Jan 26, 1998
Kodak have patented a new method of creating optical components.
Despite the popularity of cheap plastic lenses, glass lenses are still essential for many applications. To make a glass lens, a gob of molten glass is dropped onto a catching tool, which compresses it into the desired shape. This glass blank is then polished to the correct magnification.
However, the compression method used to manufacture glass lenses can cause imperfections in the material. Kodak with Patent 5709723 have developed a method to get rid of two of the more common problems - chill winkle and shear marks. Chill winkle happens when the gob of hot glass meets the cold surface of the catching tool: as the glass cools down, a wave-like pattern (the winkle) develops on the surface. Shear marks are caused by the teardrop shape of the gob as it falls under gravity. This shape causes marks to be absorbed into the blank as the gob cools rapidly.
In Kodak's process, a gob of molten glass is ejected onto a heated catching tool which stays warm until the gob achieves the correct shape. As the glass retains its elasticity and heat, the gob can settle into the correct shape without blemishes appearing on the surface.