Abstract: A method for coating substrates is provided. The method includes diamond turning a substrate to a surface roughness of between about 60 ? and about 100 ? RMS, wherein the substrate is one of a metal and a metal alloy. The method further includes polishing the diamond turned surface of the substrate to a surface roughness of between about 10 ? and about 25 ? to form a polished substrate, heating the polished substrate, and ion bombarding the substrate with an inert gas. The method includes depositing a coating including at least one metallic layer on the ion bombarded surface of the substrate using low pressure magnetron sputtering, and polishing the coating to form a finished surface having a surface roughness of less than about 25 ? RMS using a glycol based colloidal solution.

Abstract: A method for coating substrates is provided. The method includes diamond turning a substrate to a surface roughness of between about 60 ? and about 100 ? RMS, wherein the substrate is one of a metal and a metal alloy. The method further includes polishing the diamond turned surface of the substrate to a surface roughness of between about 10 ? and about 25 ? to form a polished substrate, heating the polished substrate, and ion bombarding the substrate with an inert gas. The method includes depositing a coating including at least one metallic layer on the ion bombarded surface of the substrate using low pressure magnetron sputtering, and polishing the coating to form a finished surface having a surface roughness of less than about 25 ? RMS using a glycol based colloidal solution.

Abstract: A method for coating substrates is provided. The method includes diamond turning a substrate to a surface roughness of between about 60 ? and about 100 ? RMS, wherein the substrate is one of a metal and a metal alloy. The method further includes polishing the diamond turned surface of the substrate to a surface roughness of between about 10 ? and about 25 ? to form a polished substrate, heating the polished substrate, and ion bombarding the substrate with an inert gas. The method includes depositing a coating including at least one metallic layer on the ion bombarded surface of the substrate using low pressure magnetron sputtering, and polishing the coating to form a finished surface having a surface roughness of less than about 25 ? RMS using a glycol based colloidal solution.

Abstract: An optical element based on a graphite substrate is provided. The optical element may be a reflective element and may include a finishing layer, adhesion layer, and/or galvanic compatibility layer. Finishing layers include Ni and Si and provide a surface that can be processed to a low finish to support a reflective layer or reflective stack. Graphite substrates are light weight, are amenable to diamond turning and can be machined to near net shape, have low coefficients of thermal expansion to enable operation over wide temperature ranges, and have high chemical stability.

Abstract: The disclosure is directed to optical elements including a performance-enhancing coating on the surface of a metal or ceramic substrate and to methods for making the optical elements. The optical elements are suitable for use in harsh environments, including salt fog and high humidity environments. The performance-enhancing coating and substrate have similar thermal expansion properties and the performance-enhancing coating has a diamond-turned surface. The performance-enhancing coating may also be polished with a solution of colloidal silica in glycol to an RMS surface roughness less than 30 ?.

Abstract: A method for coating substrates is provided. The method includes diamond turning a substrate to a surface roughness of between about 60 ? and about 100 ? RMS, wherein the substrate is one of a metal and a metal alloy. The method further includes polishing the diamond turned surface of the substrate to a surface roughness of between about 10 ? and about 25 ? to form a polished substrate, heating the polished substrate, and ion bombarding the substrate with an inert gas. The method includes depositing a coating including at least one metallic layer on the ion bombarded surface of the substrate using low pressure magnetron sputtering, and polishing the coating to form a finished surface having a surface roughness of less than about 25 ? RMS using a glycol based colloidal solution.

Abstract: A low density substrate material for reflecting optics. The substrate material is a magnesium alloy or composite material that is capable of being finished by diamond turning to form an optically smooth surface with low root-mean-square roughness. The finish quality of the diamond-turned surface is sufficiently good to permit use of the magnesium material as a substrate for a reflecting optic without further processing. The magnesium substrate material contains at least 80 wt % Mg and may also include Al, Si and/or other elements. The density of the magnesium substrate material is much lower than the density of current Al alloy substrate materials.