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AssigneesShin-Etsu Quartz Products Co., Ltd., Haraeus Quarzglas GmbH
InventorsAkira Fujinoki, Akihiko Sugama, Masaatsu Kataoka, Wolfgang Englisch
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A high purity ball-shaped optical article formed of silica glass useful in optical systems employed in photolithography applications. The optical article is characterized by end faces and a side face positioned between the end faces. The side face is externally projected beyond the outline of the end faces and has a spherical configuration. The optical article is uniquely characterized by a smaller number of cords per unit area, viewed in a direction perpendicular to a line connecting the end faces, than the number of cords per unit area viewed in a direction along the line connecting the end faces. The article is also defined by optical homogeneity in a direction perpendicular to the line connecting the end faces.
A high purity ball-shaped optical article comprising a synthetic silica glass characterized by being ball-shaped and having end faces and a side face positioned between said end faces, said side face externally projected beyond the outline of said end faces, said optical article characterized by a smaller number of cords per unit volume, viewed in a direction perpendicular to a line connecting said end faces, relative to the number of cords per unit volume viewed in a direction along said line connecting said end faces;
Dependencies are inferred from the claim text.