, Julie Karen1 and Perry Robins1
(1)
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
Laser | Wavelength (nm)/color | Purposes |
|---|---|---|
Carbon dioxide | 10,600 (infrared) | Resurfacing, destruction, coagulation, and cutting |
Erbium:YAG | 2,940 (infrared) | Superficial resurfacing, superficial destruction |
Neodynium:YAG | 1,064; 1,320 (infrared) | Deep dermal pigmentation, tattoo (black, blue), laser hair removal (LHR), non-ablative resurfacing, large leg veins |
Diode | 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 |
Krypton | 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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