X-ray illuminators with high flux and high flux density

Patent metadata

Field	Value
Publication number	US-9449781-B2
Application number	US-201414544191-A
Country	US
Kind code	B2
Filing date	Dec 8, 2014
Priority date	Dec 5, 2013
Publication date	Sep 20, 2016
Grant date	Sep 20, 2016

Abstract

This disclosure presents systems for x-ray illumination that have an x-ray brightness several orders of magnitude greater than existing x-ray technologies. These may therefore useful for applications such as trace element detection or for micro-focus fluorescence analysis. The higher brightness is achieved in part by using designs for x-ray targets that comprise a number of microstructures of one or more selected x-ray generating materials fabricated in close thermal contact with a substrate having high thermal conductivity. This allows for bombardment of the targets with higher electron density or higher energy electrons, which leads to greater x-ray flux. The high brightness/high flux x-ray source may then be coupled to an x-ray optical system, which can collect and focus the high flux x-rays to spots that can be as small as one micron, leading to high flux density.

First claim

We claim:

1. An x-ray illumination system comprising:
an x-ray source; and
at least one x-ray optical subsystem;
said x-ray source comprising:
a vacuum chamber;
a window transparent to x-rays attached to the wall of the vacuum chamber;
and, within the vacuum chamber:
an anode target comprising:
a substrate comprising:
 a first selected material; and
 a planar first surface, from which thickness is measured in a direction perpendicular to the first planar surface, and two orthogonal lateral dimensions are measured parallel to the first planar surface; and
a plurality of discrete structures embedded into the first planar surface of the substrate such that each of the plurality of discrete structures is in thermal contact with the substrate,
the plurality of discrete structures comprising:
 one or more materials selected for its x-ray generation properties;
in which at least two of the plurality of discrete structures are arranged on an axis;
in which the axis is parallel to the first planar surface of the substrate;
in which the axis passes through the first window;
in which each of the plurality of discrete structures has a thickness of less than 20 microns, and
in which each of the plurality of discrete structures has a lateral dimension in the direction of the axis of less than 50 microns; and
at least one electron beam emitter; and
a means of directing electrons emitted by the at least one electron beam emitter onto the at least two arranged discrete structures such that x-rays are generated from each of the at least two arranged discrete structures;
in which at least a portion of the generated x-rays propagating on the axis from each of the two arranged discrete structures is transmitted through the window; and

said at least one x-ray optical subsystem comprising:
an optical axis positioned to correspond to the axis on which the at least two discrete structures are arranged; and
in which the at least one x-ray optical subsystem is further positioned to collect diverging x-rays generated by the at least two arranged discrete structures in the anode target and produce an x-ray beam with predetermined beam properties;

the at least one x-ray optical subsystem additionally comprising
a central beam stop positioned to block x-rays propagating parallel to said optical axis.

2. The x-ray illumination system of claim 1 , in which
the plurality of discrete structures are buried into the first surface of the substrate within a thickness of less than 100 microns.

3. The x-ray illumination system of claim 1 , in which
the plurality of discrete structures are arranged in a linear array.

4. The x-ray illumination system of claim 1 , in which
the plurality of discrete structures are fabricated to have similar shapes.

5. The x-ray illumination system of claim 4 , in which
the similar shapes are selected from the group consisting of:
regular prisms, right rectangular prisms, cubes, triangular prisms, trapezoidal prisms, pyramids, tetrahedra, cylinders, spheres, ovoids, and barrel-shapes.

6. The x-ray illumination system of claim 1 , in which
the first selected material is selected from the group consisting of:
beryllium, diamond, graphite, silicon, boron nitride, silicon carbide, sapphire, and diamond-like carbon.

7. The x-ray illumination system of claim 1 , in which the one or more materials selected for its x-ray generating properties comprises a second material selected from the group consisting of:
aluminum, titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, gallium, zinc, yttrium, zirconium, molybdenum, niobium, ruthenium, rhodium, palladium, silver, tin, iridium, tantalum, tungsten, indium, cesium, barium, gold, platinum, lead, and combinations and alloys thereof.

8. The x-ray illumination system of claim 1 , additionally comprising:
an additional plurality of discrete structures comprising
a third material selected for its x-ray generation properties;

in which each of the additional plurality of discrete structures are embedded into the first planar surface of the substrate such that each of the additional plurality of discrete structures is in thermal contact with the substrate; and
in which each of the additional plurality of discrete structures has a thickness of less than 20 microns, and
in which each of the additional plurality of discrete structures has a lateral dimension in the direction of the axis of less than 50 microns.

9. The x-ray illumination system of claim 8 , in which
the third material is selected from the group consisting of:
aluminum, titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, gallium, zinc, yttrium, zirconium, molybdenum, niobium, ruthenium, rhodium, palladium, silver, tin, iridium, tantalum, tungsten, indium, cesium, barium, gold, platinum, lead, and combinations and alloys thereof.

10. The x-ray illumination system of claim 9 , in which
the third material is selected to generate x-rays with a lower energy than the x-rays generated by the second material;
and in which the at least one x-ray optical subsystem additionally comprises:
one set of optical elements aligned to reflect lower energy x-rays from the third material; and
an additional set of optical elements aligned to reflect x-rays from the second material.

11. The x-ray illumination system of claim 10 ,
in which the additional set of optical elements in the at least one x-ray optical subsystem additionally comprises:
an x-ray filter.

12. The x-ray illumination system of claim 11 ,
in which the x-ray filter has a higher transmission for higher energy x-rays generated by the second material than for the lower energy x-rays generated by the third material.

13. The x-ray illumination system of claim 1 , in which
one edge of the substrate consists of a second surface that forms a predetermined angle with said first surface of the substrate, and
said at least one of the discrete structures is positioned to be within 500 microns of said one edge of the substrate.

14. The x-ray illumination system of claim 1 , in which the plurality of discrete structures of the anode target are aligned such that x-rays generated by a predetermined one of the plurality of discrete structures when exposed to electrons emitted by the at least one electron beam emitter are transmitted through another of the plurality of discrete structures.

15. The x-ray illumination system of claim 14 , in which the plurality of discrete structures of the anode target are aligned such that x-rays generated by a predetermined number of the plurality of discrete structures when exposed to electrons emitted by the at least one electron beam emitter are transmitted through one predetermined discrete structure selected from the plurality of discrete structures.

16. The x-ray illumination system of claim 1 , in which the at least one x-ray optical subsystem has a reflecting surface comprising a material selected from the group consisting of:
boron carbide, silicon dioxide, silicon nitride, quartz, glass, chromium, copper, rhodium, palladium, gold, nickel, iridium, and platinum.

17. The x-ray illumination system of claim 1 , in which
the at least one x-ray optical subsystem
has a reflecting surface comprising multilayers of pairs of materials, said pairs of materials selected from the group of material pairs consisting of:
tungsten/carbon (W/C), tungsten/silicon (W/Si), tungsten/tungsten silicide (W/WSi 2 ), molybdenum/silicon (Mo/Si), nickel/carbon (Ni/C), chromium/scandium (Cr/Sc), lanthanum/boron carbide (

Assignees

• Sigray Inc

Inventors

• Yun Wenbing
• Lewis Sylvia Jia Yun
• Kirz Janos

Classifications

• G01N23/223

  by irradiating the sample with X-rays or gamma-rays and by measuring X-ray fluorescence · CPC title

• H01J2235/081

  Target material · CPC title

• H01J2235/086

  Target geometry · CPC title

• G21K1/06 Primary

  using diffraction, refraction or reflection, e.g. monochromators (G21K1/10, G21K7/00 take precedence) · CPC title

• H01J35/08 Primary

  Anodes; Anti cathodes · CPC title