The invention provides a bandgap circuit for providing stable reference voltages. Individual amplifier stages are controlled by a control signal generated by a pulsed current source of a definable pulse length T. A scanning apparatus is attached to the arms which comprise structures that cooperate to cause an optical element to be able to simultaneously rotate about a central axis and move in a linear motion along that axis to achieve any desired scan pattern. The monitor device receives information from the server system to monitor and control the plurality of blade servers. The main body portion may be shaped to form a third seal for engagement with the secondary sealing surface behind the position of the secondary seal.