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UC Santa Cruz Laser Safety Training

UC Santa Cruz Laser Safety Training. Acknowledgements UCR Rick Mannix Laser Safety Officer Karen Janiga , MS Radiation Safety Officer Laser Safety Officer Janette De La Rosa Ducut , Ed.D . Training Manager. Determine laser classes and components

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UC Santa Cruz Laser Safety Training

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  1. UC Santa CruzLaser Safety Training Acknowledgements UCR Rick MannixLaser Safety Officer Karen Janiga, MSRadiation Safety OfficerLaser Safety Officer Janette De La Rosa Ducut, Ed.D.Training Manager

  2. Determine laser classes and components Identify hazards Biological Non-Beam Implement controls Engineering Administrative Work Practice PPE Objectives 2

  3. What is a Laser? Light Amplification by Stimulated Emission of Radiation Lasers Intense light that can cause tissue damage, burns, and damage to the eye and skin. 3

  4. Light Properties Ordinary light is incoherent, visible, dispersed, and low powered. Laser light is different from ordinary light, like the type you find in a light bulb. Ordinary light is incoherent. This means that it has many wavelengths, that move in many directions, and thus can emit many different colors. This results in light that has a low concentration of power per surface area. 4

  5. Laser Properties In contrast, laser light is coherent. This means that the light rays have the same wavelength (that move in unison), travel in one direction, and have one specific color of light (or what is known as “monochromatic”). This results in a narrow laser beam that has a high concentration of power per surface area. Laser light is coherent, sometimes invisible, directional, and high powered. 5

  6. Laser Components • All lasers have three common elements: a pump, a lasing medium, and an arrangement of two mirrors. • The pump produces energy used to excite the lasing medium, and controls the laser's output power. Examples of energy sources include flash lamps, electricity, chemical reactions, and other lasers. • The lasing medium is a substance that emits coherent light as the result of exposure to the pumping system. • Two mirrors form a feedback mechanism. When light is bounced back and forth between the mirrors, its energy is amplified (hence the term “stimulated emission”). The amplified light escapes from the partially transmitting mirror (also known as the “optical resonator”), resulting in an actual laser beam.

  7. Laser Components Pump MirrorReflectant MirrorTransparent Lasing Medium 7

  8. Output Lasers also differ from each other based on their output characteristics. They can be a continuous wave or a pulsed laser beam. > ¼ sec Continuous < ¼ sec Pulsed 8

  9. Output Continuous wave lasers emit beams at a constant power (similar to a flashlight) for at least ¼ of a second. This is enough time for serious eye damage, if the laser has a high enough power. Power for these lasers is expressed in the form of Watts. > ¼ sec Continuous 9

  10. Output Pulsed lasers emit beams in a single pulse, or train of pulses for a period less than ¼ of a second. If you’re struck in the eye by one pulse, you are unlikely to be struck by a second pulse due to this time gap. However, pulsed lasers are usually more hazardous than continuous lasers because the peak power for each pulse can be very high, causing biological damage to the eyes and skin. Energy for these lasers is expressed in the form of Joules per second. < ¼ sec 10

  11. d f= r 1 ft f = = 0.001 radian 1000 ft = 1 mrad BEAM DIVERGENCE f d LASER r If the beam is 1 foot in diameter when it hits a wall 1000 feet away, the beam divergence angle is: Laser-Professionals.com

  12. Some mathematics covering physical features of a laser beam Follow this slide BEAM DIVERGENCE This allows us to calculate the energy or power density at any distance IRRADIANCE CALCULATION This illustrates the change in power density introduced by a focusing lens

  13. d f= r 1 ft f = = 0.001 radian 1000 ft = 1 mrad BEAM DIVERGENCE f d LASER r If the beam is 1 foot in diameter when it hits a wall 1000 feet away, the beam divergence angle is: Laser-Professionals.com

  14. Power Irradiance = Area p D2 Area = 4 • IRRADIANCE AT LENS: • 20 watts • (3.14)(1cm)2/4 • E1 = 25 watts/cm2 E1 = IRRADIANCE CALCULATION 20 Watt Laser D2 = 0.01 cm D1 = 1 cm IRRADIANCE OF FOCUSED SPOT: E2 = 250,000watts/cm2 The diameter is reduced by a factor of 100. The irradiance is increased by a factor of 10,000. Laser-Professionals.com

  15. Peak Irradiance Average Irradiance d1/e 1/e = 0.368 d1/e2 1/e2 = 0.135 d1/e2 2 d1/e= BEAM DIAMETER Gaussian beam shape 86.5% 63% 99% Laser-Professionals.com

  16. Physical State Lasers differ from each other based on the kind of lasing medium they use. This medium can be a gas (such as Argon), solid-state (such as Ruby crystal), liquid (or a dye), or semi-conducting material (such as a diode). HeNe ExcimerArgon Gas Liquid Dye Semiconductor RubyNd:YAGTi:Sapphire Solid Diode 16

  17. Laser Classification - Class 1 - Class 1M - safe for viewing without optics - Class 2 - Class 2M- hazardous if viewed with optical aids - Class 3R – used to be called 3A - Class 3B - Class 4

  18. Class 1 Laser • Power output is too low to cause eye or skin injury • Examples: • power = few microwatts • high-powered expanded beam A class 1 product is a totally contained laser system, does not present a hazard during normal operation. The goal of laser safety is to have every laser set up a class 1 product. A class 1 product will contain a higher class laser

  19. Class 2 Laser - Output less than 1 milliwatt in visible range (400-700nm). • If struck in the eye by a Class 2 laser, one will normally blink or turn away. This reflex takes less than one quarter of a second, which is adequate time to protect the eye. • Since the eye must see the light to cause the blink reflex, there are no Class 2 lasers that emit invisible wavelengths. - Can be a hazard if the aversion response is overridden or slowed

  20. Class 3R Laser (formerly 3A) - Safe for momentary viewing - Can be visible or invisible (Only visible for commercial products) - Between 1-5 mW - Can be a hazard if momentary viewing is through optics capable of collecting enough energy from a large diameter beam and focusing it onto the eye.

  21. Class 3B Laser - Visible or invisible - Intra beam viewing hazard - Specular reflection hazard - CW output between 5-500 mW - Pulse limit cannot produce 125mJ in less than 0.25 s

  22. Class 4 Laser - Pose greatest danger - Any output higher than Class 3B - Intra beam viewing hazard - Specular reflection hazard - Possible Diffuse reflection hazard - Fire hazard

  23. Non-Classical Lasers Non-linear optics -Harmonic generation of light waves at integral multiples of the frequency of the original wave. -You may have to protect yourself simultaneously from multiple wavelengths, depending upon the circumstances.

  24. Biological Effects When used improperly, lasers can cause injuries. The organs affected by exposure to are the eyes and skin. Some lasers can cause delayed effects after low-level exposures over long time periods (perhaps even for years). Most effects, however, are immediate following acute, brief exposures, lasting seconds or even much less. Examples of two very dangerous lasers include the XeCl gas excimer which causes cataracts in the eyes, and the Nd:YAG Invisible laser which causes most skin injuries. XeCl gas excimer 24

  25. Biological Effects Cornea Lens Photokeratisis(200 – 315 nm) Thermal retinalinjury(315 – 400 nm) Cataracts(750 – 1400 nm) Retina Photochemical Cataracts(315 – 400 nm) Corneal burn(1400 – 1,000,000 nm) UV-C UV-B UV-A IR-A IR-B IR-C 1400 180 280 315 400 700 3000 Ultraviolet Visible Infrared 25

  26. Biological Effects • Blue Light Hazards • Do not stare at sun, welding arcs, or blue lamps • Prevent lengthy exposures greater than 10 seconds • Beware of delayedappearance (24-48 hours) Photobleaching(400 – 500 nm) UV-C UV-B UV-A IR-A IR-B IR-C 280 315 400 700 1400 3000 180 Ultraviolet Visible Infrared 26

  27. Biological Effects Ultraviolet Radiation • 180 - 400nm (damages cornea and lens) • Hazardous Properties • Invisible to eye • Delayed sensation effect • Chronic health effects (cataracts) • If you are taking a medication and working around UV laser light, you should check to see if the medication will make you photosensitive. UV-C UV-B UV-A IR-A IR-B IR-C 180 280 315 400 700 3000 Ultraviolet Visible Infrared

  28. Biological Effects IntrabeamViewing Direct viewing Flat Surface (mirror like)ex: plastic, glass SpecularReflections Rough Surface(diffusion)ex: table top Diffuse Reflections 28

  29. Biological Effects Flat Surface (mirror like)ex: plastic, glass SpecularReflections Rough Surface(diffusion)ex: table top Diffuse Reflections Lasers that have shorter wavelengths (such as those in the UV region up to 315 nm) easily disperse off of rough surfaces through diffusion. In contrast, lasers that have longer wavelengths (such as those above 315 nm) tend to disperse easily off of flat surfaces through specular reflection. 29

  30. Signs and Symptoms Before After • Check for eye injury • See: Flash and after-image in opposite color OR difficulty detecting blue or green colors • Feel: Burning pain on cornea • Hear:“Pop” sound Colors

  31. BiologicalEffects Accelerated AgingIncreased Pigmentation(280 – 315 nm) Burns and Pigment Darkening(315 – 400 nm) Eurythema and Cancer(200 – 315 nm) Burns and Photosensitive reactions(400 – 780 nm) UV-C UV-B UV-A IR-A IR-B IR-C 180 280 315 400 700 1400 3000 Ultraviolet Visible Infrared 31

  32. Emergency Procedures Disable machineTurn off, unplug, and post sign Seek medical attentionTreat minor skin damage with first aid OR transport major skin or any eye injuries to medical facility 32

  33. Non-Beam Hazards • Electrical Hazard • High voltage risk • Eliminate contact with high voltage • Arrange for repairs • Lockout / Tagout • Inspect cords and plugs • Ground all equipment • Complete training 33

  34. Many lasers have high voltage power supplies that can present a risk of electrocution unless • sufficient care is taken when servicing them. Thus, ensure that you eliminate any contact with high voltage equipment. • Do not perform electrical service or maintenance on a laser unless you are properly trained. Allow the experts, including the service representatives for the laser manufacturer, or the campus electricians, to make any necessary repairs. • When there are known issues with equipment, lockout or tagout the equipment until it is safe to use. • Make sure that you inspect cords, plugs, and accessories for missing or damaged wiring. Look for shorts and overheated components. Do not overload circuits / outlets, place near water, or wear metal objects around electrical equipment. • Ground all equipment and complete training in basic electrical safety. • If personnel in your work area are working with high voltage power supplies, then Environmental Health & Safety recommends that you take a First Aid and CPR class.

  35. Non-Beam Hazards • Electrocution • Emergency Procedures • Kill the circuit • Call 911 • Use nonconductor to remove victim • Initiate CPR (if trained) 35

  36. Non-Beam Hazards • Chemical (Liquid) • Liquid phase dye lasers • May be carcinogenic or mutagenic and require special precautions, • Mix in fume hood • Wear PPE • Use secondary containment • Review MSDS 36

  37. Non-Beam Hazards • Chemical (Gas) • Excimers involve use of • toxic fluorine or chlorine gas • Store in ventilated gas cabinets • Use halogen detection and alarm systems or halogen gas scrubbers in rare cases 37

  38. Non-Beam Hazards • Chemical (Gas) • Gases generate harmful • airborne contaminants • High powered lasers can vaporize materials • Prevent from inhaling • Ventilate adequately • Use local exhaust systems 38

  39. Non-Beam Hazards Fires Class 4 Lasers can ignite some substances Irradiance greater than 10 W/cm2Improperly ventilated beam enclosuresFlammable dyes 39

  40. Non-Beam Hazards Non-Beam Hazards • Fire Hazard • Explosions and Radiation • Separate flammables • Construct with fire-resistant materials • Keep fire extinguishers nearby • Shield against radiation(X-ray, Plasma, RF, and Microwaves) 40

  41. Engineering Controls ProtectiveHousing Warning Light Interlock Beam Block • Eliminate Exposure • Use physical structures • as your first line of defense • Protective housing • Interlocks • Aperture beam blocks • Warning lights Laser 41

  42. Engineering Controls Fire Extinguisher Interlockto laser or shutter Storageof eyewear protection Warning labelson equipment Laser curtainat entry Warning light Controlled Accessto laser area Warning signon door 42

  43. Engineering Controls • Eliminate Exposure • Use physical structures • as your first line of defense Beam attenuatorsdecrease the power per unit area of laser beams through absorption and scattering of the beam. Use beam attenuators on high powered lasers: Class 3B Class 4 43

  44. Administrative Controls • Rules and Policies • Follow all rules and guidelines • Laser Safety Training-Every 3 Years (You and everyone you are working with) • Follow posted rules and regulations • Post warning signs if hazards are present • Restrict access • Register all laser machines

  45. Administrative Controls NOTICE sign Alignment, installation, or repair in progress.Injury possible. CAUTION sign Strong lasers (Class 2, 2M)Eye damage possible. DANGER sign High powered lasers (Class 3B, 3R, 4)Eye damage (permanent) or burn possible. 45 45

  46. Administrative Controls Never leave unattended Follow procedures Isolate laser operations 46

  47. Alignment Procedures • Safety Precautions- • Most laser-related injuries occur during alignment! • When performing alignment on “beam out of the box” devices, follow these rules: • Remove metal jewelry, watches, and badges before beginning any activities • Prepare all equipment and materials prior to beginning • Use non-reflective tools • Arrange for someone else to be present • Remove unnecessary equipment, tools, and combustible material to minimize the possibility of stray reflections and non-beam accidents. • Make sure to keep objects out of the path of the beam. 47

  48. Exclude unnecessary personnel from the laser area during alignment. • 2. Where possible, use low-power visible lasers for path simulation of high power visible or invisible lasers. • 3. Wear protective eyewear during alignment. Use special alignment eyewear when circumstances permit their use. • 4. When aligning invisible beams, use beam display devices such as image converter viewers or phosphor cards to locate beams. • 5. Perform alignment tasks using high-power lasers at the lowest possible power level. • 6. Use a shutter or beam block to block high-power beams at their source except when actually needed during the alignment process. • 7. Use a laser rated beam block to terminate high-power beams downstream of the optics being aligned. • 8. Use beam blocks and/or laser protective barriers in conditions where alignment beams could stray into areas with uninvolved personnel. • 9. Place beam blocks behind optics to terminate beams that might miss mirrors during alignment. • Locate and block all stray reflections before proceeding to the next optical component or section. • Be sure all beams and reflections are properly terminated before high-power operation. • Post appropriate area warning signs during alignment procedures where lasers are normally class 1. • 13. Alignments should be done only by those who have received laser safety training.

  49. Other Safety Precautions • WHENEVER Working with laser machines: • Wear PPE at all times during operation, and when a Class 1 laser enclosure is open. • Reduce the beam power using filters, beam splitters and dumps, or the lowest possible power supply. Avoid using high-power during alignment. • Label the areas where the beam leaves the horizontal plane. • Work around (or avoid) beam paths that are at sitting or standing eye level. Direct beam away from eye level, and keep body parts out of the beam path. • Simulate the beam path using lower power visible lasers • Terminate any stray or unused beams. Use beam shutters to block high power beams any time they aren't needed. Terminate the beam at the end of its useful path. Eliminate all beams and reflections prior to high power operation. • View invisible beams with IR/UV cards or sensor cards; taking care to avoid specular reflections off of some of these materials. • Do not look directly at the beam! You can prevent from intentional intra-beam viewing with the eye by using cameras or fluorescent devices to view the beam

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