An object of the present invention is to provide an improved and simplified filter assembly. The method can include introducing a first etchant into a chamber that encloses an optical component and a source of electromagnetic radiation that is suitable for lithography, ionizing the first etchant, and removing debris from a surface of the optical component. In other words, the correction part controls the quantity of the object supplied to a dispersion feeder on the basis of measured data indicating an actually measured value. The assembly can be part of the door or separately attached to the door. The coated metal plate is heat treated to transform the coating layer into a protective film formed on the surface of the metal plate. Authorization is then attempted using the preferred authorization process.