Abstract: A system for eliminating distortion of optical ports during supersonic flight includes an electrohydraulic pump which is controlled by a potentiometer actuated by expansion and contraction of a gas that acts on a piston which is mounted in a cylinder. The cylinder is mounted in thermal contact with a frame which supports one or more layers of optical glass. The electrohydraulic pump operates to pump cooling fluid into the frame thereby cooling the frame and the optical glass when the gas expands as a result of heating during supersonic flight.