The invention provides an image shifting device including at least one image shifting part for periodically shifting the position of an optical axis. The lamp preferably includes two heating elements, a first element for initial heating, such as a heat blanket, resistive glass coating, or a submerged ring, and a second heating element generally providing both heat and lighting. Each mass support section has an opening extending from the front side to the back side, and a plurality of heat activated expandable masses supported on both the front side and the back side of the carrier member. While the ball angulates freely in the socket, the rotation of the ball in the socket has a limited range due to interference between an interference pin’s rounded head that extends into the socket and a curvate recess on the ball. As an example, the application may be a software test suite.