LASERS QUESTIONS
What does LASER stand for? - answer Light Amplification of the Stimulated Emission of
Radiation
What are characteristics of lasers? - answer coherent (same phase), collimated
(unidirection), monochromatic (same wavelength - IR, visible or UV).
What is the function/definition of a laser? - answer Defines the process by which form of
energy is converted into light energy. intense controlled beam of light.
How do lasers work? - answer Energy can be either absorbed or emitted, depending if
the laser moves from a ground energy state to a higher energy state or visa versa.
What is spontaneous emission? - answer Occurs in a random manner and results in
incoherent light (out of phase). If all the light emitted by each atom was made to be in
phase (coherent), this results in an enormous increase in light intensity.
Einstein - answer
What are the components of a laser apparatus? - answer laser medium (holds the
substance energized to produce laser light), optical cavity (provides the environment in
which the medium is confined) and an external power source (energy supply to the laser
medium that generates light).
optical cavity of a laser - answer• When >1/2 of the atoms are in an excited state
spontaneous emission
occurs in all directions
• Mirrors within the cavity reflect photons back, which then strike exciting atoms
stimulated emission making a large amount of photons with same wavelength, direction,
and phase
• One mirror only partially reflects and allows release out of the cavity aperture laser
beam!
classes of lasers - answer
Effect of laser on tissue - answerenergy can be reflected, absorbed, conducted as heat
or scattered. This dpeneds on the type of laser and tissue properties.
What do thermal effects depend on? - answerenergy density and flux
What does a temperature below 55C of a laser to do tissue? - answerslight destructive
shrinking
, What does a temperature above 55C of a laser to do tissue? - answerwelding of cell
walls
What does a temperature of 65C of a laser to do tissue? - answerearly denaturation of
cell proteins
What does a temperature of 100C of a laser to do tissue? - answercell water boils and
vaporizers
types of lasers? - answersolid state, semiconductor, liquid laser, gas laser
What are some examples of solid state lasers? - answerfirst laser in 1960. Ruby,
neodymium (YAG), KTP
What are some examples of semiconductor lasers? - answergallium arsenide, lower
power output
What are some examples of liquid lasers? - answerorganic dye molecules
What are some examples of gas lasers? - answerhelium-neon, argon, CO2
What are applications of a CO2 laser? - answer• Laryngeal laser surgery (e.g., laryngeal
condylomata, papillomas, tumors, stenosis, etc)
• Gynecologic surgery (intraepithelial neoplasms, condylomas)
Is the CO2 laser visible? Why or why not? - answer• Long wavelength (10.6 um) and
does not emit visible
light
• Often employs a coaxial helium-neon laser that emits a red light pointer
(alignment must be checked before use)
How does the CO2 laser work? - answerheat is absorbed by cells. It heats the water
within cells and denatures proteins, causes thermal necrosis, water vapor, explosive
vaporization and charring
What are advantages of CO2 lasers? - answerPredicision (0.2mm), total absorption in
the first few cell ayers (minimal damage to underlying/surrounding structures) --> this
causes less edema than cautery. Also, its bloodless because is causes hemostasis to
vessels up to 0.5mm.
What are disadvantages of CO2 lasers? - answercannot be used fiberoptically (must
use line-of-sigh delivery mechanism). Errant beams can result in corneal damage. (This
can be stopped with any clear lens material).
What does LASER stand for? - answer Light Amplification of the Stimulated Emission of
Radiation
What are characteristics of lasers? - answer coherent (same phase), collimated
(unidirection), monochromatic (same wavelength - IR, visible or UV).
What is the function/definition of a laser? - answer Defines the process by which form of
energy is converted into light energy. intense controlled beam of light.
How do lasers work? - answer Energy can be either absorbed or emitted, depending if
the laser moves from a ground energy state to a higher energy state or visa versa.
What is spontaneous emission? - answer Occurs in a random manner and results in
incoherent light (out of phase). If all the light emitted by each atom was made to be in
phase (coherent), this results in an enormous increase in light intensity.
Einstein - answer
What are the components of a laser apparatus? - answer laser medium (holds the
substance energized to produce laser light), optical cavity (provides the environment in
which the medium is confined) and an external power source (energy supply to the laser
medium that generates light).
optical cavity of a laser - answer• When >1/2 of the atoms are in an excited state
spontaneous emission
occurs in all directions
• Mirrors within the cavity reflect photons back, which then strike exciting atoms
stimulated emission making a large amount of photons with same wavelength, direction,
and phase
• One mirror only partially reflects and allows release out of the cavity aperture laser
beam!
classes of lasers - answer
Effect of laser on tissue - answerenergy can be reflected, absorbed, conducted as heat
or scattered. This dpeneds on the type of laser and tissue properties.
What do thermal effects depend on? - answerenergy density and flux
What does a temperature below 55C of a laser to do tissue? - answerslight destructive
shrinking
, What does a temperature above 55C of a laser to do tissue? - answerwelding of cell
walls
What does a temperature of 65C of a laser to do tissue? - answerearly denaturation of
cell proteins
What does a temperature of 100C of a laser to do tissue? - answercell water boils and
vaporizers
types of lasers? - answersolid state, semiconductor, liquid laser, gas laser
What are some examples of solid state lasers? - answerfirst laser in 1960. Ruby,
neodymium (YAG), KTP
What are some examples of semiconductor lasers? - answergallium arsenide, lower
power output
What are some examples of liquid lasers? - answerorganic dye molecules
What are some examples of gas lasers? - answerhelium-neon, argon, CO2
What are applications of a CO2 laser? - answer• Laryngeal laser surgery (e.g., laryngeal
condylomata, papillomas, tumors, stenosis, etc)
• Gynecologic surgery (intraepithelial neoplasms, condylomas)
Is the CO2 laser visible? Why or why not? - answer• Long wavelength (10.6 um) and
does not emit visible
light
• Often employs a coaxial helium-neon laser that emits a red light pointer
(alignment must be checked before use)
How does the CO2 laser work? - answerheat is absorbed by cells. It heats the water
within cells and denatures proteins, causes thermal necrosis, water vapor, explosive
vaporization and charring
What are advantages of CO2 lasers? - answerPredicision (0.2mm), total absorption in
the first few cell ayers (minimal damage to underlying/surrounding structures) --> this
causes less edema than cautery. Also, its bloodless because is causes hemostasis to
vessels up to 0.5mm.
What are disadvantages of CO2 lasers? - answercannot be used fiberoptically (must
use line-of-sigh delivery mechanism). Errant beams can result in corneal damage. (This
can be stopped with any clear lens material).
