A device to facilitate the mounting of an optical sensor on a windshield glass using a clear adhesive tape is disclosed. The device holds the sensor, with tape exposed, in a vacuum chamber which is sealed against the glass. The chamber is evacuated, and the sensor is then pressed against the glass by the longitudinal movement of a drive shaft. The sensor may be installed with consistent force and with no trapped air pockets or air bubbles. Air pockets are a special concern because air pockets adversely effect the optical performance of the sensor. The vacuum chamber device may be controlled by a computer, and features a latching mechanism which prevents the sensor from making contact with the glass until the chamber is evacuated.