1. 1 1.Determine laser classes and components 1.Identify hazards Biological Non-Beam 1.Implement controls Engineering Administrative Work Practice PPE Objectives

2. L ight A mplification by S timulated E mission of R adiation 2 Lasers Intense light that can cause tissue damage, burns, and damage to the eye and skin. What is a Laser ?

3. Ordinary light is incoherent, visible, dispersed, and low powered. 3 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. Light Properties

4. Laser light is coherent, sometimes invisible, directional, and high powered. 4 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 Properties

5. 5 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.

6. Pump Lasing Medium Mirror Reflectant 6 Mirror Transparent Laser Components

7. Output Continuous Pulsed > ¼ sec < ¼ sec 7 Lasers also differ from each other based on their output characteristics. They can be a continuous wave or a pulsed laser beam.

8. Output 8 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. Continuous > ¼ sec

9. Output < ¼ sec 9 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.

10. 10 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

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

12. 12 IRRADIANCE CALCULATION The diameter is reduced by a factor of 100. The irradiance is increased by a factor of 10,000. IRRADIANCE OF FOCUSED SPOT: E2 = 250,000 watts/cm2 Power Irradiance = Area  D2 Area = 4 20 Watt Laser D1 = 1 cm D2 = 0.01 cm IRRADIANCE AT LENS: 20 watts  (3.14)(1cm)2/4 E1 = 25 watts/cm2 E1 = Laser-Professionals.com

13. 13 1/e2 = 0.135 Average Irradiance Peak Irradiance d1/ e 2 d1/ e 1/e = 0.368 BEAM DIAMETER Laser-Professionals.com 63% 86.5% 99% Gaussian beam shape d1/e = 2 d1/ e 2

14. Semi conduc tor Diode Liquid Dye Solid Ruby Nd:YAG Ti:Sapphire Gas HeNe Excimer Argon Physical State 14 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).

15. 15 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

16. 16 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

17. 17 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

18. 18 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.

19. 19 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

20. 20 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

21. 21 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.

22. 22 Biological Effects XeCl gas excimer 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.

23. 180280315400700 1400 3000 UV-CUV-BUV-A UltravioletVisibleInfrared IR-AIR-BIR-C Photokeratisis (200 – 315 nm) Photochemical Cataracts (315 – 400 nm) Thermal retinal injury (315 – 400 nm) Cataracts (750 – 1400 nm) Corneal burn (1400 – 1,000,000 nm) Cornea Lens Retina 23 Biological Effects

24. 28031540070014003000 Biological Effects UV-CUV-BUV-A UltravioletVisible Infrared IR-AIR-BIR-C Blue Light Hazards Do not stare at sun, welding arcs, or blue lamps Prevent lengthy exposures greater than 10 seconds Beware of delayed appearance (24-48 hours) Photobleaching (400 – 500 nm) 24

25. 25 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. 1802803154007003000 UV-CUV-BUV-A UltravioletVisibleInfrared IR-AIR-BIR-C

26. Biological Effects Intrabeam Viewing Specular Reflections Diffuse Reflections Direct viewing Flat Surface (mirror like) ex: plastic, glass Rough Surface (diffusion) ex: table top 26

27. Specular Reflections Diffuse Reflections 27 Flat Surface (mirror like) ex: plastic, glass Rough Surface (diffusion) ex: table top Biological Effects 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.

28. 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 BeforeAfter Signs and Symptoms Colors

29. 18028031540070014003000 Biological Effects UV-CUV-BUV-A UltravioletVisibleInfrared IR-AIR-BIR-C Accelerated Aging Increased Pigmentation (280 – 315 nm) Eurythema and Cancer (200 – 315 nm) Burns and Pigment Darkening (315 – 400 nm) Burns and Photosensitive reactions (400 – 780 nm) 29

30. Emergency Procedures Disable machine Turn off, unplug, and post sign Seek medical attention Treat minor skin damage with first aid OR transport major skin or any eye injuries to medical facility 30

31. Electrical Hazard High voltage risk Eliminate contact with high voltage Arrange for repairs Lockout / Tagout Inspect cords and plugs Ground all equipment Complete training Non-Beam Hazards 31

32.  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. 32

33. Non-Beam Hazards 33 Electrocution Emergency Procedures Kill the circuit Call 911 Use nonconductor to remove victim Initiate CPR (if trained)

34. 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 Non-Beam Hazards 34

35. 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 Non-Beam Hazards 35

36. Chemical (Gas) Gases generate harmful airborne contaminants High powered lasers can vaporize materials Prevent from inhaling Ventilate adequately Use local exhaust systems 36 Non-Beam Hazards

37. Fires Class 4 Lasers can ignite some substances Irradiance greater than 10 W/cm2 Improperly ventilated beam enclosures Flammable dyes 37 Non-Beam Hazards

38. 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) 38 Non-Beam Hazards

39. Laser Protective Housing Interlock Warning Light Beam Block 39 Engineering Controls Eliminate Exposure Use physical structures as your first line of defense 1.Protective housing 2.Interlocks 3.Aperture beam blocks 4.Warning lights

40. Engineering Controls Interlock to laser or shutter Laser curtain at entry Storage of eyewear protection Controlled Access to laser area Warning sign on door Warning light Fire Extinguisher Warning labels on equipment 40

41. 41 Engineering Controls Eliminate Exposure Use physical structures as your first line of defense Beam attenuators decrease 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

42. Administrative Controls Rules and Policies Follow all rules and guidelines 1.Laser Safety Training- Every 3 Years (You and everyone you are working with) 2.Follow posted rules and regulations 3.Post warning signs if hazards are present 4.Restrict access 5.Register all laser machines

43. 43 DANGER sign High powered lasers (Class 3B, 3R, 4) Eye damage (permanent) or burn possible. NOTICE sign Alignment, installation, or repair in progress. Injury possible. CAUTION sign Strong lasers (Class 2, 2M) Eye damage possible. 43 Administrative Controls

44. Follow proceduresIsolate laser operations Never leave unattended 44 Administrative Controls

45. 45 Alignment Procedures Safety Precautions- Most laser-related injuries occur during alignment! When performing alignment on “beam out of the box” devices, follow these rules: 1. Remove metal jewelry, watches, and badges before beginning any activities 2. Prepare all equipment and materials prior to beginning 3. Use non-reflective tools 4. Arrange for someone else to be present 5. Remove unnecessary equipment, tools, and combustible material to minimize the possibility of stray reflections and non-beam accidents. 6. Make sure to keep objects out of the path of the beam.

46. 46 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. 1.Locate and block all stray reflections before proceeding to the next optical component or section. 2.Be sure all beams and reflections are properly terminated before high-power operation. 3.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.

47. 47 Other Safety Precautions WHENEVER Working with laser machines: 1.Wear PPE at all times during operation, and when a Class 1 laser enclosure is open. 2.Reduce the beam power using filters, beam splitters and dumps, or the lowest possible power supply. Avoid using high-power during alignment. 3.Label the areas where the beam leaves the horizontal plane. 4.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. 5.Simulate the beam path using lower power visible lasers 6.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. 7.View invisible beams with IR/UV cards or sensor cards; taking care to avoid specular reflections off of some of these materials. 8.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

48. 48 Never intentionally look directly into a laser. Do not stare at the light from any laser. Allow yourself to blink if the light is too bright. Do not view a Class 3a (or any higher power) laser with optical instruments. Never direct the beam toward other people. Operate lasers only in the area designed for their use and be certain that the beam is terminated at the end of its use path. Never allow a laser beam to escape its designated area of use. Position the laser so that it is well above or below eye level. Always block the beam with a diffuse reflecting beam block. Remove all unnecessary reflective objects from the area near the beam’s path. This may include items of jewelry and tools. Do not enter a designated Class 3b or Class 4 laser area (posted with a DANGER sign) without approval from a qualified laser operator. Eye protection is required in these areas. Always wear laser safety eyewear if a class 4 invisible beam is exposed.

49. 49

50. 50 Personal Protective Equipment PPE The strategy of last resort 1.Ensure proper fit 2.Select proper PPE for the job 3.Make sure PPE is properly maintained and not damaged 4.Use consistently

51. Use laser eye protection. Do not rely on your blink reflex for protection. 51 Personal Protective Equipment Your body has a natural aversion response when it comes in contact with a laser beam. Your head will tend to turn, and your eyes naturally blink. This response occurs every ¼ of a second, and is used to calculate laser hazards. However, because it may not always occur in all incidents, you should not rely on this response as a substitute for laser eye protection. Use laser eye protection. Do not rely on your blink reflex for protection.

52. 52 Safety eyewear that protects against chemicals, dust, impact, or heat do not have the proper lens filters to protect against laser beams and are not for use with Lasers Personal Protective Equipment

53. 53 Personal Protective Equipment Safety Eyewear Use safety eyewear that protects against optical radiation through: Neutral density absorbs and reflects Bandpass transmits weaker light Cut-off blocks light at one end

54. Ultraviolet VisibleInfrared Argon (488 nm and 514 nm) KTP (532 nm) Ruby (694 nm) Nd:YAG (1060 nm) 54 Personal Protective Equipment Safety Eyewear Select eyewear based on wavelength. The wavelengths that the eyewear can be used to protect against is labeled on the eyewear, generally on the lens itself.

55. 012345678012345678 100 % 10 1 0.10 0.01 0.001 0.0001 0.00001 0.000001 Optical Density (OD) Light transmission 100% transmission 10% transmission 1% transmission OD = 0 OD = 1 OD = 2 55 Safety Eyewear

56. 012345678012345678 100 % 10 1 0.10 0.01 0.001 0.0001 0.00001 0.000001 Optical Density (OD) Light transmission 100% transmission 10% transmission 1% transmission 56 Safety Eyewear

57. 012345678012345678 100 % 10 1 0.10 0.01 0.001 0.0001 0.00001 0.000001 Optical Density (OD) Light transmission 0 10 100 1,000 10,000 100,000 1,000,000 10,000,000 100,000,000 Output power mW 57 Safety Eyewear

58. 012345678012345678 100 % 10 1 0.10 0.01 0.001 0.0001 0.00001 0.000001 Optical Density (OD) Light transmission 58 Safety Eyewear

59. Select laser safety eyewear based on the optical density and wavelength of your laser. In addition to… Fit Field of Vision Prescription Sensor Card Use Degradation Too much spaceProper fit 59

60. 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

61. 61 For more information ehs.ucsc.edu (831) 459-2553 ehs@ucsc.edu rad@ucsc.edu csherma1@ucsc.edu