Transcription
LIGO-G0901007-v1Basic Laser Safety TrainingLIGO Laboratory SafetyLIGO-G090000-00-DLIGO Laboratory Safety1
Introduction Topics covered:»»»»»»»»»»Why Laser Safety?What Is A Laser?Eye InjuriesLaser ClassificationsLaser Safety EyewearLaser Warning SignsTerminologyResponsibilitiesWhat To Do In Case Of An Incident?What’s In The Laser Area?LIGO-G090000-00-DLIGO Laboratory Safety2
Laser Safety Why All TheConcern? Compared to natural light, laser light or laserradiation have some very special properties.These properties cover the nature of laser light andits biological risk factorsLIGO-G090000-00-DLIGO Laboratory Safety3
Image Formation Yielding LaserHazard The eye acts as a lensthat focuses imagesonto the retina.» focal length, f 17 mm» pupil diameter, d 7 mm Irradiated spot on theretina can be as smallas 10 – 20 μm indiameter.» 10 mW 12.7 kW cm-2LIGO-G090000-00-DLIGO Laboratory Safety4
A Laser beam or partial reflectioncan present a real eye hazard LIGO-G090000-00-DLIGO Laboratory SafetyCompared to otherlight sources laserlight depositsconsiderably moreenergy at the backof ones eyeReview chartIrradiance energyper cm21mW in 100W/cm2 at yourretina. All due todecreased spot size5
Beams between 400-1400 nmObtain an optical gain of 100,000LIGO-G090000-00-DLIGO Laboratory Safety6
The Electromagnetic SpectrumLIGO-G090000-00-DLIGO Laboratory Safety7
Say, what is a Laser? Laser is anacronym for:LightAmplification byStimulatedEmission ofRadiation.LIGO-G090000-00-DLIGO Laboratory Safety8
Properties of Laser LightLIGO-G090000-00-DLIGO Laboratory Safety9
Biological Effects of LaserRadiation The nature and site of eye injury from laser radiationare depended on the followingWavelength» Determines what part of the eye is exposed Output of the beam: irradiance at the eye» Power striking your eye Exposure duration: how long the beam is strikingyour eye» Safety calculations are done at 0.25 seconds for visiblewavelengths and 10 seconds for infrared wavelengthsLIGO-G090000-00-DLIGO Laboratory Safety10
Anatomy of the Human EyeLIGO-G090000-00-DLIGO Laboratory Safety11
Absorption of Laser Radiation bythe EyeLIGO-G090000-00-DLIGO Laboratory Safety12
Examples of Eye Injuries The following viewgraphs contain images of laserrelated eye injuries.We do not want to add you image to this collectionDo you?LIGO-G090000-00-DLIGO Laboratory Safety13
Eye Injuries Direct hit whilst aligning a Pockels cell.Vision reduced to 20/200 – a visual acuity of 0.1.» Visual acuity improved to 0.4 after 3 weeks. Deteriorated to 0.2after 2 years.» Hole developed in the macular.LIGO-G090000-00-DLIGO Laboratory Safety14
Eye Injuries Right eye visual acuity decreased to 0.7.» Improved to 1 within 2 months. Permanently scarred.LIGO-G090000-00-DLIGO Laboratory Safety15
Eye Injuries – Nd:YAG Laser Taken 4 hours after exposure to an Nd:YAG laser.» Large hæmorrhaging, part of which going into the vitreous humour. Taken 3 days after exposure to an Nd:YAG laser.» Small hæmorrhage spot smaller than the optic disc.LIGO-G090000-00-DLIGO Laboratory Safety16
Eye Injuries – Nd:YAG Laser(cont.) Ten days after the injury, a hole in the maculaappeared.Six months after the injury, scarring is evident.LIGO-G090000-00-DLIGO Laboratory Safety17
Laser Hazard Classifications Laser’s are divided into a number of hazard classes,the higher the class number the greater the potentialhazard.» Class 1, Class 1M» Class 2, Class 2M– output power less than 1 mW» Class 3R,» All the classes listed above present little to no eye hazard» Within LIGO we are primarilyconcerned withClass 3B and Class 4.LIGO-G090000-00-DLIGO Laboratory Safety18
Lasers: Class 3B, 4 Comparison Class 3B Can be visible or invisible Output between 5-500mWHazard from Direct or intra beamexposure Specular reflection Eye hazard LIGO-G090000-00-DClass 4Can be visible or invisible Output Greater then 0.5WHazard from Direct or intra beamexposure Specular reflection Diffuse reflection Eye hazard Skin Hazard Combustion hazard (gas,paper, skin etc) LIGO Laboratory Safety19
How Do We Protect Ourselves? Awareness through trainingBeam enclosuresLaser protective eyewearFollowing procedures - Standard OperatingProcedures- SOPWarning signsAccess controlCommunication to and with othersLIGO-G090000-00-DLIGO Laboratory Safety20
Laser Safety Eyewear The purpose of laser protective eyewear is to attenuate anylaser radiation that might strike it to a safe level. In laser safetyspeak, below the MPEMPE Maximum Permissible Exposure upper limit of laserirradiation to our eye that will not cause damage. The higher theexposure over MPE, the greater possible damageDefinition of optical density (OD)» OD -log10(transmittance) Laser safety eyewear is characterized by its OD.All Laser Safety Eyewear is required to be labeled with its ODfor the wavelengths it provided protection for.Eyewear is wavelength or wavelength range specificLIGO-G090000-00-DLIGO Laboratory Safety21
Optical DensityLIGO-G090000-00-DLIGO Laboratory Safety22
Matching Eyewear toLaser Use AreaLIGO-G090000-00-DLIGO Laboratory Safety23
Identification of the Correct LaserSafety Eyewear Before putting on your laser safety eyewear pleasecheck the following:» That the OD is correct for the applicable laser wavelength.» That the frames and lenses are in good condition, i.e. no scratchesand pits in the lenses, no loose joints in the temples.» If you are uncertain, please check with the LSO.LIGO-G090000-00-DLIGO Laboratory Safety24
Inspection of Laser SafetyEyewear At a cursory glance this set of laser glasses mightseem okay apart from a seemingly minor cosmeticfault. But » 300 mW was transmitted through a “good” region.» 4.3 W was transmitted through the damaged region.LIGO-G090000-00-DLIGO Laboratory Safety25
Laser Warning SignsLIGO-G090000-00-DLIGO Laboratory Safety26
Terminology Laser Safety Officer (LSO)» One who has the responsibility and authority to monitor and enforcethe control of laser hazards and effect the knowledgeableevaluation and control of laser hazards. Maximum Permissible Exposure (MPE)» The level of laser radiation to which an unprotected person may beexposed without adverse biological effects to the eye or skin.LIGO-G090000-00-DLIGO Laboratory Safety27
Terminology (cont.) Nominal Hazard Zone (NHZ)» The space within which the level of direct, reflected or scatteredradiation may exceed the applicable MPE. Exposure levels beyondthe NHZ are below the appropriate MPE.» At the observatories, the entire LVEA is a NHZ. Standard Operating Procedure (SOP)» Formal written description of the safety and administrativeprocedures to be followed in performing a specific task.LIGO-G090000-00-DLIGO Laboratory Safety28
Responsibilities As a person with basic laser safety training you areallowed to:» do what you are told you can do As a person with basic laser safety training you areNOT allowed to:» Operate a laser by yourself.» Make changes to the beam path by yourself.LIGO-G090000-00-DLIGO Laboratory Safety29
Incident Procedures What do I do if I think I was hit by a laser?»»»»Notify those in the immediate area and switch off the laser.Remove yourself from the hazard zone.Seek medical attention as necessary.Notify your supervisor or the LSO as soon as possible.LIGO-G090000-00-DLIGO Laboratory Safety30
You Can Choose Your Peers LIGO-G090000-00-DLIGO Laboratory Safety31
Non-Beam HazardsRemember that more can hurt you than the laser ElectricityPressureChemicalsMechanicalConfined spaceCryogenicsLaser-generated air contaminantsHousekeeping hazardsSleepinessLIGO-G090000-00-DLIGO Laboratory Safety32
Summary Working safely around lasers is possible and verydesirable. Respect all warning signs. Wear your eyewear. Always, always, always. If you have questions, ask the LSO.LIGO-G090000-00-DLIGO Laboratory Safety33
Laser Safety Eyewear The purpose of laser protective eyewear is to attenuate any laser radiation that might strike it to a safe level. In laser safety speak, below the MPE MPE Maximum Permissible Exposure upper limit of laser irradiation to our eye that will not cause damage. The higher the exposure over MPE, the greater possible damage
