In 2001, the European (EN) and International (IEC) standards governing the safety of laser products were substantially revised, and the classification system was overhauled. This resulted in the creation of three new laser classes (1M, 2M, and 3R) and the elimination of Class 3A. A brief description of each of the current laser classes is provided below.

Lasers and LEDs are both covered by the 60825-1 standards. The term “laser” has been used extensively, but it can be replaced by “LED.” LEDs would generally be in the lower Classes (1, 1M, 2, 2M, 3R), but very rarely in Class 3B; at the time of writing, we are not aware of any Class 4 LEDs*.

The term “eye-safe” is used below. Please keep in mind that the term “eye-safe” refers to the entire optical spectrum from 180nm to 1mm wavelength, not just the retinal hazard range of 400nm to 1400nm. Outside of the retinal hazard range, the cornea may be at risk. A wavelength that is outside of the retinal hazard range is thus not necessarily eye-safe!

Classification summary

• Class 1

  This class is eye-safe under all operating conditions.

• Class 1M

  This class is safe to view with the naked eye, but it may be dangerous to view with optical instruments. In general, magnifying glasses increase the risk of a widely diverging beam (e.g., LEDs and bare laser diodes), while binoculars or telescopes increase the risk of a wide, collimated beam (e.g., those used in open-beam telecommunications systems). Radiation in classes 1 and 1M can be either visible or invisible.

• Class 2

  These are visible lasers. Under all operating conditions, this class is safe for accidental viewing. However, it may not be safe for a person who deliberately stares into the laser beam for more than 0.25 seconds in order to overcome their natural aversion response to the extremely bright light.

• Class 2M
  

  These are clearly visible lasers. As with Class 2, this class is safe for accidental viewing with the naked eye as long as the natural aversion response is not overcome, but it may be hazardous (even for accidental viewing) when viewed with the aid of optical instruments, as with Class 1M. Radiation in classes 2 and 2M is visible, but under certain conditions, it can also contain an invisible element.

  Under IEC and EN classification, classes 1M and 2M largely replace the old class 3A. Prior to the 2001 amendment, there were Class 3B lasers that were eye-safe when viewed without optical instruments. According to the current classification system, these lasers are classified as Class 1M or Class 2M.

• Class 3R
  

  This type of radiation is considered low risk but potentially hazardous. The class limit for 3R is five times that of Class 1 (invisible radiation) or Class 2 (visible radiation). As a result, CW visible lasers emitting between 1 and 5 mW are normally classified as Class 3R, which is equivalent to Class IIIA in US regulations.

• Class 3B
  

  This type of radiation is extremely dangerous. The maximum output into the eye of a continuous wave laser must not exceed 500mW. Radiation can be harmful to the eyes and skin. Viewing the diffuse reflection, on the other hand, is risk-free.

• Class 4
  

  This type of radiation is extremely dangerous. The maximum output into the eye of a continuous wave laser must not exceed 500mW. Radiation can be harmful to the eyes and skin. Viewing the diffuse reflection, on the other hand, is risk-free.

Below is a table showing the meaning of the different Classes of Lasers and LEDs according to the current version of EN 60825-1 and IEC 60825-1.

Class 1	Safe.
Class 1M	Safe provided optical instruments are not used.
Class 2	Visible lasers. Safe for accidental exposure (< 0.25 s).
Class 2M	Visible lasers. Safe for accidental exposure (< 0.25 s) providing optical instruments* are not used.
Class 3R	Not safe. Low risk.
Class 3B	Hazardous. Viewing of diffuse reflection** is safe.
Class 4	Hazardous. Viewing of diffuse reflection is also hazardous. Fire risk.

*Optical instruments – binoculars, telescopes, microscopes, magnifying glasses (but not prescription glasses).

**Diffuse reflection – the reflection of radiation from a matt surface such as a wall.

Any laser product of a given Class may contain ’embedded’ lasers of a higher Class than the product’s assigned Class, but engineering controls (protective housings and interlocks) ensure that human access to radiation in excess of the product Class is not possible. CD and DVD players, which are Class 1 laser products but contain Class 3R or Class 3B lasers, are notable examples, as are laser printers, which are Class 1 laser products but contain Class 4 embedded lasers.

Note:- To be correctly classified, a product must be tested at the maximum output accessible under reasonably foreseeable single-fault conditions (for example, in the drive circuitry). A non-M class product must pass both Conditions 1 and 2 of Table 10 in IEC/EN 60825-1, and an M-class product must pass the irradiance condition in the same table (which by definition has failed either Condition 1 or 2).

* In general, lasers are point sources, whereas LEDs are extended sources. For a given laser Class, extended sources have higher power limits than point sources. A visible LED emitting 10 mW is thus Class 2, whereas a visible laser pointer emitting the same power is Class 3B. NB Laser pointers above Class 2 are prohibited from being sold to the general public by trading standards.

CW	Continuous Wave – i.e. not pulsed
Diffuse reflection	the reflection of radiation from a matt surface such as a wall
Extended source	having an apparent source size with angular subtense of greater than 1.5 mradian
Optical instruments	binoculars, telescopes, microscopes, magnifying glasses (but not prescription glasses)
Point source	having an apparent source size with angular subtense of less than 1.5 mradian