Laser Classifications

Overview

• Laser Standards and Regulations
• Overview of Laser Classifications
• The Center for Devices and Radiological Health (CDRH)
• The International Electrotechnical Commission (IEC)
• The American National Standards Institute (ANSI)

Laser Standards and Regulations

The Federal Food and Drug Administration (FDA) Center for Devices and Radiological Health (CDRH) is responsible for implementing and enforcing the laws and regulations applicable to radiation-producing electronic products and medical devices.

Medical devices, including laser systems for medical applications, require FDA clearance before commercial distribution in the United States. This clearance may be obtained through a premarket notification under section 510(k) of the Federal Food, Drug, and Cosmetic Act (FFDCA), when the device is shown to be substantially equivalent to a legally marketed predicate. Clearances are device-specific and based on the indications for use in the cleared labeling.

Laser Classifications

Lasers are categorized based on wavelength and maximum output power. These classifications help identify the relative level of risk associated with laser exposure under defined conditions of use. Laser classifications range from Class 1 (considered low risk under normal operation) to Class 4 (capable of presenting a hazard to eyes or skin). These classes are I, II IIa, IIIa, IIIb and IV for the U.S., and 1, 1M, 2,2M, 3R, 3B and 4 for Europe.

Maximum Permissible Exposure (MPE)

MPE refers to the maximum level of laser radiation to which a person may be exposed without exceeding recognized safety thresholds. It is determined based on factors such as the laser’s wavelength, energy output, and exposure duration. MPE values are commonly used in safety evaluations, including the assessment of appropriate optical density and the extent of the nominal hazard zone.

Regulatory Agencies include:

• The Center for Devices and Radiological Health (CDRH)
• The International Electrotechnical Commission (IEC)
• The American National Standards Institute (ANSI)

State Regulations

Some states may require registration of certain medical laser devices. These regulations may apply to Class IIIB and IV medical lasers and can include specific requirements regarding their use.

Overview of Laser Classifications

The Food and Drug Administration (FDA) categorizes lasers into four major hazard classes (I to IV), with additional subclasses (IIa, IIIa, and IIIb). Higher classes generally correspond to greater output power and increased risk if not used according to proper guidelines. For lasers classified as Class II through IV, product labeling must include a warning symbol indicating the class and the output power. Products labeled under the classification system of the International Electrotechnical Commission (IEC) may also include the IEC equivalent class.

There are laws, regulations, and standards that require the implementation of engineering controls and risk communication measures to support the management of potential biological hazards associated with each laser class. However, these controls may not be effective if lasers are used outside of their intended or specified parameters.

The Center for Devices and Radiological Health (CDRH)

The Center for Devices and Radiological Health (CDRH) is a regulatory branch within the U.S. Food and Drug Administration (FDA), part of the Department of Health and Human Services.

CDRH is responsible for regulating the safety standards of electronic products that emit radiation, including laser products. Laser products manufactured and introduced into commerce after August 2, 1976, are required to comply with applicable federal regulations.

These regulations are defined in the Federal Laser Product Performance Standard (FLPPS), codified under Title 21 of the Code of Federal Regulations (CFR), Subchapter J, Parts 1040.10 and 1040.11.

The FLPPS categorizes laser products into hazard classes (Classes I, II, IIIa, IIIb, and IV), based on their emission characteristics and potential risk for biological effects, in alignment with classification approaches also described in the ANSI Z136.1 standard (2000).

Class 1 Lasers and Laser Systems (“Exempt Lasers”)

Class 1 lasers are generally exempt from the requirements of most workplace laser safety programs.

Under normal operating conditions, Class 1 lasers are not capable of emitting hazardous levels of laser radiation.

All Class 1 lasers must include appropriate labeling in accordance with FDA regulations.

Examples:

• Laser printers
• CD/DVD players

Class 2 Lasers and Laser Systems (“Low Power Visible Lasers”)

Output: Up to 1 milliwatt (mW) of continuous wave
Characteristics: Low power, diffuse output
Wavelength Range: 400–700 nanometers (nm) (visible spectrum)

Class 2 lasers are defined as low-power laser products operating in the visible wavelength range (400–700 nm). Under normal operating conditions, direct viewing is typically limited by natural aversion responses, such as the blink reflex, which generally occurs within 0.25 seconds.

Intentional, prolonged viewing of the direct beam may present a potential hazard to the eyes and should be avoided.

Class 2 laser products must be labeled in accordance with applicable federal regulations.

The laser beam should not be intentionally directed toward the eyes. When aligning laser optical systems (e.g., mirrors, lenses, or beam deflectors), precautions should be taken to ensure that neither the primary beam nor any specular reflection exceeds the Maximum Permissible Exposure (MPE) for the eye.

Example:

• Barcode scanners

Class 3A Lasers and Laser Systems (“Medium Power”)

Output: 1–5 mW continuous wave
Wavelength: Infrared spectrum (non-visible)

Class 3A refers to laser products that typically do not present a hazard when viewed momentarily with the unaided eye under controlled conditions. However, they may pose a risk if viewed through optical instruments such as binoculars or microscopes. Direct or reflected beams should not be viewed.

Class 3A laser products must bear appropriate labeling in accordance with applicable regulatory requirements.

The laser use area should be marked with warning signage to inform users not to intentionally look into the beam or direct the beam toward the eye. Removable panels or service access points should include safety interlocks to reduce the risk of unintended exposure. A fixed beam stop or beam attenuator may be employed as an added control.

If exposure levels exceed the Maximum Permissible Exposure (MPE), engineering controls such as viewing portals and display screens should be used to bring exposure within acceptable limits. Alignment procedures must be conducted in a manner that ensures exposure remains below the MPE.

Examples:

• Laser pointers
• Therapy lasers (when cleared or approved for such use by the FDA)

Class 3B Lasers and Laser Systems (“Medium Power”)

Output: 5–500 mW continuous wave
Wavelength: Infrared spectrum (non-visible)

Class 3B lasers and laser systems are capable of producing a hazard if the beam is viewed directly. This includes exposure from intrabeam viewing or from specular reflections.

Diffuse reflections from Class 3B lasers are generally not considered hazardous, except in the case of higher-powered systems.

Class 3B lasers and laser systems must be properly labeled in accordance with applicable regulations.

These lasers should be used in controlled areas where access by untrained or unauthorized individuals is restricted. If untrained individuals must enter the area, they should receive appropriate safety instructions from the laser operator or supervisor and be provided with protective eyewear, if required.

During operation or startup, a warning system (e.g., alarm, signal light, or verbal countdown) should be used. The controlled area should be designed to:

• Limit spectator access
• Include beam stops or barriers to contain the beam
• Minimize potential for diffuse and specular reflections
• Provide appropriate eye protection for all personnel
• Avoid positioning the beam at typical eye level
• Restrict exposure through windows and doorways to levels below the Maximum Permissible Exposure (MPE)
• Ensure lasers are either stored securely or disabled when not in use

If the MPE may be exceeded, viewing portals and display screens should be designed to limit exposure to acceptable levels. Alignment procedures and the use of collecting optics should also be implemented to avoid exceeding the MPE. Only personnel who are trained and authorized should perform servicing on the laser system. Written standard operating procedures for operation, maintenance, and service should be developed and adhered to.

Example:

• Therapy lasers (when cleared or approved for such use by the FDA)

Class 4 Lasers and Laser Systems

Output: 500 mW and greater, continuous wave
Wavelength: Infrared spectrum (non-visible)

Class 4 lasers are high-powered laser systems that may present potential hazards from direct, specular, or diffuse reflections. These systems may also pose risks such as fire or skin exposure hazards under certain conditions.

Class 4 lasers include all laser systems that exceed the output limitations defined for Class 3.

In addition to the control measures outlined for Class 3B, Class 4 lasers should only be operated by individuals trained in laser safety and used in areas specifically designated for their operation.

Failsafe interlocks should be used to prevent unauthorized or accidental entry into controlled areas. Access should be restricted to individuals who have been briefed on proper safety procedures and provided with appropriate protective eyewear when the laser is capable of emission.

Laser operators are responsible for ensuring that visitors or untrained personnel who may need to enter a controlled area are properly informed of safety procedures and are provided appropriate protective measures.

The laser-controlled area should:

• Be restricted to authorized personnel
• Allow for rapid emergency exit
• Include a system to deactivate the laser or reduce its output below the Maximum Permissible Exposure (MPE)
• Meet the control requirements established for Class 3B lasers
• Be equipped with entryway safety controls
• Be configured to allow monitoring and activation from a remote location
• (For pulsed systems) include interlocks that prevent laser emission by redirecting stored energy to a dummy load
• (For continuous wave systems) include interlocks that disable the power supply or interrupt the beam using shutters

The beam path must be kept free of specularly reflective surfaces and flammable materials. The beam should be terminated using a barrier or beam stop that is both non-combustible and non-reflective.

Examples:

• Surgical Lasers
  Used in medical procedures to cut or coagulate tissue. These devices must have FDA clearance for such intended uses.
• Therapeutic Lasers
  May involve non-thermal photonic interactions. Used in non-surgical settings for general wellness applications. Any references to tissue interaction must align with cleared labeling.

The International Electrotechnical Commission (IEC)

The International Electrotechnical Commission (IEC) is a global organization responsible for developing and publishing international standards for electrical, electronic, and related technologies. IEC standard 60825-1 provides guidance on the classification and labeling of laser products. Like ANSI standards, IEC classifications are based on Accessible Emission Limits (AELs) and incorporate viewing conditions as part of the classification criteria.

Class 1: Lasers classified as Class 1 have emissions that are considered low under normal operating conditions. This classification includes evaluation under foreseeable use, including the use of optical instruments for intrabeam viewing.

Class 1M: These lasers operate within wavelengths from 302.5 nm to 4000 nm. Exposure is generally considered within limits under direct viewing but may exceed exposure limits when viewed with optical instruments such as binoculars or telescopes.

Class 2: These lasers emit visible radiation between 400 nm and 700 nm and are limited to emission levels below the Class 2 AEL. Emissions outside this wavelength range must not exceed the Class 1 AEL.

Class 2M: Operating within 400 nm to 700 nm, these lasers meet Class 2 criteria for unaided viewing but may exceed limits when viewed with optical aids. Emissions outside this range must not exceed the Class 1M AEL.

Class 3R: These lasers emit between 302.5 nm and 106 nm and may exceed the AEL for Class 1 or Class 2 by a factor of up to 5. They present a reduced risk compared to Class 3B lasers but may still require caution during use.

Class 3B: Lasers in this class may pose a risk when viewed directly. However, exposure to diffuse reflections is generally considered to be within allowable limits under specified conditions.

Class 4: These lasers may present hazards under both direct and scattered beam conditions. Potential risks include exposure to skin and the possibility of ignition of materials under specific conditions.

The American National Standards Institute (ANSI)

The American National Standards Institute (ANSI) is an organization in which expert volunteers participate on committees to develop industry consensus standards across a variety of technical fields. The ANSI Z136 Committee has published, or currently has under development, several standards specific to the safe use of lasers.

The ANSI Z136.1 Standard (Z136.1-2000) categorizes lasers into hazard classes (1, 2, 3a, 3b, and 4) based on calculations related to exposure parameters. These classifications are determined by evaluating factors such as exposure time, laser wavelength, and average power for continuous wave (CW) or repetitively pulsed lasers, and total energy per pulse for pulsed lasers.

These calculations help determine a value known as the Accessible Emission Limit (AEL), defined as the product of the Maximum Permissible Exposure (MPE) specified in the standard and an area factor derived from the Limiting Aperture (LA). That is: AEL = MPE × Area of LA.

The Limiting Aperture is based on wavelength-specific factors and physical parameters, such as the approximate size of the fully dilated pupil (7 mm) or potential laser beam "hotspots" (1 mm).

For most skin exposures and infrared exposures to the eye lasting more than 10 seconds, involuntary body movement and thermal conduction generally result in irradiance being averaged over an area of about 10 mm², corresponding to a spot size of approximately 3.5 mm in diameter.

In the near-infrared range, where radiation may penetrate tissue to varying depths and scatter, irradiance is typically distributed over comparable dimensions. For wavelengths exceeding 0.1 mm, the standard specifies an aperture size of 11 mm to reduce measurement errors associated with diffraction.

Each laser class is associated with specific AEL thresholds:

Class 1: These lasers or systems are not capable of emitting accessible laser radiation above the Class 1 AEL under any conditions of operation inherent in the design or intended use. These systems are exempt from most control measures for direct beam exposure.

Class 2: These lasers include CW or repetitively pulsed lasers operating at wavelengths from 0.4 µm to 0.7 µm. These may emit above the Class 1 AEL but remain below the Class 1 AEL for exposures under 0.25 seconds, with average radiant power not exceeding 1 mW.

Class 3a: These lasers emit between 1 and 5 times the Class 1 AEL for wavelengths outside the 0.4–0.7 µm range or less than 5 times the Class 2 AEL for wavelengths within that range.

Class 3b: These lasers emit radiant power greater than Class 3a but less than or equal to 0.5 Watts for exposures of 0.25 seconds or longer. For exposures under 0.25 seconds, the energy limit is typically 0.125 Joules for wavelengths between 0.18 µm and 0.4 µm, or 1.4 µm and 1 mm. For wavelengths from 0.4 µm to 1.4 µm, lasers exceeding the Class 3a AEL cannot exceed 0.5 Watts for durations ≥ 0.25 seconds or 0.03 Joules per pulse.

Class 4: These lasers exceed the AELs defined for Class 3b and may present additional safety considerations.