Method for preparing silica glass article

摘要

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. The molten zone of the rod-shaped synthetic silica glass is thereupon deformed by the application of pressure along the axis connecting the support portions whereupon a high purity ball-shaped optical article, having end faces and a side face positioned between the end faces, is formed. The optical article is characterized by a lesser number of 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 rod-shaped synthetic silica glass is furthermore optically homogeneous in a direction perpendicular to the line connecting the end faces. The method is concluded by cutting the ball-shaped optical article at the edge support portions.