X-ray spectrum dynamic modulation detection system and signal extraction method

Abstract

The application provides an X-ray spectrum dynamic modulation detection system and a signal extraction method. The system comprises an X-ray source, a detection unit and a spectrum modulation device. The spectrum modulation device is arranged in the light path of the X-ray source and the detection unit, and is used for alternately applying a first filtering state and a second filtering state to an X-ray beam in the light path at a preset frequency; a signal processing unit is electrically connected with the detection unit, and is used for acquiring detection data corresponding to the first filtering state and the second filtering state, and acquiring a signal of a target characteristic X-ray energy interval based on the difference between the detection data of the first filtering state and the detection data of the second filtering state. The application combines the low cost of the filter method and the high background suppression capability of the modulation demodulation technology, and solves the problems of background interference, low test efficiency or high cost in the traditional method.

Description

Technical Field

[0001] This invention relates to the field of X-ray fluorescence spectroscopy analysis technology, and in particular to an X-ray spectral dynamic modulation detection system and signal extraction method. Background Technology

[0002] X-ray diffraction (XRD) is a standard method for analyzing the crystal structure, phase composition, and stress state of materials. In diffractometers based on laboratory X-ray tubes (such as copper targets, molybdenum targets, etc.), obtaining pure monochromatic X-rays is key to improving the detection signal-to-noise ratio (SNR).

[0003] In existing technologies, the following methods are commonly used for spectral purification: 1. Beta Filter Method: This is the most common low-cost approach. For example, a nickel (Ni) sheet is inserted into the optical path of a copper target (CuKα, 8.04 keV). While it effectively filters out Kβ rays, it cannot filter out the continuous spectrum (Bremsstrahlung) with energies below the absorption edge or the fluorescence generated by sample excitation. This results in a high baseline in the spectrum, making weak peaks difficult to identify.

[0004] 2. Crystal Monochromator Method: This method utilizes Bragg diffraction of a crystal for spectral dispersion. While it can achieve extremely high energy resolution and very low background, its optical path is complex and difficult to adjust. It also leads to an effective light intensity attenuation of over 90%, significantly extending the testing time and resulting in extremely high hardware costs.

[0005] 3. Energy Dispersive Detector: This type of detector utilizes the energy resolution of the semiconductor detector itself for electronic filtering. However, the energy resolution of conventional detectors (200 eV to 1000 eV) is much lower than that of crystal monochromators, making it difficult to completely separate Kα from nearby fluorescence peaks or background.

[0006] Therefore, there is an urgent need for a new detection system that can achieve high background suppression, completely eliminate fluorescence interference, and solve the problem of dynamic switching noise at low cost. Summary of the Invention

[0007] This invention provides an X-ray spectral dynamic modulation detection system and signal extraction method. By periodically applying two filtering states to an X-ray beam at a preset frequency, and using a signal processing unit to acquire detection data under the two states, the target feature X-ray signal is extracted through weighted difference calculation. This solves the problems of background interference, low testing efficiency, or high cost in traditional methods.

[0008] In a first aspect, an embodiment of the present invention provides an X-ray spectral dynamic modulation detection system, comprising: an X-ray source, positioned toward a sample, for emitting X-rays; a detection unit, for receiving a detection signal reflected by the sample; a spectral modulation device, disposed in the optical path between the X-ray source and the detection unit, for alternately applying a first filtering state and a second filtering state to the X-ray beam in the optical path at a preset frequency; and a signal processing unit, electrically connected to the detection unit, for acquiring detection data corresponding to the first filtering state and the second filtering state, and acquiring a signal of a target characteristic X-ray energy range based on the difference between the detection data of the first filtering state and the detection data of the second filtering state; wherein the first filtering state has a first absorption edge energy E1, the second filtering state has a second absorption edge energy E2, and the first absorption edge energy E1 is greater than or equal to the upper limit of the target characteristic X-ray energy range, and the second absorption edge energy E2 is less than or equal to the lower limit of the target characteristic X-ray energy range.

[0009] Optionally, the spectral modulation device is located in the diffraction optical path between the sample and the detection unit.

[0010] Optionally, the spectral modulation device is also used to block the X-ray signal reflected from the sample from reaching the detection unit during the transition period between the first filtering state and the second filtering state; or the signal processing unit is also used to stop data acquisition during the transition period.

[0011] Optionally, the spectral modulation device includes a rotating chopper wheel; the rotating chopper wheel is provided with alternating first and second filter regions, the first filter region having a first absorption edge energy E1, and the second filter region having a second absorption edge energy E2.

[0012] Optionally, the rotating abductor also includes an opaque blocking part; the opaque blocking part is disposed between the first filtering area and the second filtering area, and the width of the blocking part is greater than the spot width of the X-ray incident on the rotating abductor.

[0013] Optionally, a first filter is provided in the first filtering region, and a second filter is provided in the second filtering region; the first filter contains nickel material, and the second filter contains cobalt material.

[0014] Optionally, the first filtering region is provided with a plurality of first filters; the second filtering region is provided with a plurality of second filters; for the first filtering region, the product of the attenuation coefficient and the effective thickness of each first filter is equal to each other; for the second filtering region, the product of the attenuation coefficient and the effective thickness of each second filter is equal to each other; wherein, the effective thickness is the optical path length through which X-rays pass through the filter.

[0015] Optionally, the first filter and the second filter each have an angle adjustment structure for adjusting the effective thickness of the first filter or the second filter.

[0016] Optionally, a static pre-filter may also be included, wherein the absorption edge energy of the static pre-filter is greater than or equal to the upper limit of the target characteristic X-ray energy range.

[0017] Optionally, the first or second filtering region may further include a parylene vacuum-deposited layer.

[0018] In a second aspect, embodiments of the present invention also provide a signal extraction method, applied to the X-ray spectral dynamic modulation detection system of any one of the first aspects, comprising: The X-ray beam is subjected to a first filtering state and a second filtering state alternately in the optical path according to a preset frequency. Acquire detection data corresponding to the first and second filtering states; Based on the difference between the detection data of the first filter state and the detection data of the second filter state, the signal of the target feature X-ray energy range is obtained.

[0019] Optionally, the detection data corresponding to the first filtering state and the second filtering state is acquired, including: Record the arrival time of each incident X-ray photon; The modulation period is determined according to a preset frequency, and the arrival time of all photons is mapped to the corresponding phase within the modulation period. Based on the phase, the first signal strength corresponding to the first filtering state and the second signal strength corresponding to the second filtering state are obtained by accumulating the signals respectively. Based on the difference between the detection data in the first filtering state and the detection data in the second filtering state, the signal of the target feature X-ray energy range is obtained, including: Calculate the weighted difference between the first signal strength and the second signal strength.

[0020] Optionally, the detection unit operates in a time-driven photon counting mode, recording the arrival time of each incident X-ray photon without the need for external hardware triggering; the signal processing unit calculates the chopping frequency and phase using an autocorrelation algorithm, performs timestamp folding, and automatically discards invalid photons mapped to the corresponding phase of the opaque blocking part.

[0021] Optionally, based on the difference between the detection data in the first filtering state and the detection data in the second filtering state, the signal of the target feature X-ray energy range is obtained, including: Calculate the intensity ratio coefficient k between the first and second filtering states; where k satisfies the condition that the background signal without diffraction peaks... =0; where, The signal strength under the first filtering state. The signal strength under the second filtering state; According to the formula I= Calculate the signal in the characteristic X-ray energy range of the target.

[0022] Optionally, the intensity ratio coefficient k between the first and second filtered states is calculated, including: Obtain the background signal intensity under the first filtering state and the background signal intensity under the second filtering state when there are no diffraction peaks; According to the formula: Calculate the strength ratio coefficient k, where, The average background signal strength under the first filtering state. The average background signal strength under the second filtering state.

[0023] This invention provides an X-ray spectral dynamic modulation detection system and signal extraction method. The system uses a rotating chopper wheel in the optical path between the X-ray source and the detection unit. Alternating nickel and cobalt filter regions on the chopper wheel are periodically applied to the X-ray beam at a preset frequency, applying two filtering states. Simultaneously, an opaque blocking section blocks the signal during the transition period. A signal processing unit acquires the detection data from both states, and the target feature X-ray signal is extracted through weighted difference calculation. This invention combines the low cost of the filter method with the high background suppression capability of modulation and demodulation technology, solving the problems of background interference, low testing efficiency, or excessive cost in traditional methods. Through dynamic differential filtering, this system achieves "physical-level" bandpass filtering (bandwidth of approximately 600 eV), suppressing more than 95% of continuous spectral and fluorescence backgrounds, achieving results approaching those of expensive crystal monochromators. Furthermore, this invention also provides a signal extraction method based on the X-ray spectral dynamic modulation detection system. Without using an opaque blocking section, photons during the dead time are automatically discarded, achieving the same technical effect of acquiring detection data from both states. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the structure of an X-ray spectral dynamic modulation detection system provided in an embodiment of the present invention; Figure 2 This is a schematic diagram of another X-ray spectral dynamic modulation detection system provided in an embodiment of the present invention; Figure 3 This is a schematic diagram of the structure of a rotating light-cutting wheel provided in an embodiment of the present invention; Figure 4 This is a schematic diagram of another rotating light-cutting wheel provided in an embodiment of the present invention; Figure 5 This is a schematic diagram of another rotating light-cutting wheel provided in an embodiment of the present invention; Figure 6This is a schematic flowchart of a signal extraction method provided in an embodiment of the present invention; Figure 7 A time-domain photon counting signal waveform diagram provided in an embodiment of the present invention during the signal extraction process; Figure 8 A schematic flowchart of another signal extraction method provided in an embodiment of the present invention; Figure 9 This is a flowchart illustrating another signal extraction method provided in an embodiment of the present invention. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be fully described below with reference to the accompanying drawings in the embodiments of this invention, through specific implementation methods. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort fall within the protection scope of this invention.

[0026] Figure 1 This is a schematic diagram of the structure of an X-ray spectral dynamic modulation detection system provided in an embodiment of the present invention. Figure 2 This is a schematic diagram of another X-ray spectral dynamic modulation detection system provided in this embodiment of the invention. The X-ray spectral dynamic modulation detection system provided in this embodiment can be specifically applied in scenarios such as powder diffraction, thin film analysis, or residual stress testing. This system is used to extract pure target feature X-ray signals from strong background signals and fluorescence interference. (Reference) Figure 1 Figure 2 An embodiment of the present invention provides an X-ray spectral dynamic modulation detection system, comprising: an X-ray source 10, positioned toward a sample 1, for emitting X-rays; a detection unit 20, for receiving a detection signal reflected by the sample 1; a spectral modulation device 30, disposed in the optical path between the X-ray source 10 and the detection unit 20, for alternately applying a first filtering state and a second filtering state to the X-ray beam in the optical path at a preset frequency; and a signal processing unit 40, electrically connected to the detection unit 20, for acquiring detection data corresponding to the first filtering state and the second filtering state, and acquiring a signal of a target characteristic X-ray energy range based on the difference between the detection data of the first filtering state and the detection data of the second filtering state; wherein the first filtering state has a first absorption edge energy E1, the second filtering state has a second absorption edge energy E2, and the first absorption edge energy E1 is greater than or equal to the upper limit of the target characteristic X-ray energy range, and the second absorption edge energy E2 is less than or equal to the lower limit of the target characteristic X-ray energy range.

[0027] According to the curve of X-ray absorption rate varying with energy, under normal circumstances, X-rays follow the general physical attenuation law of low-energy absorption and high-energy penetration; when the energy of X-ray photons is sufficient to ionize the inner-layer electrons of an atom, the absorption rate will increase sharply; when the energy greatly exceeds the requirement of the inner-layer electrons, the absorption rate again follows the law of low-energy absorption and high-energy penetration. The absorption edge described in the present invention refers to the critical energy value when the energy of X-ray photons is exactly sufficient to ionize the inner-layer electrons of an atom.

[0028] Among them, the detection unit 20 can be understood as an energy-dispersive or counting-type X-ray detector (such as a silicon drift detector SDD), which is used to receive X-ray photons after diffraction or scattering by the sample and convert them into electrical signals; the spectral modulation device 30 can be understood as an optical element (such as a rotating chopper wheel) that can switch between two different filtering characteristics at a fixed frequency, and its function is to alternately place the X-ray beam in the optical path in the first filtering state or the second filtering state; the first filtering state can be understood as the state where a filter with the first absorption edge energy E1 is inserted in the optical path, which is used to absorb or attenuate X-rays with energy lower than E1, so that the light above the upper limit of the target characteristic X-ray energy range passes through; the second filtering state can be understood as the state where a filter with the second absorption edge energy E2 is inserted in the optical path, which is used to absorb or attenuate X-rays with energy higher than E2, so that the light below the lower limit of the target characteristic X-ray energy range passes through; the target characteristic X-ray energy range can be understood as the energy range where the characteristic X-ray spectrum to be detected (such as CuKα, with an energy of about 8.04 keV) is located.

[0029] Specifically, during the working process, the X-ray beam emitted by the X-ray source 10 irradiates the sample 1, generating diffraction or scattering signals. The spectral modulation device 30 alternately switches between the first filtering state (such as inserting a Ni filter, whose K absorption edge E1 is about 8.33 keV, higher than 8.04 keV of CuKα) and the second filtering state (such as inserting a Co filter, whose K absorption edge E2 is about 7.71 keV, lower than 8.04 keV of CuKα) in the optical path at a preset frequency. The detection unit 20 continuously collects the X-ray photons that pass through the sample and are then filtered by the spectral modulation device 30, and converts them into electrical signals and transmits them to the signal processing unit 40. The signal processing unit 40 extracts the signal intensity I(E>E1) in the first filtering state and the signal intensity I(E<E2) in the second filtering state according to the modulation frequency. Since there is a significant difference in the transmittance of the target characteristic X-ray energy range (CuKα) under the two filtering states (the first filtering state allows Kα to pass through, and the second filtering state blocks Kα), while the transmittance of background noise (such as sample fluorescence, bremsstrahlung continuum) is similar under the two states, by calculating the difference between the two signals, the background noise can be effectively deducted and the pure target characteristic X-ray signal can be extracted.

[0030] This invention provides an X-ray spectral dynamic modulation detection system. By placing a spectral modulation device in the optical path between the X-ray source and the detection unit, the system periodically applies two filtering states to the X-ray beam at a preset frequency using the spectral modulation device. A signal processing unit acquires the detection data under the two states, and the target feature X-ray signal is extracted through weighted difference calculation. This embodiment combines the low cost of the filter method with the high background suppression capability of modulation and demodulation technology, solving the problems of background interference, low testing efficiency, or excessive cost in traditional methods.

[0031] refer to Figure 2 In an optional embodiment, a reflector 11 is provided in the optical path between the X-ray source 10 and the sample 1 to collimate or focus the original diverging X-ray beam emitted by the X-ray source 10, forming a more parallel X-ray beam that irradiates the sample 1. In the optical path between the sample 1 and the detection unit 20, a spectral modulation device 30 and a slit 50 are sequentially arranged. The diffracted or scattered X-rays generated from the sample 1 first undergo alternating modulation of the filtered state by the spectral modulation device 30, then pass through the slit 50 for spatial beam confinement to remove stray light and scattered background, and finally enter the detection unit 20 for signal acquisition. By introducing the reflector 11 and the slit 50, the collimation and spatial resolution of the beam can be further optimized, thereby further reducing background noise and improving the signal-to-noise ratio and energy resolution of the signal received by the detection unit 20.

[0032] Optionally, the spectral modulation device 30 is disposed in the diffraction optical path between the sample 1 and the detection unit 20.

[0033] Specifically, the spectral modulation device 30 is disposed in the diffraction optical path between the sample 1 and the detection unit 20. The reason for placing the spectral modulation device 30 in the diffraction optical path between the sample 1 and the detection unit 20, rather than in the incident optical path between the X-ray source 10 and the sample 1, is primarily based on the following considerations: Firstly, if the spectral modulation device is placed in the incident optical path, prolonged direct irradiation by the high-intensity X-ray beam will accelerate the aging and damage of the filter material, and the pre-absorption of the continuous spectrum at the incident end of the filter may generate additional scattering or fluorescence, thus increasing background noise. Secondly, the core of this invention is to extract the target feature X-ray signal by alternately switching between two filtering states and utilizing the difference in detection data. This scheme requires the filtering operation to be applied to the diffraction signal that already carries sample structural information, ensuring that the difference between the two filtering states can accurately reflect the intensity change of the target feature X-ray before and after sample diffraction, while effectively eliminating fluorescence interference from the sample and stray background in the optical path. Placing the modulation element in the incident light path only allows for pre-modulation of the incident beam, failing to distinguish and subtract the fluorescence signal generated by the sample itself, and also making it difficult to suppress other background sources in the light path besides the light source. Therefore, this invention places the spectral modulation device in the diffraction light path, enabling direct modulation of the sample's emitted signal, better suppressing fluorescence and stray background, improving the purity and accuracy of signal extraction, and thus solving the problem of sample autofluorescence (such as Cu target for Fe samples) that has plagued the XRD field without replacing expensive array detectors or multicolor instruments.

[0034] Optionally, the spectral modulation device 30 is also used to block the X-ray signal reflected by the sample 1 from reaching the detection unit 20 during the transition period between the first filtering state and the second filtering state; or the signal processing unit 40 is also used to stop data acquisition during the transition period.

[0035] The transition time period can be understood as the short time interval required for the spectral modulation device 30 to switch from the first filtering state to the second filtering state, or from the second filtering state back to the first filtering state.

[0036] Specifically, during the process of the spectral modulation device 30 alternately switching the filter states at a preset frequency, there is a brief transition period. During this period, the optical path may simultaneously partially cover both filters or be exposed in the gap between the filters, causing the signal received by the detection unit 20 to not purely represent the first or second filter state. Acquiring this data will introduce errors. To solve the noise problem of dynamic switching, this invention introduces a "transition state suppression" mechanism. At the instant of switching between the first and second filter states (i.e., the moment the physical boundary sweeps across the light spot), the system enters a signal blanking state. Specifically, one or a combination of the following two schemes can be adopted: First, the spectral modulation device 30 actively blocks the X-ray signal from reaching the detection unit 20 during the transition period; second, the signal processing unit 40 stops data acquisition during the transition period, that is, it only records the signal during the effective time period after the filter state stabilizes, thereby avoiding signal aliasing in the transition state and ensuring the purity and accuracy of the first and second filter state data in the subsequent difference calculation.

[0037] Figure 3 This is a schematic diagram of a rotating light-cutting wheel provided in an embodiment of the present invention. Figure 4 This is a schematic diagram of another rotating light-cutting wheel provided in an embodiment of the present invention. (Reference) Figures 1 to 4 In an optional embodiment, the spectral modulation device 30 includes a rotating chopper wheel 31; the rotating chopper wheel 31 is provided with alternating first filter regions 32 and second filter regions 33, the first filter region 32 having a first absorption edge energy E1, and the second filter region 33 having a second absorption edge energy E2.

[0038] The rotating chopper wheel 31 can be understood as a disc-shaped mechanical chopper driven by a motor to rotate, used to alternately cut different filtering regions into the X-ray optical path at a fixed frequency through circular motion, so as to realize the periodic switching of the filtering state; the first filtering region 32 can be understood as a filter or coating region with a first absorption edge energy E1 set on the rotating chopper wheel 31; the second filtering region 33 can be understood as a filter or coating region with a second absorption edge energy E2 set on the rotating chopper wheel 31.

[0039] For details, please refer to Figure 1 Figure 4The spectral modulation device 30 employs a rotating chopper wheel 31 to achieve periodic switching of the filtering state. The rotating chopper wheel 31 is driven by a motor to rotate at a constant speed. Its disc has alternating first filtering regions 32 (such as a Ni filter with a K absorption edge of approximately 8.33 keV) and second filtering regions 33 (such as a Co filter with a K absorption edge of approximately 7.71 keV) arranged along its circumference. As the rotating chopper wheel 31 rotates, the two filtering regions sequentially and periodically enter the X-ray diffraction path, applying corresponding filtering states to the X-ray beam. By controlling the motor speed, the switching frequency between the first and second filtering states can be set. This mechanical chopper modulation scheme has a simple structure, controllable cost, and can achieve a large modulation depth, suitable for the signal modulation needs of conventional laboratory X-ray sources. Furthermore, compared to crystal monochromators, the scheme provided in this embodiment has extremely low hardware costs (requiring only a motor and metal foil) and retains 3-5 times higher effective light intensity than monochromators, greatly improving testing efficiency.

[0040] Continue to refer to Figure 3 Figure 4 In an optional embodiment, the rotating abductor wheel 31 further includes an opaque blocking portion 34; the opaque blocking portion 34 is disposed between the first filtering region 32 and the second filtering region 33, and the width of the blocking portion 34 is greater than the spot width of the X-ray incident on the rotating abductor wheel 31.

[0041] The opaque blocking part 34 can be understood as a completely light-blocking area (such as a shield made of heavy metal material, preferably a rotating beam cutter with solid spokes, the width of which is greater than the diameter of the light spot) set on the rotating beam cutter 31 between the first filter area 32 and the second filter area 33. It is used to physically block the X-ray path during the transition time between the two filter areas. The light spot width can be understood as the lateral dimension of the irradiation area of ​​the X-ray beam on the plane of the rotating beam cutter 31, which is used as the basis for designing the width of the opaque blocking part 34.

[0042] For details, please refer to Figure 3 Figure 4An opaque blocking section 34 is provided between the first filter region 32 and the second filter region 33 in the rotating chopper wheel 31. The width of the opaque blocking section 34 is designed to be greater than the width of the X-ray spot incident on the rotating chopper wheel 31. When the rotating chopper wheel 31 rotates, the X-ray spot will first enter the opaque blocking section 34 region during the process of moving from the first filter region 32 to the second filter region 33 (or in the opposite direction). Since the width of the blocking section 34 is greater than the width of the spot, the X-ray beam is completely blocked during the switching transition period and cannot reach the detection unit 20. Only after the spot completely crosses the blocking section 34 and enters the next filter region will the X-ray transmission resume. The opaque blocking section 34 can effectively prevent some filtered and mixed filtered signals from entering the detector due to the edges or gaps of the filter region during the filtering state switching process, ensuring that the signal collected by the detection unit 20 is only processed when it is completely in the first filtering state or completely in the second filtering state, thereby ensuring the data purity and accuracy of subsequent difference calculations.

[0043] Continue to refer to Figure 3 Figure 4 In an optional embodiment, a first filter region 32 is provided with a first filter 321, and a second filter region 33 is provided with a second filter 331; the first filter 321 contains nickel material, and the second filter 331 contains cobalt material.

[0044] For details, please refer to Figure 3 Figure 4 A first filter 321, containing nickel (Ni), is disposed in the first filtering region 32 of the rotating chopper wheel 31; a second filter 331, containing cobalt (Co), is disposed in the second filtering region 33. When the target characteristic X-ray is copper target Kα radiation (CuKα, energy approximately 8.04 keV), the K absorption edge of nickel (approximately 8.33 keV) is slightly higher than the CuKα energy, therefore the first filter 321 allows CuKα radiation to pass through (while absorbing X-rays slightly higher than 8.33 keV); the K absorption edge of cobalt (approximately 7.71 keV) is slightly lower than the CuKα energy, therefore the second filter 331 strongly absorbs CuKα radiation. By employing a nickel / cobalt filter pair, "on / off" modulation of the copper target characteristic X-ray is achieved: the CuKα signal passes through in the first filtering state, and is blocked in the second filtering state. Meanwhile, the two filters exhibit similar attenuation levels for sample fluorescence and continuous spectral background, enabling the difference calculation to effectively extract the pure CuKα signal and eliminate background interference. Nickel and cobalt, as common transition metal filter materials, are readily available and moderately priced, making them suitable for the modification or integration of conventional X-ray diffractometers.

[0045] Continue to refer to Figure 4In an optional embodiment, the first filtering region 32 is provided with a plurality of first filters 321; the second filtering region 33 is provided with a plurality of second filters 331; For the first filtering region 32, the product of the attenuation coefficient and the effective thickness of each first filter 321 is equal to each other; For the second filtering region 33, the product of the attenuation coefficient and the effective thickness of each second filter 331 is equal to each other.

[0046] Among them, the attenuation coefficient can be understood as the linear attenuation coefficient of the filter material for X-rays; the effective thickness is the optical path length of X-rays passing through the filter.

[0047] For details, please refer to Figure 4 On the rotating acervette 31, a first filtering region 32 is provided with a plurality of first filters 321 (e.g., a plurality of identical Ni filters arranged at equal intervals along the circumference), and a second filtering region 33 is provided with a plurality of second filters 331 (e.g., a plurality of identical Co filters arranged at equal intervals along the circumference). To ensure that the attenuation effect of the plurality of first filters 321 on X-rays is consistent in each modulation cycle, and that the attenuation effect of the plurality of second filters 331 on X-rays is consistent, for the first filtering region 32, the product of the attenuation coefficient and the effective thickness of each first filter 321 is equal to each other, i.e., the transmittance is a constant value. Similarly, for the second filtering region 33, the product of the attenuation coefficient and the effective thickness of each second filter 331 is equal to each other.

[0048] Continue to refer to Figure 4 In an optional embodiment, the first filter 321 has a first unit thickness H1 and the second filter 331 has a second unit thickness H2; the first unit thickness H1 and the second unit thickness H2 have a preset ratio, such that the ratio of their transmittance to X-rays in the background energy region of non-target characteristic rays remains a stable constant, so that the signal processing unit can extract the intensity ratio coefficient (k) based on the constant and perform background difference calculation.

[0049] Wherein, the first unit thickness H1 can be understood as the physical thickness dimension of the first filter 321; the second unit thickness H2 can be understood as the physical thickness dimension of the second filter 331; according to the Beer-Lambert law... Where I is the emitted light intensity, I0 is the incident light intensity, e is the natural constant, and μ is the attenuation coefficient (unit: cm). -1 ), where d is the optical path length (medium thickness, unit: cm); It is known that if the first filter 321 has a first attenuation coefficient A1, and the second filter 331 has a second attenuation coefficient A2, in order to ensure that each of the first filtering regions 32 and the second filtering regions 33 in the rotating chopper 31 has the same transmittance, thereby facilitating the processing of detection results with a unified coefficient, H1×A1 and H2×A2 have a fixed difference, so that the ratio of the transmittance of the first filter 321 and the second filter 331 to X-rays in the background energy region of non-target characteristic rays remains a stable constant.

[0050] Furthermore, to ensure that the attenuation of background signals (e.g., the continuous spectrum of X-rays with energies higher or lower than the target characteristic X-rays and sample fluorescence) is as consistent as possible in both filtering states, thereby improving the background suppression effect of the difference calculation, the thickness of the filter and the material attenuation coefficient satisfy H1×A1=H2×A2. Through this matching condition, in both the first and second filtering states, the total transmittance of non-target energy X-rays after passing through the two filters is essentially the same, resulting in similar background signal intensities generated on the detector. However, the transmittance of target characteristic X-rays (such as CuKα) differs significantly between the two filters due to the difference in absorption edges (one passes through, the other blocks). Therefore, by calculating the signal difference between the two states, the target characteristic X-ray signal can be effectively separated from the background while simultaneously subtracting the background signal.

[0051] Figure 5 This is a schematic diagram of another rotating light-cutting wheel provided in an embodiment of the present invention, with reference to... Figure 5 In one specific embodiment, the first filter and the second filter have an angle adjustment structure 35 for adjusting the effective thickness of the first filter or the second filter.

[0052] Specifically, with Figure 5 Taking the first filter 321 as an example, each filter is fixed to the rotating abductor wheel 31 by four spring-loaded angle adjustment structures 35 (such as bolts). The spring structure provides a stable preload force to prevent the filter from loosening or shifting during high-speed rotation, while allowing fine-tuning of the filter's flatness and angle to ensure that the X-ray beam is incident perpendicularly or passes through the filter at a preset angle, thereby ensuring the matching of the attenuation coefficient and the effective thickness. When the filter tilt angle increases, the optical path of X-ray penetration (effective thickness = physical thickness / cosθ) increases, and the attenuation is enhanced; when the tilt angle decreases, the effective thickness decreases, and the attenuation is weakened.

[0053] It should be noted that, in actual processing, it is difficult to ensure that the thickness of the first filter 321 and the second filter 331 fully meets the design requirements. The angle adjustment structure 35 can keep the ratio of the transmittance of the first filter 321 and the second filter 331 to X-rays in the background energy region of non-target characteristic rays a stable constant when there are differences in thickness.

[0054] In a specific embodiment, the first filter 321 has a third unit thickness H3, and the second filter 331 has a fourth unit thickness H4 (not shown in the figure); the angle between the first filter 321 and the optical axis of the X-ray is a first angle θ1, and the angle between the second filter 331 and the optical axis of the X-ray is a second angle θ2; the third unit thickness H3, the fourth unit thickness H4, the first angle θ1, and the second angle θ2 satisfy: H3 / cos(θ1) and H4 / cos(θ2) have a preset ratio, so that the ratio of their transmittance to X-rays in the background energy region of non-target characteristic rays remains a stable constant, so that the signal processing unit can extract the intensity ratio coefficient k based on the stable constant and perform background difference calculation.

[0055] Wherein, the third unit thickness H3 can be understood as the physical thickness of the first filter 321 in the direction perpendicular to its surface; the fourth unit thickness H4 can be understood as the physical thickness of the second filter 331 in the direction perpendicular to its surface; the first angle θ1 can be understood as the angle between the surface normal of the first filter 321 and the X-ray optical axis; and the second angle θ2 can be understood as the angle between the surface normal of the second filter 331 and the X-ray optical axis.

[0056] For details, please refer to Figure 5 To address the issue of difficulty in precisely matching the thickness of Co filters (leading to a coefficient deviation from 1.0), this embodiment designs an inclined groove at the Co window of the chopper wheel. When the filter surface normal L2 is not parallel to the X-ray optical axis L1, the actual effective path length of the X-ray in the filter is equal to the physical thickness of the filter divided by the cosine of the angle θ between the optical axis and the normal (i.e., H / cosθ). To achieve matched attenuation of the background signal in both filtering states, the effective total transmittance of the two filters at their respective installation angles needs to be equal. For example, a 20μm standard Co foil is installed at an angle (tilt angle θ≈27°), and its effective optical thickness is finely adjusted to 22.4μm, thereby achieving physical matching with the transmittance of a 20μm Ni foil in the background region.

[0057] In an optional embodiment, the difference or ratio between the value of the stability constant and 1 is less than or equal to a preset threshold.

[0058] The preset threshold can be understood as a small value (e.g., 0.05 or 5%) set according to the system background suppression accuracy requirements, to ensure that the transmittance of the first filter and the second filter to X-rays is basically equal in the background energy region of non-target characteristic rays.

[0059] Specifically, to enable the signal processing unit to effectively subtract background noise through differential calculation, the first filter and the second filter are configured with a preset thickness ratio, such that the ratio of their transmittance in the background energy region of non-target characteristic rays (e.g., the continuous spectrum and fluorescence signal region with energy higher or lower than the target characteristic X-ray energy range) is as close to 1 as possible (e.g., a ratio between 0.95 and 1.05). When the difference or ratio between the transmittance ratio and 1 is less than or equal to a preset threshold, it indicates that the attenuation of the background signal is highly consistent in the two filtering states. At this time, the signal processing unit can directly perform background differential calculation (I1 - I2) based on this stable ratio relationship (i.e., the intensity ratio coefficient k≈1) without complex coefficient calibration; or use this stable constant as a reference to obtain an accurate intensity ratio coefficient through simple calibration, thereby effectively subtracting background noise while significantly simplifying the data processing flow and improving detection accuracy and efficiency.

[0060] Optionally, the X-ray spectral dynamic modulation detection system also includes a static pre-filter (not shown in the figure), the absorption edge energy of which is greater than or equal to the upper limit of the target characteristic X-ray energy range.

[0061] Among them, the static pre-filter can be understood as a filter that is fixedly installed in the X-ray optical path and does not switch over time. It is used to pre-filter out X-ray components with energy lower than the lower limit of the target characteristic X-ray energy range before the X-rays reach the sample or the spectral modulation device.

[0062] Specifically, to further improve the signal-to-noise ratio and make the intensity ratio coefficient k approach 1, this embodiment adds an additional static pre-filter in the incident light path between the X-ray source 10 and the sample 1. Its absorption edge energy is selected to be greater than or equal to the upper limit of the target characteristic X-ray energy range. Taking copper target Kα (approximately 8.04 keV) as the target characteristic X-ray as an example, a cobalt filter with an absorption edge energy of approximately 7.71 keV, or a material of the same type as the first filtering state (such as nickel, with a thickness of approximately 1020 μm) can be used as the static pre-filter. Through pre-filtering with the static pre-filter, continuous spectrum components with energies higher than the upper limit of the target characteristic X-ray (such as the low-energy tail of bremsstrahlung) and X-ray components that may excite fluorescence interference in the sample can be effectively attenuated or blocked in advance. This results in the background rays reaching the chopper wheel being mainly composed of high-energy hard X-rays. After introducing the pre-filter, the average energy of the background rays increases (absorption is much stronger than the absorption edge, slightly weaker than the absorption edge, slightly stronger than the absorption edge, and much weaker than the absorption edge; therefore, the pre-filter can increase the average energy). The difference in mass absorption coefficient between the first and second filter states in the high-energy region decreases, which increases the intensity ratio coefficient k, reduces the proportion of effective signal that is forced to be discarded in order to balance the baseline, and improves the overall detection efficiency of the system.

[0063] In one specific embodiment, the intensity ratio coefficient k is approximately 0.43 without pre-filtering and approximately 0.60 after beam hardening.

[0064] Optionally, the first filter region 32 or the second filter region 33 may further include a parylene vacuum-deposited layer.

[0065] Specifically, parylene (PDX) has extremely low X-ray absorption (mainly composed of low atomic number carbon and hydrogen), therefore it does not significantly affect the original X-ray transmittance curve or modulation performance of the filter. Simultaneously, this coating effectively blocks oxygen and moisture from the air, preventing oxidation of nickel or cobalt materials, and improves the filter's wear and vibration resistance, enhancing its mechanical strength. By introducing a parylene vacuum coating, the filter's service life during long-term operation is extended, making it particularly suitable for X-ray diffraction systems requiring continuous operation for extended periods, thus reducing maintenance costs and frequency.

[0066] In one specific embodiment, a 2 μm thick parylene protective layer can be pre-deposited on the Co foil surface of the filter.

[0067] In one specific embodiment, this embodiment provides a dynamic spectral modulation system for a copper target (CuTarget, Kα≈8.04keV) X-ray diffractometer. The system's optical path consists sequentially of an X-ray source 10, an incident optical path assembly (such as a reflector 11), a sample 1, a slit 50, a rotating chopper wheel 31 of the spectral modulation device 30, and a detection unit 20. The rotating chopper wheel 31 modulates not only the X-rays from the X-ray source 10 but also the secondary fluorescence generated by the excited sample 1 (e.g., 6.4keV fluorescence generated by an iron-containing sample). Since the fluorescence energy is outside the passband window and has undergone differential modulation by the first filter 321 (Ni) and the second filter 331 (Co), it is ultimately filtered out as background in the difference calculation of the signal processing unit 40, thereby efficiently extracting the pure copper target Kα characteristic X-ray signal. The chopper wheel substrate is made of 7075 aerospace aluminum alloy, with an outer diameter of 100mm and a thickness of 2.5mm. The wheel body has four pairs (eight in total) of fan-shaped windows arranged in a circular pattern. Odd-numbered windows are bonded with nickel (Ni) foil, approximately 20 μm thick; even-numbered windows are bonded with cobalt (Co) foil, approximately 2530 μm thick. Between adjacent Ni and Co windows, solid aluminum alloy spokes with a width of 4 mm are maintained. It is known that the beam width at the receiving slit is typically less than 2 mm. When the 4 mm wide spokes sweep across the optical path, they completely block the beam, creating a period of "complete darkness" where no X-rays reach the detector. This physically eliminates the mixed signal artifacts generated when the Ni / Co boundary sweeps across the beam.

[0068] also, Figure 6 This is a flowchart illustrating a signal extraction method provided in an embodiment of the present invention. Figure 7 This is a waveform diagram of a time-domain photon counting signal during a signal extraction process provided in an embodiment of the present invention. (Reference) Figure 6 This signal extraction method can be applied to the X-ray spectral dynamic modulation detection system as described in any of the above embodiments. The signal extraction method includes: S110. The first filtering state and the second filtering state are alternately applied to the X-ray beam in the optical path according to a preset frequency.

[0069] The preset frequency can be understood as the modulation frequency of the spectral modulation device (such as a rotating chopper); the first filtering state can be understood as having a first absorption edge energy E1 (E1 ≥ the upper limit of the target characteristic X-ray energy range); the second filtering state can be understood as having a second absorption edge energy E2 (E2 ≤ the lower limit of the target characteristic X-ray energy range).

[0070] Specifically, by rotating the light-cutter wheel at a constant speed, the first filtering region 32 (such as a Ni filter) and the second filtering region 33 (such as a Co filter) are alternately inserted into the X-ray diffraction path at a preset frequency, thereby achieving periodic filtering and modulation of the X-ray beam.

[0071] S120. Obtain detection data corresponding to the first filtering state and the second filtering state.

[0072] The detection data can be understood as the X-ray photon count or intensity signal collected by the detection unit in the first or second filtering state.

[0073] Specifically, synchronous data acquisition is achieved through hardware triggering. Utilizing an integrated photoelectric encoder on the rotating chopper wheel, when either the first filter region 32 or the second filter region 33 fully enters the optical path during the chopper wheel's rotation, the encoder outputs a TTL level signal. This signal is connected to the detector's gate interface. The detector only begins acquisition during the window period when it receives the TTL trigger signal, recording X-ray photons in the corresponding filter state. During the transition period between filter regions (such as when the opaque blocking part 34 passes through the optical path), the detector stops acquisition, directly acquiring the first detection data corresponding to the first filter state and the second detection data corresponding to the second filter state, without requiring additional software alignment or interpolation processing.

[0074] S130. Based on the difference between the detection data of the first filtering state and the detection data of the second filtering state, obtain the signal of the target feature X-ray energy range.

[0075] Among them, the signal in the energy range of the target characteristic X-ray can be understood as the diffraction intensity of pure target characteristic X-rays (such as CuKα).

[0076] Specifically, the detection data acquired under the first filtering state (denoted as I_Ni) and the detection data acquired under the second filtering state (denoted as I_Co) are compared using a difference calculation. Since the first filter (Ni) allows target feature X-rays to pass through while attenuating the background signal to some extent, and the second filter (Co) blocks target feature X-rays but attenuates the background signal to a similar degree as the first filter, the difference between the two (I_NiI_Co) can effectively subtract background noise (including continuous spectrum, sample fluorescence, etc.) and extract the pure target feature X-ray signal. This difference signal can be directly used for subsequent X-ray diffraction pattern analysis, significantly improving the identification ability of weak peaks and the overall data quality.

[0077] refer to Figure 7In the figure, the vertical axis represents the photon count N, which represents the number of X-ray photons received by the detector per unit time. The horizontal axis represents the time axis of signal acquisition. N1: corresponds to the first filtering state (Ni filter state), where the absorption edge energy E1 is greater than or equal to the upper limit of the target characteristic X-ray energy range; N2: corresponds to the second filtering state (Co filter state), where the absorption edge energy E2 is less than or equal to the lower limit of the target characteristic X-ray energy range. The waveform presents a stable cycle of N2 low pulse → N1 high pulse → N2 low pulse → N1 high pulse, corresponding to the alternating entry of the two filtering regions on the spectral modulation device (such as a rotating chopper) into the optical path, achieving dynamic switching between the two filtering states at a preset frequency.

[0078] Furthermore, it can be observed in the waveform diagram that there is a vertical transition segment with a photon count of 0 between the low pulse N2 and the high pulse N1 (and before N1 falls back to N2). This region is the dead zone. It directly corresponds to the opaque blocking part 34 in the patent structure (located between the first filter area 32 and the second filter area 33 of the rotating light-chopping wheel 31). Alternatively, the detection unit 20 can continuously collect signals, but the signal processing unit 40 can actively stop data acquisition and discard the sampled data during the preset transition time period, thus "erasing" the transition signal at the software level.

[0079] In a specific embodiment, in the spectral dynamic modulation system of the copper target (CuTarget, Kα≈8.04keV) X-ray diffractometer, the filter region is Ni and Co, and the intensity of the original signal collected by the detection unit 20 changes periodically over time: High(Ni)→Zero(Spoke)→Low(Co)→Zero(Spoke).

[0080] Figure 8 This is a flowchart illustrating another signal extraction method provided in an embodiment of the present invention. (Refer to...) Figure 8 The step "S120, acquiring detection data corresponding to the first filtering state and the second filtering state" in the above embodiment can be further refined as follows: Record the arrival time of each incident X-ray photon; The modulation period is determined according to a preset frequency, and the arrival time of all photons is mapped to the corresponding phase within the modulation period. Based on the phase, the first signal strength corresponding to the first filtering state and the second signal strength corresponding to the second filtering state are obtained by accumulating the signals respectively. Furthermore, step "S130, obtaining the signal of the target feature X-ray energy range based on the difference between the detection data of the first filtering state and the detection data of the second filtering state" can be further refined as follows: Calculate the weighted difference between the first signal strength and the second signal strength.

[0081] For details not covered in this embodiment, please refer to the previous embodiment.

[0082] like Figure 8 As shown, another signal extraction method may include the following specific steps: S210. The first and second filtering states are alternately applied to the X-ray beam in the optical path according to a preset frequency.

[0083] S221. Record the arrival time of each incident X-ray photon.

[0084] The arrival time can be understood as the moment when the X-ray photon is captured by the detection unit, and its function is to provide a time stamp for subsequent phase mapping.

[0085] Specifically, for the time-driven photon counting detector (detection unit 20), when each incident X-ray photon is detected, the detection unit 20 records the arrival time and energy information of the photon, and transmits this data to the signal processing unit 40 in the form of a data stream.

[0086] S222. Determine the modulation period according to the preset frequency, and map the arrival time of all photons to the corresponding phase within the modulation period.

[0087] The modulation period can be understood as the time required for a spectral modulation device (such as a rotating chopper) to complete one full filtering cycle; the phase can be understood as the relative time position of a photon within the modulation period.

[0088] Specifically, the signal processing unit calculates the modulation period T based on the preset modulation frequency. Utilizing the periodic variation characteristics of X-ray intensity, the rotation frequency and initial phase of the chopper wheel are calculated from the acquired photon arrival time series using an autocorrelation algorithm or phase-locked loop technology. Subsequently, the arrival time t of each photon is mapped to the corresponding phase φ=mod(t,T) within the modulation period. Based on the interval of phase φ (corresponding to the first filter region 32, the second filter region 33, or the opaque blocking part 34), it can be determined which filtering state the photon was acquired under.

[0089] S223. Accumulate the signals according to the phase to obtain the first signal strength corresponding to the first filtering state and the second signal strength corresponding to the second filtering state.

[0090] The first signal strength can be understood as the sum of the counts or the cumulative intensity of all photons determined to be acquired under the first filtering state; the second signal strength is the corresponding cumulative value of photons acquired under the second filtering state.

[0091] Specifically, the signal processing unit 40 accumulates photons mapped to the first filter state phase interval to obtain a first signal intensity I1; and accumulates photons mapped to the second filter state phase interval to obtain a second signal intensity I2. Simultaneously, photons within the dead time are automatically discarded.

[0092] S231. Calculate the weighted difference between the first signal strength and the second signal strength.

[0093] The weighted difference can be understood as multiplying the first signal intensity I1 and the second signal intensity I2 by weight coefficients and then subtracting them. Its function is to compensate for the slight difference in background transmittance under the two filtering states and further optimize the background subtraction effect.

[0094] Specifically, the calculated weighted difference signal is the pure signal of the extracted target feature X-ray energy range, which can be used for subsequent X-ray diffraction pattern analysis. This software folding method does not require the detector to have gating function and can automatically remove invalid photons during the transition time period. It has the advantages of low hardware requirements, flexible data processing, and high signal-to-noise ratio.

[0095] In an optional embodiment, the detection unit operates in a time-driven photon counting mode, recording the arrival time of each incident X-ray photon without the need for external hardware triggering; the signal processing unit 40 calculates the chopping frequency and phase using an autocorrelation algorithm, performs timestamp folding, and automatically discards invalid photons mapped to the phase corresponding to the opaque blocking part 34.

[0096] Specifically, the detection unit operates in a time-driven photon counting mode. In this mode, the detector runs continuously without relying on external hardware triggering, recording a timestamp (i.e., arrival time) for each incident X-ray photon. All timestamped photon data streams are transmitted to the signal processing unit 40. The signal processing unit 40 processes the received photon arrival time sequence using an autocorrelation algorithm. Since the X-ray intensity exhibits a strictly periodic change with the rotation of the chopper wheel, the autocorrelation algorithm can automatically calculate the current chopping frequency (i.e., modulation period) and the initial phase corresponding to the optical path state (first filter region 32 or second filter region 33), without the need for an additional photoelectric encoder or hardware synchronization signal.

[0097] After calculating the modulation period, the signal processing unit performs a timestamp folding operation on the arrival time of each photon, mapping each timestamp to the corresponding phase within a single modulation period. Based on preset phase ranges (e.g., the first filter region 32 corresponds to a phase range of 0°-120°, the second filter region 33 corresponds to 120°-240°, and the opaque blocking part 34 corresponds to 240°-360°; more complex phase ranges can be found by referring to…), the signal processing unit performs a timestamp folding operation on the arrival time of each photon, mapping each timestamp to the corresponding phase within a single modulation period. Figure 3(As shown in the chopper), the signal processing unit 40 automatically classifies photons: those mapped to the phase of the first filter region are classified as "first state photons", those mapped to the phase of the second filter region are classified as "second state photons", and those mapped to the phase of the opaque blocking part are determined to be invalid photons and are automatically discarded, and do not participate in subsequent differential calculations.

[0098] Figure 9 This is a flowchart illustrating another signal extraction method provided in an embodiment of the present invention, referred to... Figure 9 The step "S130, obtaining the signal of the target feature X-ray energy range based on the difference between the detection data of the first filtering state and the detection data of the second filtering state" in the above embodiment can be further refined as follows: Calculate the intensity ratio coefficient k between the first and second filtering states; where k satisfies the condition that the background signal without diffraction peaks... =0; where, The signal strength under the first filtering state. The signal strength under the second filtering state; According to the formula I= Calculate the signal in the characteristic X-ray energy range of the target.

[0099] For details not covered in this embodiment, please refer to the previous embodiment.

[0100] like Figure 9 As shown, another signal extraction method may include the following specific steps: S310. Apply the first filtering state and the second filtering state to the X-ray beam in the optical path alternately according to the preset frequency.

[0101] S320. Obtain detection data corresponding to the first filtering state and the second filtering state.

[0102] S331. Calculate the intensity ratio coefficient k between the first filtering state and the second filtering state.

[0103] Where k satisfies the condition of background signal without diffraction peaks =0, The signal strength under the first filtering state. The signal intensity is in the second filtering state; the intensity ratio coefficient k is a proportional factor used to compensate for the difference in transmittance of the background signal in the two filtering states, and is used to make the weighted difference between the two filtering states in the background signal without diffraction peaks zero, so that the target feature X-ray signal can be extracted more purely during sample measurement.

[0104] Specifically, in the unfiltered state without a sample, the signal intensities corresponding to the two filtering states are measured respectively: the signal intensity in the first filtering state and the signal intensity in the second filtering state. Then, the intensity ratio coefficient k is calculated using these two unfiltered signals. When there is no diffraction peak, the background signal is the only source. The background transmittance is different in the two filtering states, and direct subtraction will leave a residual value. After introducing k, the two signals are weighted, so that the weighted difference of the unfiltered signals without diffraction peak is 0. When the sample is actually measured, the background and irrelevant signals will be completely canceled out, leaving only the effective signal of the target characteristic X-rays.

[0105] S332, According to the formula I= Calculate the signal in the characteristic X-ray energy range of the target.

[0106] Specifically, during actual sample measurement, the sample signal intensity I1 under the first filtering state and the sample signal intensity I2 under the second filtering state are obtained. Using a pre-calibrated intensity ratio coefficient k, I = is calculated. Since k has already compensated for the difference in background transmittance under the two filtering states, background noise (including the continuous spectrum, sample fluorescence, etc.) is effectively subtracted in I, and the extracted signal is the pure target feature X-ray diffraction signal. This method does not require prior assumption that the backgrounds under the two filtering states are completely identical, but rather uses actual calibration coefficients for precise compensation, further improving the accuracy of background suppression and the reliability of signal extraction.

[0107] In a specific embodiment, calculating the intensity ratio coefficient k between the first filtering state and the second filtering state includes: Obtain the background signal intensity under the first filtering state and the background signal intensity under the second filtering state when there are no diffraction peaks; According to the formula: Calculate the strength ratio coefficient k, where, The average background signal strength under the first filtering state. The average background signal strength under the second filtering state.

[0108] Specifically, under the condition of no diffraction peaks (i.e., no signal conforming to Bragg's equation when X-rays pass through the sample at certain angles), the signal intensity in the first filtered state was measured. Signal strength in the second filtering state Since there is no sample diffraction signal in the optical path at this time, the detector only receives the background signal of the light source (including the continuous spectrum, air scattering, etc.) after passing through the two filters. Through calculation... This allows for complete cancellation of the two background signals when no diffraction peaks are present. The coefficient k is used to compensate for the difference in transmittance of the two filters for background and non-target X-rays; it is an inherent calibration parameter of the system and can be determined and stored during the debugging phase. During actual sample measurement, after the two signals are weighted and subtracted by k, the background and interference signals are simultaneously subtracted, retaining only the differential signal of the target characteristic X-rays generated by the sample. This effectively suppresses baseline drift and improves the signal-to-noise ratio and measurement purity of the diffraction signal.

[0109] Note that the above description is merely a preferred embodiment of the present invention and the technical principles employed. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and various obvious changes, readjustments, combinations, and substitutions can be made without departing from the scope of protection of the present invention. Therefore, although the present invention has been described in detail through the above embodiments, the present invention is not limited to the above embodiments, and may include many other equivalent embodiments without departing from the concept of the present invention, the scope of which is determined by the scope of the appended claims.

Claims

1. A dynamic modulation detection system for X-ray spectroscopy, characterized in that, include: An X-ray source, positioned towards the sample, is used to emit X-rays; The detection unit is used to receive the detection signal reflected by the sample; A spectral modulation device is disposed in the optical path between the X-ray source and the detection unit, and is used to alternately apply a first filtering state and a second filtering state to the X-ray beam in the optical path at a preset frequency; A signal processing unit, electrically connected to the detection unit, is used to acquire detection data corresponding to the first filtering state and the second filtering state, and to acquire a signal of the target characteristic X-ray energy range based on the difference between the detection data of the first filtering state and the detection data of the second filtering state; wherein the first filtering state has a first absorption edge energy E1, the second filtering state has a second absorption edge energy E2, and the first absorption edge energy E1 is greater than or equal to the upper limit of the target characteristic X-ray energy range, and the second absorption edge energy E2 is less than or equal to the lower limit of the target characteristic X-ray energy range.

2. The X-ray spectral dynamic modulation detection system according to claim 1, characterized in that, The spectral modulation device is disposed in the diffraction optical path between the sample and the detection unit.

3. The X-ray spectral dynamic modulation detection system according to claim 1, characterized in that, The spectral modulation device is further configured to block the X-ray signal reflected from the sample from reaching the detection unit during the transition time between the first filtering state and the second filtering state; or The signal processing unit is also used to stop data acquisition during the transition period.

4. The X-ray spectral dynamic modulation detection system according to claim 3, characterized in that, The spectral modulation device includes a rotating chopper wheel; The rotating light-cutting wheel is provided with alternating first and second filter regions. The first filter region has a first absorption edge energy E1, and the second filter region has a second absorption edge energy E2.

5. The X-ray spectral dynamic modulation detection system according to claim 4, characterized in that, The rotating light-cutting wheel also includes an opaque blocking part; The opaque blocking part is disposed between the first filtering area and the second filtering area, and the width of the blocking part is greater than the spot width of the X-ray incident on the rotating chopper.

6. The X-ray spectral dynamic modulation detection system according to claim 4, characterized in that, The first filtering area is provided with a first filter, and the second filtering area is provided with a second filter; The first filter contains nickel, and the second filter contains cobalt.

7. The X-ray spectral dynamic modulation detection system according to claim 6, characterized in that, The first filtering region is provided with a plurality of first filters; the second filtering region is provided with a plurality of second filters; For the first filtering region, the product of the attenuation coefficient and the effective thickness of each of the first filters is equal to each other; For the second filtering region, the product of the attenuation coefficient and the effective thickness of each second filter is equal to each other; wherein the effective thickness is the optical path length through which X-rays penetrate the filter.

8. The X-ray spectral dynamic modulation detection system according to claim 7, characterized in that, The first filter and the second filter each have an angle adjustment structure for adjusting the effective thickness of the first filter or the second filter.

9. The X-ray spectral dynamic modulation detection system according to claim 6, characterized in that, The first filter and the second filter are configured with a preset thickness ratio, so that the ratio of their X-ray transmittance in the background energy region of non-target characteristic rays remains a stable constant, so that the signal processing unit can extract the intensity ratio coefficient and perform background difference calculation based on the stable constant; wherein, the difference or ratio between the value of the stable constant and 1 is less than or equal to a preset threshold.

10. The X-ray spectral dynamic modulation detection system according to claim 6, characterized in that, It also includes a static pre-filter, wherein the absorption edge energy of the static pre-filter is greater than or equal to the upper limit of the X-ray energy range of the target feature.

11. The X-ray spectral dynamic modulation detection system according to claim 6, characterized in that, The first or second filtering region further includes a parylene vacuum-deposited film layer.

12. A signal extraction method, characterized in that, The X-ray spectral dynamic modulation detection system according to any one of claims 1 to 11 comprises: The X-ray beam is subjected to a first filtering state and a second filtering state alternately in the optical path according to a preset frequency. Acquire detection data corresponding to the first filtering state and the second filtering state; Based on the difference between the detection data of the first filtered state and the detection data of the second filtered state, the signal of the target feature X-ray energy range is obtained.

13. The signal extraction method according to claim 12, characterized in that, Acquiring detection data corresponding to the first filtering state and the second filtering state includes: Record the arrival time of each incident X-ray photon; The modulation period is determined according to the preset frequency, and the arrival time of all photons is mapped to the corresponding phase within the modulation period; Based on the phase, the first signal strength corresponding to the first filtering state and the second signal strength corresponding to the second filtering state are obtained by accumulating them respectively. Based on the difference between the detection data in the first filtered state and the detection data in the second filtered state, the signal of the target feature X-ray energy range is obtained, including: Calculate the weighted difference between the first signal strength and the second signal strength.

14. The signal extraction method according to claim 13, characterized in that, The detection unit operates in a time-driven photon counting mode, and the step of recording the arrival time of each incident X-ray photon does not require external hardware triggering; the signal processing unit calculates the chopping frequency and phase using an autocorrelation algorithm, performs timestamp folding, and automatically discards invalid photons mapped to the corresponding phase of the opaque blocking part.

15. The signal extraction method according to claim 12, characterized in that, Based on the difference between the detection data in the first filtered state and the detection data in the second filtered state, the signal of the target feature X-ray energy range is obtained, including: Calculate the intensity ratio coefficient k between the first and second filtering states; where k satisfies the condition that the background signal without diffraction peaks... =0; where, The signal strength under the first filtering state. The signal strength under the second filtering state; According to the formula I= Calculate the signal within the X-ray energy range characteristic of the target.

16. The signal extraction method according to claim 15, characterized in that, The calculation of the intensity ratio coefficient k between the first and second filtered states includes: Obtain the background signal intensity under the first filtering state and the background signal intensity under the second filtering state when there are no diffraction peaks; According to the formula: Calculate the strength ratio coefficient k, where, The average background signal strength under the first filtering state. The average background signal strength under the second filtering state.

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