Week 2 Flashcards
What is the definition of spontaneous?
When an electron drops from an excited state, back to its ground state, this emits a photon…
What is the definition of absorption?
When an incoming photon is absorbed by an atom, leaving it in an excited state.
What is the definition of stimulated?
When an atom is in an excited state & is forced by an incoming photon of the same wavelength, to give up the gained photon, thus emitting 2 photons!
What is the ‘Gain medium’
The Laser cavity.
T/F? Laser is monochromatic
True
What does monochromatic mean?
One color
What does power density measure?
How much energy in a specific area
T/F? Power density will increase with the decrease of a beam area.
True
How is a circular beam area calculated?
3.14 X R2
How to I find out the measurement of energy?
Watt X time = Energy
How do I find out the energy density?
ED = Energy / Beam area
What units is the Laser Output power measured in?
Watts
What units is the time measured in?
seconds
what units is the beam area measured in
cms
What must you always do 1st when given the figures for a calculation?
convert to the correct units eg: mm -> cm
When light falls on tissue, it will undergo one of four processes… What are these?
Reflection, Scatter, Absorption or Transmission
What are 3 main targets in the skin for the laser?
hemoglobin, melanin & water
at what nm is melanin best absorbed?
520nm
at what nm is hemoglobin best absorbed?
550nm
What are 5 types of tissue interactions?
Photo thermal, photo ablative, photo acoustic, photo chemical & biomodulatory.
which type of tissue interaction is used by the treatment PDT?
photo chemical
which of the tissue interactions can cause biological damage?
photo thermal, photo acoustical & photo chemical.
is photo acoustical or photo thermal damage more destructive?
photo acoustical
