Monochromatic focusing polarized X-ray optical system and use method and fluorescence spectrometer

Abstract

The present invention provides a monochromatic focusing polarized X-ray optical system and a method of using the system and a fluorescence spectrometer, including an X-ray tube for emitting X-rays; a bent crystal is used to diffract, focus and polarize the X-rays emitted by the X-ray tube, and re-emit the X-rays onto a sample to excite X-ray fluorescence; the X-ray tube, the bent crystal and the sample form an optical plane and are placed on the circumference of the Rowland circle. The present invention forms an optical plane with the X-ray tube, the bent crystal and the sample and places it on the circumference of the Rowland circle, thereby realizing the polarization-monochromatic-focusing function achieved by using bent crystals in the XRF optical path design; the detector detects from a direction perpendicular to the optical plane and blocks the polarized X-rays propagating along the detector direction, thereby reducing background interference; thus, an independent monochromatic-focusing-polarized X-ray optical system and a fluorescence spectrometer thereof are formed with unique X-ray properties and can significantly improve the signal-to-noise ratio and detection sensitivity.

Description

Technical Field

[0001] The invention relates to the technical field of optical equipment, and in particular to a monochromatic focusing polarized X-ray optical system and a use method thereof, and a fluorescence spectrometer. Background Art

[0002] X-ray fluorescence spectroscopy has a wide range of applications in various fields. It irradiates samples with X-rays, and then uses detectors to detect the fluorescence signal of the sample after excitation to complete the X-ray fluorescence analysis test of the sample. However, after the X-ray tube is powered on, it emits X-rays in the form of a point source. At this time, the X-rays emitted from the X-ray tube are X-ray continuous spectra, which produce large background interference and are not conducive to X-ray fluorescence analysis tests. Summary of the invention

[0003] The purpose of the present invention is to provide a monochromatic focusing polarized X-ray optical system and a method of using it, and a fluorescence spectrometer, which can reduce the continuous spectrum background of the X-ray excitation source, improve the peak-to-background ratio of the analyzed elements, increase the detection sensitivity of the X-ray fluorescence spectrum analysis, and effectively reduce the element detection limit.

[0004] According to one object of the present invention, the present invention provides a monochromatic focusing polarization X-ray optical system, comprising:

[0005] X-ray tube, used for emitting X-rays;

[0006] The bent crystal is used to diffract, focus and polarize the X-rays emitted by the X-ray tube.

[0007] and re-emit the X-rays onto the sample, stimulating X-ray fluorescence;

[0008] The X-ray tube, the bent crystal and the sample form an optical plane and are placed on the circumference of the Rowland circle;

[0009] The detector is arranged at 90 degrees with the sample and is used to receive and collect the X-ray fluorescence signal emitted by the sample.

[0010] Furthermore, the diffraction of X-rays obeys Bragg's law.

[0011] Furthermore, through the bent crystal diffraction, X-rays of required wavelengths are screened out from X-rays of continuous wavelengths.

[0012] Furthermore, the surface of the curved crystal is a concave mirror, and on the sagittal plane perpendicular to the Rowland circle plane, the spherical crystal performs two-dimensional focusing of the light according to the concave mirror imaging principle.

[0013] Furthermore, after the X-rays are scattered by the bent crystal at 90°, highly polarized X-rays are generated.

[0014] Furthermore, the curved crystal is a spherical curved crystal, a cylindrical curved crystal, or a toroidal curved crystal.

[0015] According to another object of the present invention, the present invention provides a method for using a monochromatic focusing polarization X-ray optical system, comprising the following steps:

[0016] S1, after the X-ray tube is powered on, it emits X-rays in the form of a point source;

[0017] S2, X-rays are diffracted by the bent crystal and re-emitted;

[0018] S3, after S1 and S2, the X-rays irradiated onto the sample are monochromatic, focused and polarized. The X-ray fluorescence produced by the elements in the sample is anisotropic, and the incident plane polarized light cannot propagate along its plane. Therefore, when the detector is 90° to the sample and intersects with the polarizer and X-ray tube planes, the background from the X-ray tube is reduced.

[0019] Furthermore, in S1, the X-rays emitted by the X-ray tube are continuous spectrum, divergent and unpolarized X-rays.

[0020] Furthermore, in S2, X-rays change from white light to monochromatic light, from divergent light to focused light, and from unpolarized light to polarized light.

[0021] According to the third object of the present invention, the present invention provides a fluorescence spectrometer, which includes the above-mentioned X-ray optical system.

[0022] The technical solution of the present invention forms an optical plane with an X-ray tube, a bent crystal and a sample, and places the plane on the circumference of a Rowland circle, thereby realizing the polarization-monochromatic-focusing function of using a bent crystal in the XRF optical path design; the detector detects from a direction perpendicular to the optical plane and blocks the polarized X-rays propagating along the detector direction, thereby reducing background interference; thus, an independent monochromatic-focusing-polarization X-ray optical system and a fluorescence spectrometer thereof having unique X-ray properties and significantly improving the signal-to-noise ratio and detection sensitivity are formed by the design. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0024] Figure 1 It is a structural schematic diagram of an embodiment of the present invention;

[0025] In the figure, 1, X-ray tube; 2, bent crystal; 3, sample; 4, detector. DETAILED DESCRIPTION

[0026] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0027] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0028] In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, "multiple" means two or more, unless otherwise clearly and specifically defined. In addition, the terms "installed", "connected" and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal connection of two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0029] Example 1

[0030] like Figure 1 As shown,

[0031] A monochromatic focusing polarized X-ray optical system comprises an X-ray tube 1 for emitting X-rays; a bent crystal 2 for diffracting, focusing and polarizing the X-rays emitted by the X-ray tube, wherein the X-ray tube 1, the bent crystal 2 and a sample 3 form an optical plane and are placed on the circumference of a Rowland circle; the bent crystal 2 can re-emit the X-rays onto the sample 3 to stimulate X-ray fluorescence;

[0032] The detector 4 is arranged at 90 degrees to the sample 3 and is used to receive and collect the X-ray fluorescence signal emitted by the sample 3 .

[0033] The diffraction of X-rays follows the Bragg law. Through the diffraction of the curved crystal 2, the X-rays of the required wavelength are screened out from the X-rays of continuous wavelength. The surface of the curved crystal 2 is a concave mirror. On the sagittal plane perpendicular to the Rowland circle plane, the spherical crystal focuses the light in two dimensions according to the imaging principle of the concave mirror. After being scattered by the curved crystal 2 at 90°, highly polarized X-rays are generated.

[0034] The curved crystal 2 in this embodiment can be one of a spherical curved crystal, a cylindrical curved crystal or a toroidal curved crystal.

[0035] Example 2

[0036] The method for using the above-mentioned monochromatic focusing polarized X-ray optical system comprises the following steps:

[0037] Step 1. After the X-ray tube 1 is powered on, it emits X-rays in the form of a point source. The X-rays emitted from the X-ray tube at this time have the following properties: ① X-ray continuous spectrum. X-rays are usually produced by high-energy particles bombarding the anode target. When high-energy particles interact with the anode target, X-ray characteristic spectrum and continuous spectrum will be generated. Taking visible light as an example, visible light is composed of light of different wavelengths. After refraction through a prism, from the perspective of colors visible to the human eye, it can be simply and roughly summarized as "red, orange, yellow, green, blue, indigo and violet". ② Divergent light. Generally speaking, the X-ray tube is a point light source, and the light emitted from such a light source has a propagation direction that radiates outward. ③ Unpolarized X-rays.

[0038] Step 2. X-rays are diffracted by the crystal and re-emitted. In this step, the X-rays undergo the following changes: ① From white light to monochromatic light. In order to obtain monochromatic X-rays, an X-ray diffraction process is required. The X-ray diffraction process follows the Bragg law. When a beam of X-rays is irradiated on the crystal surface of the crystal, if the optical path difference 2d sinθ is an integer multiple of the wavelength, then the X-rays undergo constructive interference, and if it is not an integer multiple, destructive interference occurs. Therefore, through crystal diffraction, the X-rays of the required wavelength can be screened out from the X-rays of continuous wavelength. ② The divergent light becomes focused light. Since the concave mirror has a convergent effect on the light, the spherical crystal can focus the light in two dimensions according to the concave mirror imaging principle on the sagittal plane perpendicular to the Rowland circle plane. The original divergent light passes through the curved surface of the curved crystal and can be converged, thereby forming a focused light source and enhancing the energy of the light source. ③ Non-polarized light becomes polarized light. The scattering effect with the material can produce polarized X-rays. When the scattering angle is 90°, almost completely polarized X-rays can be produced. Unpolarized X-rays emitted by the X-ray tube are scattered by the bent crystal at 90° to produce highly polarized X-rays.

[0039] Step 3. After steps 1 and 2, the X-rays irradiated on the sample are monochromatic, focused and polarized. ① Monochromaticity ensures that the XRF energy of the sample is selective and specific; ② Focusing ensures the intensity value of the X-rays; ③ When the highly polarized X-rays irradiate the sample, the X-ray fluorescence generated by the elements in the sample is anisotropic, and the incident plane polarized light cannot propagate along its plane. Therefore, when the detector is 90° to the sample and intersects with the polarizer and the X-ray tube plane, the background from the X-ray tube is reduced.

[0040] This embodiment completes the change of optical properties through X-ray tube 1, curved crystal 2, sample 3 and detector 4: emitted from the X-ray tube; irradiated on curved crystal 2, and emitted again after diffraction; irradiated on the sample, stimulating X-ray fluorescence; irradiated on the detector, and the signal is collected by the detector. X-rays propagate along the optical path, resulting in changes in the properties of X-rays, completing the color-focusing-polarization of X-rays, and then stimulating the target X-ray fluorescence signal of the sample, which is finally collected by the detector, completing the X-ray fluorescence analysis test of the sample, and achieving the purpose of reducing the detection background.

[0041] Example 3

[0042] A fluorescence spectrometer comprises the X-ray optical system described in Example 1.

[0043] In this embodiment, the X-ray tube, the bent crystal and the sample form an optical plane and are placed on the circumference of the Rowland circle, thereby realizing the polarization-monochromatic-focusing function of the bent crystal in the XRF optical path design; the detector detects from a direction perpendicular to the optical plane and blocks the polarized X-rays propagating along the detector direction, thereby reducing background interference; thus, an independent monochromatic-focusing-polarized X-ray X-ray fluorescence spectrometer with unique X-ray properties and significantly improved signal-to-noise ratio and detection sensitivity is formed by the design.

[0044] The present invention uses a crystal with polarization effect as a basic material between the X-ray excitation source and the X-ray fluorescence detector, designs and manufactures spherical curved crystals, cylindrical curved crystals, and toroidal curved crystals, thereby realizing monochromatic, polarized, and focusing of the X-ray excitation source, and applies polarization orthogonal geometric design to enhance the X-ray excitation intensity by focusing, reduce the continuous spectrum background of the X-ray excitation source by polarization geometric settings, and improve the peak-to-background ratio by monochromatic light excitation, thereby reducing the continuous spectrum background of the X-ray excitation source, improving the peak-to-background ratio of analyzed elements, improving the XRF detection sensitivity, and effectively reducing the element detection limit.

[0045] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A monochromatic focusing polarized X-ray optical system, characterized in that: include: X-ray tube, used for emitting X-rays; The bent crystal is used to diffract, focus and polarize the X-rays emitted by the X-ray tube. and re-emit the X-rays onto the sample, stimulating X-ray fluorescence; The curved crystal is a spherical curved crystal, a cylindrical curved crystal, or a toroidal curved crystal; The X-ray tube, the bent crystal and the sample form an optical plane and are placed on the circumference of the Rowland circle; A detector, the detector is arranged at 90 degrees to the sample, and is used to receive and collect X-ray fluorescence signals emitted by the sample; the detector detects and blocks polarized X-rays propagating along the detector direction from a direction perpendicular to the optical plane, thereby reducing background interference; The propagation of X-rays along the optical path produces changes in the properties of X-rays, completing the monochromatic-focusing-polarization of X-rays, and then stimulating the target X-ray fluorescence signal of the sample, which is finally collected by the detector to complete the X-ray fluorescence analysis test of the sample, thereby achieving the purpose of reducing the detection background; When highly polarized X-rays irradiate the sample, the X-ray fluorescence produced by the elements in the sample is anisotropic, and the incident plane polarized light cannot propagate along its plane. Therefore, when the detector is 90° to the sample and intersects the plane of the bent crystal and the X-ray tube, the background from the X-ray tube is reduced.

2. The monochromatic focusing polarized X-ray optical system according to claim 1, characterized in that: The diffraction of X-rays obeys Bragg's law.

3. The monochromatic focusing polarized X-ray optical system according to claim 1, characterized in that: Through the bent crystal diffraction, X-rays of required wavelengths are screened out from X-rays of continuous wavelengths.

4. The monochromatic focusing polarized X-ray optical system according to claim 1, characterized in that: The surface of the curved crystal is a concave mirror. On the sagittal plane perpendicular to the Rowland circle plane, the curved crystal performs two-dimensional focusing of light according to the concave mirror imaging principle.

5. The monochromatic focusing polarized X-ray optical system according to claim 1, characterized in that: After being scattered by the bent crystal at 90°, the X-rays generate highly polarized X-rays.

6. The method for using the monochromatic focusing polarized X-ray optical system according to any one of claims 1 to 5, characterized in that: The steps include: S1, after the X-ray tube is powered on, it emits X-rays in the form of a point source; S2, X-rays are diffracted by the bent crystal and re-emitted; S3, after S1 and S2, the X-rays irradiated onto the sample are monochromatic, focused and polarized. The X-ray fluorescence produced by the elements in the sample is anisotropic, and the incident plane polarized light cannot propagate along its plane. Therefore, when the detector is 90° to the sample and intersects with the bent crystal and the X-ray tube plane, the background from the X-ray tube is reduced.

7. The method for using the monochromatic focusing polarized X-ray optical system according to claim 6, characterized in that: In S1, the X-rays emitted by the X-ray tube are continuous spectrum, divergent and unpolarized X-rays.

8. The method for using the monochromatic focusing polarized X-ray optical system according to claim 6, characterized in that: In S2, X-rays change from white light to monochromatic light, from divergent light to focused light, and from unpolarized light to polarized light.

9. A fluorescence spectrometer, characterized in that: The fluorescence spectrometer comprises the monochromatic focusing polarized X-ray optical system as described in any one of claims 1-5.

Images