• Usually monochromatic (narrow bandwidth of light)
• Low beam divergence
• Coherent (in-phase in time and space)
• Optical radiation (IR, Visible, and UV)
Class 3b
Class 1
Generally exempt from radiation
hazard controls during operation.
Class 2
Class 3a
Low power not exceeding 1 mW. The
blink reflex can protect the eye.
However, these lasers present a hazard
if an individual stares into the beam.
Power levels between 1 and 5 mW. If the
irradiance is 2.5 W/cm2 or less then the
blink reflex can protect the individual (same
as a Class 2 beam). Eye exposure to higher
irradiance can damage the eye, and some
control measures are needed.
No laser beam should be viewed directly.
Moderately powerful
lasers having power levels
between 5 and 500 mW. Staring
at the reflection can be
hazardous. Direct beam viewing
damages the eye. Can ignite
flammable gases.
Class 4
Powerful
lasers having
power levels of 500 mW
and higher. Direct and
indirect viewing hazard.
Can also damage the skin
and ignite combustible
materials.
Exposure to the eye can result in loss of some or all vision
depending upon duration of exposure, beam power,
wavelength, and whether viewing the beam is direct or
indirect. Note: wavelength affects the type of damage
sustained by the eye - retinal &/or corneal damage.
The only known accidents that have led to fatalities
related to use of lasers have been electrocutions.
However, some beams can ignite combustible or flammable
materials.
Fumes emitted from things being burned by high powered
lasers can also present an inhalation hazard to individuals.
Hazardous energy must be dissipated, and the circuit opened and locked out
before removing the cover of a laser power supply.
Eye damage from a laser exposure is dependant upon the beam
power, bandwidth, duration of exposure, and whether the beam is
viewed directly. Damage received by the eye can include:
Protect your eyes from:
Damage Mechanisms
Photokeratitis
Photomechanical – rapidly expanding
plasma destroys tissue.
Photoretinitis
Thermal effects – burns, caused by
any laser of sufficient power.
Cataracts
Photochemical – Photoretinitis caused
by bright light with a wavelength of
primarily 400 to 480 nm.
Retinal lesions
High powered lasers can also damage the skin.
Control measures are
needed if there is
potential to be exposed
above the exposure
limits. In general,
exposure controls are
needed for use of Class
3b and 4 lasers.
Engineering
controls
(e.g. beam enclosure)
Administrative controls
(e.g. work practices)
Personal protective equipment
(e.g. laser eyewear)
Institute engineering controls, then administrative, and then personal protective
equipment. All three are important if there is an open beam path.
Exposure Control Measures
Class 3a
1. Administrative controls to limit who
can enter the area where the laser
beam is being used.
2. Use of properly rated eyewear
3. Management of optical lenses that
could magnify the beam.
4. Written alignment procedures
5. Clearly delineated beam path
6. Training
Laser controls are needed if individuals could be exposed above the maximum permissible
exposure limit. If you have questions contact the University Laser Safety Officer (422-4468).
Exposure Control Measures
Class 3b
Class 4
1. Establishment of a control area [including a nominal hazard
zone (NHZ)] delineated by a physical barrier.
2. Control areas have non-defeatable safety latches,
entryway, or area interlocks whenever possible.
3. Hazard warning signs placed at entrance to the control
area.
4. Audible or visible signal at entryway.
5. Beam height below 4 feet unless approved by the laser
safety officer
6. Properly rated eyewear
7. Management of reflective & magnifying surfaces.
8. Skin covering when necessary
9. Written alignment procedures
10.Clearly delineated beam path
11.Training (through Risk Management)
If you will be using class IIIb or IV lasers then contact the university Laser Safety Officer
(422-4468) or the college Health & Safety Officer (422-6589).
Note: Some controls are needed if use of a class IIIa laser creates an exposure hazard.
Introduction of optical lenses
can create or increase laser
hazards. Laser labs need to
manage the introduction of
optical lenses.
Before selecting protective
eyewear you need to know:
• Wavelength(s) of the laser
beam
• Viewing conditions (direct or
diffuse beam viewing) Note:
alignment is considered direct
if the beam is open.
• Power/energy of the beam
(watts for continuous wave
laser beams and joules for
pulsed beams) Note: you will
also need to know the pulse
length (seconds) and repetition
rate (hertz) for pulsed beams.
Selection Steps
1. Contact the Risk Management
Certified Laser Safety Officer and
request assistance. He will help you
determine optical density for the
eyewear. Optical density must be
known before ordering your eyewear.
2. Select a frame style that meets
your application
3. Select a filter for the eyewear that
will block the wavelength(s) of the
beam. More than one pair of
protective eyewear or a custom filter
will be needed to address hazardous
beams that contain more than one
wavelength.
Optical Density (OD) = log10 (ML/EL) and is the level of attenuation
needed to reduce the measured level (ML) to the exposure limit (EL).
Typically laser light that escapes from a fiber optic spreads out
rapidly, however there have been instances where the escaping
light exhibits beam like qualities.
Before installing a fiber optic cable, the cable should be
inspected for signs of damage. Do not use damaged cables.
Cables that are in use need to be protected from damage.
And, as an extra precaution they can be enclosed to provide
containment of any escaping light.
Laser Safety Training Requirements
Prior to using a class IIIB or IV laser
individuals need to have completed laser
safety training provided by the
University Laser Safety Officer (801422-5779). Note: Training hours are
very flexible during normal working hours.