A search option input by a user is obtained through a user interface and a search term is determined based on the search option. The method detects an index of refraction of the immersion medium in a volume of the immersion medium through which an exposure pattern is configured to traverse and determines if the index of refraction is acceptable for exposing the wafer with the exposure pattern. In one embodiment, the invention may detect at least one document within the cluster; analyze a parameter corresponding to the document; and compute a cluster score based, in part, on the parameter, wherein the cluster score corresponds with at least one document within the cluster. A first one of the vertically extending channels receives air entering the housing from the air inlet. A plurality of engaging members provided on an outer peripheral surface of the lens barrel are positioned between the annular sheets disposed in the inner peripheral groove.