The present invention relates to a device for the reading and/or writing of optical recording media (AT) of various structures, which device operates with a single objective lens OL. The invention proposes to use a diaphragm varying in diameter, in particular a polarising filter arranged in the optical path in order to adapt the aperture to each type of optical recording medium (AT) used. The wavefront can be corrected using a divergent lens (SL) which can also be positioned in the beam path. The diaphragm formed by the polarising filter PF is linked to the objective lens (OL). The field of application of the invention relates to, in particular, devices for reading and/or writing optical recording media (AT) of various structure such as compact discs and digital video discs.