Small double-focusing mass spectrum imaging system for space and use method

Abstract

The invention relates to the technical field of instruments and meters, in particular to a small-sized double-focusing mass spectrum imaging system for space and a use method, the system comprises an ion source, a coding plate, an electrostatic analyzer, a magnetic analyzer and an FOP detector, the ion source adopts a symmetrical magnetic field structure, and a cathode emission device and a hot filament are respectively located at two ends of the ion source; the coding plate is arranged right in front of the ion source; the electrostatic analyzer is composed of two coaxial cylindrical electrodes; the magnetic field structure of the magnetic analyzer is a direct asymmetric fan-shaped magnetic field; the electrostatic analyzer and the magnetic analyzer are combined in a reverse serial connection manner; the FOP detector adopts a micro-channel plate + fluorescent screen + CMOS camera imaging mode. According to the invention, the limitation of large sizes of ion beams and imaging light spots thereof under a conventional single-slit outlet structure of a mass spectrometer is overcome by adopting a coding aperture mode, so that the mass resolution of the mass spectrum imaging device is remarkably improved, the sensitivity is high, the imaging speed is high, the signal-to-noise ratio is high, and the detection of lower-content substances is realized.

Description

Technical Field

[0001] This application relates to the field of instrumentation technology, and more specifically, to a small dual-focusing mass spectrometry imaging system for space use and its method of use. Background Technology

[0002] Space exploration, as the cornerstone of studying planetary evolution and utilizing extraterrestrial resources, is leading humanity on a new journey to explore the mysteries of the universe. Among various mass spectrometers, dual-focusing mass spectrometers (DFMS) are characterized by high resolution and strong quantitative capabilities, making them highly advantageous in isotope measurement and source tracing. However, due to constraints imposed by launch payload mass and the extreme space environment, miniaturization design has led to a significant degradation in the core performance of DFMS instruments used in space exploration.

[0003] Currently reported space mass spectrometers are increasingly showing the common problem of insufficient resolution, and their sensitivity is also insufficient to meet the requirements for accurate determination of isotope abundance.

[0004] How to break through the existing technical framework and achieve a synergistic improvement in resolution and sensitivity has become a major challenge restricting the development of miniaturized DFMS spatial mass spectrometry. Summary of the Invention

[0005] This application provides a small dual-focusing mass spectrometry imaging system for space use and a method of using it, which introduces two-dimensional coded aperture technology from spectroscopy into the field of mass spectrometry analysis, and solves the problem of mutual constraint between light flux and resolution in traditional imaging.

[0006] To achieve the above objectives, this application provides a small dual-focusing mass spectrometry imaging system for space applications, comprising an ion source, an encoding plate, an electrostatic analyzer, a magnetic analyzer, and an FOP detector, wherein: the ion source adopts a symmetrical magnetic field structure, with the cathode emitting device and the hot filament located at opposite ends of the ion source; the encoding plate is positioned directly in front of the ion source; the electrostatic analyzer consists of two coaxial cylindrical electrodes; the magnetic field structure of the magnetic analyzer is a direct-fiber asymmetric sector magnetic field; the electrostatic analyzer and the magnetic analyzer are connected in reverse series; and the FOP detector employs a microchannel plate + fluorescent screen + CMOS camera imaging method.

[0007] Furthermore, the encoding board adopts an S-type Hadamard matrix template or a 0-1 pseudo-random measurement matrix template.

[0008] Furthermore, the encoder board has a aperture of a micro silicon wafer slit array.

[0009] Furthermore, during operation, the free electrons generated by the heating of the filament in the ion source bombard neutral gas molecules to produce an ion beam. After being modulated by the encoding plate, the beam sequentially enters the electrostatic analyzer and the magnetic analyzer. After being focused and deflected, the beam is finally imaged in the FOP detector.

[0010] In addition, this application also provides a method for using a small dual-focusing mass spectrometry imaging system for space applications, comprising the following steps: Step 1: Based on the sparsity characteristics of mass spectrum signals in a specific transform domain, establish a sparse representation model and construct a projection measurement matrix and encoding board with optimal cross-correlation characteristics; Step 2: The ion beam generated by the ion source is modulated by the encoder and then enters the electrostatic analyzer and the magnetic analyzer in sequence. After being focused and deflected, it is projected onto the corresponding detection position of the FOP detector. Step 3: Based on the equation set composed of the mass spectrometry signals at each detection position and the coding plate of the coding aperture, develop an efficient and robust orthogonal matching pursuit reconstruction algorithm to achieve accurate data cube restoration under noise interference and obtain the mass spectrometry image of the target sample. Step 4: Combine the mass spectrometry image of the target sample with the morphology of the target sample obtained through the camera, and use image processing methods to perform image fusion to obtain a mass spectrometry image of the target sample with visible morphology.

[0011] This application provides a small dual-focusing mass spectrometry imaging system and its usage method for space applications, which have the following advantages: This application overcomes the limitations of large ion beam and imaging spot size in conventional single-slit mass spectrometers by employing an coded aperture method, significantly improving the mass resolution of the mass spectrometry imaging device, with an optimal resolution of 0.02 amu. The coded aperture consists of a high-precision array of open and closed apertures, achieving a fusion of the high-resolution characteristics of pinhole imaging and the flux advantages of porous structures. It features high sensitivity, fast imaging speed, high signal-to-noise ratio, and enables the detection of substances with lower concentrations. Attached Figure Description

[0012] The accompanying drawings, which form part of this application, are used to provide a further understanding of the application and to make other features, objects, and advantages of the application more apparent. The illustrative embodiments and descriptions of this application are used to explain the application and do not constitute an undue limitation of the application.

[0013] In the attached diagram: Figure 1 This is a schematic diagram of the structure of a small dual-focusing mass spectrometry imaging system for space according to an embodiment of this application; Figure 2 This is a schematic diagram of an S-cyclic matrix template provided according to an embodiment of this application; Figure 3 This is a schematic diagram of a 0-1 pseudo-random measurement matrix template provided according to an embodiment of this application; In the diagram: 1-Ion source, 2-Encoding board, 3-Electrostatic analyzer, 4-Magnetic analyzer, 5-FOP detector. Detailed Implementation

[0014] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort should fall within the scope of protection of the present application.

[0015] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate for the embodiments of this application described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0016] In this application, the terms "upper," "lower," "left," "right," "front," "rear," "top," "bottom," "inner," "outer," "middle," "vertical," "horizontal," "lateral," and "longitudinal" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. These terms are primarily for the purpose of better describing this application and its embodiments, and are not intended to limit the indicated device, element, or component to having a specific orientation, or to be constructed and operated in a specific orientation.

[0017] Furthermore, in addition to indicating location or positional relationship, some of the aforementioned terms may also have other meanings. For example, the term "above" may also be used in some cases to indicate a certain dependency or connection relationship. Those skilled in the art can understand the specific meaning of these terms in this application based on the specific circumstances.

[0018] In addition, the term "multiple" should mean two or more.

[0019] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0020] like Figure 1As shown, this application provides a small dual-focusing mass spectrometry imaging system for space use, including an ion source 1, an encoding plate 2, an electrostatic analyzer 3, a magnetic analyzer 4, and an FOP detector 5. The ion source 1 employs a symmetrical magnetic field structure, with the cathode emitting device and the hot filament located at opposite ends of the ion source 1. The encoding plate 2 is positioned directly in front of the ion source 1. The electrostatic analyzer 3 consists of two coaxial cylindrical electrodes. The magnetic field structure of the magnetic analyzer 4 is a direct-fiber asymmetric fan-shaped magnetic field. The electrostatic analyzer 3 and the magnetic analyzer 4 are connected in reverse series. The FOP detector 5 uses a microchannel plate + fluorescent screen + CMOS camera imaging method.

[0021] Specifically, the space-use miniature dual-focusing mass spectrometry imaging system provided in this application overcomes the limitations of traditional dual-focusing mass spectrometry in terms of resolution and sensitivity, achieving high resolution, high sensitivity, and rapid imaging capabilities while maintaining a miniaturized design. It is suitable for in-situ mass spectrometry analysis in extreme environments such as space exploration. Specifically, an electron bombardment ion source 1 generates an ion beam; an encoding plate 2 is used for spatial modulation of the ion beam; an electrostatic analyzer 3 and a magnetic analyzer 4 are used for energy and mass screening and focusing of the ions; and an FOP detector 5 is used to receive and image the modulated ion signal.

[0022] Furthermore, such as Figure 2-3 As shown, the encoding plate 2 adopts an S-type Hadamard matrix S-cyclic matrix template or a 0-1 pseudo-random measurement matrix template, and combines the inverse transformation of the corresponding encoding template with computational imaging techniques to achieve mass spectrometry imaging. In the embodiments of this application, the encoding plate 2 preferably adopts an S-type Hadamard matrix S-cyclic matrix template or a 0-1 pseudo-random measurement matrix template. Since they are both two-dimensional patterns, the FOP detector 5 can capture the encoded mixed information of the entire field of view in a single measurement, instead of collecting it point by point as in point scanning, which greatly improves the imaging speed. Furthermore, compared with the traditional single-slit structure, they have an aperture ratio of about 50%, which increases the ion flux by 1-2 orders of magnitude, directly improving the signal-to-noise ratio and sensitivity.

[0023] More specifically, the S-cyclic matrix template has the best signal-to-noise ratio and stable and efficient reconstruction, making it suitable for scenarios with extreme requirements for sensitivity and signal-to-noise ratio; while the 0-1 pseudo-random measurement matrix template has universal reconstruction guarantee and is effective for various sparse signals, making it suitable for scenarios where the signal characteristics of the sample to be measured are unknown or variable and the strongest robustness is required.

[0024] Furthermore, the encoder plate 2 has a micro-silicon wafer slit array. The encoder aperture consists of a high-precision array of open and closed apertures, which greatly increases the total ion flux while maintaining the narrow width of each slit (thus ensuring high resolution). This increases the ion throughput by 1 to 2 orders of magnitude while keeping the resolution unchanged.

[0025] Furthermore, during operation, the free electrons generated by the heating of the filament in the ion source 1 bombard neutral gas molecules to produce an ion beam. After being modulated by the encoding plate 2, the beam sequentially enters the electrostatic analyzer 3 and the magnetic analyzer 4. After being focused and deflected, the beam is finally imaged in the FOP detector 5.

[0026] Furthermore, this application also provides a method using a small dual-focusing mass spectrometry imaging system for space applications. Based on compressed sensing theory, a novel encoding and decoding function system for mass spectrometry data is constructed. Simultaneously, based on a two-step iterative shrinkage threshold algorithm, a quantitative relationship model between convergence speed and ill-conditioning degree is established to achieve synergistic optimization of the accuracy and efficiency of mass spectrometry data cube reconstruction. The specific steps include the following: Step 1: Based on the sparsity characteristics of mass spectrum signals in a specific transform domain, establish a sparse representation model and construct a projection measurement matrix and encoding board 2 with optimal cross-correlation characteristics; Step 2: The ion beam generated by ion source 1 is modulated by encoder plate 2 and then enters electrostatic analyzer 3 and magnetic analyzer 4 in sequence. After being focused and deflected, it is projected onto the corresponding detection position of FOP detector 5. Step 3: Based on the equation set composed of the mass spectrometry signals at each detection position and the coding plate 2 with the coding aperture, develop an efficient and robust orthogonal matching pursuit reconstruction algorithm to achieve accurate data cube restoration under noise interference and obtain the mass spectrometry image of the target sample. Step 4: Combine the mass spectrometry image of the target sample with the morphology of the target sample obtained through the camera, and use image processing methods to perform image fusion to obtain a mass spectrometry image of the target sample with visible morphology.

[0027] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A compact dual focusing mass spectrometry imaging system for space use, characterized by, The ion source, the encoding plate, the electrostatic analyzer, the magnetic analyzer and the FOP detector are included, wherein: The ion source adopts a symmetric magnetic field structure, and a cathode emission device and a hot filament are respectively located at two ends of the ion source; The encoding plate is arranged in front of the ion source; The electrostatic analyzer is composed of two coaxial cylindrical electrodes; the magnetic field structure of the magnetic analyzer is a straight-shooting asymmetric fan-shaped magnetic field; the electrostatic analyzer and the magnetic analyzer adopt a reverse series connection combination mode; The FOP detector adopts a micro-channel plate + fluorescent screen + CMOS camera imaging mode.

2. The compact dual focusing mass spectrometry imaging system for space use according to claim 1, characterized in that, The encoding plate adopts an S-cyclic matrix template of an S-shaped Hadamard matrix or a 0-1 pseudo-random measurement matrix template.

3. The compact dual focusing mass spectrometry imaging system for space use according to claim 2, characterized in that, The aperture of the encoding plate is a micro-silicon slit array.

4. The compact dual focusing mass spectrometry imaging system for space use according to claim 3, characterized in that, In operation, free electrons generated by heating of the hot filament in the ion source bombard neutral gas molecules to generate an ion beam, which is modulated by the encoding plate, sequentially enters the electrostatic analyzer and the magnetic analyzer, and is finally imaged on the FOP detector after focusing and deflection.

5. A method of using the compact dual focusing mass spectrometry imaging system for space use according to claim 4, characterized in that, The method comprises the following steps: Step 1: a sparse representation model is established based on the sparse characteristics of mass spectrum signals in a specific transform domain, a projection measurement matrix and an encoding plate with optimal cross-correlation characteristics are constructed; Step 2: an ion beam generated by the ion source sequentially enters the electrostatic analyzer and the magnetic analyzer after being modulated by the encoding plate, and is finally shot on the corresponding detection position of the FOP detector after focusing and deflection; Step 3: a high-efficiency robust orthogonal matching pursuit reconstruction algorithm is developed according to the equation group composed of the mass spectrum signals of each detection position and the encoding plate of the encoding aperture, accurate data cube recovery under noise interference is realized, and a mass spectrum image of the target sample is obtained; Step 4: the mass spectrum image of the target sample is combined with the morphology of the target sample obtained by the camera, image fusion is performed by using an image processing method, and a mass spectrum image with visible morphology of the target sample is obtained.

Images