Diffractoid grating configuration for X-ray and ultraviolet focusing
First Claim
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1. A diffractord grating means for obtaining stigmatic imaging of a soft X-ray and extreme ultraviolet emitting object at a focal point, comprising;
- a support block;
a concave surface formed on a portion of said support block, said concave surface having a non-constant radius of curvature over the entirety thereof, and said non-constant radius of curvature surface having a surface of revolution about a coordinate axis defined by a diffractoidal curve specified in terms of cartesian coordinates x and z having a characteristic such that for a selected grating parameter (A) defined in terms of diffraction order (m), wavelength (λ
) and ruling interval (σ
), all emitted radiation of a specified wavelength from a point source directed substantially parallel to said axis will be deflected to a sharp point at said focal point and conversely, all emitted radiation of said specified wavelength directed from said sharp point at said focal point located at the origin of said cartesian coordinates will be deflected substantially parallel to said axis; and
diffraction rulings formed on said non-constant radius of curvature surface having a ruling interval (σ
);
wherein said diffractoidal curve is defined by a solution of a non-linear differential equation expressed in the form
space="preserve" listing-type="equation">mλ
/σ
=[1+(dx/dz).sup.2 ].sup.-1/2 [ cos θ
.sub.r +sin θ
.sub.r (dx/dz)-1] where dx/dz is the derivative of x with respect to z, θ
r is the angle a ray (r) from the origin to a point on said curve makes with the z coordinate axis.
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Abstract
There is disclosed herein an aspheric grating which is operable to image local or distant point sources sharply in a designated wavelength, i.e. produce a perfectly stigmatic image in the given wavelength at grazing angles of incidence. The grating surface comprises a surface of revolution defined by a curve which does not have a constant radius of curvature but is defined by a non-linear differential equation specified in terms of the diffraction condition expressed as (mλ/σ)2 =A>O where m is the diffraction order, λ is the wavelength and σ is the grating surface ruling interval.
67 Citations
13 Claims
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1. A diffractord grating means for obtaining stigmatic imaging of a soft X-ray and extreme ultraviolet emitting object at a focal point, comprising;
-
a support block; a concave surface formed on a portion of said support block, said concave surface having a non-constant radius of curvature over the entirety thereof, and said non-constant radius of curvature surface having a surface of revolution about a coordinate axis defined by a diffractoidal curve specified in terms of cartesian coordinates x and z having a characteristic such that for a selected grating parameter (A) defined in terms of diffraction order (m), wavelength (λ
) and ruling interval (σ
), all emitted radiation of a specified wavelength from a point source directed substantially parallel to said axis will be deflected to a sharp point at said focal point and conversely, all emitted radiation of said specified wavelength directed from said sharp point at said focal point located at the origin of said cartesian coordinates will be deflected substantially parallel to said axis; anddiffraction rulings formed on said non-constant radius of curvature surface having a ruling interval (σ
);wherein said diffractoidal curve is defined by a solution of a non-linear differential equation expressed in the form
space="preserve" listing-type="equation">mλ
/σ
=[1+(dx/dz).sup.2 ].sup.-1/2 [ cos θ
.sub.r +sin θ
.sub.r (dx/dz)-1]where dx/dz is the derivative of x with respect to z, θ
r is the angle a ray (r) from the origin to a point on said curve makes with the z coordinate axis. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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Specification