe for eye, may exceed for skin |
Eye-safe by design |
Biocontrols, enclosures |
|
1M |
Naked-eye safe, not with magnifiers |
Yes, with optics |
Warning label |
|
2 |
≤ 1 mW visible |
Blink protects |
Labels |
|
2M |
≤ 1 mW visible; safe to blink but not with optics |
Yes, with optics |
Labels |
|
3R |
≤ 5 mW visible or equivalent |
Low risk |
Labels, user training |
|
3B |
≤ 0.5 W or pulse equivalent |
Hazardous direct/specular |
Goggles, restricted area |
|
4 |
0.5 W (CW) |
Severe, even diffuse |
Full laser safety program |
11. Why These Classes Matter to You
Manufacturers must label products clearly with their class and include appropriate warnings and safety features.
Users can choose devices suitable for their setting—e.g., Class 1 devices for kids and public use, Class 3B/4 for labs or cutting equipment.
Regulators and safety officers rely on these classes to require safety gear, goggles, training, and controlled areas.
12. Practical Safety Tips
Always read the laser label—it tells you the class and safety precautions.
Never stare into any laser beam, even low-powered ones.
Avoid magnifying tools when dealing with Class 1M or 2M laser beams.
For Class 3B and 4, use goggles, enclosed rooms, key switches, interlocks, warning signs, and trained personnel.
Maintain distance and control—even reflections can be harmful.
13. Summary
Laser safety classes range from safe under normal use (Class 1) to highly dangerous (Class 4).
Subclasses (1C, 1M, 2M, 3R) address specific hazards like skin exposure or magnified beams.
Knowing the class helps you know what protective gear, training, and controls are needed.
Always follow guidelines from IEC 608251 or ANSI Z136 to stay safe.
