1. LASERS : BASIC PRINCIPLE AND
USES IN DERMATOLOGY
Dr Rohit Kr. Singh
Res. (Dermatology)
Base Hospital
LKO

2. Contents
• Introduction
• History of lasers
• Basics components of laser
• Principle and working of laser
• Effect of laser on skin tissue
• Applications of laser principles
• Laser hazards and protections

3. Introduction
DEFINITION
• Light Amplification by the Stimulated Emission of Radiation
(acronym coined by Gordon Gould)
Conceptualization

4. A fantasy well-established in the past
• In 1898, H.G. Wells describes in his
book “The War of the Worlds” a
“fiery ray” impressively similar to
modern day lasers:
• « It was as if they were hit by an
invisible ray that exploded into white
fire on impact. Suddenly, it seemed
they were all turned to flame, and I
stood there stupefied, unable to
comprehend that it was death that
leaped from one man to another (...)
I only had the impression that it was
something very strange, this silent jet
of light that knocked down
everything it touched, and when this
invisible line passed over them, even
the pine trees and the bushes burst
into flame with a deafening
sound... »
The “fiery ray” described by H.G. Wells is the incarnation of the absolute weapon: fired out of
a vibrating funnel, a narrow ray straight as a rod sweeps over the surrounding countryside
destroying everything in its path. It is hardly surprising that this fantasy of ultimate power (a
“death ray” that quickly and “cleanly” kills the potential target from afar) was extremely
popular during the first half of the 20th century and when the research scientist T.

5. History : Some important dates
• 1917: Albert Einstein developed the theoretical
concept of photons & stimulated emission
• 1954: Charles Townes & Arthur Schawlow built the
first MASER using ammonia and microwave energy
• 1960: Thomas Maiman produced the first laser using
a synthetic ruby rod
• 1960: Dr. Ali Javan-first continuous laser (He-Ne
632.6 nm red gas ion laser

6. Pioneers

7. History of laser
• 1960s: Dr. Leon Goldman: Father of Laser Medicine
& Surgery-usage of laser in medical practice
• 1962: Bennett et al: blue-green argon laser (retinal
surgery)
• 1964: Kumar Patel: CO2 laser
• 1964: Nd:YAG laser
• 1969: Dye laser
• 1975: Excimer laser (noble gas-halide)

8. PIONEERS

9. BASICS COMPONENTS
OF LASER

10. • A laser consists of two fundamental elements - LASER AMPLIFIER
• These two components are sufficient to amplify an existing light source
1. AMPLIFYING OR GAIN MEDIUM (solid, liquid or gas)
– This medium is composed of atoms, molecules, ions or electrons whose energy levels are used to
increase the power of a light wave during its propagation.
– The physical principle involved is called stimulated emission
2. PUMPING SYSTEM - a system to excite the amplifying medium
– This creates the conditions for light amplification by supplying the necessary energy.
– There are different kinds of pumping system:
1. Optical (the sun, flash lamps, continuous arc lamps or tungsten-filament lamps, diode or other
lasers)
2. Electrical (gas discharge tubes, electric current in semi-conductors)
3. Chemical
3. OPTICAL RESONATOR (OR CAVITY) in order to produce a very special radiation
– The laser oscillator uses reflecting mirrors to
amplify the light source considerably
by bouncing it back and forth within the cavity
– It also has an output beam mirror that enables
part of the light wave in the cavity to be removed
and its radiation used
• Technically, the whole device is known as a LASER OSCILLATOR, but this term is often shortened to simply
“laser”.

11. Principle of laser
• Atom will absorb and
emit light photons at
particular wavelength
corresponding to the
energy differences
between orbits. The
wavelength l of
emitted or absorbed
photon can be
obtained by the
formula
• where E is the
change in energy
between the initial
and final orbits.
hf
hc
E  


12. Principle of laser (cont...)
• “Stimulated emission” of radiation
• Atoms or molecules are characterized by a set of discrete
allowed energy states
• An atom can move from one energy state to another when it
receives or releases an amount of energy equal to the energy
difference between the two states
Three distinct process may occur in the medium
1. Stimulated absorption
2. Spontaneous emission
3. Stimulated emission

13. Principle of stimulated emission of radiation
• Two energy levels E1 and E2 (E1 < E2) whose atoms can
interact with light of frequency
• The group E1-E2 is called radiative transition if atoms can
only pass from E1 to E2 (or from E2 to E1 ) by interacting with
light
• E1 is called the lower energy level
• E2the upper energy level

14. The emission-absorption principle
• Absorption:
– An atom in a lower level absorbs a photon of frequency hν and moves to an upper level
• Spontaneous emission
– An atom in an upper level can decay spontaneously to the lower level and emit a photon of
frequency hν if the transition between E2 and E1 is radiative
– This photon has a random direction and phase
• Stimulated emission
– An incident photon causes an upper level atom to decay, emitting a “stimulated” photon
whose properties are identical to those of the incident photon
– The term “stimulated” underlines the fact that this kind of radiation only occurs if an incident
photon is present
– The amplification arises due to the similarities between the incident and emitted photons

15. Population inversion and pumping
• To favour stimulated emission over
absorption, there need to be more
excited-state atoms than ground-state
atoms
• Spontaneous emission naturally tends
to empty the upper level so this level
has to be emptied faster by
stimulated emission
• It has been proved that stimulated
emission is much more likely to
happen if the medium used is flooded
with light (i.e. with a large number of
photons)
+
• A good way to do this is to confine
the photons in an optical cavity
• The confinement of the light
increases the probability of
stimulated emission rather than
spontaneous emission occurring
•If there are more atoms in the upper
level (N2) than in the lower level (N1),
the system is not at equilibrium
•A situation not at equilibrium must be
created by adding energy via a process
known as “pumping” light in order to
raise enough atoms to the upper level
•This is known as population
inversion and is given by N2 - N1 = Δ
•Light is amplified when the population
inversion is positive
•Pumping may be electrical, optical or
chemical

16. Spectroscopic systems used to create
a laser
• Every pumping system (particularly optical
or electrical) corresponds to a certain
energy, which must be transferable to the
atoms of the medium
• The difference in energy between the
excited state and the ground state must
match the pumping energy
• The objective is to store atoms in level
E2 by absorbing “pumping” radiation
whose wavelength is shorter than that of
the laser transition
• At least half of this population must be
excited to level 2 to obtain population
inversion
• Moreover, level 2 must be able to store
these atoms so spontaneous emission
must be very unlikely

17. Gaussian beam
An optical cavity selects a specific beam (a Gaussian beam) from the many
photons spontaneously emitted by the “lamp-amplifying medium” and the
number of photons carried by this beam is increased considerably, as it travels
back and forth, by the process of stimulated emission. This beam can have a
very low divergence and can be very precisely focused if the right optical tools
are used.

18. Monochromaticity
• The spectral bandwidth of a laser is given by the
width of the spontaneous emission: if the
transition between the upper and lower levels is
narrow, then the spontaneous emission will be
fractions of a nanometre (this is the case for the
red line in neon, which has a width equal to
1/1000th of a nanometre and a frequency of 1
GHz)
• The spectrum of a helium-neon laser is
therefore “monochromatic” in the sense that
only one colour is visible to the naked eye as the
line is very narrow
• The spectral properties of lasers become even
more interesting when just one frequency can
be selected (using a series of filters placed in
the optical cavity)
• The optical cavity is capable of filtering the
spontaneous emission in the form of discrete
frequencies (the longitudinal modes)

19. COLLIMATION TEMPORAL COHERENCE
Directionality
Temporal
coherence
Monochromicity

20. LASER characteristics
LASER characteristics Symbol Unit of measurement
Wavelenght lambda nm
Spot size d ( diameter)
s ( square)
cm
Pluse duration p (power)
energy delivered per unit
time
Watt ( w) = joules × sec
(j/sec)
Fluence ɸ
Energy delivered per unit
area
joule/cm2
Irradiance Power delivered per unit
area
w/cm2

21. LASER beam types
Continuous – wave (CW) LASERS Quasi – continuous – mode (
QSM)
Pulsed LASERS
Mechanism of
action
Continuous beam of light Continuous – wavelength lasers
that are mechanically
shuttered to deliver pulses of
light as short as 20 ms
Select pulse duration based
on target size
Long pulse (millisecond) :
0.5 to 400 ms allows
targeting of most hair and
blood vessels ( ie visible to
near IR)
Short pulse ( microsecond)
Modified to produce very
short pulses with high peak
power in a repititive
fashion; developed to
reduce the amount of
thermal damage allows
safer skin resufacing ( CO2)
Q- switched (QS)
nanosecond: allow build up
of extremely high energy in
laser cavity before
discharging in very short
single pulses
Characteristics Little or no variation in power
output over time (stable avg.
beam power)
Produces individual pulses of
light
Energy within the pulse is not
constant but rather builds,
peaks and tapers off within a
very short time
Peak power outputs are upto
100 time the max. output of
CW lasers
Complications Non – selective tissue injuries (
scar) as heat spreads from
chromophore
Lower risk of thermal injury to
surrounding non – targeted
structures
Examples CO2 LASER
ARGON LASER
KTP laser

22. Q- switched (QS) LASER
•In order to store many atoms in an upper level,
the flow to a lower level must first be limited
•Thus, stimulated emission must be prevented by
placing an attenuator in the cavity to stop light
from travelling back and forth
•When the pumping system supplies more atoms
per second than lose energy by spontaneous
emission, the population in the upper level can
become very large
•Stimulated emission becomes very probable and
the laser is suddenly triggered
•The flow due to stimulated emission is much
greater than the other flows (filling by pumping
and emptying by spontaneous emission): all the
atoms stored in the upper level fall sharply,
emitting stimulated photons (starting with the
spontaneous emission trapped in the cavity)

23. The different types of laser can be classified according to the nature of the amplifying
medium: gas, liquid(dye) or solid state

24. Gas lasers
•Same pump source:
electricity
•The gaseous species
enter the excited state
either directly, by
collision with electrons,
or indirectly, by collision
with other gases,
themselves electrically
excited
•Gas lasers cover the
whole optical spectrum,
from the ultraviolet to
the far infrared
Dye lasers
•Dye lasers use organic
materials that
generally emit in the
visible spectrum and
are thus coloured
•The pump source of
dye lasers is optical:
either an arc lamp or,
in the majority of
cases, another laser
(gas or solid state)
•Dye lasers are the
only ones to cover the
visible spectrum
entirely
Solid state lasers
•Solid state lasers
are either
semiconductor (or
diode) lasers
pumped electrically
or those with a
crystalline or glass
matrix pumped
optically
•Also have range in
visible and
ultraviolet spectrum

25. Excimer
lasers
• Name is derived from the
terms excited and dimers
• Use reactive gases, chlorine
and fluorine mied with inert
gases such as argon,
krypton,, or xenon
• When electrically stimulated,
a psedo – molecule (dimer) is
produced
• Hen lased, the dimer
produces light in the UV
range
Non – Laser light
sources
Intense pulse light
Non – coherent light
within 500 to 1200 nm

27. Chromophores (absorbing molecules)
Mechanism
• Chromophores exhibit characteristic bands of absorption at certain wavelengths
• When absorption occurs, the photon surrenders its energy to a chromophore.
• Once absorbed, the photon ceases to exist and the chromophore becomes excited
• It is this fact that allows for the delineation of specific targets for laser activity
• Three primary skin chromophores are
– Water
– Hemoglobin
– Melanin
• Melanin absorbs broadly across the visible and ultraviolet (UV) spectrum
• Oxyhemoglobin and reduced hemoglobin in blood exhibit strong bands in the UV, blue,
green and yellow regions
• Water has strong absorption in the infrared (IR) region

29. “Effect Of Laser On Skin Tissue”
Skin optics
Fresnel reflectance : 4–7% of
light is typically reflected
because of the difference in
the refractive index between
air (n = 0) and stratum
corneum (n = 1.45)

30. Penetration of lasers
• In pigmented epidermis, melanin
absorption - optical spectrum (200–
1000 nm)
• In the dermis, there is strong,
wavelength-dependent scattering by
collagen fibres
• In general, between 280 and 1300
nm, the depth of penetration
increases with wavelength
• Above 1300 nm, penetration
decreases due to the absorption of
light by water
• The most deeply penetrating
wavelengths are 650–1200 nm, while
the least penetrating wavelengths are
within the far-UV and far-IR regions
Penetration of laser depends
upon
1. Absorption and scattering
2. Dept of penetration increases
with wavelength
3. Amount of scattering is
inversely proportional to
wavelength

31. The depth of optical penetration for CO2 lasers is only ~20 microns, but
FRACTIONAL CO2 LASERS can vaporize nearly full-thickness microchannels through the dermis

32. Penetration of lasers
• Ablative laser treatments work mainly on the epidermis
(surface skin cells)
• Non-ablative treatments work solely on dermal collagen (mid-layer
of skin) only
• Fractional laser treatment works at both the epidermal and
dermal layers of the skin

33. THERMAL INTERACTIONS
Photocoagulation
• A Laser heating of tissues above
50 oC but below 100oC induces
disordering of proteins and other
bio-molecules
Photo-vaporization
• With very high power densities,
instead of cooking, lasers will
quickly heat the tissues to above
100o C , water within the tissues
boils and evaporates. Since 70%
of the body tissue is water, the
boiling change the tissue into a
gas

34. Thermal relaxation time (TRT)
• Thermal relaxation time (TRT) is defined, for a given tissue
structure, as the time required for the heated tissue to cool
halfway towards its initial temperature
Most of the absorbed energy is converted to heat
Diffuse into the surrounding tissue
Heat diffusion via conduction is also called thermal relaxation
The key to clean ablation of tissue is to ablate it quickly,
before much heat is conducted into surrounding tissue

35. Photochemical ablation
• When using high power lasers of ultraviolet
wavelength, some chemical bonds can be broken
without causing local heating; this process is called
photo-chemical ablation
• The photo-chemical ablation results in clean-cut
incision
• The thermal component is relatively small and the
zone of thermal interaction is limited in the incision
wall

36. Selective photothermolysis
• First arose to guide the design of a laser for treating
pediatric port-wine stains
• Selective, localized heating (with focal destruction of
“target” structures) is achieved by a combination of
selective light absorption and a pulse duration shorter
than or approximately equal to the TRT of the targets
• The optimal pulse duration for selective photothermolysis
is approximately equal to the TRT

39. Skin cooling
• Epidermal melanin damage most undesirable side
effect of LASER treatment
• All cooling methods extract heat at the skin
surface via a cooling agent
– Spray cooling, a cold liquid - liquid fluorocarbon is
sprayed on the skin
– Solid contact cooling - cold sapphire window held
against the skin, through which laser or IPL energy is
delivered
– Cold air or cold gels - passive skin cooling

40. Skin cooling
• Three basic types of skin cooling
1. Pre-cooling
– Pulsed dye and all Q-switched lasers (pulse durations shorter
than ~5 milliseconds )
– Cryogen spray
2. Parallel cooling
– For pulses longer than ~5 milliseconds
– Solid contact cooling with a cold sapphire window pressed
against the skin just before and during
3. Post-cooling
– Bulk skin cooling before and after laser treatments (e.g. with ice
or cold air) is useful for minimizing pain, erythema and edema

41. Applications of laser principles
• Ablative (Vaporizing) Skin Resurfacing
• Treatment of Vascular Lesions
• Interactions During Treatment of Pigmented
Lesions and Tattoos
• Interactions During Hair Removal
• Interactions During Non-ablative Skin
Rejuvenation
• Fractional Photothermolysis
• Laser-Based Diagnostics

42. Ablative (Vaporizing) Skin Resurfacing
• The ablative lasers are far-IR
– CO2 (10 600 nm)
– Erbium:yttrium aluminum garnet (Er:YAG; 2940 nm)
• Chromophore - water
• Pulsed and/or scanned focused beams are used to precisely vaporize
superficial tissue, causing a “plume” of material leaving the skin.
• Most of the heat is removed during vaporization, but a thin layer of
residual thermal damage remains that is useful for hemostasis.
• Laser resurfacing is very useful for treating
– Photoaging
– Scars
– Epidermal nevi
– Seborrheic keratoses
• Resurfacing removes the old epidermis and stimulates contraction and
remodeling of the dermis for many months after treatment
• Complications - Scarring, transient hyperpigmentation, delayed-onset
permanent hypopigmentation, prolonged erythema, and bacterial, viral
and fungal infections have been reported after laser resurfacing

43. Treatment of Vascular Lesions
• A peak of absorption by oxyhemoglobin occurs at 577 nm within
the yellow spectrum
1. Flashlamp-pumped pulsed dye lasers (PDLs) (585–600 nm) with
pulse durations ranging from 0.45 to 40 milliseconds
2. Pulsed neodymium:YAG (Nd:YAG) lasers (1064 nm)
3. Alexandrite lasers (755 nm, ~3 millisecond pulse duration)
– Hypertrophic lesions
– PDL-resistant vascular lesions
– This difference may be due to preferential absorption by
oxyhemoglobin at 1064 nm, in contrast to preferential absorption by
deoxyhemoglobin at 755 nm

44. Cont…
4. Copper vapour or copper bromide lasers emit either green light at
511 nm or yellow light at 578 nm
5. Potassium titanyl phosphate (KTP) lasers, at a wavelength of 532
nm
• Complications
– Purpura is the result of microvascular hemorrhage,
– Subsequent thrombosis
– Delayed appearance of vasculitis
When the pulse duration exceeds -20 milliseconds, there is little or
no immediate purpura because cavitation and vessel rupture are
avoided

45. Laser used for vascular lesions
Indication laser
Port – wine stain PDL
IPL
Hemangiomas PDL
Telangiectasia Green light lasers ( 532nm) PDL
Diode laser
Long – plse Nd:YAG ( 1064nm)
Pyogenic granuloma PDL
CO2 laser, combined continuous
– wave/pulse
Angiofibromas PDL
CO2

46. PROLIFERATING HEMANGIOMAS

47. Interactions During Treatment of
Pigmented Lesions and Tattoos
• Melanin has a broad absorption spectrum which lends itself to possible
targeting by a wide variety of lasers
• Choice of treatment wavelength is based on
– Avoiding absorption by other chromophores
– Matching depth of penetration to the depth of the lesion
• Red and near-IR lasers are the most selective
• Mechanism
– Treatment of tattoos with Q-switched lasers fragments the ink particles and
selectively kills pigment-containing cells, with
– Resultant ink particle release
– Subsequent removal of tattoo ink particles can occur via an epidermal crust
and/or lymphatic transport, and some particles are re-phagocytosed by
dermal cells

48. Laser treatment for tattoo pigment
Laser type Wavelength ( nm) Tattoo pigment colour
Pigmented PDL 510 Orange, yellow, purple
QS Nd:YAG, frequency
doubled
532 Red, orange, yellow
QS ruby 694 Red, blue-black
Occasionally green and
brown
QS alexandrite 755 Blue, black and green
QS Nd: YAG 1064 Blue-black

49. TATTOOS

50. • LASER commonly are used
1. Q-switched ruby ( 694 nm)
2. Alexandrite lasers (775 nm)
3. Q-switched Nd:YAG laser emits at 1064 nmwith typical pulse durations
of 10 nanoseconds
Other conditions
• Lentigines,
• Nevus of Ota
• Café-au-lait macules
• Melanocytic nevi
• Side effects: pigment & textural changes, allergic reactions, ink darkening,
tissue aerosolization with possible infectious particles.

51. Interactions During Hair Removal
• Red to near-IR region of the spectrum (i.e. deeply
penetrating)
• High-energy,
• Millisecond-domain pulses of wavelengths
– Ruby Lasers ( 694nm)
– Alexandrite Lasers ( 755nm)
– Diode Lasers ( 800 – 810 nm)
– Nd:YAG Lasers ( 1064 nm)

52. Mechanism
• Damage to follicular stem cells in the bulge region of the
outer root sheath and/or the dermal papilla at the base of
the hair follicle
Temporary hair loss
– Induction of catagen, which can occur at very low fluences;
– An 810 nm diode laser source intended for home use
Permanent loss of terminal hair
– Miniaturization to produce vellus-like hairs
– Complete degeneration with local fibrosis
Unwanted stimulation of a vellus-to-terminal hair transition can
occur after laser or IPL treatments, particularly on the face

53. Interactions During Non-ablative
Skin Rejuvenation
• Non-ablative facial rejuvenation
• Fine lines
• Non-dynamic rhytides
• Mid-IR lasers
– 1320 nm Nd:YAG
– 1450 nm diode
– 1540 nm erbium:glass lasers
– IPL sources
Mechanism
• These work by subtle thermal effects on the dermis, presumably
stimulating a wound healing response
• Responses to non-ablative rejuvenation are usually gradual and subtle

54. TREATMENT OF RHYTIDES

55. Fractional Photothermolysis
• Thousands of nearly invisible, microscopic
zones of thermal injury are created
• Stimulating turnover
• Remodelling of both the epidermis and dermis

56. • Non-ablative FP uses focused mid-IR laser microbeams to create a
pixilated pattern of small columns of thermal damage, called
microthermal treatment zones (MTZs)
• Ablative FP uses carbon dioxide or erbium (Er:YAG) lasers to vaporize a
similar pattern of small vertical channels that can extend deeply into the
skin
Uses
• Scars,
• Fine rhytides,
• Telangiectasias,
• Dermatoheliosis
• Poikiloderma
• Ablative FP may also bean effective mechanism for topical drug delivery,
by providing many channels directly into the dermis.

57. Laser-Based Diagnostics
1.Optical coherence tomography (OCT)
– Near-IR,
– low-coherence light
– Used for high-resolution crosssectional imaging of body
tissues
• Doppler version has been shown to be capable of imaging
blood flow before and after laser treatment of vascular
lesions

58. 2. Laser confocal microscopy
• Captures light scattered or emitted from a thin plane “section”
inside skin
• In vivo with histology-like resolution down to a depth of
approximately 0.3 mm
• Because histochemical stains are not used, confocal microscopy of
skin tumors reveals diagnostic features that are different from
those of conventional histology
• Microvascular blood flow and trafficking of lymphocytes can be
observed
• In a preliminary study, the sensitivity and specificity of in vivo
confocal microscopy for differentiating melanocytic nevi and
seborrheic keratoses from cutaneous melanoma and basal cell
carcinoma were 94% and 98%, respectively

59. Laser hazards and protections

60. Hazards to the eye
The cornea and lens
•Cornea is accessible to danger of UV and most of IR
lasers,
•UV-A, UV-B (between 295nm and 320 nm) and IR-A
(between 1 to 2 mm) are dangerous for lens,
•308-nm (UV-B) excimer XeCl laser is particular dangerous
because of it can simultaneously damage the lens, the
cornea and the retina.

61. Hazards to the eye
The retina
The directionality of a laser beam permits the ray to be
focused to an extremely small spot on the retina. A
collimated laser will be concentrated by a factor of
100,000 when passing from cornea to retina.
Visible or near IR lasers (400
nm to 1400nm) are particularly
dangerous to the retina and
always requires eye-protection
when working with these kind
of lasers.

62. Protection to the eye
Eye protection
Eyewear (goggles) is the most common laser protective
measure, especially for open laser beams. It should be
good design with all around shielding and adequate
visible light transmission.
Identification of the eyewear : All laser protective
eyewear shall be clearly labelled with information
adequate to ensure the proper choice of eyewear with
particular lasers.

63. Fire hazards
• FIRE HAZARDS
• Drapes, clothing, dry hair and plastic
materials, including endotracheal
tubes, can be ignited, especially
when oxygen is in use
• Greatest risk is with the CO2 and
erbium:YAG lasers used for skin
resurfacing and ablative fractional
treatments
• PREVENTION OF FIRES
• Remember to place the laser in
STANDBY mode when not actually
treating the patient
• Avoid inadvertently activating the
laser foot-switch
• Moisten any hair near the treatment
field; remove mascara and eye
makeup when working around
eyelids
• Alcohol, acetone or other flammable
skin-cleaning solutions must be
allowed to completely dry before
laser use
• Reduce intraoperative oxygen
concentration to <40%
• A fire extinguisher and water should
be readily available

64. Cutaneous burns
• POSSIBLE CUTANEOUS
BURNS
• Can occur with essentially
all dermatological laser, IPL,
RF or therapeutic
ultrasound devices
• Primarily due to improper
device, dosimetry and/or
treatment technique
• PREVENTION OF
CUTANEOUS BURNS
• Knowledge and careful
observation of specific
clinical endpoint responses
for a particular laser–lesion
combination

65. “Plume” materials
• INHALATION OF LASER-GENERATED
“PLUME”
MATERIALS
• Particularly with resurfacing or
vaporization of hair during its
removal; latter can release
irritating sulfur and other
oxides
• PREVENTION OF LASER
“PLUME” BIOHAZARDS
• Smoke evacuator and good
ventilation are most effective
measures
• Sub-micrometer surgical filter
masks provide some
protection when worn
properly
• Q-switched lasers capture
particulate material in plastic
cones

66. Conclsion
• Lasers and IPL should just be considered as “drugs”,
i.e. something that can be manipulated to ease the
burden of those suffering from skin diseases
• Total internal reflection of spontaneous emission of
radiation (TRASER) devices, which are neither lasers
nor IPL, are more efficient than lasers and are
tunable

67. REFERENCES
1) FITZPATRICK’S DERMATOLOGY IN
GENERAL MEDICINE
2) ROOK’S TEXTBOOK OF DERMTOLOGY
3) IADVL TEXTBOOK & ATLAS OF
DERMATOLOGY BY R.G. & AMEET
VALIA
4) TEXT BOOK OF DERMATOLOGY BY
BOLOGNIA 3ed

68. THANK YOU