A biometric capture device having an optical block integrating an acquisition surface, an optical acquisition system arranged so that a first light ray propagating, outside the optical block, along an optical axis of the said optical acquisition system forms at the level of the acquisition surface, an angle with respect to a normal to the acquisition surface of a value greater than a critical angle depending on the refractive indices of the optical block and of the air, the optical system also being arranged so that the optical axis forms an angle with respect to a normal to the exit face less than said critical angle, an illumination system configured to provide illumination of the acquisition surface, the illumination system generating a light beam defined by an illumination axis, a second light ray propagating along the illumination axis out of the optical block.