2. L ight
A mplification by
S timulated
E mission of
R adiation
3. Contents
• Historical background
• Laser physics
• Photobiology of Lasers
• Laser safety
• Types of Lasers
• Clinical Applications
• Medico legal considerations in Laser Surgery
• Future Trends
4. Historical background
•Albert Einstein – 1917 – Quantum theory
•Theodore Maiman – 1960 – 1st Laser using Ruby crystal
•Javan – 1961 – HeNe Continuous mode of laser
•Johnson – 1961 – Nd:YAG Laser
•Leon Goldman – 1963 – Father of modern lasers
•Patel – 1964 – CO2 Laser
•Anderson RR & – 1983 – Selective Photothermolysis
Parrish JA
5. Laser physics
ELECTROMAGNETIC SPECTRUM
ALEXANDRITE
ERBIUM-YLF
KRYPYON
EXCIMER
Nd: YAG
Ho:YAG
ARGON
HE NE
RUBY
KTP
CO2
X - RAYS
TV & RADIO WAVES
Frequency 1020 1019 1018 1017 1016 1015 1014 1013 1012 1011 1010 109 108 107 106 105 104 103 102 101 100
3AO 3nm 3µm 3mm 3cm 3m
Wave length 3km
MICROWAVES
GAMMA WAVES
ULTRAVIOLET VISIBLE LIGHT INFRARED
IONISING NON - IONISING
6. Generation of Laser Energy
Certain laser medium or LASANT with in the resonator
space is energized by internal or external energy to
produce an excited population of atoms, molecules and
rare gases (SPECIES). The energy with in the resonator
reaches a population inversion in which the greatest
cohort of species is in an excited state and in which
photons are emitted and amplified within a laser cavity.
The radiant energy is released as a laser beam.
7. The basic requirements for the laser activity are
– Active medium – LASANT
– Energy input – external or internal
– A population inversion through quantum
electronics
– Some form of optical feedback or optical
resonator
8. Laser Cavity
Fundamental components of laser system include
• Resonator cavity housing active medium
• Energy input – external or internal.
The cavity is bound by two mirrors
• One totally reflecting
• Other partially reflecting
9. • The mirrors are essentially parallel to each other and
placed at the either end of the cylinder
• The mirrors are separated by a fixed distance (d) forming
a Fabry-Perot interferometer.
• Principle of interference. Two or more waves
simultaneously penetrate some material, forms a combied
wave. Resulting a larger wave.
» Constructive interference
» Destructive interference
35. FACIAL SKIN RESURFACING
Indications:
1. Photo damage: Dyschromias & Rhytides
2. Atrophic (depressed) scars : Post acne
Chromophore : water
Mechanism : Thermal ablation of Epidermis &
papillary dermis
Post op Care
Lasers
a) Single pass CO2