Last updated: November 6, 2023
Laser Safety Manual
It is a privilege to use lasers at Stanford University. All individuals who currently or will work with lasers are responsible for knowing and adhering to applicable requirements as stated in this manual. Failure of any individual to comply with requirements can cause injury as well as jeopardize the research, the laboratory involved, and the institution.
This manual provides the laser safety policies and procedures we have implemented to ensure a safe environment for all users, including students, visitors, and the public in research and teaching environments. Our goal is to ensure a safe working environment consistent with our policy, which is guided by ANSI Z136.1, the American National Standard Institute on the Safe Use of Lasers.
The Laser Safety Officer, appointed by the Manager of Radiation Safety Programs in Environmental Health and Safety, is responsible for managing the laser safety program. The Laser Safety Officer (LSO) is authorized to monitor safety control measures for laser hazards and to take steps necessary to control and mitigate those hazards including restricting or terminating laser operations.
Consult the current Laser Safety Officer at 650-723-3201 for specific information.
This Laser Safety Manual has been approved by the University Laser Safety Committee, 5/2019.
In addition, changes are proposed to the section on Engineering Controls as shown below. This change would require individuals to document and obtain approval for deviations from the ANSI standard.
Alternate Control Measures
Upon review and approval by the LSO, the control measure requirements specified in this manual may be replaced by other controls that provide equivalent protection. If alternate control measures are used, all directly affected persons must be provided appropriate laser safety and operational training. Alternate control measures must be documented in a written SOP.
2.1Laser Safety Commitee
2.2Laser Safety Officer (LSO)
- Program development and implementation
- Approve Standard Operating Procedures (SOPs), alignment procedures and other procedures that may be subject to administrative and procedural controls
- Conduct Hazard Evaluations for each Class 3b and Class 4 laser
- Classify constructed or modified lasers and laser systems
- Provide laser safety training
- Provide ANSI approved warning signs and labels
- Periodically audit lasers use facilities
- Investigate laser accidents
- Maintain inventory of Class 3b and Class 4 lasers and laser systems, including a Controlled Laser Authorization (CLA) number for each laser and laser system.
Supervisors/ Principal Investigators (PI):
- Submit a Laser Registration Form to the LSO for each Class 3b and Class 4 laser or laser system
- Identify laser hazards present in the work area, implement appropriate hazard controls (including ANIS approved signs and labels) and correct any identified unsafe conditions
- Develop and submit to the LSO the current Standard Operating Procedures (SOPs) for each Class 3b and Class 4 laser or laser system using the Laser SOP as a guide.
- Identify all authorized personnel who are eligible to operate or maintain a Class 3b or Class 4 laser or laser system
- Provide job specific Tier III training for each laser user (including physical hazards, health hazards, and emergency procedures)
- Conduct annual self-inspection of lasers and laser use area using the Laser Safety Self-Inspection Checklist
- Designate a Laser Safety Contact (LSC) for each laser or laser systems
- Ensure that laser users follow established safety procedures
- Keep copies of all current SOPs, trainings, and inspections/investigations
- Maintain a copy of this written program in the workplace
- Know the hazards and the precautionary procedures for laser use in their work area
- Attend required training(s)
- Plan and conduct operations in accordance with established procedures and good safety practices
- Use personal protective equipment in accordance with prescribed training
3.1Laser System Classes
A Class 1 laser system:
- Considered to be capable of producing exposure conditions during normal operation unless the beam is viewed witA Class 1 laser system is:h an optical instrument such as an eye-loupe (diverging beam) or telescope (collimated beam), and
- Exempt from any control measures other than to prevent potentially hazardous optically aided viewing; and is exempt from other forms of surveillance.
A Class 2 laser system:
- Emits radiation in the visible portion of the spectrum (0.4 to 0.7μm), and
- Eye protection is normally afforded by the aversion response
A Class 2M laser system:
- Emits inthe visible portion of the spectrum (0.4-0.7μm) and
- Eye protection is normally afforded by the aversion response for unaided viewing.
- However, Class 2 M is potentially hazardous if viewed with certain optical aids.
A Class 3 laser system (medium power):
- May be hazardous under direct and specular reflection viewing conditions, but is normally not a diffuse reflection or fire hazard.
There are two subclasses:
- A Class 3 R laser system is potentially hazardous under some direct and specular reflection viewing conditions if the eye is appropriately focused and stable, but that probability of an actual injury is small. The laser will not post either fire hazard ordiffuse-reflection hazard.
- A Class 3B laser system may be hazardous under direct and specular reflection viewing conditions, but is normally not a diffuse reflection or fire hazard.
A Class 4 laser system (high power):
- Is a hazard to the eye or skin from the direct beam, and
- May pose a diffuse reflection or fire hazard
- May also produce laser generated air contaminants (LGAC) and hazardous plasma radiation.
Commercially produced lasers are classified according to the CDRH Federal Standard (FLPPS, 21 CFR 1040) and identified by labels affixed to the laser. Removal of protective housing or system modification can increase a laser’s classification. Contact the LSO for review prior to servicing or system modification.
4Laser Aquisition, Transfer and Disposal
The PI/LSC must notify the LSO of all Class 3b or Class 4 lasers/laser systems by submitting a Laser Registration form for each laser/laser system to the LSO. A form must be re-submitted when significant modifications are made to the original laser/laser system. The LSO will conduct a hazard evaluation of the laser work area and make necessary recommendations. Each officially registered laser or laser system will be provided a CLA number and a laser identification tag. The laser identification tag must be placed on laser or laser system by the PI/LSC. Information on the laser identification tag will include:
- The inventory number
- The serial number and location of the laser or laser system
- The contact name (PI/LSC)
The LSO must be notified when a Class 3b or 4 laser is transferred from the jurisdiction of one PI to another PI on campus. The new PI/LSC must complete a Laser Registration form. A new laser identification tag will be provided. The LSO must also be notified if the laser is transferred off-campus.
The LSO must be notified when a Class 3b or 4 laser is sold or disposed of and will coordinate with the hazardous Waste Program, as appropriate.
5.1Class 1, 2, & 3R Laser Systems
When used as intended Class 1, 2, and 3R laser systems are generally low hazard devices; however some requirements still apply.
- As with any piece of equipment PIs/LSC are responsible for ensuring training on proper use of that equipment.
- Exposure to laser radiation must be kept below the Maximum Permissible Exposure (MPE) under all conditions of operation or maintenance. See the glossary for definitions.
- Laser systems must have the appropriate warning labels with the laser sunburst logotype symbol and the appropriate cautionary statement. See Chapter 7: Warning Signs and Equipment Labels.
- Removal of protective housing or system modification can increase a laser’s classification. Contact the LSO for review prior to servicing or system modification.
- Use of class 3R laser with telescopes, microscopes, or alignment devices should be reviewed by the LSO prior to operation.
5.2Class 3b and Class 4 Laser Systems
Control Area Requirements
A laser hazard analysis, including determination of the MPE and Nominal Hazard Zone (NHZ), must be made by the LSO. If it is determined that the classification associated with the maximum level of accessible radiation is Class 3b or 4, a laser-controlled area is established and control measures instituted. Control measures are only required within the NHZ.
CLASS 3B CONTROL AREAS
- Must be controlled to permit lasers and laser systems to be operated only by authorized personnel.
- Must be posted with the appropriate warning sign(s). See Chapter 7: Warning Signs and Equipment Labels Section.
- All area or entryway safety controls must be designed to allow rapid egress by laser personnel and admittance to the laser controlled area under emergency conditions.
- Must be operated in a manner such that the laser beam path is well defined and projects into a controlled airspace when the laser beam must extend beyond an indoor controlled area, particularly to the outdoors under adverse atmospheric conditions, i.e. rain, fog, snow, etc.
- Must be under the direct supervision of an individual knowledgeable in laser safety.
- Must have all windows, doorways, open portals, etc. either covered or restricted in such a manner as to reduce the transmitted laser radiation to levels at or below the applicable ocular MPE.
- Must have only diffusely reflecting materials in or near the beam path where possible.
- Must have appropriate personal protective equipment readily available (i.e., eye protection).
CLASS 4 CONTROL AREAS
Class 4 laser control areas must incorporate all Class 3b control measures, plus the following:
- Control area interlocks or alternate controls to preclude the entry of unprotected personnel while Class 4 laser radiation is present in the control area. The interlock system may be designed to preclude entry while the laser is operating or to terminate laser operation when the door is opened without deliberate overriding of the interlock by a trained laser user.
(a) Blocking barrier, screen, curtains, etc. must be used to block, screen, or attenuate the laser radiation levels so that the MPE is not exceeded at the entry point.
(b) At the entryway there must be a visible or audible signal indicating that the laser is energized and operating at Class 4 levels. A lighted laser warning sign or flashing light (visible through protective eyewear) is acceptable entryway warning light alternatives.
(c) Personnel trained on entryway procedures and adequate personal protective equipment provided upon entry.
The engineering control measures required for Class 3b and 4 lasers are listed below. Where specific engineering controls are infeasible they may be replaced with specific administrative and procedural controls and personal protective equipment (PPE) with prior review by the LSO. Alternative controls and PPE requirements must be documented in a written SOP. See the glossary for additional explanation of each feature.
Administrative and Procedural Controls
Administrative and procedural controls are methods or instructions that specify rules, or work practices, or both, which implement or supplement engineering controls. Necessary administrative and procedural controls for 3b and 4 laser and laser systems include, but are not limited to:
- Standard Operating Procedures (SOPs) – written laser specific SOPs should be developed for Class 3b lasers and laser systems. Written SOPs are required for Class 4 lasers and must include procedures for operation, maintenance, and other relevant safety considerations.
- Authorized Personnel – PI/LSC must identify authorized personnel and ensure that those personnel are the only ones that operate maintain, or service a Class 3b or 4 laser or laser system. EHS 4820, Laser Safety Training, has been completed as well as on the job training and that PPE are provided before access to Class 3b and 4 laboratories are granted.
- Alignment Procedures – ensure SOPs specify alignment procedures. See Laser Alignment Guidelines for more information.
- Use minimum laser radiation required for the application. If necessary, the LSO may require the reduction of levels of accessible power or radiant energy during the operation or maintenance of a Class 3b or Class 4 laser system.
- Lasers or laser systems must have the appropriate warning labels. See Chapter 7 for warning label requirements.
- Maintain beam height at a level other than the normal position of the eye of a person in the standing or seated position.
6.1Personal Protective Equipment
Appropriate eye protection devices must be worn when working with Class 3b and Class 4 lasers or laser systems. Laser protective eyewear is usually not required for Class 2 or Class 3R lasers or laser systems, except in conditions where intentional long-term (>0.25 seconds) direct viewing is required. Eyewear must be specifically selected to withstand either direct or diffusely scattered beams and shall meet all provisions of ANSI Z87.1-1989.
- Refer to the Eyewear Selection Chart. Eyewear must be inspected before each use, and replaced if necessary, to maintain the eyewear in good condition. Contact the LSO for assistance in selecting protective eyewear.
Factors in selecting appropriate eyewear:
- Laser power and /or pulse energy
- Wavelength(s) of laser output
- Potential for multi-wavelength operation
- Radiant exposure or irradiance levels for which protection (worst case) is required
- Exposure time criteria
- Maximum permissible exposure
- Optical density requirement of eyewear filters at laser output wavelength
- Angular dependence of protection afforded
- Visible light transmission requirement and assessment of the effect of the eyewear on the ability to perform tasks while wearing the eyewear
- Need for side-shield protection and maximum peripheral vision requirement
- Radiant exposure or irradiance and the corresponding time factors at which laser safety filter characteristics change occurs, including transient bleaching especially for ultra short pulse lengths
- Need for prescription glasses
- Comfort and fit
- Degradation of filter media, such as photo bleaching
- Strength of materials (resistance to mechanical trauma and shock)
- Capability of the front surface to produce a hazardous specular reflection
- Requirement for anti-fogging design or coatings
Skin protection can best be achieved through engineering controls. If potential skin damaging exposures exist, skin covers and or “sun screen” creams are recommended. Minimize exposure to UV radiation by using beam shields and clothing (opaque gloves, tightly woven fabrics, laboratory jacket or coat) which attenuate the radiation to levels below the MPE for specific UV wavelengths. Consider flame-retardant materials forClass 4 lasers Special attention must be given to the possibility of producing undesirable reactions in the presence of UV radiation (formation of skin sensitizing agents, ozone, etc.).
6.2Facility Window Protection
Exterior or interior windows that are located within the NHZ of a Class 3b or Class 4 laser of laser system must be provided with appropriate absorbing filter, scattering filter, blocking barrier or screen to reduce any transmitted laser radiation to levels below the applicable MPE level. Important factors for selection include: ability to withstand direct and diffusely scattered beams, flammability and decomposition products of the window material.
6.3Laser Protective Barriers and Curtains
A blocking barrier, screen or curtain which can block or filter the laser beam at the entryway should be used inside the controlled area to prevent Class 3b or Class 4 laser light from exiting the area at levels above the applicable MPE level. Important factors for selection include: ability to withstand direct and diffusely scattered beams, flammability and decomposition products of the protective barrier or curtain.
7Warning Signs and Equipment Labels
Laser controlled areas must be posted with the appropriate warning signs at the entryway(s) and within the laser controlled area
- Warning: Must be used with all signs and labels associated with all Class 3R and most Class 4 lasers and laser systems that exceed the appropriate MPE for irradiance, and all Class 3b lasers and most Class 4 laser systems.
- Danger: Must be used with all signs and labels associated with a Class 4 laser and laser system with high power (multi-kW) or pulse energy.
- Caution: Must be used with all signs and labels associated with Class 2 and 2M lasers and laser systems, and all Class 3R lasers and laser systems that do not exceed the appropriate MPE for irradiance.
- Notice: Must be used on signs posted outside a temporary laser controlled area. The area within the temporary controlled area must also have appropriate signs posted (danger warning for Class 3b or Class 4).
- All lasers or laser systems (except Class 1) must have appropriate warning labels affixed to a conspicuous place on both the housing and the control panel (if separated by more than 2 meters).
- Class 2 lasers and laser systems, “Laser Radiation – Do Not Stare into Beam”
- Class 3R lasers and laser systems (accessible irradiance does not exceed MPE based upon 0.25 second exposure for wavelengths between 0.4 and 0.7 um), “Laser Radiation – Do Not Stare into Beam or View Directly with Optical Instruments”
- All other Class 3a lasers or laser systems, “Laser Radiation – Avoid Direct Eye Exposure”
- Class 3b lasers or laser systems, “Laser Radiation – Avoid Direct Exposure to Beam”
- Class 4 lasers or laser systems, “Laser Radiation – Avoid Eye or Skin Exposure to Direct or Scattered Radiation”
7.3Labeling of Protective Equipment
a) Labeling of Protective Eyewear
All eyewear must be clearly labeled with the optical density and wavelength. Color-coding or other distinctive identification is recommended in multi-laser environments.
b) Labeling of Laser Protective Windows and Collecting Optic Filters
All laser protective windows must be labeled with the optical density and wavelength(s) for which protection is afforded, and should be labeled with the threshold limit and exposure time for which the limit applies, and the conditions under which protection if afforded.
c) Labeling of Laser Protective Barriers
All laser protective barriers must be labeled with the barrier threshold limit and exposure time for which the limit applies, and beam exposure conditions under which protection is afforded. Contact LSO for any assistance.
An electrical shock hazard can occur from contact with exposed utility power utilization, device control, and power supply conductors operating at potentials of 50 volts and above. Individuals involved in such uses must be trained in electrical safety and in proper lockout-tagout procedures.
- Class 3b and 4 lasers should have a separate circuit and local cut-off switch (breaker) for the circuit.
- Label and post electrical high voltage hazards and switches. Clearly identify the main switches to cut-off power. Before working on a laser, de-energize the machine. Positively disconnect it, if there is more than one source of power, disconnect them all. Lock out and tag the disconnect switches so that power is not reconnected while you are working on the laser.
- Have at least two persons in an area while working on high-energy power systems.
Keep cooling water connections away from main power and high voltage outlets and contacts. Use double hose clamps on cooling water hoses. Inspect cooling water hoses and connections and power cables and connectors periodically as part of a regular equipment inspection. Check with Environmental Health & Safety on the proper installation of cooling water lines.
Laser Layout Guide (LLNL)
Reference: Section 3A, Environmental Factors: Electrical Power
10.2Laser-Generated Air Contaminants
Laser-Generated Air Contaminants (LGACs) may be generated when certain Class 3b and Class 4 lasers beams interact with matter. Characteristics of the contaminants depend upon the target material, cover gas, and beam irradiance. The LSO will coordinate with the EH&S Occupational Health and Safety Program to ensure proper evaluation and recommendation of appropriate controls, if necessary.
10.3Collateral and Plasma Radiation
Refers to radiation produced by system components other than the primary laser beam. The LSO will coordinate with various departments within EH&S to ensure proper evaluation and recommendation of appropriate controls, if necessary.
Radiation (Ionizing Radiation)
May be produced from electrical components of laser systems greater than 15 kV and from laser-metal induced plasmas.
Ultraviolet (UV) and Visible Radiation
May be generated from laser discharge tubes and pump lamps. Can cause skin and eye damage.
Some lasers contain RF excited components.
Created during certain processes, and may contain hazardous UV and blue light emissions.
Class 4 laser beams represent a fire hazard and under some situations it is possible that Class 3 lasers can initiate fires. Use flame retardant materials wherever applicable with all laser applications. Users should be aware that opaque laser barriers, e.g. curtains, can be designed to offer a range of protection, however, they normally cannot withstand high irradiance levels for more than a few seconds without some damage, e.g., production of smoke, open fire, or penetration. Operators of Class 4 lasers should also be aware of the ability of unprotected wire insulation and plastic tubing to catch on fire from intense reflected or scattered beams, particularly from lasers operating at invisible wavelengths. Contact SU Fire Marshall’s Office for additional guidance.
High-pressure arc lamps, filament lamps, and capacitor banks in laser equipment must be enclosed in housings which can withstand the maximum explosive pressure resulting from component disintegration.
Individuals who work with compressed gasses must take the EHS-2200 Compressed Gas training course. Contact the EH&S at (650) 723-0448 for more details regarding use of compressed gasses or for training information. Toxic gas users should refer to the Toxic Gas subtopic.
10.7Laser Dyes and Solvents
Laser dyes are complex fluorescent organic compounds which, when in solution with certain solvents, form a lasing medium for dye lasers. Certain dyes are highly toxic or carcinogenic. PIs/supervisors must ensure that all individuals who work with laser dyes and solvents receive appropriate Tier III training on hazardous material handling, storage, and disposal. Additional information can be found in the SU Chemical Hygiene Plan.
Note: The use of dimethylsulfoxide (DMSO) as a solvent for cyanine dyes in dye lasers should be discontinued if possible. DMSO aids in the transport of dyes through the skin and into the blood stream.
Laser Layout Guide (LLNL)
Reference: Section 3A, Environmental Factors: Ventilation
A good “rule of thumb” for determining if your work area or activity requires hearing protection is as follows:
If you have difficulty hearing or understanding a “normal” tone of voice at a distance of about three feet, noise levels are probably exceeding safe levels and you should be using hearing protection. Please contact EH&S at (650) 723-0448 for an evaluation.
Dispose of all wastes in accordance with the relevant guidelines. Contact the Chemical Waste Program at (650) 723-0448 or see the Waste Disposal topic for additional help.
10.10Limited Work Space
Limited workspace can be a problem especially while working near or around mechanical or high voltage equipment. Cal/OSHA (8 CCR 2340.16 & 3272) requires a minimum aisle width of 24” with 36” clearance around electrical panels. In all cases there must be sufficient room for personnel to turn around and maneuver freely.
Consider ergonomic principles in laser system designs, such as positioning of the laser system and area illumination.
11.1Service of Embedded Class 3b or Class 4 Lasers
Access to Class 3b or Class 4 lasers or laser systems enclosed within a protective housing or protected area enclosure is limited to properly trained individuals and by specific engineering and administrative controls. Contact EH&S for more information.
11.2Outdoor Control Measures
Projection of Class 3r, 3b, or 4 lasers beams in the outside environment requires prior review by the LSO. Contact EH&S for additional information.
11.3Additional Laser Uses
Lasers may also be used in optical fiber transmission systems and robotic installations. Contact the LSO for more information regarding applicable control measures.
11.4Laser Alignment Guidelines
- Exclude unnecessary personnel from the laser area during alignment.
- Use low-power visible lasers for path simulation of higher power visible or invisible lasers whenever possible.
- Wear laser protective eyewear during alignment. Use special alignment eyewear when circumstances (e.g. wavelength, power, etc.) permit their use.
- When aligning invisible (e.g. UV, IR) beams, use beam display devices such as image converter viewers or phosphor cards to locate beams.
- Perform alignment tasks using high-power lasers at the lowest possible power level.
- Use a shutter or beam block to block high-power beams at their source except when actually needed during the alignment process.
- Use a laser rated beam block to terminate high-power beams downstream of the optics being aligned.
- Use beam blocks and/or laser protective barriers in conditions where alignment beams could stray into areas with uninvolved personnel.
- Place beam blocks behind optics (e.g.: turning mirrors) to terminate beams that might miss mirrors during alignment.
- Locate and block all stray reflections before proceeding to the next optical component or section.
- Be sure all beams and reflections are properly terminated before high-power operation.
- Post appropriate area warning signs during alignment procedures where lasers are normally Class 1 (enclosed).
- Alignments should be done only by those who have received laser safety training.
12.1Response/ Reporting Procedures
All accidents/exposures are to be reported to supervisor as soon as possible.
Serious Injury/ Illness
For health-threatening injuries/ illnesses, call x9-911 or proceed immediately to the Stanford Hospital Emergency Department. Supervisor is to immediately contact EH&S @ 725-9999 to report deaths, or serious injury or illness.
Cal/OSHA defines an injury or illness as “serious” and reportable if it involves:
- inpatient hospitalization, regardless of length of time, for other than medical observation or diagnostic testing;
- loss of an eye; or
- serious degree of permanent disfigurement.
All Other Injuries
For treatment of all other injuries, proceed to:
Standardized Forms for Accident/Exposures
- Supervisors are to provide Employee’s Claim for Workers’ Compensation Benefits (Form DWC-1) to injured employee immediately. Supervisors andemployees are to complete within 24 hours.
- The SU-17 Accident, Incident or Exposure Report (for all incidents/ injuries/ exposures) has two sections: one for the supervisor and one for the employee to complete. To be completed within 24 hours and sent to Risk Management.
- Cal-OSHA 5020 to be completed (typed) within 24 hours by the supervisor (for cases when one or more workdays is lost by an employee or when treatment of the employee is required by a physician in a medical facility).
- SU-16 Workers’ Compensation Lost Workdays Report is completed by the supervisor when an employee has one or more workdays is lost.
- All forms are available from the Stanford University Office of Risk Management.
Upon notification of an accident, LSO will conduct an investigation. Steps of the investigation include:
- LSO interviews injured workers and witnesses
- LSO examines workplace for factors associated with the accident/exposure
- LSO determines the possible causes of the accident/exposure
- Supervisor takes corrective action to prevent the accident/exposure from recurring
- Supervisor records the findings and corrective actions taken