To minimize direct reflection, the incident path should be kept _____________ to the skin's surface.

Keeping the incident path perpendicular to the skin's surface is essential in laser hair removal because it maximizes the efficiency of the laser energy absorption by the hair follicles. When the laser hits the skin at a perpendicular angle, it minimizes the chances of reflection off the skin’s surface, allowing for more energy to penetrate deeply into the dermis where the hair follicles reside. This is crucial for effective treatment, as the goal is to target and damage the hair follicles without causing harm to the surrounding skin.

In contrast, angles that are not perpendicular can result in increased reflection, leading to reduced energy transmission, ineffective treatment, and a risk of skin damage. Proper angling ensures optimal performance of the laser device and enhances the overall efficacy of the hair removal procedure.