This document discusses lasers, including: 1. How lasers work using stimulated emission to produce coherent, monochromatic beams of light. 2. The components of laser systems including the power source, lasing cavity, and waveguide. 3. Applications of various medical lasers including treating benign lesions, vascular lesions, pigmented lesions, and hair removal. Common lasers used are CO2, pulsed dye, argon, Nd:YAG, and intense pulsed light systems. 4. Properties of laser light that make it useful for dermatology such as being collimated, monochromatic, and coherent.

1. LASER
Light Amplification by Stimulated Emission
of Radiation
Ashwin kumar sanapala
MIMS

2. Quantum physics

5. Stimulated emission
• Is the process by which an incoming photon of a
specific frequency can interact with an excited
atomic electron, causing it to drop to a
lower energy level. The liberated energy transfers
to the electromagnetic field, creating a new
photon with identical
phase, frequency, polarization, and direction of
travel as the photons of the incident wave.
• This is in contrast to spontaneous emission which
occurs at random intervals without regard to the
ambient electromagnetic field.

6. • A laser is a device that generates an intense beam
of light.
• The wavelength : is defined as the distance
between the crests of each wave and that
determines the functional properties of the laser
energy..
• Wavelengths in the 0.4-0.7um range form the
visible light of the spectrum.
• Ultraviolet rays, X-rays and gamma are forms of
electromagnetic radiation with the wavelengths
shorter than the visible light.

8. • Surgical lasers fall between the longest and
the shortest wavelengths, in the infrared and
visible as well as the ultraviolet portions of the
electromagnetic spectrum.
• The type of laser depends on the active
medium used.
• The most commonly used medical lasers are,
the carbon dioxide, ruby, argon, krypton, YAG
and Excimer.

9. LASER - skeleton

10. The components of laser system:
Power source:
• pumps energy into the lazing medium.
• The power pumping energy is related to the
composition of the medium in the laser.
• The power source in lasers may be electrical
as in Argon and carbon dioxide or flash lamps
as in pulsed dye laser.

11. Lasing cavity:
• which is a tube with mirrors placed at each end
where amplification of stimulated emissions of
radiation occurs.
• Photons traveling the length of the tube are
reflected back through the medium.
• Each time the beam reflects back and forth or
resonates through the axis of the medium, more
atoms are stimulated to release photons, and the
laser effect is amplified.
• The end of the mirrors has a small opening
allowing a minute part of the laser light to be
transmitted.

12. A wave guide:
• The laser light is invisible and therefore a
fibro- optic HeNe low beam is used to guide
the laser light towards the desired tissue to be
treated.

13. PROPERTIES OF LASER LIGHT
Laser light has three special qualities that distinguish, it from the
conventional light source .
• Collimated: means that laser light travels parallel in a single
direction with very little divergence even for a long distance and
therefore there is minimal loss of power along the beam . A
laser beam is a 1000 times brighter than the daylight and is
brighter than the sunlight.
• Monochromatic: consists of one color or wavelength and thus
the laser beam is very pure. In contrast, white light from a
regular light bulb involves the spontaneous emission of photons
of many wavelengths or colors, traveling in various directions
and emitting diffuse light.

14. • Coherent: means all of the light waves move
parallel in phase together in both time and
space. Ordinary light from a lamp consists of a
mixture of wavelengths radiating in different
directions and out of phase . It is in a laser
term considered as incoherent.

15. MODES OF ACTION OF LASER LIGHT
• This depends mainly on the absorption of a photon
by a chromophore or the target tissue such as
melanin pigment, water or hemoglobin.
• The photon surrenders its energy to the
chromophore and then ceases to exist where the
energy is converted into heat, which is dissipated
to the neighboring tissue, by conduction or
radiation.
• In the cells most proteins , DNA, RNA, membranes
and their integral structures start to melt at
temperature more than 40 degree centigrade
where tissue becomes coagulated .
• The severity of coagulation or tissue denaturation
depends on both the fluence and time of exposure.

19. LASER TERMS
• Ablation: removal of tissue by vaporization.
• Beam: a ray of light.
• Divergence: increase in beam diameter with distance
from the exit aperture of laser.
• Chromophore: optically active material in tissues that
can act as an absorptive target for laser (melanin,
hemoglobin water).
• Absorb: To take up matters or energy.
• Absorption coefficient: Ability of light to be absorbed.
• Active medium: The active material in the laser.

21. • Intensity: the power transmitted by a light
wave across a unit area perpendicular to the
wave.
• Power: the time rate of doing work (watt)
• Power density: the power of the laser beam
per unit area (watts/cm2).
• Excitation: The addition of energy to a particle
or system.

22. • Fiberoptics: a system of flexible quartz or
glass fibers with internal reflective surfaces
that pass light through thousands of glancing
reflexes.
• Aiming beam: HeNe of low density beam used
to guide the invisible laser light to the
treatment area.
• Laser medium: (active medium) material used
to emit the laser light.

23. • Coagulation: destruction of tissues by heat
without physically removing it.
• Collimation: all rays coming from laser are
parallel to each other.
• Coherent radiation: same wavelengths move
together to different points.
• Thermal relaxation time: The time it takes heat
to diffuse out of a structure and into surrounding
structures by thermal conduction.
When pulsed, duration of a laser is
shorter than the time required for heat to spread
out of a target, the heat damage will be confined
to the target.

24. • Target site: tissue that is aimed or fired with
the laser beam.
• Photocoagulation: tissue coagulation by
laser light.
• Mode : the way in which laser beam is
distributed.

25. TYPES OF LASERS USED IN
DERMATOLOGY

26. Lasers can be categorized into three types:
1. Lasers that emit visible light:
- These lasers, which emit visible light ranging from
the blue to the red portions of the
electromagnetic spectrum, are used in treating
vascular and benign pigmentary conditions.
- They include argon, argon pumped tunable dye,
flash lamp pumped pulsed dye, copper vapor,
copper bromide and krypton lasers.
- The blue,green, red and yellow emission
wavelengths are characteristically absorbed by
the two main natural chromophores of the skin,
hemoglobin and melanin.

27. 2. Lasers that emit infrared light:
- These include the carbon dioxide and
neodymium:yttrium–aluminium–garnet( Nd:YAG) laser.
- Both these emit energy in the infrared portion of the
electromagnetic spectrum so there is no preferential
absorption of the laser light energy by melanin or
hemoglobin.
- The carbon dioxide laser, in the far infrared portion, is
selectively absorbed by water and the effect of this laser
on tissue is determined by the water content.
- The invisible, near-infrared wavelength of light from the
Nd:YAG laser is not specifically absorbed by any
component of the skin or internal organs resulting in a
diffuse nonspecific thermal effect. Since its energy is
absorbed by volume, it has been used mainly as a
coagulator.

28. 3. Lasers that emit very short pulse (nano-
seconds) of visible or infrared light:
- These are Q-switched lasers that produce
short, high intensity nano-second bursts.
- The movement of the wave through the tissue
produces kinetic energy which can fracture or
disintegrate tattoo pigments or melanin.
- These lasers are used for the treatment of
benign pigmented lesions and the removal of
tattoos.

30. Indications

31. Treatment of Benign Cutaneous
Lesions
1. Carbon dioxide laser:
• The CO2 laser emits far infrared radiation at 10,600
nm.
• The chromophore of absorption is water.
• The laser energy is superficially absorbed by tissue
water, which limits penetration of the laser to a depth
of 0.1 to 0.2 mm with minimal scatter.
• Continuous-wave CO2 laser can produce a more
limited area of tissue damage (peripheral damage
limited to 50 to 100 mm).
• treatment of choice are refractory warts, rhinophyma,
epidermal nevi, seborrheic keratosis, angiofibromatous
and angiolymphoid lesions, and benign superficial
dermal tumors.

32. 2. Pulsed dye laser at 585 mm:
• The PDL is pulsed at 450ms with a
wavelength of 585 nm, which makes
hemoglobin the primary target
chromophore.
• This high energy and short pulse
duration impart the capacity to
destroy target blood vessels with high
specificity and with minimal damage
to the epidermis and surrounding
structures, which results in a very low
incidence of scarring.
• It is used for benign lesions with a
vascular component like verruca
vulgaris, verruca plana, keloids,
angiofibromas, and rosacea.

33. 3. Argon laser:
• The argon laser, with wavelengths of 488 and
514.5 nm, targets hemoglobin and melanin.
• It is used for benign lesions with a vascular or
pigmented componen like telangiectasia,
seborrheic keratosis, rosacea, angiofibromas
and pyogenic granulomas.

34. 4. Neodymium: Yttrium–Aluminium–Garnet laser:
• The Nd:YAG laser has a wavelength of 1064 nm,
which is absorbed by proteins of any opaque
tissue, darker tissue showing preferential
absorption.
• Its frequency can be doubled to a 532 nm
wavelength.
• Treatment of keloids and early lesions of
seborrheic keratosis.

35. 5. Pulsed dye pigmented laser:
The pulse dye-pigmented laser, at a wavelength
of 510 nm, has been used to treat flat
seborrheic keratoses.
6. Q-switched ruby laser:
The Q-switched ruby laser, with a wavelength of
694 nm, has been reported to achieve 75%
resolution of seborrheic keratoses.

36. Treatment of Vascular Lesions
A variety of lasers is available for vascular lesions
and telangiectasias.
• Continuous Wave (CW) units utilize wavelengths
from 488 to 578 nm.
• The target chromophore is oxyhemoglobin,
although some melanin absorption also occurs,
principally at shorter wavelengths.
• Penetration is approximately 1 mm and is
greatest at longer wavelengths.
• Facial telangiectasia is the most common
indication of CW laser.

37. • The pulsed dye laser (the flashlamp-pumped
pulsed dye laser; FLPDL) was developed
specifically for vascular lesions especially port-
wine stain.
• In addition to telangiectasias, capillary
hemangiomas, venous lakes, small cherry
angiomas also respond to treatment.
• The double Nd:YAG laser (532 nm) is effective
for treating telangiectasias.

38. • The alexandrite 755 nm and Nd:YAG (1064nm)
lasers have been used to treat bulky
malformations and port-wine stain.
• The intense pulse light (IPL) laser has a
noncoherent broadband light source with
wavelengths in the range of 515–1200 nm and
various pulse widths.
• Filters are used to block unwanted wavelengths.
• It has been used to treat port-wine stain,
hemangioma, and telangiectasias.

39. Treatment of Pigmented Lesions
1. Continuous wave lasers:
• These are argon (488 and 514nm), green light KTP (532 nm)
and carbon dioxide (10,600nm) lasers.
• used to treat epidermal but not dermal lesions through
nonspecific thermal damage.
2. Q-switched ruby laser:
• The laser beam produced is red light of wavelength 694
nm.
• Q-switching results in pulsed emission of coherent light.
• It is used in the treatment of lentigo, café-au-lait patches,
melasma, nevus of Ota, and infraorbital skin darkening.

40. 3. Nd:YAG laser:
• Its high power pulses and short exposure time allows precise
treatment of target tissue with minimal thermal damage.
• It is used in the treatment of tattoos, caféau lait macules,
Becker’s nevus, and post-inflammatory pigmentation.
4. 510 nm Pulsed dye laser:
• It is used for removal for pigmented lesions confined to the
epidermis.
• Used for treatment of cafe-au-lait patches, Becker’s nevus,
postinflammatory pigmentation, nevus of Ota, nevus of Ito,
and melasma.
5. Alexandrite laser:
• The alexandrite laser 760 nm penetrates into the dermis and
is used to treat dermal pigmented lesions.

41. Lasers for Hair Removal
• The chromophore for selective targeting of hair follicles
can be endogenous or exogenous:
1. Endogenous chromophore (Melanin):
• Melanin in the hair shaft of the follicle provides a
chromophore that is not present in the surrounding
dermis and that allows selective targeting of hair in
the skin.
• Thus, at deeply penetrating wavelengths in the 600
nm to 1100 nm region, melanin absorption may be
used for selective photothermolysis of hair follicles.

42. Lasers that target melanin are:
a. Diode laser:
• The diode laser emits a
wavelength of 800 nm and also
causes hair removal by
effectively targeting melanin
while deeply penetrating the
dermis.
• This may allow safer treatment
in dark skinned individuals.
b. 694-nm Ruby lasers:
• Because of high melanin
absorption at 694 nm, ruby
lasers are indicated in
lightskinned (Fitzpatrick skin
types I to III) individuals.

43. c. 755-nm Alexandrite lasers:
• Several long-pulsed alexandrite lasers have
been introduced recently for hair removal.
• The longer wavelength allows a slightly
greater depth of penetration, and there is a
lower risk of epidermal damage because of
slightly less melanin absorption at this
wavelength.

44. 2 . Exogenous chromophore:
• Rather than targeting endogenous melanin, an
exogenous chromophore (e.g. dyes,
photosensitizers, and carbon particles) can be
introduced into the hair follicle and then
irradiated with light of a wavelength that matches
its absorption peak.
• The technique is inadequate for inducing
permanent hair loss because penetration of the
chromophore into all depths of the hair follicle is
not reliable

45. The Q-switched Nd:YAG laser targets exogenous
chromophores.
• It produces light at 1064 nm in the near infrared spectrum.
• Water, hemoglobin and melanin are poorly absorbed at
this wavelength.
• Hence, the laser is employed in combination with a topical
pigmented carbon-based suspension as an exogenous
chromophore.
• This method provides a selective target that is independent
of the color of the hair shaft.
• This permits effective treatment of even light-haired
individuals who lack significant hair melanin, the main
chromophore for other laser systems.

46. Intense Pulsed Light Systems
• Pulsed, noncoherent broadband light sources are
now widely used for hair removal and other
applications. Intense pulsed light (IPL) systems
utilize a xenon bulb as a light source, which
produces polychromatic light with wavelengths
from 550–1200 nm.
• This is in contrast to laser light sources, which
produce monochromatic light of a specific
wavelength. Light emitted by the bulb passes
through a filter that excludes shorter wavelengths
that may severely damage the skin.

47. • The ability to “tune” the wavelength of light
emitted by these systems gives IPL systems the
advantage of versatility. Using different filters, a
pulsed light system could mimic any number of
laser systems, allowing the operator to treat
many different conditions amenable to light
therapy, including, of course, the removal of
unwanted hair.
• Studies have shown intense pulsed light to be
an effective method of hair removal.

48. • The variability of light output can also be a
disadvantage of IPL systems.
• The light spectrum may vary slightly with each
pulse, and reproducibility of treatments varies
between operators.
• The hand pieces of IPL systems are typically
larger than laser-based systems, which makes
treatment of fine areas of the skin difficult.

49. Laser Resurfacing of the Face
1. Carbon dioxide laser:
• The carbon dioxide laser available in CW or pulse
mode is used for both excisional and ablative
surgeries.
• The excisional mode is used for keloid removal,
scalp reduction, debulking rhinophyma, and
removal of malignancies.
• The ablative/vaporizing mode has become
popular for treating rhytides, photoaging, acne
scars, adenoma sebaceum, and multiple
trichoepitheliomas, through resurfacing
techniques as the cosmetic results are excellent.

50. 2. Erbium:YAG laser: It is used for resurfacing
wrinkles and scars.
3. Combined CO2/Er:YAG laser: Both the laser
energies are
• combined simultaneously in a synchronized
manner.
• The combined system gives the benefit of precise
ablation, short recovery, minimal side effect,
collagen tightening, an ability to treat deep
wrinkles

51. LASER SAFETY

52. 1) The operating room
• Instruments used should be of special type
not reflecting laser light.
• The room should not contain volatile
substances such as ether, alcohol .
• Gauze used should be moistened with water
to prevent inflammation by the laser light.

53. 2) Safety measures for the patient:
• Special glasses should be used.
• different lasers have different glasses.
• Eye shields: applied and cover the eyes by moist
gauze before applying the glasses.
• Patient's lips can be protected by moist gauze.
When operating in the oral cavity, care should be
taken to protect teeth and bone by using wet
gauze or other nonflammable, heat absorbing
protective material.
• Char can be removed by moist saline gauze , where
charred areas may reach very high temperature as
laser energy continues to be applied causing more
destruction to tissues.

54. General measures
• The surgeon and the assistants should use the
special glasses for the particular laser.
• NEVER look directly into the laser source or at
sites of laser reflection.
• Both direct and reflected laser output can contain
enough energy to cause permanent eye injury.
• NEVER allow anyone near the laser while it is in
use without protective eyewear.
• NEVER point the hand probe in any direction,
except toward the area to be treated.
• Before activating a hand piece, confirm that the
tip of the probe is pointed in safe direction.
.

55. • If the HeNe beam (which is weak laser beam used
to guide the direction of the intense laser beam
emitted from the machine for surgical application)
is absent, first make sure first that the" Manual
Safety Shutter" is in the open position.
• NEVER place hands or other objects in the path of
the carbon dioxide beam. Severe burn may occur.
• NEVER discharge the laser without a target to
absorb it and without consideration giving to
what lies behind the target. Saline soaked gauze
sponges or saline moist gauze or water soaked
clean gauze can be used to protect tissues

56. • LASER FOOT SWITCH :only the surgeon should
have access to the laser Footswitch.
• NEVER press the foot paddles unless you are
starting treatment and all safety precautions
should be considered.
• NEVER use the laser in inflammable situation.
• STAND BY position: keep the laser in the standby
position when you stopped working temporarily
for any reason to prevent accidental exposure to
laser surgery.
• MASKS: Special masks should be used especially
when removing viral lesions to prevent inhalation
of the viral particles .

57. ELECTRICAL HAZARDS
• NEVER remove the laser protective covers.
• NEVER operate the laser if there is any
leakage of water from the console. (Certain
types of lasers contain water inside)
• NEVER operate the laser if the power cable is
faulty

58. EQUIPMENT PRECAUTIONS
• Certain types of lasers contain water. The high
voltage used to excite the laser and water used for
the cooling system may cause dangerous hazards.
• Proper training- how the machine can work is of
prime importance .
• Ensure that the operator-selected beam delivery
and the beam alignment are working properly.
• Ensure that the HeNe guiding beam is working
before any surgical treatment.
• NEVER fire the laser if the helium-neon beam is
invisible in the field.

59. ANESTHESIA FOR SKIN RESURFACING
Local anesthesia
• EMLA cream is composed of Lidocaine and
Prilocaine.
• Regional block : used for deeper resurfacing or
sensitive patients, or wide area to be treated.
• Local infiltration of the lesions by xylocaine.

60. Complications of laser surgery
• In vascular lesions treatment, scarring may occur if
too much light energy is absorbed by the epidermis
and perivascular dermis below the reticular layer of
the skin.
• If the epidermis is damaged it can regenerate
without scaring, while damage of the dermis may
cause hypertrophic scarring.
• This is the worst complication when treating a
vascular lesion as port wine stain with the use
of Blue/Green wavelength especially in young
children.
• Other complications are hypopigmentation, hyper
pigmentation and texture changes.

61. SKIN CARE INSTUCTIONS AFTER LASER
SURGERY
• Do not rub, scratch or put pressure on the treated
area until skin changes like erythema and crusting
clears.
• Do not apply make-up if there is severe reaction
like oozing and blistering of the treated areas.
• Washing of the face gently by water may be
allowed, while swimming is postponed for 2-4
weeks.
• The treated area should be kept away from
exposure to sunlight and sun blocks should be used
two weeks before and four weeks after surgery.

62. • Post laser hyperpigmentation and scarring are the main
problems of laser surgery.
• To minimize post laser hyperpigmentation the following
formula can be used by the patient two weeks before
and eight weeks after laser surgery.
- 0.2% Retin A
- 2% Hydrocortisone
- 4% Hyroxyquinone
• It can be used gently twice daily. The concentrations of
the ingredients can be modified according to the type of
skin , condition of the treated area and age of the
patient.
• Acyclovir tablets used 5 days before the operation in
patients having history of herpes lesions.
• Oral antibiotic such as Cephalosporin can be given as a
prophylactic measure.

63. Postoperative measures.
• Apply polysporin ointment.
• combination of Pufexamac and Muperacin cream (
Droxaryl & Bactropan) that proved to have an
excellent post-operative healing and minimizing
erythema and hyper pigmentation .
• The resurfaced area can be covered by Vaseline
dressing. The dressing is left in site for 48 hours
and then removed using only the medication
without covering .
• Ice bags, cold milk compresses or Pufexamac
cream (Parfenac, Droxaryl cream) can be applied
several times a day to alleviate erythema and
edema.

64. don’ts
• Do not remove the Crusts.
• Emollients such as can be used to keep the skin moist.
Washing can be permitted.
• Avoiding tissue papers for drying of the skin. Soft cotton
towels can be used.
• Minimize irritation of the skin by gently drying without
rubbing , just to press gently the cotton towel to the area.
• Avoid irritants to the resurfaced areas such as perfumes
or strong soaps. Mild soaps can be used such as white
Dove soap.
• Avoid direct sun exposure- This may lead to
hyperpigmentation especially in colored individuals.

65. Thank you