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Laser Safety

Laser Safety. Introduction. Lasers are high-energy focused electromagnetic radiation that, if misused or abused, can cause serious injuries or blindness. The materials in this program are designed to provide an overview of Lasers, their potential health effects, and how to protect yourself.

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Laser Safety

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  1. Laser Safety

  2. Introduction • Lasers are high-energy focused electromagnetic radiation that, if misused or abused, can cause serious injuries or blindness. • The materials in this program are designed to provide an overview of Lasers, their potential health effects, and how to protect yourself.

  3. Objectives • Laser classifications • Class III safety rules • Class IV safety rules • How can I recognize laser hazards in the workplace? • What are some examples of possible solutions for workplace hazards?

  4. LASER • L ight • A mplification • S timulated • E mission • R adiation

  5. Laser Basics • Lasers differ from ordinary light in 3 ways: • Monochromatic • Directional • Coherent • Lasers can be more hazardous than ordinary light because their energy is concentrated on a very small area.

  6. Laser Basics • Laser components

  7. Laser Basics • Laser Design • Lasing Medium • Gas • Liquid • Solid • Semiconductor • Dye • Excitation Mechanism • Power Supply • Flashlamp • Laser

  8. Laser Basics • Laser Design (cont’d) • Feedback Mechanism • Mirrors • Output Coupler • Semi-Transparent Mirror

  9. Laser Basics • Types of Lasers • Continuous Wave (CW) • Pulsed • Q-Switched

  10. Laser Radiation • Lasers emit focused light radiation • Infrared (780-nm – 1-mm) • Far-IR (IR-B, IR-C) (1400-nm – 1-mm) • Near-IR (IR-A) (780-nm – 1400-nm) • Visible (400-nm – 780-nm) • Ultraviolet (200-nm – 400-nm) • Far-UV (UV-B, UV-C) (200-nm – 316-nm) • Near-UV (UV-A) (315-nm – 400-nm)

  11. Laser Hazards • Bioeffects – Damage to living organisms/tissues • Primary damage sites • Eyes • Skin • Lasers can damage • Thermally • Acoustically • Photochemically

  12. Laser Hazards • Skin (Dermal) Damage • Dermis • IR-A • Epidermis • UV-B, UV-C

  13. Laser Hazards • Eye Damage • Retina • IR-A, Visible Light • Lens • UV-A • Cornea • UV-B, UV-C, IR-B, IR-C

  14. Laser Hazards – Eye Damage Retina subject to damage from intense visible light and IR-A Human Eye

  15. Laser Hazards – Eye Damage Lens subject to damage from UV-A Human Eye

  16. Laser Hazards – Eye Damage Cornea subject to damage from UV-B, UV-C, IR-B, and IR-C Human Eye

  17. Laser Hazards - Exposure Limits • Maximum Permissible Exposure (MPE) • The highest level of laser energy to which the eye or skin can be exposed for a given laser without suffering significant adverse effects • Nominal Hazard Zone (NHZ) • Area within which the MPE could be equaled or exceeded. • Nominal Ocular Hazard Distance (NOHD) • Distance from the laser source along the axis of the beam beyond which eye exposures should cause no significant adverse effects

  18. Laser Hazards - Electrical • Most common non-beam related hazard • Power supplies and capacitors can possess high voltage • Employ proper lockout/tagout procedures when working with lasers

  19. Laser Hazards - Chemical • Many organic dyes used in certain lasers can be hazardous • Can be mutagenic, carcinogenic, toxic, and/or reactive • Depending upon the target, many lasers can cause the release of toxic decomposition products • Employ proper chemical safety procedures, including proper ventilation, containment, respiratory protection, and personal protective equipment, as needed to control the hazard.

  20. Laser Hazards - Fire • Fires can result from laser use due to: • Electrical circuits (overheating/short circuits) • Improper beam enclosures • Ignition of gases/vapors/fumes in laser area • Ignition of flammable/combustible dyes • Use fire-resistant enclosures, and make sure electrical circuits are frequently checked and repaired

  21. Laser Hazards – Non-Beam • UV radiation can be emitted from laser welding or cutting operations • Discharge tubes and pumping lamps may emit UV radiation • Pumping stations may emit visible and IR-A radiation • Use shielding to prevent exposure to non-beam hazards

  22. Laser Classifications • Class I • Class II • Class IIa • Class IIIa • Class IIIb • Class IV • Classes can change if safety measures are bypassed or if the laser is disassembled

  23. Class I • Denotes lasers or laser systems that do not, under normal operating conditions, pose a hazard. • Example: CD-ROM Drive/Players

  24. Class II • Denotes low-power visible lasers or laser systems which, because of the normal human aversion response (i.e. blinking, eye movement, etc.) do not normally present a hazard, but may present some potential for hazard if viewed directly for extended periods of time (as with many conventional light sources). • Example: Supermarket Scanner

  25. Class IIa • Denotes low-power visible lasers or laser systems that are not intended for prolonged viewing, and under normal operating conditions will not produce a hazard if the beam is viewed directly for periods not exceeding 1000 seconds.

  26. Class IIIa • Denotes some lasers or laser systems having a CAUTION label that normally would not injure the eye if viewed for only momentary periods (within the aversion response period) with the unaided eye, but may present a greater hazard if viewed using collecting optics. • Example: Laser Pointers

  27. Class IIIa • Another group of Class IIIa lasers have DANGER labels and are capable of exceeding permissible exposure levels for the eye in 0.25-seconds and still pose a low risk of injury.

  28. Class IIIb • Denotes lasers or laser systems that can produce a hazard if viewed directly. This includes intrabeam viewing of specular reflections. Normally, Class IIIb lasers will not produce a hazardous diffuse response. • Example: Research Lasers

  29. Class IV • Denotes lasers or laser systems that produce a hazard not only from direct or specular reflections, but may produce hazardous diffuse reflections. Such lasers may produce significant skin hazards as well as fire hazards. • Example: Research or Manufacturing Lasers

  30. Basic Safety Rules for Class III • Never aim a laser at a person’s eye. • Know where a laser (especially laser pointer) is pointed at all times • Use proper safety eyewear if there is a chance that the beam or a hazardous specular reflection could expose the eyes (in excess of MPE). • Permit only experienced personnel to operate the laser and do not leave an operable laser unattended if there is a chance that the unauthorized user may attempt to operate the laser. • Applies even to laser pointers there is the potential for abuse by students or other unauthorized personnel

  31. Class III Safety Rules • A key switch should be used if untrained persons may gain access to the laser. A warning light or buzzer may be used to indicate when the laser is operating. • Does not apply to many laser pointers • Enclose as much as the beam's path as practical.

  32. Class III Safety Rules • Avoid placement of the unprotected eye along or near the beam axis as attempted in some alignment procedures. • The chance of hazardous specular reflections is greatest in this area. • Terminate the primary and secondary beams if possible at the end of their useful paths. • Aim laser pointers at object to be highlighted • Avoid aiming laser pointers out windows or open doors • Use beam shutters and laser output filters to reduce the beam power to less hazardous levels when the full output power is not required. • Does not apply to laser pointers

  33. Class III Safety Rules • Ensure that any spectators are not potentially exposed to hazardous conditions. • Includes electrical and fire hazards, as well as from direct laser exposure • Attempt to keep laser beam paths above or below eye level at either sitting or standing position. • Operate lasers only in well-controlled areas. For example, within a closed room with covered or filtered windows and controlled access. • Does not directly apply to laser pointers

  34. Class III Safety Rules • Make sure lasers are labeled with appropriate Class IIIa or IIIb warning statements. Post appropriate warning signs if personnel can be overexposed. • Mount the laser on a firm support to assure that the beam travels along the intended path. • Be aware of the laser beam path at all times, even with laser pointers

  35. Class III Safety Rules • Ensure that individuals do not look directly into a laser beam with optical instruments unless an appropriate protective filter is present within the optical train. • Eliminate unnecessary specular (mirror-like) surfaces from the vicinity of the laser beam path, and avoid inadvertently aiming at such surfaces.

  36. Class IV Safety Rules • Enclose the entire laser beam path if as much as possible. If done correctly, the laser’s status could revert to a less hazardous classification. • Confine open-beam indoor laser operations to a light-tight room. Interlock entrances to ensure that the laser cannot emit when the door is open, if the NHZ extends to the entrances.

  37. Class IV Safety Rules • Ensure that all personnel wear adequate eye protection, and if the laser beam irradiance represents a serious skin or fire hazard, that a suitable shield is present between the laser beam and personnel. • Use remote firing and video monitoring, or remote viewing through a laser safety shield where feasible.

  38. Class IV Safety Rules • Use beam shutter and laser output filters to reduce the laser beam irradiance to less hazardous levels whenever the full beam power is not required. • Ensure that the laser device has a key-switch master control to permit only authorized personnel to operate the laser.

  39. Class IV Safety Rules • Install appropriate signs and labels as needed. • Use dark, absorbing, diffuse, fire resistant target and backstops where feasible. • Design safety into laser-welding and cutting equipment, and laser devices used in miniature work. If feasible, such work should be performed in a light-tight or baffled interlocked enclosure to eliminate the requirements for eye protection.

  40. Common Causes of Accidents • Altering beam path without accounting for location of beam termination • Inserting reflective objects into the beam path • Bypassing interlocks • Accidentally activating power supply • Accidentally firing the laser

  41. Hazard Control - Engineering • Engineering controls should be utilized in preference to administrative or PPE controls, whenever feasible • Engineering controls rely on structural or system controls to prevent exposures • Beam Housings • Shutters • Attenuators • Remote firing controls • Interlocks

  42. Hazard Control - Administrative • Administrative controls can be utilized if engineering controls are determined to be infeasible. • Administrative controls rely on work practices and warnings to prevent exposures • Warning signs and labels • Standard Operating Procedures (SOPs) (OCC Laser Safety Program) • Training

  43. Hazard Control – Administrative • Administrative Safety Practices • Only properly trained and authorized employees may use Class IIIb or IV lasers • Employees utilizing lasers are responsible for restricting access to the area and the proper use of the laser • Designate the NHZ for the laser for Class IIIb or IV lasers • Address non-beam hazards in work practices • Follow guidelines and procedures found in the OCC Laser Safety Program

  44. Warning Labels

  45. Hazard Control - Personal Protective Equipment • Use flame-resistant materials when dealing with Class IV beams • Use appropriate protective eyewear • Eyewear is characterized by Optical Density (OD) • Example: OD of 6 represents a reduction of the incident radiation by a factor of 1 million. • Eyewear must be marked with OD and wavelength for proper selection. • Eyewear must be comfortable

  46. Hazard Control - Personal Protective Equipment

  47. Hazard Control - Personal Protective Equipment • Properly use and maintain protective eyewear • Refer to the OCC Personal Protective Equipment Program for guidelines and requirements for protective eyewear • Inspect protective eyewear before each use for pitting, crazing, or solarization of the lenses

  48. Contacts • Michael Schmidt Manager of Environmental Health and Safety • 248-232-4234 (Phone) • 248-232-4254 (Fax) • 248-467-4477 (Cell) • mschmid@oaklandcc.edu

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