rain sensor mount for use in a vehicle u201d to niall r lynam now u s pat no 6 250 148 the disclosures of which are incorporated herein by reference as shown in the various figures of the ser no 09 003 966 application it is desirable that the rain sensor mounting member attached to the windshield and the rearview mirror mounting button provided on the rain sensor module are generally aligned along a common axis when the rain sensor module is mounted to the vehicle in order to provide a mounting of a rearview mirror assembly to the rain sensor module that is generally coaxial with the mounting of the rain sensor module to the windshield optionally a ceramic black frit layer as is commonly known in the windshield fabrication art can be used on the inner surface of the windshield to hide the attachment location of the rain sensor module however the center portion of such a ceramic layer should include a central opening or at least provide efficient transmission for the output of the light emitters and the rain sensor unit at the point of contact of its detecting surface to the windshield or to an adhesive layer the rain sensor module assembly includes the rain sensor unit which is positioned in the housing and projects through an opening or port provided on a windshield facing side of the housing and extends through an inner hollow open central portion of the rain sensor mounting button to contact the inner surface of the windshield the rain sensor unit preferably comprises a compact rain sensor unit available from itt automotive europe gmbh of frankfurt germany the rain sensor unit includes a detecting surface which projects through an opening provided in adhesive layer so that direct contact is achieved between.