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Is a 5mW Laser Powerful? 4 Laser Classes discussed

Is a 5mW Laser Powerful? 4 Laser Classes discussed

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Laser pointers may seem harmless at a glance, so would they be sufficiently powerful to cause some kind of damage? Lasers are generally categorized into different classes, determined by the output power.

In this article, we will take a look at the classes of power outputs and the effects of powerful lasers.

In a nutshell, 5mW lasers are very powerful and can cause severe damage if not handled properly. They could cause permanent damage to your eyes and burn certain materials. Make sure to use lasers responsibly!

Laser Classifications

There are four main classifications and a few sub-classifications when it comes to lasers. They are Class 1, 1M, 2, 2M, 3R, 3B, and 4. You will sometimes see it written as I, II, IIIa, IIIb, and IV instead, but they are basically the same.

Below are a few basic details on the classifications.

Class 1

Safe for use under all conditions. Lasers in this category are not visible to the eye.

Class 1M

Safe for use under all conditions, except when the laser is passed through optical devices that can magnify it such as microscopes and telescopes.

Class 2

Generally considered safe for human use, because of a human’s blink reflex which will limit any exposure to 0.25 seconds.

Class 2 lasers are either limited to 1mW of power if it’s a continuous beam or more only if the emission time does not exceed that 0.25 seconds limit.

Class 2M

Safe for human use because of the blink reflex, as long as not viewed through an optical instrument. The amount of light emitted is the same as with Class 2.

Class 3R

Considered safe if handled properly, but make sure not to view it with optical instruments. This category of laser has a bit of risk of injury, as it can exceed the maximum permissible exposure (MPE).

Lasers in this class range from 1 – 5 mW, with visible continuous lasers in this class limited to 5 mW.

Class 3B

This is where we step into hazardous territory. Lasers in this class range from 5 to 499 mW in power output.

Besides the possibility of causing damage to the human eye, Class 3B lasers can heat up your skin and possibly burn at higher output levels. Protective eyewear is a must when handling lasers in this class. It is also recommended for the laser to have a key switch and safety lock.

Class 4

Most dangerous class of lasers. Class 4 laser can burn your skin and even cause permanent damage to your eyes if exposed to it directly, or via diffused/indirect beam viewing. It is also possible to cause combustible material to burn using Class 4 lasers.

The above hazards can happen even if applied indirectly or via reflections, so it’s crucial to be very careful with these lasers. A key switch and a safety lock are a must for such lasers.

For more safety tips, check out this video by the U.S. Food and Drug Administration (FDA):

Laser Pointer Safety

How Powerful is a 5mw Laser?

As you can see from the list, even Class 1M lasers which are mostly about 1 mW in power output can hurt your eyes if mishandled.

If pointed directly at a person’s eye, a low-powered laser can cause temporary flash blindness, just like what happens if you stare directly at the sun. You may also get a headache or see ‘spots’ in your vision in severe cases.

As for lasers with an output of 5 mW and above, you also already have a clue through the many classifications listed above. Class 3B and 4 categorizes lasers with a power output that’s high enough to burn your eye’s retina before you can even blink, which will then result in permanent damage to your vision. This can also happen if the laser is being reflected.

To sum it up, a 5mW laser is very powerful and could cause permanent damage to your eyes, and burn certain materials. Fortunately, at 5mW or less, you can avoid such permanent damage if you manage to shield your eye by blinking and turning away quickly.

Example of Injuries Caused by Laser Misuse

Eye damage caused by laser pointers is a very real threat. In a publicized case in Australia back in November 2015, a 14-year-old boy from Tasmania damaged both of his eyes.

This happened because he shone a laser pointer pen into his eyes. According to ABC News, the boy had burned the retina tissue near the macula at the back of the eye, resulting in permanent loss of 75% of his vision.

Types of Lasers Available to the Public

The types of laser pointers you can legally own depends on the country you live in. In many countries, only higher power lasers of Class 3B and 4 are prohibited for public use.

However, there are also some countries that allow for only up to Class 2 or Class 1 laser pointers to be used by the public.

For example, while the USA allows the possession of all classes of lasers as long as it is FDA-compliant, Europe and the UK outright bans all lasers with a power output of more than 1 mW.


Laser pointers, even when rated at lower classes of outputs, can cause substantial damage when mishandled. Make sure to use lasers responsibly, and keep them out of the reach of young children.

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