Aplanatic and quasi-aplanatic diffraction gratings
AssigneeThe United States of America as represented by the United States Department of Energy
InventorMichael C. Hettrick
Life of this patent
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Abstract
A reflection diffraction grating having a series of transverse minute grooves of progressively varying spacing along a concave surface enables use of such gratings for X-ray or longer wavelength imaging of objects. The variable groove spacing establishes aplanatism or substantially uniform magnification across the optical aperture. The grating may be used, for example, in X-ray microscopes or telescopes of the imaging type and in X-ray microprobes. Increased spatial resolution and field of view may be realized in X-ray imaging.
Claims10
A grazing incidence diffraction grating for focusing intercepted x-rays from a first region into an image at a substantially normal incidence focal surface located at another region, said grating having a concave surface formed of reflective material and having a plurality of transverse grooves in said concave surface which define a series of diffraction zones along said concave surface, wherein the spacing of corresponding points in successive ones of said grooves progressively varies along at least a portion of said concave surface and wherein the change of spacing at successive grooves establishes substantially similar magnification along all ray paths from said grating to said focal surface.
In an optical system for producing a two dimensional image of an object at a spaced apart focal surface, the combination comprising first and second reflection diffraction gratings disposed between said object and focal surface, said first diffraction grating having a first concave surface formed of reflective material which is positioned to intercept rays from said object at grazing incidence and to direct convergent diffracted rays towards said second diffraction grating, said second diffraction grating having a second concave surface formed of reflective material and which is positioned to receive said diffracted rays from said first diffraction grating at grazing incidence and to direct convergent re-diffracted rays to said focal surface at normal incidence, said first and second concave surfaces being oriented in orthogonal relationship, and wherein each of said concave surfaces has a plurality of grooves formed therein which grooves are transverse to the path of intecepted rays and which form a series of diffraction zones on said gratings, said grooves at each of said concave surfaces having a progressively varying spacing therealong which establishes a substantially uniform magnification across the optical aperture of said system.
Dependencies are inferred from the claim text.