Product for molding glass lenses having difficult shapes
AssigneeEastman Kodak Company
InventorsDavid A. Richards, John C. Pulver
Life of this patent
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Abstract
An improved tool is provided for pressing glass into a precision optical element having a strong concave surface. The tool is selected from ceramic and metal materials having coefficients of thermal expansion greater than the coefficient of the pressed glass. Preferred tools include a base material selected from Invar, steel and alumina with a surface layer selected from alumina, zirconia, chromium oxide and chromium carbide, having a finished thickness in the range between ten to two thousand angstroms.
Claims9
A tool for pressing a surface of a glass preform, the glass having a predetermined coefficient of thermal expansion, into a strong concave surface of a precision optical element;
- characterized in that:
- said tool (i) has at least one convex surface and is made of a base tool material having a coefficient of thermal expansion greater than the coefficient of thermal expansion of said glass;
- and
- (ii) has a coating surface layer with a thickness in the range of about ten angstroms to about two thousand angstroms, and a surface quality of a precision optical element, said coating being free from glass adhesion at temperatures of 500.degree. C. and greater.
Dependencies are inferred from the claim text.