Patent ID: 7384581

Claim:
A method of forming an optical element, the method comprising the steps of: (a) providing an ingot of at least one silver halide selected from the group consisting of silver chloride, silver bromide, silver iodide, silver chloro-bromide, silver bromo-iodide, silver chloro-iodide, and silver chlorobromo-iodide and including at most about one part per million of metallic impurities, by steps including: (i) mixing silver nitrate with at least one acid selected from the group consisting of hydrochloric acid, hydrobromic acid and hydroiodic acid, to precipitate said at least one silver halide as at least one powder; (ii) melting said at least one powder to provide a melt, and (iii) cooling said melt to form said ingot; and (e) pressing said ingot between an upper die and a lower die while said ingot is confined laterally by a split die.