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Laser users:• in the event of an accident or incident terminate
laser emission and report to management;
• Seek medical attention in the event of a real orsuspected laser injury.
LSO:• Possible eye-injured persons must be seen by a
qualified ophthalmologist within 24 hours of thepotential exposure;
• Investigate the circumstances and assess likelyexposure, document the conclusions of theinvestigation and review system of control beforelaser is permitted to be used.
Procedures for laser use inthe research environment
StructureElements of procedures:
1. Essential generalinformation
2. Procedures foremergencies
3. Procedures fornormal operation
4. Procedures foralignment
5. Procedures forexternal contractors
Point out basic good practice (e.g. terminating beams,secure fixing of turning mirrors)
Identify administrative controls and use of PPE.
Highlight any deviations from best practice.
The normal shut-down procedure should be described.
Include requirements for safety checks (interlocks etc.).
Servicing procedures should address the establishmentof temporary hazard areas, administrative controls,PPE and who should carry out the work. It shouldinclude procedures for controlling the work of outsideservice engineers e.g. permits to work.
Identify potentially injurious situations(all operations, all hazards)
Benefits
RISKASSESS
Step 1
Assess the risk for each situation(severity of injury, likelihood of exposure; then refer torisk tables)
Step 2
Review controls for each situations where the riskis intolerable(compare with current best practice and state whetheror not you consider existing controls to be satisfactory)
Step 3
Involving users inidentifying hazardousactivities encouragesparticipation andownership of safety
Identify potentially injurious situations(all operations, all hazards)
Benefits
RISKASSESS
Step 1
Assess the risk for each situation(severity of injury, likelihood of exposure; then refer torisk tables)
Step 2
Review controls for each situations where the riskis intolerable(compare with current best practice and state whetheror not you consider existing controls to be satisfactory)
Step 3
Review the new situation (repeat steps 2 and 3)Step 4
Review the riskassessmentperiodically
Involving users inidentifying hazardousactivities encouragesparticipation andownership of safety
Is:• Information of the current laser hazard clearlydisplayed at point of access to the laser area?
• Low level lighting used for ‘lights-out’ operation?• A safe method of beam alignment provided?• A visible or audible warning of the potential laserhazard provided?
• Laser safety eyewear provided?Are:• Persons at risk of exposure to the laser radiationadequately trained and instructed?
• Precautions in place to safeguard visitors enteringthe laser area?
• Unauthorised persons prevented from gainingaccess to the laser area?
Arrange for a fireassessment whereverClass 4 lasers are used
Carry a fire extinguisherand fit a smoke detector__________________
A Class 4 dye laser ignited the methanol solventused in the laser.
A small explosion and fire occurred in a laser dye(dioxane) mixture pump. Arcing in the pump motor,which ignited the flammable air/dioxane mixture,apparently caused the fire.
A Class 4 CO2 laser beam was reflected upwardsand ignited ceiling tiles in a laser laboratory. Theresearcher had left the room to examine samplesand returned a few minutes later when a smokedetector sounded.
A technician was replacing a flashlamp on a Nd:YAGlaser. The unit was electrically isolated, shut downand locked out. After 5 minutes wait for thecapacitor to discharge the worker touched thenegative terminal and was shocked. This wasidentified as a bleed circuit malfunction. No seriousharm.
A service engineer was electrocuted while installinga copper vapour laser. An interlocked protectivepanel had been manually bypassed during theinstallation to make adjustments. Despite CPR theserviceman expired.
Electrical hazards inlasers can be lethal
Proper HV training isessential
Provide earthing sticks
Consider secondaryscreening of internal HV__________________
An untrained summer research assistant wascarrying out alignment on his first day at work usinga 150 mW argon/dye laser. The laser was “slung” ina laser holder located under optical bench and thebeam was directed upwards through a beamchannel in the optical bench. The student chose tostand on top of the table and look downward whileattempting to align a turning mirror. No protectiveeyewear was used. The turning mirror slipped andthe beam was directed into his eye causing animmediate retinal burn on the edge of the macula.
During an experiment, a student climbed onto astool to adjust a periscope with a visible laser. Thestudent noticed a bright flash in her right eye. Noeyewear was worn ‘since she needed to observe thespot on a card’. No pain or bleeding, but anexamination the next day revealed a parafoveallesion.
Fully guard upward-travelling beams
Provide alignmentprocedures that facilitatethe use of protectiveeyewear
A student received a reflected Ti-Sapphire laserbeam from the plastic lid of a toolbox while he wasinstalling a laser beam safety tube. No eyeprotection was worn. The student had not receivedlaser safety training.
During optics alignment involving a 30 mJ pulsedNd:YAG laser (10 Hz) on a target using a prism, thebeam exceeded the prism’s critical angle and struckthe scientist in the eye resulting in a permanentretinal burn. No protective eyewear was worn.
A scientist bumped a mirror mount in a complexoptical array, causing a stray beam to move out ofthe horizontal plane. When leaning over the table, hewas struck in his left eye. An examination confirmeda macular lesion. No eyewear worn and safetyknowledge was limited.
Require the use of safetyeyewear wherever thereare exposed Class 3Band 4 laser beams
Control the use ofreflecting objects nearopen beam paths
Locally enclose prismsand other sources ofsecondary beams
A field service engineer was working on an argonlaser photocoagulator. During the inspection, theengineer was looking down the tube bore when thelaser spontaneously fired. He received an intrabeamocular exposure causing a permanent retinal lesion.
A Ti-sapphire accidentally discharged during beamalignment. The graduate student undertaking thealignment sustained a left eye injury. At 4 days, a300 µm hole and sub- retinal haemorrhage wasobserved.He suffers central vision loss and floaters.
A new frequency doubler didn't have A/R coatingsas requested. As the student left the room, beam hithim in the corner of his eye and caused inter-ocularbleeding. He still complains at 8 yrs of floaters andvision that looks "like looking through a dirtywindow".
Do not rely solely oncontrol circuits: add abeam stop or power down
Do not rely on coatingspecification for safety__________________
A technician received a 60 mW exposure from theBrewster window of an argon laser. Laser protectiveeyewear was available, but was not used theyapparently fogged easily and were annoying to use.A blind spot has persisted in the area of the lesion.
A frequency doubled Nd:YAG laser beam (532 nm)was Raman shifted to 770 nm in a methane cell. Thelaser protective eyewear provided protection at 532nm but did not protect for 770 nm and the techniciansuffered a retinal burn from a 0.8 µJ, 770 nm pulse.
During an alignment of a Nd:YAG laser, a productionworker looked through an opening in the top of achamber and his eyewear slid up as he leaned over.The beam reflection from a target paper went intohis eye causing a bright afterimage lasting 20minutes, which led to a permanent central retinalburn.
Nd:YAG reflectionfrom a surface coatedfilter. Safety gogglesmisted so he took themoff to get a better view ofthe display ….
A technician received a 60 mW exposure from theBrewster window of an argon laser. Laser protectiveeyewear was available, but was not used theyapparently fogged easily and were annoying to use.A blind spot has persisted in the area of the lesion.
A frequency doubled Nd:YAG laser beam (532 nm)was Raman shifted to 770 nm in a methane cell. Thelaser protective eyewear provided protection at 532nm but did not protect for 770 nm and the techniciansuffered a retinal burn from a 0.8 µJ, 770 nm pulse.
During an alignment of a Nd:YAG laser, a productionworker looked through an opening in the top of achamber and his eyewear slid up as he leaned over.The beam reflection from a target paper went intohis eye causing a bright afterimage lasting 20minutes, which led to a permanent central retinalburn.
Select eyewear that iscomfortable to wear,secure and does not fogup
Isolate wavelengths if theeyewear can’t provideadequate protection at all__________________