Vehicle rearview mirror assembly containing a fluid light controlling medium

A casing has a transparent window plate sealed therein. A reflector plate is mounted on a diaphram which forms a sealed chamber with the rearwall of the casing. The casing is mounted on a conventional mirror adjustment mechanism. A plurality of conical compression springs urge the reflector plate against the inside surface of the window plate in the day position of the reflector plate. To move the reflector plate from a day position to a night position, a pump draws an optically dense light attenuating fluid from a reservoir and pumps it into an annular chamber and between the window plate and reflector plate, to move the reflector plate rearwards so that the fluid forms a masking layer between the reflector plate and window plate. The masking layer extinguishes reflections from the reflector plate in the night position. A solenoid valve prevents return of the fluid to the reservoir in the night position.