A skin treatment device for locally treating skin with light is provided that comprises a tip, a light emission element, a safety mechanism comprising an optical element and an optical element positioning structure. The optical element receives a converging light beam from the light emission element. The optical element is configured to operate as a diverging lens. The optical element positioning structure positions the optical element in a safety position, or in a treatment position when the tip is in contact with the skin to be treated, and allows movement of the optical element between both positions. In the safety position, the optical element is arranged at a position on the optical axis to generate an eye-safe light beam. In the treatment position, the optical element is arranged at another position on the optical axis to generate a treatment light beam.