Explain the difference between short-pulse and long-pulse lasers in hair removal and how pulse duration relates to hair follicle targeting.

Explain the difference between short-pulse and long-pulse lasers in hair removal and how pulse duration relates to hair follicle targeting.

• A. Short-pulse delivers energy quickly to damage the follicle with less diffusion; long-pulse heats more slowly, reducing epidermal damage in darker skin but may be less efficient for follicle destruction.
• B. Short-pulse heats more slowly; long-pulse damages the follicle immediately.
• C. Short-pulse reduces energy density; long-pulse increases diffusion across tissue.
• D. There is no difference.

Answer: (A)

Pulse duration relative to the hair follicle’s thermal relaxation time determines where the heat stays. Short-pulse energy is delivered in a very brief moment, causing rapid heating of the pigmented follicle while leaving little time for heat to spread into surrounding tissue. This concentrates the damage in the follicle, making destruction efficient with minimal diffusion and less impact on the epidermis. Long-pulse energy is released over a longer period, allowing heat to diffuse more into adjacent tissues, including the epidermis. That diffusion lowers peak temperatures in the epidermis, which helps reduce epidermal damage in darker skin, but the heat is less concentrated in the follicle, so follicle destruction per pulse can be less efficient and may require adjustments in fluence or timing. So the best description is that short-pulse delivers energy quickly to damage the follicle with less diffusion; long-pulse heats more slowly, reducing epidermal damage in darker skin but may be less efficient for follicle destruction.

Pulse duration relative to the hair follicle’s thermal relaxation time determines where the heat stays. Short-pulse energy is delivered in a very brief moment, causing rapid heating of the pigmented follicle while leaving little time for heat to spread into surrounding tissue. This concentrates the damage in the follicle, making destruction efficient with minimal diffusion and less impact on the epidermis.

Long-pulse energy is released over a longer period, allowing heat to diffuse more into adjacent tissues, including the epidermis. That diffusion lowers peak temperatures in the epidermis, which helps reduce epidermal damage in darker skin, but the heat is less concentrated in the follicle, so follicle destruction per pulse can be less efficient and may require adjustments in fluence or timing.

So the best description is that short-pulse delivers energy quickly to damage the follicle with less diffusion; long-pulse heats more slowly, reducing epidermal damage in darker skin but may be less efficient for follicle destruction.