An apparatus for monitoring a position of a semiconductor process fluid interface in a dispense nozzle includes an extended optical source adapted to provide an optical beam propagating along an optical path. There are provided the organic electroluminescent devices exhibiting a long life and a high efficiency of light emission which are capable of emitting a blue light having a high color purity, as well as the aromatic amine derivatives capable of realizing such organic electroluminescent devices. A spool is contained within the valve body and includes a plurality of ports to provide a plurality of respective vacuum paths to a rotating count roll. The method includes the steps of cutting between an outer surface and an inner surface of at least one liner panel, removing at least one panel that is adjacent the area of the liner that was cut, and installing a replacement panel into the combustor for each panel that was removed from the combustor. By imprinting the magnetic domains into the neighboring data storage layer, the bits are copied from one data storage layer to another. The template comprising at least receiving means for receiving the at least one image plate and displaying means for displaying information in order to associate a patient with the at least one image plate.