A non-invasive device for the treatment of the skin (30) using a laser light, the device comprising: - an optical system (10) having a laser light source (20) to generate a light beam (21), which is configured in such a way that, during use, the light beam (21) leaves the device and strikes an outer surface of the skin (30) to be treated； the optical system being configured to focus, during use, the light beam (21) in a position of a treatment location within the skin, whereby laser induced optical decomposition is induced in the position of the treatment location ； - an opening (13) arranged so that, during use, the light reflecting on the skin enters the device as a beam of measuring light (23)； and - a first intensity detection channel (31) and a second intensity detection channel (32) configured and arranged to detect the intensity in, respectively, a first and a second bandwidth range of the measuring light beam (23), wherein: - the first bandwidth interval (94) and the second bandwidth interval (96, 97) both comprise a wavelength of light produced on the skin as a result of induced optical decomposition by laser, - the first bandwidth range comprises the wavelength of the second harmonic generation of the laser light source (20), - the second bandwidth range is adjacent to the first bandwidth range, and - the second bandwidth interval excludes the wavelength of the second harmonic generation of the laser light source (20).Un dispositivo no invasivo para el tratamiento de la piel (30) que usa una luz láser, comprendiendo el dispositivo: - un sistema óptico (10) que tiene una fuente de luz láser (20) para generar un haz de luz (21), que está configurado de tal manera que, durante el uso, el haz de luz (21) sale del dispositivo e incide sobre una superficie exterior de la piel (30) a tratar； estando el sistema óptico configurado para enfocar, durante el uso, el haz de luz (21) en una posición de una localización de tratamiento dentro de la piel, por lo que se ind
