The present invention refers to a skin or hair treatment device for emitting intense light radiation with an integrated sensor. The device comprises: a housing (1)； a treatment light source (2) disposed inside the housing of the treatment device for illuminating a surface, in particular a skin surface, through a device treatment window (6) disposed outside the housing in front of the device treatment window, wherein the treatment light source comprises an array of a plurality of light emitting elements arranged on a substrate (4)； a sensor system (3) disposed inside the housing (1) of the treatment device, said sensor system comprising at least one sensing light source (3b) for emitting sensing light and at least one light sensor (3a) for detecting the sensing light, wherein the at least one sensing light source (3b) and the at least one light sensor (3a) are directed towards the device treatment window (6)； and a control circuit having a processor, the control circuit being adapted to control the treatment light source (2), the at least one sensing light source (3b) and the at least one light sensor (3a). The device further comprises: a circular polarizer (7) interposed between the device treatment window (6) and the at least one sensing light source (3b) and the at least one light sensor (3a)； and a shielding (5c, 8, 10) interposed between the at least one sensing light source (3b) and the at least one light sensor (3a) such that sensing light is prevented from directly entering the at least one light sensor (3a) without passing the circular polarizer. In addition, the invention refers to a method for manufacturing such a device.
