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US 5,344,476 AGranted
Method for forming an optical element
AssigneeCanon Kabushiki Kaisha
InventorMasayuki Tomida
Life of this patent
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Abstract
An improved method of forming an optical element, wherein heated upper and lower molds are used in conjunction with radiation heating glass material placed in an optical forming surface of the lower mold. The molds are heated to a necessary temperature, then the glass material is heated by exposure to heat by radiation. The glass blank then is pressed between the upper and lower molds to transfer the optical forming surfaces of each mold to the glass material, and define the optically functional surfaces of an optical element.
Claims2
A method of forming an aspherical lens, said method comprising the steps of:
- providing upper and lower molds, where at least one of said molds has an optical forming surface that is aspherical;
- heating said upper and lower molds to a predetermined temperature;
- providing a glass blank, which is at a temperature lower than its forming temperature, on said lower mold with a conveying means;
- heating the glass blank to its forming temperature by exposing the glass blank to infrared radiation;
- and
- closing said upper and lower molds and pressing the glass blank to form an aspherical lens and gradually reducing the amount of infrared radiation to which the glass blank is exposed in accordance with the start of contact between said upper mold and the glass blank while maintaining the upper and lower molds at the predetermined temperature.
3 more elements
Dependencies are inferred from the claim text.