Which unit expresses the duration of a light pulse?

Which unit expresses the duration of a light pulse?

• A. Milliseconds (ms)
• B. Seconds
• C. Nanoseconds
• D. Minutes

Answer: (A)

Light pulse duration is the length of time a single laser pulse lasts. In cosmetic hair removal, pulses are created as brief bursts long enough to deposit energy into the hair follicle but short enough to spare surrounding skin. That balance is typically achieved with durations on the order of milliseconds, making milliseconds the appropriate unit to express the pulse length. Seconds or minutes would describe far longer exposures and aren’t how a single pulse is characterized, while nanoseconds describe ultrafast pulses used in other applications—not the common range for hair-removal devices.

Light pulse duration is the length of time a single laser pulse lasts. In cosmetic hair removal, pulses are created as brief bursts long enough to deposit energy into the hair follicle but short enough to spare surrounding skin. That balance is typically achieved with durations on the order of milliseconds, making milliseconds the appropriate unit to express the pulse length. Seconds or minutes would describe far longer exposures and aren’t how a single pulse is characterized, while nanoseconds describe ultrafast pulses used in other applications—not the common range for hair-removal devices.