Multilayer diffraction grating

An X-ray to VUV reflection multilayer diffraction grating, that comprises:

• a reflection laminar diffraction grating of grating period D, that comprises a multiplicity of parallel and equally spaced flat-topped grating bars that are all attached to a common base, with all the flat tops of the grating bars being coplanar with one another and providing a surface;
• a multiplicity of layered synthetic microstructures of microstructure period d, with each microstructure comprised of a common number of flat and parallel alternating layers of two different materials, with all the layers comprised of the first material being approximately equal in thickness and all the layers comprised of the second material being approximately equal in thickness, and with a single microstructure coveringly disposed over the flat top surface of each of the multiplicity of grating bars so that all the corresponding layers of each of the microstructures are coplanar with one another;
• and
• said reflection laminar diffraction grating and said multiplicity of layered synthetic microstructures cooperatively interacting to provide that when radiation is incident on the reflection multilayer diffraction grating at an angle A with respect to the surface of the grating, the radiation is grating dispersed from the zero order reflective path at an angle B, such that the generalized grating equation for the multilayer diffraction grating is given with a high degree of accuracy by ##EQU11## wherein, m is the grating order of the dispersed radiation,
• n is the order of Bragg reflection, and
• f is one minus the spatially averaged index of refraction of the layered synthetic microstructures;
• wherein the multiplicity of parallel grating bars have a grating period D in the approximate range from 3,000 to 50,000 Angstroms;
• wherein any two adjacent microstructure layers have a combined thickness in the approximate range from 10 to 400 Angstroms;
• wherein the multiplicity of flat-topped grating bars of the reflection laminar diffraction grating are commonly fabricated by being anisotropically etched from a single crystal of silicon;
• wherein all the corresponding layers of each of the microstructures are commonly synthesized in place by physical vapor deposition employing individual magnetron sputter sources for each of the two different materials;
• and
• wherein the two different materials of the alternating layers of the microstructures are material pairs selected from the group consisting of rhodium and carbon, molybdenum and silicon, tungsten and carbon, tungsten and silicon, stainless steel and silicon, palladium and carbon, molybdenum disilicide and silicon, and tungsten carbide and carbon.