A method for removing post-processing residues in a single wafer cleaning system is provided. Further, a fixing device and an image forming apparatus in which such a toner can be suitably used are provided. The method generates the search query to use to find documents by reference to the text of the document in the Web site being accessed by the user. The traffic, traffic monitoring data and application runtime data may contain information regarding the scope and frequency of the functionality tested by the actual traffic received by the network system. The method is general and can be applied to any standard, such as the IEEE floating-point standard, in any precision. The method for manufacturing an optical element, described above, has the steps of polishing a CaF2 substrate and performing plasma treatment, such as sputtering or plasma cleaning, in a chamber in which the polished CaF2 substrate is placed.