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.
or
(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.
Engineering Controls
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.
| Engineering controls | Laser Class 3b | Laser class 4 |
|---|---|---|
| Protective Housing – for active laser work with housing off, contact LSO for hazard analysis and appropriate controls | √ | √ |
| Interlocks on Protective Housing | √ | √ |
| Service Access Panels Interlocked or tool required and appropriate warning label on the panel | √ | √ |
| Key Control | + | √ |
| Remote Interlock Connector | + | √ |
| Beam stop or Attenuator | + | √ |
| Laser Activation Warning System | + | √ |
| Emission Delay | √ | |
| Remote Firing and Monitoring | √ | |
| Panic Button | √ | |
| Viewing windows, diffuse display screens, or collecting optics (lenses, microscopes, etc.) are controlled with interlocks, filters, or attenuators to maintain laser radiation at the viewing position at or below the applicable MPE. | √ | √ |
| Enclosed Beam Path | + | + |
√ Required
+ Recommended
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.
