Patent Number: 
Section: abstract

A monochromator is adapted to select at least one band of wavelengths from diverging incident radiation. The apparatus includes a first crystal and a second crystal. A band of emitted wavelengths of the first crystal is adapted to the at least one band of wavelengths. A surface curvature of the first crystal is adapted to focus emitted radiation in a first plane. A band of emitted wavelengths of the second crystal also is adapted to the at least one band of wavelengths. Parallel faces of a lattice structure of the second crystal are oriented at a first predetermined angle from a surface of the second crystal. In another embodiment, an apparatus is adapted to select at least one band of wavelengths from diverging incident synchrotron radiation in a given range of wavelengths with an energy resolution finer than about five parts in 10000 and optical efficiency greater than about 50 percent.