and Other Technology

, Julie Karen1 and Perry Robins1

New York University School of Medicine, New York, NY, USA


Laser Overview: Light Amplification by Stimulated Emission of Radiation

Basic principles

  • Laser treatment works by selective photothermolysis: targeted lesion may be destroyed by chromophore absorption of laser light without significant thermal damage to surrounding normal tissue

  • Depth of penetration directly proportional to laser wavelength

  • Endogenous chromophores: hemoglobin, melanin, and water

  • Exogenous chromophores: tattoos

Key terms/units

  • J = Joules = Measures of energy

  • W = Watts = Measure of power (W = J/s) Fluence (energy density) = J/cm2

  • Irradiance = Power density = W/cm2

  • Thermal relaxation time = Time for structure to cool to 1/2 temperature to which it was heated

Table 5.1
Lasers used in dermatology


Wavelength (nm)/color


Carbon dioxide

10,600 (infrared)

Resurfacing, destruction, coagulation, and cutting


2,940 (infrared)

Superficial resurfacing, superficial destruction


1,064; 1,320 (infrared)

Deep dermal pigmentation, tattoo (black, blue), laser hair removal (LHR), non-ablative resurfacing, large leg veins


810; 1,450 (infrared)

LHR, acne

Long-pulsed (ms) alexandrite

755 (infrared)

LHR, vascular lesions

Q-switched (ns) alexandrite

755 (infrared)

Tattoo (black, blue, and green), pigmentation

Picosecond (ps) alexandrite

755 (infrared)

Tattoo (black, blue, and green), pigmented lesions, scars

Q-switched ruby

694 (red)

Pigmentation (epidermal and dermal), tattoo (black, blue, and green), LHR, Nevus of Ota

Argon-pumped tunable red dye

504–690 (green-yellow-red)

Vascular lesions, epidermal pigment

Flashlamp-pumped dye laser (PDL), long-pulsed pulsed PDL (LP-PDL)

595 (yellow)

Vascular lesions, hypertrophic scars

Flashlamp-pumped yellow dye

585 (yellow)

Vascular lesions, hypertrophic scars, warts

Copper vapor/bromide

578 (yellow), 511 (green)

Vascular lesions, epidermal pigment


568 (yellow), 521/531 (green)

Vascular lesions, epidermal pigment

KTP (potassium titanyl phosphate)

532 (green)

Vascular lesions, epidermal pigment

Q-switched (frequency doubled) Nd:YAG

532 (green)

Vascular lesions, epidermal pigment, red tattoo

Argon continuous (gas)

514 (green), 488 (blue)

Vascular lesions, epidermal pigment

Flashlamp-pumped green dye

504,510 (green)

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Apr 1, 2017 | Posted by in Dermatology | Comments Off on and Other Technology
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