Laser protective eyewear is specific to the types of laser radiation in the lab. Each project is to provide appropriate eye protection for persons working with the laser. Windows where Class 2, 3, or 4 beams could be transmitted causing hazards in uncontrolled areas, shall be covered or otherwise protected during laser operation. The following guidelines are suggested for maximum eye protection.

• Whenever possible confine (enclose) the beam (e.g.,use beam pipes), provide nonreflective beam stops, etc., to minimize the risk of accidental exposure or fire. Use fluorescent screens or similar "targets" to align the beam; avoid direct intrabeam exposure to the eyes. Laser optical systems should not be aligned by direct viewing.
• Use the lowest laser power possible for beam alignment procedures. Use Class 2 lasers for preliminary alignment procedures, whenever possible. Keep optical benches free of unnecessary reflective items.
• Confine the beam to the optical bench unless necessary for an experiment, e.g., use barriers at the sides of benches or other enclosures. Do not use room walls to align Class 3b or 4 laser beams.
• Use non-reflective tools. Remember that some tools that seem to be non-reflective for visible light may be very reflective for the non-visible spectrum.
• Do not wear reflective jewelry when working with lasers. Metallic jewelry also increases shock hazards.

Wear protective glasses whenever working with Class 4 lasers with open beams or when reflections can occur. In general, laser glasses may be selected on the basis of protecting against reflections -- especially diffuse reflections, and providing protection to a level where the natural aversion reflex will prevent eye injuries, unless intrabeam viewing is required. Generally, protective eyewear may be selected to be adequate to protect against stray reflections. Wearing such glasses allows some visibility of the beam, preventing skin burns, making more likely that persons will wear the eye protection. Also, the increased visibility afforded by this level of protection decreases potential for other accidents in the lab, i.e., tripping, etc. Glasses designed for limited protection, such as those discussed above, are not appropriate for intrabeam viewing or for highly specular reflections. An article describing the minimal level of protection for stray beams is attached as Appendix B. A table of protective lens requirements is also provided on the inside of the back cover of this Manual. It is suggested that the reader review the description of a laser incident written by an injured party, which is attached as Appendix C. Injuries may also occur when stray reflections strike reflective objects. It, therefore, is recommended that side shields be a part of protective eyewear.

Factors to consider in selection of Laser Protective eyewear include the following (From "A Guide to Eyewear" LLL-TB-87):

• Wavelength or spectral region of laser radiation
• Optical density at the particular wavelength(s)
• Maximum irradiance (W/cm_2_) or beam power (W)
• For which the eyewear provides protection for at least 5 s
• Type of laser system
• Power mode, single pulse, multiple pulse or cw, and the
• Strength, i.e., both peak and average power
• Possibilities of reflections, specular and diffuse
• Field of view provided by the design
• Availability of prescription lenses or sufficient size of goggle frames to permit wearing of prescription glasses inside of goggles.
• Comfort
• Ventilation ports to prevent fogging
• Effect upon color vision
• Absence of irreversible bleaching if filter is exposed to high peak irradiances
• Impact resistance
• Ability to perform required tasks while wearing eyewear

For double wavelength systems, glasses (goggles) can be obtained with flip-down lenses to protect against the two different wavelengths. Where invisible beams and visible beams are produced by a laser, the inner lens can be designed to protect against the invisible radiation and the flip-down lens to protect against the visible laser radiation. Health Physics has some specimens of laser glasses for some of the commonly used lasers. The specimen eyewear may be borrowed for evaluation. Broad-spectrum glasses are also available for certain applications. Health Physics has a number of catalogs and specifications for protective eyewear.

As laser protective eyewear is subject to damage and deterioration, the lab safety program should include periodic inspection of these protective items.