Abstract In accordance with the invention a high temperature resistant optical element having transparency in the visible and infrared wave length regions of the electromagnetic spectrum is manufactured by heating to a temperature of from about 800* C to 1,250* C, in a vacuum, a composition containing substantially equal molar amounts of magnesium oxide and aluminum oxide, the composition having a sub-micron particle size and having uniformly mixed therewith from about 0.2 to 4 percent by weight powdered lithium fluoride, and then applying a pressure of at least about 8000 psi to the composition for from about 1/2 to 3 hours after the temperature of the composition has been raised to about from 1300* C to 1600* C.
A method for manufacturing an optical element as set forth in claim 1 and wherein said composition with which the lithium fluoride is mixed consists essentially of magnesia-alumina spinel.
Claim 2
Dependent Claim
78 words
A method for manufacturing an optical element as set forth in claim 2 and wherein said magnesia-alumina spinel is made by freezing an aqueous solution of aluminum salt and magnesium salt, removing the water from said frozen aqueous solution to thereby provide a dry powder consisting of a mixture of said salts, and then heating said dry powder to convert said salts to metal oxides and to cause said metal oxides to react to form the magnesia-alumina spinel.
Claim 3
Dependent Claim
51 words
A method for manufacturing an optical element as set forth in claim 1 wherein the amount of lithium fluoride included in said composition is about 1.5 percent by weight, wherein the pressure applied is from about 8,000 to 15,000 psi and wherein the magnesia-alumina spinel is of sub micron particle size.