Abstract: The invention is directed to single crystal alkaline earth metal fluoride optical elements having an adhesive, hermetic coating thereon, the coating being chemically bonded to the surface of the metal fluoride optical element with a bonding energy ?4 eV and not merely bonded by van der Walls forces. The materials that can be used for coating the optical elements are selected from the group consisting of SiO2, F—SiO2, Al2O3, F—Al2O3, SiON, HfO2, Si3N4, TiO2 and ZrO2, and mixtures (of any composition) of the foregoing, for example, SiO2; HfO2 and F—SiO2/ZrO2. The preferred alkali earth metal fluoride used for the optical elements is CaF2. Preferred coatings are SiO2, F—SiO2, SiO2/ZrO2 and F—SiO2/ZrO2.

Abstract: The invention is directed to optical elements that are coated with dense homogeneous fluoride films and to a method of making such coated elements. The coatings materials are a high (“H”) refractive index fluoride material and a low (“L”) refractive index material that are co-evaporated to form a coating layer of a L-H coating material (a co-deposited coating of L and H materials). Lanthanide metal fluorides (for example, neodymium, lanthanum, dysprosium, yttrium and gadolinium, and combinations thereof) are preferred metal fluorides for use as the high refractive index materials with lanthanum fluoride (LaF3) and gadolinium fluoride (GdF3) being particularly preferred. Aluminum fluoride (AlF3) and alkaline earth metal fluorides (fluorides of calcium, magnesium, barium and strontium) are the preferred low refractive index materials, with magnesium fluoride (MgF2) being a preferred alkaline earth metal fluoride.

Abstract: The invention is directed to single crystal alkaline earth metal fluoride optical elements having an adhesive, hermetic coating thereon, the coating being chemically bonded to the surface of the metal fluoride optical element with a bonding energy ?4 eV and not merely bonded by van de Walls forces. The materials that can be used for coating the optical elements are selected from the group consisting of SiO2, F—SiO2, Al2O3, F—Al2O3, SiON, HfO2, Si3N4, TiO2 and ZrO2, and mixtures (of any composition) of the forgoing, for example, SiO2;HfO2 and F—SiO2/ZrO2. The preferred alkali earth metal fluoride used for the optical elements is CaF2. Preferred coatings are SiO2, F—SiO2, SiO2/ZrO2 and F—SiO2/ZrO2.

Abstract: The invention is directed to optical elements that are coated with dense homogeneous fluoride films and to a method of making such coated elements. The coatings materials are a high (“H”) refractive index fluoride material and a low (“L”) refractive index material that are co-evaporated to form a coating layer of a L-H coating material (a co-deposited coating of L and H materials). Lanthanide metal fluorides (for example, neodymium, lanthanum, dysprosium, yttrium and gadolinium, and combinations thereof) are preferred metal fluorides for use as the high refractive index materials with lanthanum fluoride (LaF3) and gadolinium fluoride (GdF3) being particularly preferred. Aluminum fluoride (AlF3) and alkaline earth metal fluorides (fluorides of calcium, magnesium, barium and strontium) are the preferred low refractive index materials, with magnesium fluoride (MgF2) being a preferred alkaline earth metal fluoride.