Laser Hazard Classes 19 January 2022

Laser Hazard Classes

Due to the fact that the eye is most vulnerable to excessive laser light, laser beams are categorized into Classes (Class1, Class2, Class3, Class4) according to their ability to harm people, particularly causing eye damage.

For visible-beam lasers, there are four basic classifications: Class1, Class 2, Class 3, and Class 4. Class 3 and Class 4 are the most dangerous for eye exposure. The illustration below demonstrates how the risk of eye damage rises as laser power is increased rises.

Please note that the classifications and safety distances for laser beams is usually calculated for unintentional exposure to the human eye. Which means the eye should not be exposed to the light for more than a quarter of a second (0.25 second), which is the delay time for the eye to blink and gets covered by the eye lid. Avoid eye exposure to direct or reflected laser beams, especially within the “Nominal Ocular Hazard Distance.” The closer you are to the beam the greater the risk of injury. All classes of laser are harmful to the eye when viewed intentionally from a close distance, whether in a unaided manner or by using optical devices like binoculars.



Laser Hazard Classes
Laser Hazard Classes


Laser Class 1 (Class I)

The first class of laser beam has a power that ranges from 0 to 0.004 milliwatts. Class 1 of laser is the safest for unaided eye exposure, which means having a direct or reflected beam enter the eye without using optical instruments like binoculars or an eye loupe. The Class 1 laser beam is usually contained within the product and is not visible to the end user, and even when it is visible it does not cause eye injury. Class 1 laser beam has no damage effect on skin or solid materials, and it is not dangerous to look at the beam reflection on a surface.

Laser Class 1M

Class 1M is a more powerful version of the Class 1 of laser beams, and it has a power that reaches up to 0.39 milliwatts. It is not harmful to the unaided eye when looked at unintentionally, but it can cause damage when viewed using optical instruments like binoculars or an eye loupe. However, when reflected on a surface, it is not dangerous to look at the “Reflected Dot”. Besides, Class 1M laser beams are not powerful enough to cause any damage to the skin or surfaces.

Laser Class 2 (Class II)

With a visible laser beam that reaches up to 1 milliwatt, Class 2 is not strong enough to cause skin injury or surface damage, and looking at its diffused reflection on a surface is not harmful. However, a Class 2 laser is strong enough to cause an eye injury if viewed directly for more than 0.25 of a second, which is the speed of an eye blinking. That is why it should only be handled while wearing eye protection glasses. This means that even if unintentional exposure may be safe, Class 2 laser beams can cause eye damage when looked at intentionally, especially when using optical instruments like binoculars or an eye loupe. Class 2 laser beams can easily cause eye injury after an unintentional eye exposure within the first 7 meters, and can cause temporary or permanent flash blindness up to 36 meters. After that distance, a Class 2 laser beam may cause temporary or permanent eye glare up to 159 meters. The Class 2 beam can be just visually distracting to the eye from 160 meters to 1.6 kilometers.

Laser Class 2M

There is virtually no difference between Class 2 and Class 2M laser beams, except that Class 2M laser beams can be more hazardous, especially when viewed using optical instruments. Class 2M lasers have up to 1 milliwatt of power and they have the same direct exposure hazard distances as Class 2, which are mentioned above. Similarly, Class 2M does not cause any skin or surface damage, and looking at its diffused reflection “Dot” on a surface does not cause any harm to the eye.

Laser Class 3

There are two types of Class 3 laser beams, Class 3R and Class 3B. The laser power and ocular hazard distances of Class 3R and Class 3B are significantly different. That is why there are two different categories.

Laser Class 3R (Class IIIA)

The Class 3R of laser beams is called Class 3A or Class IIIA in some countries, but all these names refer to the same class of laser beams. A Class 3R laser beam has from 1 to 4.99 milliwatts of power, which means it may be harmful to the eye because of accidental or intentional exposure. Direct or indirect eye exposure should definitely be avoided. Any eye exposure within 16 meters of a Class 3R laser beam causes damage to the eye, and after that distance it can cause permanent or temporary flash blindness up to 80 meters. From 80 meters to 356 meters, Class 3R can cause temporary or permanent glare in the eye, and from 356 meters to 3.5 kilometers it just causes a harmful bothersome distraction to the eye. On the other hand, body exposure to Class 3R laser beams does not cause skin injury. The Class 3R laser does not cause damage to surfaces either, and even looking at its diffused reflection on a wall hardly causes any eye injury.

Laser Class 3B (Class IIIB)

The power range of the Class 3B laser beam is large. It ranges from 5 milliwatts to 500 millwatts, and this range is where eye hazard becomes alarmingly high. Any direct eye exposure is highly dangerous to the unaided eye. Even by looking indirectly at a reflected laser beam on a wall, Class 3B is powerful enough to cause damage to the eye. Even more, Class 3B can gradually cause damage to human skin and solid surfaces when pointed directly at them. If kept long enough on one spot, it can cause damage to any surface and may cause heating and fire. Class 3B laser beam can cause instant eye injury from a long distance, up to 224 meters. It can also cause permanent or temporary flash blindness from 224 meters to 1.2 kilometers. Furthermore, Class 3B can cause eye glare up to 3.5 kilometers and it stays detractingly visible up to 35.6 kilometers.

Laser Class 4 (Class IV)

The fourth class of laser beams, Laser Class 4 is the most powerful and the most dangerous class of laser beams. Its power ranges from 500 milliwatts to 10 watts and even more. Any eye exposure to Class 4 of laser beams is dangerous in any circumstances, even when reflected on any surface. Class 4 laser beams can blind eyes instantly, can burn skin instantly, and can damage and burn solid surfaces instantly. It is only to be used in confined and strictly controlled spaces. A Class 4 laser beam that has 10 Watts of power can cause instant eye damage from 710 meters away. It can cause flash blindness up to 3.5 kilometers away, and it may cause eye glare if looked at from 16 kilometers away. A Class 4 beam with 10 Watts of power can theoretically be distracting to the eye up to 160 kilometers away, if we neglect calculating the curvature of the Earth.

Laser Safety Classes Chart

Class Class 1 Class 2 Class 3 Class 4 Notes
Sub-class Class 1 Class 1M Class 2 Class 2M Class 3R Class 3B Class 4
Classification Class I No special FDA class Class II No special FDA class Class IIIA (definition is different but results are similar) Class IIIB Class IV Newer ANSI/IEC number classes are now preferred over older FDA Roman numeral classes
Human accessible laser power (for visible light) For visible light, emits beam less than 0.39 milliwatts, or beam of any power is inside device and is not accessible during       Emits visible beam of less than 1 milliwatt.   For visible light, emits beam between 1 and 4.99 milliwatts. For visible light, emits beam between Class 3R limit (e.g. 5 milliwatts) and 499.9 milliwatts For visible light, emits beam of 500 milliwatts (1/2 Watt) or more Non-visible lasers emitting infrared or ultraviolet are not included in this
Caution/warning indication No special caution/ warning indication       No special caution/ warning indication   CAUTION WARNING DANGER  
Label descriptive text   DO NOT VIEW DIRECTLY WITH OPTICAL INSTRUMENTS DO NOT STARE INTO BEAM DO NOT STARE INTO BEAM OR EXPOSE USERS OF TELESCOPIC OPTICS AVOID DIRECT EYE EXPOSURE AVOID EXPOSURE TO BEAM AVOID EYE OR SKIN EXPOSURE TO DIRECT OR SCATTERED RADIATION For visible-light lasers, the word “light” can be used instead of “radiation”. The latter is more accurate for lasers emitting infrared and ultraviolet radiation.
EYE AND SKIN HAZARDS
Eye hazard for intraocular exposure
(having a direct or reflected beam enter the eye)
Safe, even for long- term intentional light, usually applies when the laser is enclosed inside a device with no human access to laser light. Safe for unaided eye exposure Safe for unintentional exposure less than 1/4 second. Do not stare into beam. Safe for unintentional (< 1/4 sec) unaided eye exposure. Unintentional or accidental exposure to direct or reflected beam has a low risk. Avoid intentional exposure to direct or reflected beam. Eye hazard; avoid exposure to direct or reflected Severe eye hazard; avoid exposure to direct or reflected   
May be hazardous if viewed with optical instruments such as binoculars or eye loupe May be hazardous if viewed with optical instruments such as binoculars or eye loupe
Maximum or typical Nominal Ocular Hazard Distance
(for 1 milliradian beam, exposure time less than 1/4 second)
Not an eye hazard -- does not apply Consult an LSO as described in the Technical Note below NOHD of 0.99 mW beam: 23 ft (7 m) Consult an LSO as described in the Technical Note below NOHD of 4.99 mW beam: 52 ft (16 m) NOHD of 499.9 mW beam: 520 ft (160 m) NOHD of 1000 mW (1 Watt) beam: 733 ft (224 m). NOHD of 10 W beam: 2320 ft (710 m) Avoid eye exposure to a direct or reflected laser beam, within the laser, the greater the chance of hazard and the more serious the injury potential.
Eye hazard for diffuse reflection exposure
(looking at the laser “dot” scattered off a surface)
None Consult an LSO None Consult an LSO None Generally safe. Avoid staring at the laser “dot” on a surface for many seconds at close To avoid injury, do not stare at laser “dot” on a surface. The light is too bright if you see a sustained afterimage, lasting more than about 10 seconds.   
Skin burn hazard None Consult an LSO None Consult an LSO None Can heat skin if beam is held long enough on skin at close range Can instantly burn skin. Avoid direct exposure to the beam. Dark materials which absorb heat, and lightweight materials such as paper and fabric, are most easily burned by visible laser light.
Materials burn hazard None Consult an LSO None Consult an LSO None Can burn materials if beam is held long enough on substance at close range Can instantly burn exposure to the beam, for materials susceptible to
VISUAL INTERFERENCE DISTANCES
Maximum or typical flash blindness distance
(FAA 100 μW/cm2, for 1 milliradian beam, 555 nm green light)
Not applicable; beam is usually contained inside a device such as a CD or DVD player Consult an LSO For a 0.99 mW beam:
117 ft
36 m
Consult an LSO For a 261 ft 80 m For a 499 mW beam:
2.614 ft (1/2 mile)
797 m (0.8 km)
For a 1 Watt beam:
3,696 ft (0.7 mile)
1,127 m (1.1 km)
For a 10 W beam:
11,689 ft (2.2 miles)
3,563 m (3.5 km)
Value given is for 555 nm, the green wavelength that appears brightest to the light-adapted human eye. This gives the longest hazard distance. To approximate for red laser light, divide the distance by about 5; for blue, divide by 20.
Maximum or typical glare distance
(FAA 5 μW/cm2, for 1 milliradian beam, 555 nm green light)
See above Consult an LSO 523 ft
159 m
Consult an LSO 1,169 ft
356 m
11,689 ft (2.2 miles)
3,563 m (3.5 km)
For a 1 Watt beam:
16,531 ft (3.1 miles)
5,039 m (5 km)
For a 10 W beam:
52,275 ft (9.9 miles)
15,933 m (16 km)
See above
Maximum or typical distraction distance
(FAA 0.05 μW/cm2 or 50 nanowatts/cm2, for 1 milliradian beam, 555 nm green light)
See above Consult an LSO 5,227 ft (1 mile)
1,593 m (1.6 km)
Consult an LSO 11,689 ft (2.2 miles)
3,563 m (3.5 km)
116,890 ft (22 miles)
35,628 m (35.6 km)
For a 1 Watt beam:165,307 ft (31 miles)
50,386 m (50 km)
For a 10 W beam:
522,746 ft (99 miles)
159,333 m (160 km)
See above
Technical Notes For a 1/4 second exposure to accessible visible- light beams, Class 1 limits are the same as Class 2, and such lasers are usually labeled as Class 2. We are unaware of any Class 1M laser devices intended for consumer use. If you do have such a laser, consult a qualified Laser Safety Officer for more detailed Class 2 (and 2M) only applies to visible ultraviolet lasers cannot be Class 2 (or 2M). We are unaware of any Class 2M laser devices intended for consumer use. If you do have such a laser, consult a qualified Laser Safety Officer for more detailed Class 3R is either: (1) From 1 to 4.99 mW into a 7mm aperture (e.g., pupil of the eye) or (2) five times the Class 2 limit of 2.5 mW/cm2, which works out to be 12.5 mW/cm2. The second method is used by LaserSafetyFacts to determine NOHD.                  
   Class 1 Class 1M Class 2 Class 2M Class 3R Class 3B Class 4  
  Class 1 Class 2 Class 3 Class 4
Table information source: lasersafetyfacts.com

Laser Safety Class 1 (Class I)

Class Class 1
Sub-class Class 1 Class 1M
Classification Class I No special FDA class
Human accessible laser power (for visible light) For visible light, emits beam less than 0.39 milliwatts, or beam of any power is inside device and is not accessible during      
Caution/warning indication No special caution/ warning indication      
Label descriptive text   DO NOT VIEW DIRECTLY WITH OPTICAL INSTRUMENTS
EYE AND SKIN HAZARDS
Eye hazard for intraocular exposure
(having a direct or reflected beam enter the eye)
Safe, even for long- term intentional light, usually applies when the laser is enclosed inside a device with no human access to laser light. Safe for unaided eye exposure
May be hazardous if viewed with optical instruments such as binoculars or eye loupe
Maximum or typical Nominal Ocular Hazard Distance
(for 1 milliradian beam, exposure time less than 1/4 second)
Not an eye hazard -- does not apply Consult an LSO as described in the Technical Note below
Eye hazard for diffuse reflection exposure
(looking at the laser “dot” scattered off a surface)
None Consult an LSO
Skin burn hazard None Consult an LSO
Materials burn hazard None Consult an LSO
VISUAL INTERFERENCE DISTANCES
Maximum or typical flash blindness distance
(FAA 100 μW/cm2, for 1 milliradian beam, 555 nm green light)
Not applicable; beam is usually contained inside a device such as a CD or DVD player Consult an LSO
Maximum or typical glare distance
(FAA 5 μW/cm2, for 1 milliradian beam, 555 nm green light)
See above Consult an LSO
Maximum or typical distraction distance
(FAA 0.05 μW/cm2 or 50 nanowatts/cm2, for 1 milliradian beam, 555 nm green light)
See above Consult an LSO
Technical Notes For a 1/4 second exposure to accessible visible- light beams, Class 1 limits are the same as Class 2, and such lasers are usually labeled as Class 2. We are unaware of any Class 1M laser devices intended for consumer use. If you do have such a laser, consult a qualified Laser Safety Officer for more detailed
   Class 1 Class 1M
  Class 1
Table information source: lasersafetyfacts.com

Laser Safety Class 2 (Class II)

Class Class 2
Sub-class Class 2 Class 2M
Classification Class II No special FDA class
Human accessible laser power (for visible light) Emits visible beam of less than 1 milliwatt.  
Caution/warning indication No special caution/ warning indication  
Label descriptive text DO NOT STARE INTO BEAM DO NOT STARE INTO BEAM OR EXPOSE USERS OF TELESCOPIC OPTICS
EYE AND SKIN HAZARDS
Eye hazard for intraocular exposure
(having a direct or reflected beam enter the eye)
Safe for unintentional exposure less than 1/4 second. Do not stare into beam. Safe for unintentional (< 1/4 sec) unaided eye exposure.
May be hazardous if viewed with optical instruments such as binoculars or eye loupe
Maximum or typical Nominal Ocular Hazard Distance
(for 1 milliradian beam, exposure time less than 1/4 second)
NOHD of 0.99 mW beam: 23 ft (7 m) Consult an LSO as described in the Technical Note below
Eye hazard for diffuse reflection exposure
(looking at the laser “dot” scattered off a surface)
None Consult an LSO
Skin burn hazard None Consult an LSO
Materials burn hazard None Consult an LSO
VISUAL INTERFERENCE DISTANCES
Maximum or typical flash blindness distance
(FAA 100 μW/cm2, for 1 milliradian beam, 555 nm green light)
For a 0.99 mW beam:
117 ft
36 m
Consult an LSO
Maximum or typical glare distance
(FAA 5 μW/cm2, for 1 milliradian beam, 555 nm green light)
523 ft
159 m
Consult an LSO
Maximum or typical distraction distance
(FAA 0.05 μW/cm2 or 50 nanowatts/cm2, for 1 milliradian beam, 555 nm green light)
5,227 ft (1 mile)
1,593 m (1.6 km)
Consult an LSO
Technical Notes Class 2 (and 2M) only applies to visible ultraviolet lasers cannot be Class 2 (or 2M). We are unaware of any Class 2M laser devices intended for consumer use. If you do have such a laser, consult a qualified Laser Safety Officer for more detailed
   Class 2 Class 2M
  Class 2
Table information source: lasersafetyfacts.com

Laser Safety Class 3 (Class III)

Class Class 3
Sub-class Class 3R Class 3B
Classification Class IIIA (definition is different but results are similar) Class IIIB
Human accessible laser power (for visible light) For visible light, emits beam between 1 and 4.99 milliwatts. For visible light, emits beam between Class 3R limit (e.g. 5 milliwatts) and 499.9 milliwatts
Caution/warning indication CAUTION WARNING
Label descriptive text AVOID DIRECT EYE EXPOSURE AVOID EXPOSURE TO BEAM
EYE AND SKIN HAZARDS
Eye hazard for intraocular exposure
(having a direct or reflected beam enter the eye)
Unintentional or accidental exposure to direct or reflected beam has a low risk. Avoid intentional exposure to direct or reflected beam. Eye hazard; avoid exposure to direct or reflected
Maximum or typical Nominal Ocular Hazard Distance
(for 1 milliradian beam, exposure time less than 1/4 second)
NOHD of 4.99 mW beam: 52 ft (16 m) NOHD of 499.9 mW beam: 520 ft (160 m)
Eye hazard for diffuse reflection exposure
(looking at the laser “dot” scattered off a surface)
None Generally safe. Avoid staring at the laser “dot” on a surface for many seconds at close
Skin burn hazard None Can heat skin if beam is held long enough on skin at close range
Materials burn hazard None Can burn materials if beam is held long enough on substance at close range
VISUAL INTERFERENCE DISTANCES
Maximum or typical flash blindness distance
(FAA 100 μW/cm2, for 1 milliradian beam, 555 nm green light)
For a 261 ft 80 m For a 499 mW beam:
2.614 ft (1/2 mile)
797 m (0.8 km)
Maximum or typical glare distance
(FAA 5 μW/cm2, for 1 milliradian beam, 555 nm green light)
1,169 ft
356 m
11,689 ft (2.2 miles)
3,563 m (3.5 km)
Maximum or typical distraction distance
(FAA 0.05 μW/cm2 or 50 nanowatts/cm2, for 1 milliradian beam, 555 nm green light)
11,689 ft (2.2 miles)
3,563 m (3.5 km)
116,890 ft (22 miles)
35,628 m (35.6 km)
Technical Notes Class 3R is either: (1) From 1 to 4.99 mW into a 7mm aperture (e.g., pupil of the eye) or (2) five times the Class 2 limit of 2.5 mW/cm2, which works out to be 12.5 mW/cm2. The second method is used by LaserSafetyFacts to determine NOHD.      
   Class 3R Class 3B
  Class 3
Table information source: lasersafetyfacts.com

Laser Safety Class 4 (Class IV)

Class Class 4
Sub-class Class 4
Classification Class IV
Human accessible laser power (for visible light) For visible light, emits beam of 500 milliwatts (1/2 Watt) or more
Caution/warning indication DANGER
Label descriptive text AVOID EYE OR SKIN EXPOSURE TO DIRECT OR SCATTERED RADIATION
EYE AND SKIN HAZARDS
Eye hazard for intraocular exposure
(having a direct or reflected beam enter the eye)
Severe eye hazard; avoid exposure to direct or reflected
Maximum or typical Nominal Ocular Hazard Distance
(for 1 milliradian beam, exposure time less than 1/4 second)
NOHD of 1000 mW (1 Watt) beam: 733 ft (224 m). NOHD of 10 W beam: 2320 ft (710 m)
Eye hazard for diffuse reflection exposure
(looking at the laser “dot” scattered off a surface)
To avoid injury, do not stare at laser “dot” on a surface. The light is too bright if you see a sustained afterimage, lasting more than about 10 seconds.
Skin burn hazard Can instantly burn skin. Avoid direct exposure to the beam.
Materials burn hazard Can instantly burn exposure to the beam, for materials susceptible to
VISUAL INTERFERENCE DISTANCES
Maximum or typical flash blindness distance
(FAA 100 μW/cm2, for 1 milliradian beam, 555 nm green light)
For a 1 Watt beam:
3,696 ft (0.7 mile)
1,127 m (1.1 km)
For a 10 W beam:
11,689 ft (2.2 miles)
3,563 m (3.5 km)
Maximum or typical glare distance
(FAA 5 μW/cm2, for 1 milliradian beam, 555 nm green light)
For a 1 Watt beam:
16,531 ft (3.1 miles)
5,039 m (5 km)
For a 10 W beam:
52,275 ft (9.9 miles)
15,933 m (16 km)
Maximum or typical distraction distance
(FAA 0.05 μW/cm2 or 50 nanowatts/cm2, for 1 milliradian beam, 555 nm green light)
For a 1 Watt beam:165,307 ft (31 miles)
50,386 m (50 km)
For a 10 W beam:
522,746 ft (99 miles)
159,333 m (160 km)
Technical Notes      
   Class 4
  Class 4
Table information source: lasersafetyfacts.com
Class Notes
Sub-class
Classification Newer ANSI/IEC number classes are now preferred over older FDA Roman numeral classes
Human accessible laser power (for visible light) Non-visible lasers emitting infrared or ultraviolet are not included in this
Caution/warning indication  
Label descriptive text For visible-light lasers, the word “light” can be used instead of “radiation”. The latter is more accurate for lasers emitting infrared and ultraviolet radiation.
EYE AND SKIN HAZARDS
Eye hazard for intraocular exposure
(having a direct or reflected beam enter the eye)
  
Maximum or typical Nominal Ocular Hazard Distance
(for 1 milliradian beam, exposure time less than 1/4 second)
Avoid eye exposure to a direct or reflected laser beam, within the laser, the greater the chance of hazard and the more serious the injury potential.
Eye hazard for diffuse reflection exposure
(looking at the laser “dot” scattered off a surface)
  
Skin burn hazard Dark materials which absorb heat, and lightweight materials such as paper and fabric, are most easily burned by visible laser light.
Materials burn hazard
VISUAL INTERFERENCE DISTANCES
Maximum or typical flash blindness distance
(FAA 100 μW/cm2, for 1 milliradian beam, 555 nm green light)
Value given is for 555 nm, the green wavelength that appears brightest to the light-adapted human eye. This gives the longest hazard distance. To approximate for red laser light, divide the distance by about 5; for blue, divide by 20.
Maximum or typical glare distance
(FAA 5 μW/cm2, for 1 milliradian beam, 555 nm green light)
See above
Maximum or typical distraction distance
(FAA 0.05 μW/cm2 or 50 nanowatts/cm2, for 1 milliradian beam, 555 nm green light)
See above
Table information source: lasersafetyfacts.com

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