PW must be equal to or shorter than Thermal Relaxation Time
(TRT) of the target (hair follicle) to confine thermal damage
Depends on hair diameter (i.e., fine vs. coarse)
PW must be matched with appropriate amount of fluence to cause
follicular damage while sparing surrounding tissue
Depends on melanin content in skin vs. surrounding tissue
Note: maximum tolerated fluence is generally inversely
proportional to melanin content in skin for a given pulse width
In general,
Treat fine/thin hair, lighter skin types with shorter pws
Treat coarse/dense hair, darker skin types with longer pws
Pulse Width Considerations Laser Tissue Interaction
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