The UNC Asheville Laser Safety Program requires that all lasers and laser systems be operated in accordance with the American National Standards Institute (ANSI) Z136.1 2014, American National Standards for Safe Use of Lasers. This is a voluntary standard that encompasses the requirements of OSHA regulations. The safe use of laser systems depends upon the basic principles of safety, which are:
- Recognition of potential hazards.
- Evaluation of potential hazards.
- Control of potential hazards.
The primary objective of the UNC Asheville Laser Safety Program is to ensure that no laser radiation in excess of the Maximum Permissible Exposure (MPE) limit reaches the human eye or skin. Additionally, the program is designed to ensure that adequate protection against collateral hazards is provided. These collateral hazards include the risk of electrical shock; fire hazard from a beam or from use of dyes and solvents; and chemical exposures from use of chemicals or vaporization of targets.
This Laser Safety Program applies to the acquisition, use, transfer, and disposal of all Class 3B and 4 lasers at UNC Asheville.
Class 3B Laser: A Class 3B laser is hazardous if the eye is exposed directly, but diffuse reflections such as those from paper or other matte surfaces are not harmful. The Accessible Emission Limit (AEL) for continuous lasers in the wavelength range from 315 nm to far infrared is 0.5 W. For pulsed lasers between 400 and 700 nm, the limit is 30 mJ. Other limits apply to other wavelengths and to ultra-short pulsed lasers.
Class 4 Laser: Class 4 is the highest and most dangerous class of laser, including all lasers that exceed the Class 3B AEL. By definition, a Class 4 laser can burn the skin, or cause devastating and permanent eye damage as a result of direct, diffuse or indirect beam viewing. These lasers may ignite combustible materials, and thus may represent a fire risk. These hazards may also apply to indirect or non-specular reflections of the beam, even from apparently matte surfaces—meaning that great care must be taken to control the beam path.
The UNC Asheville Laser Safety Officer responsibilities reside with the University's EH&S Professional in conjunction with Laser Safety Supervisors.
Laser Safety Officer:
The UNC Asheville Laser Safety Officer is responsible for overseeing the University Laser Safety Program. The duties of the Laser Safety Officer include:
- Maintain an inventory of all Class 3B and 4 lasers.
- Provide assistance in evaluating laser hazards and develping Standard Operating Procedures (SOPs).
- Provide assistance in developing Laser Safety Training.
- Participate in incident investigations involving lasers.
- Audit departmental Laser Safety Programs.
Laser Safety Supervisor:
The Laser Safety Supervisor is responsible for complying with all requirements of the University's Laser Safety Program. Compliance includes:
- Registering all Class 3B and 4 lasers used under their supervision to the Laser Safety Officer.
- Evaluating laser hazards and developing Standard Operating Procedures (SOPs) for their safe use.
- Administering training to persons operating lasers under their supervision.
- Report and aid in the investigation of all incidents involving lasers under their supervision.
- Notifying the Laser Safety Officer of changes relating to laser operation, laser transfers or laser disposal.
Hazard Assessment and Laboratory Design Requirements
A hazard assessment must be performed on all active Class 3B and 4 lasers. Assessments also must be conducted when preexisting lasers are relocated or whenever a significant change is made to a laser. A hazard assessment will include consideration of the properties of the laser (power, wavelength, etc.), the environment in which it is located, existing emergency controls, work practices and procedures, and the potential for exposure. Maintenance procedures will also be addressed. Maintenance procedures include electrical troubleshooting, gas cylinder changes and other maintenance operations where a standard operating procedure is needed.
Class 3B and 4 Design Requirements
Design requirements are based on the assumption that the nominal hazard zone includes the lab or area where the laser is located and extends through an open doorway into the adjacent hallway.
- Entry way protection - Entry ways into Class 3B and 4 laser labs must include the following elements:
- No windows may be present which could allow either direct or reflected beams to leave the work area.
- Entry to the lab must be controlled while the laser is in operation. Key locks or cipher locks should be present to prevent unauthorized and unprotected personnel from entering the nominal hazard zone. If a key lock is used to protect exterior entry, the laser user must be able to exit the lab through use of the inside door handle which overrides the door lock. All doors must have door closers unless the door is interlocked to the laser with a non-defeatable interlock.
- For Class 4 lasers - when doors are open, it must not be possible for direct or reflected beams to pass into the hallway. This can be accomplished through the use of a non-defeatable door interlock. Alternatively, procedural or administrative controls such as the use of a curtained area inside the lab may be used if judged appropriate by the laser safety supervisor and the laser safety officer.
- Warning signs must be posted at the entrance to the laser area.
- Protection Inside the Laser Area - Measures are necessary to protect the laser user and others inside the work area. Complete beam path enclosure is the primary control measure to be considered. If this is not practical, the following preventative measures must be implemented.
- Beams must be positively terminated through use of permanently attached beam stops or attenuators.
- The laser work area should be free of specular surfaces which may cause specular beam reflections and, for Class IV lasers; exposure to hazardous diffuse reflections is prevented.
- Where Class 4 lasers are in use, curtain materials (and other materials that may contact the beam) must be selected which are fire resistant to direct and prolonged beam contact.
- Labs with Class IV lasers must contain a clearly labeled "panic button" which kills power to the laser.
- For Class 4 lasers a warning light must be located outside of the lab door to indicate when the laser is firing.
Warning Signs and Labels
Warning Sign and Labels
All Class 3B, and 4 laser laboratories must have laser signs posted at the entryway to the lab or work area. Signs will comply with ANSI requirements and will include the following information:
- For Class 3B - "Laser Radiation - Avoid Direct Exposure to Beam"
- For Class 4 - "Laser Radiation - Avoid Eye or Skin Exposure to Direct or Scattered Radiation"
- For Invisible Beams - substitute words "Invisible Laser Radiation..."
- Type of radiation or emitted wavelength
- Pulse duration, if appropriate
- Maximum output
- Class of Laser
When a lab contains more than one laser, the sign will convey the hazard information for the highest power laser in the lab.
- Selection of Eyewear - Laser protective eyewear is required whenever persons are within the nominal hazard zone (NHZ). During maintenance and alignment procedures, the nominal hazard zone is considered to be the entire lab area. After a beam path has been clearly defined and contained, the nominal hazard zone may be reduced in size. Remember that class 4 lasers can produce hazardous diffuse reflections, so the nominal hazard zone will need to account for this. Eyewear must be of the correct optical density and protect in the specific wavelength(s) of the laser(s) in use. In some cases, a lower optical density laser goggle may be chosen to permit the laser beam to be seen.
- Other Protective Equipment - Where Excimer lasers and other UV emitting sources are used, long sleeves and gloves to protect the skin are recommended. Other protective equipment may be identified through the hazard assessment procedure.
Laser Accidents and Incidents
Laser Accidents and Incidents
All injuries and suspected exposures are required to be reported to the Laser Safety Supervisor and the Laser Safety Officer. Near misses should also be reported. A near miss is an unanticipated event that did not result in harm or injury but had the potential to do so. Incidents will be reviewed and modifications to SOPs will be completed if necessary to prevent the incident from happening again.
Transfer or Disposal of Lasers
Transfer of Lasers
The Laser Safety Officer should be made aware prior to transferring a laser to a different Laser Safety Supervisor or to a new location. This will ensure proper hazard assessments are completed and that the laser inventory is accurate.
Disposal of Lasers
The Laser Safety Officer should be contacted prior to disposing of any class of laser. Lasers need to be rendered "inoperable" prior to disposal. Class 3B and 4 lasers will also be removed from the University's laser inventory.