Patent Number: 051739305
Section: summary

BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to monochromators. 2. Prior Art Monochromators which can produce a monochromatic beam with narrow spectral wavebands are known. Such beams are very useful in the testing and calibrating of x-ray telescopes and microscopes, in research in biological and biomedical disciplines, in research in properties of materials and processing etc. Previous monochromators have used metal foil filters, gratings, or crystals. Metal foil monochromators have the advantage of a high throughput but do not have the narrow bandwidth needed for some applications. Much higher spectral resolution is possible with the use of crystal or grating monochromators but these have other disadvantages. Natural crystal monochromators are suitable for hard x-ray use and even some of the shorter wavelengths in the soft x-ray wavelengths but the crystal lattice structure in naturally occurring crystals is too small to permit observations in the longer wavelength soft x-ray/EUV regimes. Grating monochromators are capable of covering the soft x-ray/EUV portions of the electromagnetic spectrum, which is the concern of the present invention, but they have a very low throughput. In addition, grating monochromators are difficult to fabricate, align and maintain in optical alignment. Also, grating monochromators are typically large and expensive. SUMMARY OF THE INVENTION An x-ray monochromator wherein a plurality of parallel pairs of facing mirrors are mounted in a housing having therein an inlet window and an outlet window for each pair of mirrors. Each pair of facing mirrors is coated with identical multilayer coatings which reflect x-rays at a wavelength which is dependent on the angle of incidence of the x-rays on the mirror and the nature of the multilayer coating, with different pairs of facing mirrors having different multilayer coatings such that each pair of facing mirrors has a peak reflection of x-rays at a different wavelength. The mirrors are pivotally mounted in a row in the housing and are interconnected so that all of the mirrors pivot at the same time and amount so that the mirror surfaces always remain parallel to each other. The housing is moveable so that any pair of mirrors can be moved into position to intercept a x-ray beam traveling along a fixed path through the inlet window associated with that pair of mirrors to thereby provide a monochromatic x-ray beam of a desired wavelength.