X-RAY FLUORESCENCE SYSTEM WITH HIGH FLUX AND HIGH FLUX DENSITY

摘要

We present a micro-x-ray fluorescence (XRF) system having a high-brightness x-ray illumination system with high x-ray flux and high flux density. The higher brightness is achieved in part by using x-ray target designs that comprise a number of microstructures of 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 at the fluorescent sample. Such systems may be useful for a variety of applications, including mineralogy, trace element detection, structure and composition analysis, metrology, as well as forensic science and diagnostic systems.

主权项

1. An x-ray fluorescence system comprising:
an x-ray illumination system comprising
an x-ray source and an x-ray optical train; a mount to hold an object to be examined; a means for moving the mount; and an x-ray detector; in which the x-ray source additionally comprises: a vacuum chamber; a window transparent to x-rays attached to the wall of the vacuum chamber; and, within the vacuum chamber: at least one electron beam emitter, and an anode target comprising:
a substrate comprising a first selected material, anda planar first surface, from which thickness is measured
in a direction perpendicular to the first planar surface, andtwo orthogonal lateral dimensions are measuredparallel to the first planar surface; anda 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 discrete structures
has a thickness of less than 20 microns, andin which each of the plurality of discrete structures
has a lateral dimension in the direction of the axis of less than 50 microns; 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 system further comprising: an optical train having an optical axis positioned to correspond to the axis
on which the at least two discrete structures are arranged; in which the optical train is further positioned to collect x-rays generated by the anode target
and produce an x-ray beam with predetermined beam properties; and in which the x-ray optical train comprises reflective elements
positioned to reflect x-rays generated by the x-ray sourceand focus a portion of the reflected x-rays to a predetermined location; and in which the means of moving the mount comprises translation and rotation controls
so that the position of an object to be examined can adjustedto coincide with the predetermined location where the portion of the x-rays are focused; and in which the detector is positioned to collect fluorescence emitted by the object
when illuminated by the focused x-raysand generate corresponding electronic signals.