The present invention provides a non-invasive device, which is an optical system having a laser light source that generates a light beam, the optical system leaving the device in use when in use, Configured to impinge on the outer surface of the skin to be treated, and the optical system is configured to focus the light beam at a location of a treatment location in the skin during use, thereby An optical system in which a laser-induced optical breakdown is induced at the location of the treatment location, and an aperture arranged so that, in use, the light returning from the skin, when used, enters the device as a measuring light beam, respectively First and second intensity detection channels configured and arranged to detect intensities in the first and second bandwidth ranges of the measurement light beam. And both the first and second bandwidth ranges include wavelengths of light generated in the skin as a result of laser induced optical breakdown, and the first bandwidth range is Including a second harmonic generation wavelength, wherein the second bandwidth range is adjacent to the first bandwidth range, and the second bandwidth range is a second harmonic generation wavelength of the laser light source. And first and second intensity detection channels not included. The present invention also provides a corresponding method for treating the skin, particularly for reducing wrinkles. For the effectiveness of such a procedure, two main parameters are important: intensity at the location of the treatment location and depth of focus, and it is also important that these parameters can be measured using the same measurement system.本発明は、非侵襲的な装置を提供し、当該装置は、光ビームを生成するレーザ光源を有する光学システムであり、該光学システムは、使用時に、前記光ビームが、当該装置を出て、処置されるべき皮膚の外表面に突き当たるように構成されており、該光学システムは、使用時に前記皮膚内の処置ロケーションの位置に前記光ビームを集束させるように構成されており、それにより、前記処置ロケーションの位置にレーザ誘起オプティカルブレイクダウンが誘起される、光学システムと、使用時に、前記皮膚から戻って来る光が、測定光ビームとして、当該装置に入るように配設された開口と、それぞれ、前記測定光ビームの第１及び第２の帯域幅レンジにおける強度を検出するように構成及び配置された、第１及び第２の強度検出チャネルであり、前記第１及
