In addition to the direct laser radiation hazard, a laser can present other hazards, all of which need to be considered in a risk assessment of laser use. The tables that follow list some of the more common of these non-beam or associated hazards together with some typical situations where they arise and typical control measures.
A2.1 Hazards arising from the Laser source
|
Hazard |
Typical hazardous situation |
Typical control measure |
| High voltage | Many lasers utilise high voltages, and pulsed lasers frequently employ capacitors to store electric charge. Laser head and power supply exposed during servicing. | Containment of high voltages in normal use.
Proper screening of exposed HV. Restricted access to qualified persons.
Use of earthing stick to ensure the removal of stored energy prior to commencement of servicing work. |
| Fire and Explosion | Laser equipment can present a fire hazard by virtue of the flammable components, plastic parts etc. contained within it, which can overheat or catch fire in the event of a fault within the equipment. High-pressure flash lamps, capacitors and other internal components can explode. | Safe design conforming to relevant standards Routine electrical testing For fire: access to a fire extinguisher; smoke alarm; training. For explosion protection during maintenance activities: gloves and face shield; training. |
| Noise | The discharge of capacitor banks within the laser power supply can generate noise levels high enough to cause ear damage. Ultrasonic emissions and repetitive noise from pulsed lasers can also be harmful. | Use of acoustic barriers / enclosures.
Use of ear protectors where excessive noise levels cannot be eliminated by other means. |
| Collateral radiation | Ultraviolet, visible and infrared emission can be produced from gas laser discharge tubes.
Microwave and radio frequency radiation is produced in RF-excited lasers, and can be emitted by the equipment if not properly shielded, particularly during servicing.
Low frequency magnetic fields from switched mode power supplies and pulsed lasers may present a hazard to those dependent on active medical devices. X-rays can be produced by high-voltage thermionic valves within the laser power supply. | Proper screening combined with access restricted to service engineers.
Subject to specific regulatory requirements:
Control of Artificial Optical Radiation at Work Regulations 2010 (see STFC code 22)
Control of Electromagnetic Fields at Work Regulations 2016 (see STFC code 23). |
| Mechanical | Unloading and positioning of laser power supplies and ancillary items such as gas cylinders.
Trailing cables and water-circulation tubing can present a trip hazard. | Provide attachment points for use of lifting equipment by qualified persons.
Training and use of gloves.
Properly secure equipment. Cover cables in ducting or under a raised walkway.
|
| Chemical | The material used as the active medium in many lasers (especially laser dyes and the gases used in excimer lasers) can be toxic and carcinogenic. These chemicals often have limited life and require frequent replacement resulting in a requirement for safe handling procedures.
The solvents used in many dye lasers have the ability to carry their solutes through the skin into the body. They may also be highly volatile and should not be inhaled. | Proper storage, handling and disposal precautions should be adopted.
Ensure quality of pipework, inspection regimes and requirements for secondary containment.
Training and use of gloves and other PPE. |
A2.2 Hazards arising from the Laser process
|
Hazard |
Typical hazardous situation |
Typical control measures |
| Fume | Release of hazardous particulate and gaseous by-products into the atmosphere through the interaction of the laser beam with the target material. | General precautions include: Fume extraction and filtration. Face mask and gloves worn during cleaning operations.
|
| Hazardous substances | Cleaning solutions and also other materials used in conjunction with the laser (e.g., zinc selenide lenses) may be hazardous. | Use proper storage and implement handling and disposal precautions |
| Fire and explosion | The laser emission from high-power (Class 4) lasers can ignite target and other materials. These effects may be enhanced in oxygen-rich and other unusual atmospheres. Laser emission from even lower-class lasers, especially when focussed to very small spot sizes, can cause explosions in combustible gases or in high concentrations of airborne dust.
| Control flammable materials and beam path. Provide a fire extinguisher in the laser area. |
| Secondary radiation | X-ray, UV and blue light emitted by the plasma that can be generated by interaction of the laser beam (particularly those containing short, high power pulses) with target materials. Such emissions can include x-rays, ultraviolet radiation (UV), visible light, infrared radiation (IR), microwave radiation and radio-frequency (RF) radiation. | Enclose target area and monitor hazard. Subject to specific regulatory requirements:
Ionising Radiations Regulations 2017 (see STFC code 29)
Control of Artificial Optical Radiation at Work Regulations 2010 (see STFC code 22)
Control of Electromagnetic Fields at Work Regulations 2016 (see STFC code 23). |
| Mechanical | Beam delivery arms and robotic systems that move under remote control can cause serious injury. Large work-pieces can present manual handling problems such as cuts, strain, and crush injuries. | Guard traps and add warning signs.
Restrict access to moving parts. |
A2.3 Hazards arising from the Laser environment
|
Hazard |
Typical hazardous situation |
Typical control measures |
| Temperature and humidity | Excessive high or low ambient temperatures, or high levels of ambient humidity, can affect the performance of the laser equipment, including its in-built safety features, can compromise safe operation and make the wearing of safety eyewear uncomfortable.
| Provide air conditioning and humidity control of the local environment.
Install a gas purge in beam delivery line. |
| Mechanical shock and vibration | Misalignment of the optical path, generating hazardous errant beams. | Install a vibration isolation system on the legs of optical tables holding optical components.
Construct a floating foundation for large laser machines. |
| Atmospheric affects | Laser ignition of solvent vapour, dust, and inflammable gases present in the environment. | Enclose beam and process zone and add a gas purge.
Install gas sensors to detect presence of inflammable gases and vapours.
|
| EM and RF interference | Compromised operation of control circuits caused by interference to laser equipment resulting from exposure to EM radiation and high voltage pulses conducted down supply or data cables. | Screen equipment and filter supply and data cables. |
| Power supply interruption or fluctuation | Interruption or fluctuation of the electrical supply can affect the operation of the laser's safety system. | Install a voltage regulation system and back-up supply. |
| Computer software problems | Serious and unpredictable hazards arising without warning caused by errors in computer programming of software control. | Use only approved protocols for software control of safety functions. |
| Ergonomic and human-factor considerations | Poor arrangement of the physical layout of the laser and its associated equipment.
Lack of space resulting in a cluttered environment.
Complex or difficult operating procedures.
Human factors, including: personal aspects (mental and physical attributes of the individual, including work ability , perception of workplace risks, age and experience, and attitude to safety); job aspects (tasks or functions to be performed; influence on human performance of the equipment that has to be used); organisational aspects ("safety culture" of the organisation, including the framework within which an individual has to work and the influences and pressures (real or imagined) that the individual may be under). | Improve layout, reduce clutter and review the ergonomics of repetitive or sustained tasks.
Training to improve human factors since these play some part in the majority of work-related accidents. |
Details of safety precautions relating to particular hazards can be found in the relevant SHE Safety Codes.
