What does pulse width refer to in laser terminology?

• A. Peak power of the laser
• B. Wavelength of the light
• C. Duration of each pulse
• D. Total treatment time

Answer: (C)

Pulse width is the duration of each pulse—the length of time the laser actually emits during one burst. This is usually measured in milliseconds or microseconds. It matters because how long the tissue is exposed to energy affects how heat builds in the target versus surrounding tissue. In hair removal, choosing an appropriate pulse width helps maximize damage to the hair follicle while minimizing skin damage. Shorter pulse widths deliver energy quickly, creating a sharp heat spike with less time for heat to spread to adjacent tissue. Longer pulse widths allow heat to dissipate more during the pulse, which can reach deeper structures but carries a higher risk to the skin if not matched to the tissue’s relaxation time. Other aspects, like peak power (intensity during the pulse), the wavelength (color of light), and the total treatment time (overall session length), are different characteristics that serve different purposes.