Abstract: A method of preparing a high purity massive synthetic silica glass article. The method includes a homogenizing step, wherein a rod shaped synthetic silica glass material has a greater optical homogeneity in a plane perpendicular to its rotational axis than a plane parallel thereto, a step of forming the homogeneous synthetic silica glass and a step of cutting the formed synthetic silica glass.

Abstract: A method of preparing a ball-shaped synthetic silica glass optical article. The method includes a step of providing a rod-shaped synthetic silica glass having end faces at both sides thereof and having fewer cords per unit volume viewed in a direction perpendicular to a line connecting the end faces relative to the number of cords per unit volume viewed in a direction along the line connecting the end faces. The synthetic silica glass being optically homogeneous in the direction perpendicular to the line connecting the end faces. The method includes the further step of establishing support portions at the end faces of the synthetic silica glass. The rod-shaped synthetic silica glass is thereupon heated while being rotated around an axis connecting the support portions wherein a molten zone is formed.

Abstract: 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.