Layered infrared transmitting optical elements and method for making same

A method for bonding infrared transmitting glasses into an optical element without interlayer voids, comprising:

• stacking at least two different infrared transmitting glasses inside a vessel to form a stack of glasses, wherein each glass has a different refractive index, a different dispersion, or both, wherein the at least two different infrared transmitting glasses all have similar viscosities, thermal expansion coefficients, and glass transition temperatures, wherein the stack of glasses is placed between two non-reactive plates, and wherein one or both non-reactive plates have a flat center portion and a raised perimeter or wherein one or both non-reactive plates are in the shape of a ring;
• placing a weight on top of the stack of glasses;
• applying a vacuum to the vessel;
• applying an isostatic pressure of at least 1500 psi;
• and
• after releasing the isostatic pressure, annealing at a temperature within 10° C. of the glass transition temperature at a pressure between 0 and 1000 psi, wherein applying the vacuum, applying the isostatic pressure, and annealing are done sequentially and with no intermediate transitions to ambient temperature or pressure.