An introduction to
• What is a Laser?
• How is Laser light produced?
• What are the components of a laser
• What makes laser light special?
• How does laser light interact with
• What are the safety issues?
Laser light is a form of
400 500 600 700 1,000 10,000
Visible Light Nanometers Invisible Light
X-Ray TV and FM Radio
Cosmic AM Radio
The word laser is an acronym…it
How is laser light
Atoms of any substance are made up of
electrons, protons and neutrons.
Electrons in Orbit
Resting stage Excited stage
Electrons are usually in a “resting” stage;
when they absorb a photon, they are raised to
an “excited” stage.
to an “excited”stage,
the electron naturally
tends to return to its
does so by emitting a Spontaneous emission
photon (similar to the
one absorbed): this is
If when in its “excited” stage the
electron absorbs a second photon, it
then needs to emit two photons (similar
to the ones absorbed): this is called
A laser beam is generated by
amplification, which is
stimulated emission repeated
What Are The
Components Of A
There are four basic components
to every laser:
Totally Power Partially
reflective source reflective
The lasing medium
(located inside the optical cavity)
is the substance that produces the laser
•This could be a GAS (argon, krypton, CO2),
a SOLID (ruby crystals, alexandrite crystals),
or a LIQUID (dye).
•The lasing medium determines the wavelength
of the laser.
The power source is used to
stimulate the lasing medium to
produce the laser beam.
Power sources include:
• Other lasers
The delivery system modifies
the laser beam and brings it from the
optical cavity to the patient.
Delivery systems include:
• Articulated arms
• Optical fibers
• Focusing handpieces
There are two types of
Continuous wave lasers (pulse duration is not relevant)
Pulsed lasers (pulse duration is a variable)
Laser light has three unique
•It is monochromatic
•It is coherent
•It is collimated
Laser light is monochromatic: the wavelength
Ordinary Light Laser Light
Laser light is coherent: the light waves are
spatially and temporally in phase.
Laser light Regular “white” light
Laser light is collimated: the light
waves are parallel and not divergent.
How does laser light
interact with tissue?
a concept developed by Rox
Anderson in 1983
States that laser light of a specific
wavelength can destroy a target
containing the adequate chromophore
without damaging the surrounding
tissue. This is possible if the thermal
relaxation time of the target is longer
than the duration of the laser pulse.
What Are Laser
There are four basic laser
• Pulse duration
• Spot size
Absorption is necessary for
effect on tissue.
Reflection Scattering Transmission Absorption
Wavelength: chosen partly based on the
absorption curve of the targeted
400 500 600 700 800
• It is determined by the
• It is measured in
• As absorption
decreases the depth of
Pulse duration (pulse width) refers
to the duration of each laser pulse.
• In order to get a selective effect on the target only, the
pulse duration should be matched to the thermal
relaxation time of the target
• Smaller targets require smaller pulse durations
Spot size refers to the diameter of the
beam emitted. A larger spot size
induces deeper penetration
Distance gauges are used to set the
required spot size at the tissue
The fluence measures the rate of
energy delivery per unit area.
•It is measured in Joules per cm2.
•As the fluence increases, so does the destructive
force of the laser.
•The relationship between fluence and spot size is
In summary we choose
• To achieve the correct depth of penetration for our
• To selectively target the chormophore of interest
• To provide enough energy over an appropriate time
to have a selective photothermolysis effect
As It Relates
Lasers are classified in four broad groups:
Class I No known biological hazard
Class II Chronic viewing hazard only
Class III Direct viewing hazard
Class IV Direct and reflected hazard
All windows in a laser treatment
should be protected from beam
transmission and covered with
There should be no mirrors in the
Eye protection is a
AORN Recommended Practice II
“Eyes of patients and health care workers
should be protected from laser beams.”
Interpretive Statement I
“Laser-safe eye protection with appropriate
wavelength and optical density should be worn by
all health care workers and all patients and labeled
to protect against improper use.”
Laser eye penetration:
Erbium Corneal absorption
Nd:YAG Retinal absorption
Different eyewear for different
All doors to a laser
treatment room are to VISIBLE LASER RADIATION
AVOID EYE OR SKIN EXPOSURE TO
DIRECT OR SCATTERED RADIATION
be closed and have a CLASS IV LASER PRODUCT
laser specific danger
sign along with a pair
of laser eyewear
Fire hazard: be on the lookout for
flammable or combustible materials!
• Thermal destruction of tissue creates smoke
• Plume can contain toxic gases and vapors, dead and
live cellular materials including blood fragments
• A laser protective mask (0.1µ) should be used to
decrease inhalation of particulate
matter when appropriate
Plume issues (ctd.):
• General room ventilation is not sufficient to
• Smoke evacuators should have high efficiency in
airborne particle reduction.
• HEPA filter or equivalent is recommended for
• Generally, the use of smoke evacuators is more
effective than room suction systems.
A laser should
always be in
unless an operator
SBY is ready to use it.
“standby “laser is
please” in standby”
• Laser sign
• Doors closed
• Windows covered
• Eye protection
• Standby mode
• Electrical safety