Compact broadband grating spectrometer and spectral measurement method thereof

Abstract

The invention relates to the technical field of spectral measurement, in particular to a compact broadband grating spectrometer and a spectral measurement method thereof.The compact broadband grating spectrometer comprises a vacuum chamber, a broadband light source, a slit assembly, a multi-grating control tower assembly and a detector assembly, and the multi-grating control tower assembly is arranged in the vacuum chamber; comprising a plurality of concave-surface variable-pitch diffraction gratings which are arranged on a grating turret mechanism and have different center line densities, the concave-surface variable-pitch diffraction gratings are switched between a working position and a non-working position along with rotation of the grating turret mechanism, and a grating mirror receives light beams from an incident window, disperses the light beams and reflects the light beams to an emergent window; and the detector assembly receives the dispersed spectral signal and realizes focusing detection. The multi-grating configuration capable of being rotatably switched is utilized, the wave band coverage range is effectively expanded on the premise that a complex mechanical structure is not introduced, the concave-surface variable-pitch gratings have the dispersion and focusing functions, the light path structure is simplified, aberration is reduced, and miniaturization and high resolution of the system are achieved.

Description

Technical Field

[0001] This invention relates to the field of spectral measurement technology, and in particular to a compact wideband grating spectrometer and its spectral measurement method. Background Technology

[0002] Grating spectrometers are important tools for analyzing material composition and studying light source characteristics, and have wide applications in fields such as laser plasma diagnostics, synchrotron radiation, and materials science. Spectroscopic measurements in the 1–80 nm wide band (extreme ultraviolet to soft X-ray band) are particularly important for cutting-edge scientific research; however, the core performance and structural design of traditional grating spectrometers face many challenges in this band.

[0003] First, in terms of optical performance, the grating design of traditional grating spectrometers exhibits significant low diffraction efficiency over a wide wavelength range, resulting in insufficient signal acquisition sensitivity. Limited by manufacturing processes, insufficient grating line density or poor uniformity is common, severely impacting wavelength separation accuracy and hindering improvements in spectral resolution. Furthermore, the silicon-based materials used in transmission gratings exhibit significant absorption of photons over a wide wavelength range, causing additional losses in optical efficiency.

[0004] Secondly, in terms of instrument structure, grazing incidence spectrometers designed for high-resolution measurements are typically bulky (e.g., the McPherson 248 / 310, with a focal plane of 40mm), making them unsuitable for miniaturized applications such as space exploration and laboratory micro-area analysis, which have strict requirements for equipment size. The complex internal optical path design of grazing incidence spectrometers often includes redundant mirror-grating coordination mechanisms, further increasing the equipment size and reducing stability.

[0005] Furthermore, in terms of wide-band measurement implementation, existing spectrometers mostly adopt a single-grating design, which makes it difficult to achieve both wide band coverage and high resolution. To achieve wide band coverage, it is usually necessary to switch multiple gratings or introduce complex mechanical structures, which not only leads to poor optical path stability and low measurement efficiency, but also increases the complexity and cost of the system.

[0006] With the development of related technologies and the continuous expansion of application scenarios, miniaturization, on-site application, wide spectral coverage, and high resolution have become important directions for the future development of grating spectrometers. Therefore, there is an urgent need to design wide-band grating spectrometers that feature easy grating replacement, wide-band measurement capabilities, compact structure, and low cost, so as to provide comprehensive and accurate raw data for scientific research and industrial testing in a more portable and efficient manner. Summary of the Invention

[0007] This invention provides a compact wideband grating spectrometer and its spectral measurement method to solve the aforementioned defects of traditional grating spectrometers in wideband spectral measurement.

[0008] This invention provides a compact broadband grating spectrometer, comprising a vacuum chamber, a slit assembly, a multi-grating tower assembly, and a detector assembly. The vacuum chamber has an entrance window and an exit window disposed on its wall, the entrance window and the exit window being opposite to each other and respectively serving to form the beginning and end of an optical path within the vacuum chamber. The slit assembly is fixed inside the entrance window of the vacuum chamber to form an entrance slit. The multi-grating tower assembly is disposed within the vacuum chamber and includes a rotatable grating turret mechanism and multiple grating mirrors disposed on the grating turret mechanism. Each grating mirror is a concave variable-pitch diffraction grating with different centerline densities. The grating mirror switches between a working position and a non-working position as the grating turret mechanism rotates. In the working position, the grating mirror is located on the optical path inside the vacuum chamber. The grating mirror receives the light beam from the entrance window and disperses the beam, reflecting it towards the exit window. The detector assembly is movably connected to the outside of the exit window of the vacuum chamber and is used to receive the spectral signal dispersed by the grating mirror and form a focus. The detector assembly is coupled with a microchannel plate to enhance the spectral signal.

[0009] According to the present invention, a compact wideband grating spectrometer is provided, wherein the slit width of the slit assembly is adjustable, and the slit assembly is mounted on a multi-degree-of-freedom adjustable bracket on the inner wall of the vacuum chamber, and is adapted to allow the incident light beam emitted by the wideband light source to irradiate the surface of the grating mirror in the working position at an incident angle of 87° to 88.6° by adjusting the angle of the slit assembly.

[0010] According to the present invention, a compact broadband grating spectrometer is provided, wherein the grating turret mechanism includes a sealing flange, a drive motor, a rotary displacement stage, and multiple mirror mounts. The sealing flange is connected to the vacuum chamber; the drive motor is located outside the vacuum chamber, and the output shaft of the drive motor passes through the sealing flange; the rotary displacement stage is connected to the output shaft of the drive motor, and the rotary displacement stage has a regular polyhedral structure; the multiple mirror mounts are fixed to multiple circumferential sides of the rotary displacement stage for detachably mounting the grating mirrors.

[0011] According to the present invention, a compact broadband grating spectrometer is provided, wherein the rotary displacement stage is a regular triangular prism structure, and three concave variable-pitch diffraction gratings with different center line densities are correspondingly mounted on the three sides of the rotary displacement stage via the mirror frame. The rotary displacement stage is adapted to be driven by the drive motor to rotate 120° or 240° to switch one of the three concave variable-pitch diffraction gratings with different center line densities to the working position.

[0012] According to the present invention, a compact wideband grating spectrometer is provided, wherein the center line densities of three concave variable-spacing diffraction gratings are 300 grooves / mm, 1200 grooves / mm and 2400 grooves / mm, respectively, which are used to cover the long-wave, medium-wave and short-wave bands; the surfaces of the three concave variable-spacing diffraction gratings are all coated with a gold reflective layer.

[0013] According to the present invention, a compact wideband grating spectrometer is provided, wherein the detector assembly includes a two-dimensional precision moving platform and a CCD detector. The two-dimensional precision moving platform is movably connected to the outside of the exit window of the vacuum chamber. The two-dimensional precision moving platform is adapted to form a displacement variation in a first direction toward or away from the vacuum chamber, and to form a displacement variation in a second direction perpendicular to the first direction. The CCD detector is fixed on the two-dimensional precision moving platform and is used to receive the spectral signal dispersed by the grating mirror and form a focus. The microchannel plate is coupled to the side of the CCD detector facing the vacuum chamber.

[0014] According to the present invention, a compact wideband grating spectrometer is provided, wherein a receiving ring is provided on the two-dimensional precision moving platform, the CCD detector is installed on the side of the receiving ring facing away from the vacuum chamber, and the side of the receiving ring facing the vacuum chamber is connected to the exit window of the vacuum chamber through a flexible corrugated tube.

[0015] According to the present invention, a compact broadband grating spectrometer is provided, wherein the vacuum chamber includes a cylindrical stainless steel chamber, the top of which is covered and sealed by a rubber sealing ring; the bottom of which is provided by the multi-grating tower assembly; the entrance window and the exit window are disposed on the side wall of the stainless steel chamber, and an observation window and a vacuum pumping adapter flange are also provided on the side wall of the stainless steel chamber, wherein the vacuum chamber is externally connected to a vacuum pump assembly through the vacuum pumping adapter flange.

[0016] The present invention also provides a spectral measurement method applicable to the compact wideband grating spectrometer described in any one of the above-mentioned methods, the spectral measurement method comprising the following steps S1 to S5.

[0017] S1. Start the vacuum pump unit to pump the air pressure inside the vacuum chamber to a vacuum state.

[0018] S2. Based on the band information of the broadband light source, drive the multi-grating tower assembly to rotate and switch the grating mirrors with the corresponding center line density to the working position.

[0019] S3. The light emitted by the broadband light source is controlled to form a beam through the entrance window and slit assembly of the vacuum chamber and irradiate the grating mirror in the working position in a grazing incidence manner.

[0020] S4. After the beam is dispersed and focused by the grating mirror, it is directed towards the exit window of the vacuum chamber to form a spectrum.

[0021] S5. Control the detector assembly to move along the dispersion direction at the exit window of the vacuum chamber, so that the receiving surface of the detector assembly coincides with the focusing position of the spectrum, and obtain spectral data.

[0022] This invention provides a compact wideband grating spectrometer. Composite light emitted from a wideband light source enters a vacuum chamber through an entrance window, where a narrow beam is formed by a slit assembly. This beam illuminates a grating mirror in its working position via grazing incidence. A concave variable-pitch grating simultaneously performs dispersion and focusing functions, reflecting light of different wavelengths towards the exit window. The detector assembly moves to match its receiving surface with the focusing position of the spectrum, thereby capturing high-resolution spectral line information. This invention utilizes a rotatable, switchable multi-grating configuration to effectively expand the band coverage without introducing complex mechanical structures, significantly improving measurement efficiency and system stability. The concave variable-pitch grating combines dispersion and focusing functions, simplifying the optical path structure, reducing aberrations, and facilitating system miniaturization and high resolution. The spectrometer adopts a compact vacuum chamber design, overcoming the bulky problem of traditional grazing incidence spectrometers, making it better suited for space-constrained micro-area analysis and on-site detection applications. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0024] Figure 1 This is a front view schematic diagram of the compact wideband grating spectrometer provided by the present invention.

[0025] Figure 2 This is a top view schematic diagram of the compact wideband grating spectrometer provided by the present invention.

[0026] Figure 3 This is a schematic diagram of the structure of the multi-grating tower assembly provided by the present invention.

[0027] Figure 4 This is a schematic diagram of the connection structure of the vacuum chamber and detector assembly provided by the present invention.

[0028] Figure 5 This is a simulation diagram of the optical system in an embodiment of the present invention.

[0029] Figure 6This is a schematic diagram illustrating the influence of the entrance slit width and diffraction order on the resolution of the optical system in an embodiment of the present invention.

[0030] Figure 7 This is a curve showing the variation of the root mean square radius of the spectral direction with wavelength in an embodiment of the present invention.

[0031] Figure 8 This is the spectral emission pattern of the strontium target surface in the range of 4~15nm in this embodiment of the invention.

[0032] Reference numerals: 1. Vacuum chamber; 11. Stainless steel chamber; 12. Cover plate; 13. Rubber sealing ring; 14. Observation window; 15. Vacuum transfer flange; 2. Multi-grating tower assembly; 21. Grating turret mechanism; 211. Sealing flange; 212. Drive motor; 213. Rotary displacement stage; 214. Frame; 22. Grating mirror; 3. Detector assembly; 31. Two-dimensional precision moving platform; 32. Receiving ring; 33. Flexible corrugated tubing. Detailed Implementation

[0033] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. 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 are within the scope of protection of this invention.

[0034] The following is combined Figures 1 to 8 This invention describes a compact wideband grating spectrometer and its spectral measurement method.

[0035] One embodiment of the present invention provides a compact broadband grating spectrometer, combined with Figure 1 and Figure 2As shown, the compact broadband grating spectrometer includes a vacuum chamber 1, a slit assembly, a multi-grating tower assembly 2, and a detector assembly 3. The vacuum chamber 1 has an entrance window and an exit window on its wall, which are arranged opposite to each other to form the beginning and end of the optical path within the vacuum chamber 1, respectively. A broadband light source is positioned outside the entrance window of the vacuum chamber 1 to provide the detection beam. The slit assembly is fixed inside the entrance window of the vacuum chamber 1 to form the entrance slit. The multi-grating tower assembly 2 is located within the vacuum chamber 1 and includes a rotatable grating turret mechanism 21 and a detector assembly 3. Multiple grating mirrors 22 on the structure 21 are concave variable-spacing diffraction gratings with different centerline densities. The grating mirrors 22 switch between working and non-working positions as the grating turret mechanism 21 rotates. In the working position, the grating mirrors 22 are located on the optical path inside the vacuum chamber 1. The grating mirrors 22 receive the light beam from the entrance window and disperse the light beam, reflecting it towards the exit window. The detector assembly 3 is movably connected to the outside of the exit window of the vacuum chamber 1 to receive the spectral signal dispersed by the grating mirrors 22 and form a focus. The detector assembly 3 is coupled with a microchannel plate to enhance the spectral signal.

[0036] It is understood that this compact wideband grating spectrometer, as described in this embodiment, employs a highly integrated vacuum optical path structure and a switchable multi-grating tower assembly to achieve high-performance spectral measurements over a wide wavelength range. The compact wideband grating spectrometer includes a vacuum chamber 1, with an entrance window and an exit window arranged opposite each other on the walls of the chamber 1 to form an optical path channel; a wideband light source is placed outside the entrance window to provide a detection beam; a slit assembly is fixed inside the entrance window to form an entrance slit; a multi-grating tower assembly 2 is located inside the vacuum chamber 1, on which multiple concave variable-spacing diffraction gratings (grating mirrors 22) with different centerline densities are mounted, and a specific grating can be switched to a working position by rotating the grating turret mechanism 21, thereby dispersing the incident beam and reflecting it towards the exit window; a detector assembly 3 is movably connected to the outside of the exit window to receive the dispersed spectral signal and achieve focused detection.

[0037] The composite light emitted by the broadband light source enters the vacuum chamber 1 through the entrance window. A narrow beam is formed by the slit assembly and illuminates the grating mirror 22 in a grazing incidence manner. The concave variable-pitch grating simultaneously performs dispersion and focusing functions, reflecting light of different wavelengths towards the exit window. The detector assembly 3 moves to match its receiving surface with the focusing position of the spectrum, thereby capturing high-resolution spectral information. The entire optical path operates in a vacuum environment, reducing the attenuation of extreme ultraviolet and soft X-ray signals due to gas absorption.

[0038] It is important to understand that, addressing the shortcomings of traditional spectrometers in wide-band measurements, such as low diffraction efficiency, complex structure, large size, and limited band coverage, this compact wide-band grating spectrometer, utilizing a rotatable and switchable multi-grating configuration, effectively expands the band coverage range without introducing complex mechanical structures, significantly improving measurement efficiency and system stability. The concave variable-pitch grating combines dispersion and focusing functions, simplifying the optical path structure, reducing aberrations, and facilitating system miniaturization and high resolution. Furthermore, the concave variable-pitch grating, with its grating density distributed polynomially along the meridional direction, not only provides dispersion but also eliminates defocus and coma through optimized variable-pitch parameters, achieving flat-field focusing of the spectrum on the detector plane. (focusing), which allows the detector assembly 3 of the present invention to directly use a planar CCD detector, without the need for the complex curved guide rails or bent detectors required by traditional Roland circular spectrometers, thereby greatly reducing the size and simplifying the mechanical structure; the spectrometer as a whole adopts a compact vacuum chamber design, overcoming the problem of the large size of traditional grazing incidence spectrometers, making it better suited to space-constrained micro-area analysis and on-site detection applications.

[0039] In some embodiments of the compact wideband grating spectrometer of the present invention, the slit width of the slit assembly is adjustable in the range of 0.05 mm to 0.2 mm. The slit assembly is mounted on a multi-degree-of-freedom adjustment bracket on the inner wall of the vacuum chamber 1, and is adapted to allow the incident beam emitted by the wideband light source to irradiate the surface of the grating mirror 22 in the working position at an incident angle of 87° to 88.6° by adjusting the angle of the slit assembly.

[0040] Understandably, the slit assembly, as a key component initiating the optical path, in this embodiment, has a core structure comprising a double-bladed slit with a width precisely adjustable within the range of 0.05mm to 0.2mm. Its opening and closing are achieved via an external micrometer-driven mechanism. The entire slit body is not directly fixed but is mounted on a multi-degree-of-freedom adjustment bracket fixed to the inner wall of the vacuum chamber 1. This adjustment bracket typically includes precision threaded set screws (with springs for reset) for translation in the X, Y, and Z directions, as well as kinematic mechanisms or flexible hinges for adjusting the pitch and yaw angles. During implementation, translation adjustment is first used to ensure that the physical center of the slit coincides with the theoretical optical axis; subsequently, the pitch and yaw angles are finely adjusted to ensure that the plane of the slit is perpendicular to the optical path, and that its length direction (Y direction) is strictly parallel to the grating's scribe line direction.

[0041] The precise installation and adjustment method of the slit assembly in this embodiment has two significant advantages. First, in terms of optical performance, it ensures that the incident beam can be grazing-incident at a precise incident angle of 87° to 88.6° (preferably 87°) onto the grating surface, thereby maximizing the excitation and utilization of the grating's high reflectivity in the extreme ultraviolet band, laying the foundation for high signal-to-noise ratio spectral detection. Second, in terms of system performance, by eliminating astigmatism and spectral line tilt caused by slit tilt or inaccurate orientation, the system's limiting resolution is directly improved, making it possible to achieve a high resolution of 0.03 nm. Simultaneously, multi-degree-of-freedom adjustment also compensates for manufacturing and assembly errors, enhancing the system's reliability and repeatability.

[0042] In some embodiments of the compact broadband grating spectrometer of the present invention, see Figure 3 As shown, the grating turret mechanism 21 includes a sealing flange 211, a drive motor 212, a rotary displacement stage 213, and multiple lens holders 214. The sealing flange 211 is connected to the vacuum chamber 1. The drive motor 212 is located outside the vacuum chamber 1, and the output shaft of the drive motor 212 passes through the sealing flange 211. The rotary displacement stage 213 is connected to the output shaft of the drive motor 212 and has a regular polyhedral structure. Multiple lens holders 214 are fixed on multiple circumferential sides of the rotary displacement stage 213 for detachably mounting the grating mirrors 22.

[0043] Combination Figure 1 and Figure 3 As shown, it can be understood that the grating turret mechanism 21 of the multi-grating turret assembly 2 constitutes the core drive and support structure for achieving rapid and precise switching of gratings. Specifically, it consists of a sealing flange 211, a drive motor 212, a rotary displacement stage 213, and multiple lens mounts 214. The sealing flange 211 is fixedly connected to the bottom of the vacuum chamber 1, forming a reliable vacuum sealing interface. The drive motor 212 is placed outside the chamber in the atmospheric environment, and its output shaft extends into the vacuum chamber 1 through the sealing flange 211. The rotary displacement stage 213 is directly connected to the motor output shaft, and its main body is a regular polyhedron structure (such as a regular triangular prism). Multiple lens mounts 214 are respectively fixed on the various sides of this regular polyhedron for detachably mounting grating mirrors 22 of different specifications. In implementation, the drive motor 212 receives a control signal and drives the rotary displacement stage 213 to precisely rotate a specific angle (e.g., 120° or 240°), thereby transporting the lens mount 214 carrying a specific grating to a preset working position.

[0044] This embodiment, through its "external motor and internal transmission" layout, ensures both a high vacuum level in the chamber and reliable drive operation. The cooperation between the regular polyhedral rotary displacement stage 213 and multiple mirror mounts 214 allows for the integration of multiple gratings within a compact space, enabling on-demand access. This replaces the complex multi-grating mechanical switching mechanism found in traditional spectrometers, significantly simplifying the system. The detachable mounting method of the grating mirrors 22 not only facilitates grating replacement and maintenance but also endows the spectrometer with high flexibility and scalability. Users can flexibly configure the grating combinations on the mirror mounts 214 according to specific band and resolution requirements, enabling a single device to adapt to diverse measurement tasks.

[0045] See again for some specific examples. Figure 3 As shown, the rotary displacement stage 213 is a regular triangular prism structure. Three concave variable-pitch diffraction gratings with different center line densities are correspondingly mounted on the three sides of the rotary displacement stage 213 via the mirror frame 214. The rotary displacement stage 213 is adapted to be driven to rotate 120° or 240° by the drive motor 212 to switch one of the three concave variable-pitch diffraction gratings with different center line densities to the working position.

[0046] It is understood that the rotary stage 213 in this example is specifically a regular triangular prism structure. Three concave variable-pitch diffraction gratings with different centerline densities are fixedly mounted on the three outer surfaces of this geometry via a precision mirror frame 214. During implementation, the control system drives a drive motor 212 located outside the vacuum chamber 1 via commands. The motor's output shaft drives the regular triangular prism rotary stage 213 to perform precise angular displacement. By controlling its rotation by 120° or 240° through a preset program, any one of the three gratings can be accurately and stably positioned to the preset working optical path position, thereby achieving rapid switching of measurement bands. This example highly integrates three gratings covering different bands (such as long-wave, medium-wave, and short-wave) onto a compact tower, replacing the complex linear displacement or replacement mechanisms in traditional spectrometers with simple rotary motion, greatly simplifying the operation process and shortening the band switching time. The symmetrical rotational positioning mechanism of the regular triangular prism structure ensures a high degree of repeatability of the grating's working position after each switch, effectively avoiding optical path changes and performance fluctuations caused by grating positioning deviations, ensuring the accuracy and consistency of measurement data, and providing a solid mechanical guarantee for achieving wide-band, high-stability spectral measurements.

[0047] Specifically, the center line densities of the three concave variable-pitch diffraction gratings are 300 grooves / mm, 1200 grooves / mm, and 2400 grooves / mm, respectively, to cover the long-wave, medium-wave, and short-wave bands; the surfaces of the three concave variable-pitch diffraction gratings are all coated with a gold reflective layer. In this example, the three concave variable-pitch diffraction gratings constitute a gradient combination covering long-wave, medium-wave, and short-wave bands. During implementation, when the spectrometer needs to measure different wavelength bands, the rotating tower switches the corresponding linear density gratings to the working position: the 300 grooves / mm grating, due to its weaker dispersion capability, is suitable for resolving long-wavelength spectral lines and is mainly used for dispersing and focusing wide-band beams with wavelengths ranging from 20 nm to 80 nm; the 1200 grooves / mm grating, as the mainstay in the mid-wavelength band, is mainly used for dispersing and focusing wide-band beams with wavelengths ranging from 5 nm to 20 nm; and the 2400 grooves / mm high linear density grating, with its strong dispersion capability, is specifically used to resolve the fine spectral structure of short-wavelength bands and is mainly used for dispersing and focusing wide-band beams with wavelengths ranging from 1 nm to 7 nm. The three different linear density gratings, switched by the tower, form a seamless wide-band measurement system, effectively solving the inherent contradiction that a single grating cannot simultaneously maintain high resolution and high diffraction efficiency across a wide wavelength range. Furthermore, all grating surfaces are uniformly coated with a gold reflective layer, typically 30 nm thick. This gold reflective layer has a much higher reflectivity than other materials in the extreme ultraviolet to soft X-ray bands, significantly improving the system's light throughput and signal acquisition sensitivity. By using three concave, variable-spacing diffraction gratings in this example to create a gradient combination covering long, medium, and short wavelengths, the compact spectrometer in this example achieves near-theoretical signal-to-noise ratio and resolution across a wide wavelength range of 1–80 nm, overcoming the dilemma of wavelength coverage and performance trade-offs inherent in traditional equipment that relies on a single grating.

[0048] In some embodiments of the compact broadband grating spectrometer of the present invention, see Figure 4 As shown, the detector assembly 3 includes a two-dimensional precision moving platform 31 and a CCD detector (not shown in the figure). The two-dimensional precision moving platform 31 is movably connected to the outside of the exit window of the vacuum chamber 1. The two-dimensional precision moving platform 31 is adapted to form a displacement change in a first direction that is close to or away from the vacuum chamber 1, and to form a displacement change in a second direction that is perpendicular to the first direction. The CCD detector is fixed on the two-dimensional precision moving platform 31 and is used to receive the spectral signal dispersed by the grating mirror 22 and form a focus. A microchannel plate is coupled to the side of the CCD detector facing the vacuum chamber 1 to enhance the optical signal.

[0049] Understandably, detector assembly 3 is primarily used to achieve accurate capture and efficient detection of spectral signals. See also... Figure 4As shown, the detector assembly 3 includes a high-precision two-dimensional precision moving platform 31, which is movably connected to the outside of the exit window of the vacuum chamber 1. The two-dimensional precision moving platform 31 has two independent degrees of freedom: firstly, it can drive the entire CCD detector to move along a direction perpendicular to the exit window (i.e., towards or away from the vacuum chamber 1) to precisely adjust the focal plane position; secondly, it can drive the CCD detector to move along a direction parallel to the exit window (i.e., the dispersion direction of the spectrum). The CCD detector is rigidly fixed to the two-dimensional platform, and a microchannel plate is optically coupled to its side facing the vacuum chamber 1 to enhance the signal. During implementation, by controlling the two-dimensional precision moving platform 31, the receiving surface of the CCD detector can be precisely aligned with the focusing position of different wavelengths and scanned along the dispersion direction to record the complete spectral lines. Simultaneously, the microchannel plate performs electron multiplication on the incident extreme ultraviolet or soft X-ray photons, achieving signal enhancement.

[0050] It is important to understand that the two-dimensional precision moving platform 31 in this embodiment achieves active control of the CCD detector's focal plane position and scanning reception, overcoming the image plane curvature problem caused by the fixed focal plane in traditional spectrometers. This ensures that a clear, focused spectral image can be obtained throughout the entire dispersion range, thereby fully utilizing the inherent resolution of the optical system. The coupling between the microchannel plate and the CCD detector constitutes a highly sensitive detection front end, enabling the detector assembly 3 to possess strong gain capabilities. This converts extremely weak photon signals into measurable electrical signals, greatly improving the system's detection sensitivity and signal-to-noise ratio under low-throughput conditions such as the extreme ultraviolet band, providing hardware support for capturing weak spectral signals and achieving rapid measurements.

[0051] Furthermore, combined Figure 2 and Figure 4 As shown, a receiving ring 32 is provided on the two-dimensional precision moving platform 31. A CCD detector is installed on the side of the receiving ring 32 facing away from the vacuum chamber 1. The side of the receiving ring 32 facing the vacuum chamber 1 is connected to the exit window of the vacuum chamber 1 through a flexible corrugated tube 33.

[0052] It is understood that in the detector assembly 3 structure of this embodiment, a rigid receiving ring 32 is fixed on the two-dimensional precision moving platform 31, and the CCD detector is installed on the side of the receiving ring 32 facing away from the vacuum chamber 1. A flexible metal corrugated tube connects the side of the receiving ring 32 facing the vacuum chamber 1 and the exit window of the vacuum chamber 1, forming a sealed transition optical path. During implementation, when the two-dimensional precision moving platform 31 moves for focusing or scanning, the flexible corrugated tube 33 undergoes elastic deformation, ensuring the vacuum sealing of the optical path without generating significant reaction force or constraint on the platform's precision displacement. This allows the CCD detector to freely and accurately position itself to the optimal focal plane while maintaining a vacuum environment. It is important to understand that the flexible corrugated tube 33 must be made of a highly flexible, low-stiffness material, or the design of the two-dimensional precision moving platform must have a load margin reserved to overcome the vacuum negative pressure, so as to ensure that the platform can still maintain micron-level positioning accuracy under the action of vacuum suction. As a dynamic sealing element, the flexible corrugated tube 33 allows the two-dimensional precision moving platform 31 and the CCD detector to move in two-dimensional space to accurately track the spectral focal plane, while ensuring that the entire optical path from the exit window of the vacuum chamber 1 to the receiving surface of the CCD detector is in a high vacuum state, effectively preventing the absorption of extreme ultraviolet light by the atmosphere and ensuring the integrity of the signal.

[0053] In some specific embodiments of the compact wideband grating spectrometer of the present invention, see also Figure 4 As shown, the vacuum chamber 1 includes a cylindrical stainless steel chamber 11. A cover plate 12 is installed on the top of the stainless steel chamber 11 and sealed by a rubber sealing ring 13. A multi-grating tower assembly 2 is installed at the bottom of the stainless steel chamber 11. An entrance window and an exit window are provided on the side wall of the stainless steel chamber 11. An observation window 14 and a vacuum transfer flange 15 are also provided on the side wall of the stainless steel chamber 11. The vacuum chamber 1 is connected to a vacuum pump group through the vacuum transfer flange 15.

[0054] Understandably, as the core carrier of the spectrometer, the structural design and sealing reliability of vacuum chamber 1 are of paramount importance. Combined with... Figure 2 and Figure 4 As shown, the main body of the chamber is a cylindrical stainless steel chamber 11. This shape can effectively withstand atmospheric pressure and optimize the internal space. The top of the stainless steel chamber 11 is equipped with a removable cover plate 12 via a flange, and a rubber sealing ring 13 is used to achieve static vacuum sealing, which facilitates the installation and maintenance of internal optical components. The bottom of the stainless steel chamber 11 is specifically designed to pass through and seal the rotating shaft of the multi-grating tower assembly 2, forming a dynamic sealing interface. In addition, entrance windows, exit windows, observation windows 14, and evacuation transition flanges 15 are precisely arranged on the side walls of the chamber. During implementation, the vacuum pump unit evacuates the chamber through the evacuation transition flange 15 to maintain its internal air pressure at 4 × 10⁻⁶.-4 A high vacuum of around Pa provides the necessary conditions for optical transmission in the extreme ultraviolet band.

[0055] It is important to understand that the cylindrical stainless steel body combined with the openable top cover design, while ensuring structural strength and vacuum sealing, greatly facilitates the assembly, adjustment, and daily maintenance of internal optical components. The observation window 14 on the side wall provides an intuitive view for optical path alignment and system status monitoring, improving the efficiency of debugging and diagnosis. This highly integrated chamber design in this embodiment compactly houses all optical components in a stable vacuum environment, effectively eliminating the influence of air absorption on soft X-ray and extreme ultraviolet signals, and solving the problem of bulky size in traditional large spectrometers. This enables the instrument to be miniaturized, portable, and applied in demanding micro-area analysis scenarios.

[0056] In another aspect, the present invention provides a spectral measurement method applicable to the compact wideband grating spectrometer in any of the above embodiments or examples. In some embodiments of the spectral measurement method of the present invention, the method specifically includes the following steps S1 to S5.

[0057] S1. Start the vacuum pump unit to evacuate the air pressure inside the vacuum chamber 1 to a vacuum state.

[0058] S2. Based on the band information of the broadband light source, drive the multi-grating tower assembly 2 to rotate and switch the grating mirror 22 with the corresponding center line density to the working position.

[0059] S3. The light emitted by the broadband light source is controlled to form a beam through the entrance window and slit assembly of the vacuum chamber 1 and irradiate the grating mirror 22 in the working position in a grazing incidence manner.

[0060] S4. After the beam is dispersed and focused by the grating mirror 22, it is directed towards the exit window of the vacuum chamber 1 to form a spectrum.

[0061] S5. Control the detector assembly 3 to move along the dispersion direction at the exit window of the vacuum chamber 1, so that the receiving surface of the detector assembly 3 coincides with the focusing position of the spectrum, and obtain spectral data.

[0062] The spectral measurement method in this embodiment is based on the aforementioned compact wideband grating spectrometer. It completes the entire process from wideband light source to spectral data acquisition through intelligent grating switching and precise optical path control. Specifically, firstly, the vacuum chamber 1 is evacuated to a vacuum state using a vacuum pump unit. Then, based on the wavelength information of the light source under test, the multi-grating tower is automatically rotated to switch the linear density-matched grating to its working position. Subsequently, in the established vacuum environment, the light beam emitted by the light source is collimated through a slit and then illuminated onto the grating with high precision in a grazing incidence manner. The concave grating utilizes its inherent dispersion and focusing characteristics to disperse the composite light, and then the dispersed spectrum is injected into a 40mm diameter microchannel plate (MCP), coupled to a CCD detector through a coherent fiber bundle. Finally, by controlling the CCD detector to move along the dispersion direction, its receiving surface is precisely matched to the focal plane position of different wavelengths, thereby capturing complete spectral information.

[0063] Understandably, the spectral measurement method in this embodiment addresses the issue of a single grating's inability to simultaneously achieve both wide spectral band coverage and high resolution. Through a multi-grating intelligent switching mechanism, it achieves optimal matching across different spectral bands, extending the effective measurement range while maintaining high resolution. Compared to traditional methods relying on complex mechanical structures or manual grating replacement, this embodiment significantly improves measurement efficiency and automation. The coordinated design of the vacuum optical path and grazing incidence angle effectively suppresses light signal attenuation in the extreme ultraviolet band, enhancing measurement sensitivity. The entire process is completed on a highly integrated, compact platform, overcoming the limitations of traditional grazing incidence spectrometers, which are bulky and difficult to adapt to field applications. This provides an efficient and reliable wide-band spectral measurement method for laboratory micro-area analysis, space exploration, and other scenarios.

[0064] Furthermore, in some embodiments of the spectral measurement method of the present invention, before step S1 above, a simulation optimization step of the optical system is included, which includes the following steps S100 to S700.

[0065] S100. Based on the Zemax optical simulation platform, an optical system simulation model of a wideband grating spectrometer is established. The optical system simulation model includes a point source corresponding to the wideband light source, an entrance slit corresponding to the slit assembly, a concave variable-pitch diffraction grating corresponding to the grating mirror 22, and a CCD detector corresponding to the detector assembly 3.

[0066] S200. Set the initial system parameters of the optical system simulation model, including the wavelength range of the point light source, the aperture, the radius of curvature of the concave variable-pitch diffraction grating, the distance from the concave variable-pitch diffraction grating to the entrance slit, and the distance from the concave variable-pitch diffraction grating to the CCD detector.

[0067] S300: Based on a custom surface model program, a dynamic link library file for diffraction algorithm was developed to simulate a concave variable-pitch diffraction grating. The dynamic link library file for diffraction algorithm was then called in the Zemax optical simulation platform to achieve ray tracing simulation of the variable-pitch grating.

[0068] S400 utilizes the Zemax optical simulation platform with multiple structural configurations to simulate the diffraction paths of gratings with different centerline densities at different wavelengths, and sets the diffraction order, incident angle, and grating spacing coefficient as variables.

[0069] S500. In the evaluation function editor of the Zemax optical simulation platform, the root mean square radius of the dot plot or the wavefront error is used as the evaluation standard to optimize the optical system simulation model. The optimization variables include: the slit width of the slit assembly, the variable spacing coefficient of the grating mirror 22, and the focal plane position of the detector assembly 3.

[0070] S600: Through iterative optimization, evaluate the actual resolution of the spectrometer until the minimum wavelength interval that the wideband grating spectrometer can resolve reaches the preset index, and obtain the parameter combination that reaches the preset index, where the preset index is a minimum resolvable wavelength interval of 0.03nm.

[0071] S700. Based on the optimized parameter combination, determine the width of the slit assembly, the variable spacing coefficient of the grating mirror 22, and the focal plane positioning of the detector assembly 3 in the actual wideband grating spectrometer, so as to guide the subsequent physical assembly and debugging.

[0072] It is understood that in the spectral measurement method of this embodiment, an optical system simulation optimization step is introduced before the actual spectral measurement is performed. Based on the Zemax optical simulation platform, a high-fidelity wideband grating spectrometer virtual prototype is constructed, and its process covers the entire process from model building to parameter guidance.

[0073] First, in steps S100-S400, the simulation environment is set up. A sequence model including a point source, an entrance slit, a concave variable-pitch diffraction grating, and a CCD detector is established in Zemax. To address the insufficient support of commercial Zemax for this type of special grating, a custom diffraction algorithm dynamic link library (DLL) file is developed in step S300, enabling accurate simulation of ray tracing of the variable-pitch grating under grazing incidence conditions. Subsequently, using the multi-structure configuration function, the diffraction paths of different gratings (300 grooves / mm, 1200 grooves / mm, 2400 grooves / mm) at multiple characteristic wavelengths from 5 to 20 nm are simulated simultaneously. The diffraction order, incident angle, and grating variable-pitch coefficient are set as key variables, laying the foundation for system optimization.

[0074] Subsequently, in the core optimization phase (steps S500~S600), the slit width, grating spacing coefficient, and detector focal plane position are collaboratively optimized using the root mean square (RMS) radius of the dot plot or wavefront error as the core evaluation criteria. For example... Figure 5 As shown, by analyzing the dot plots of two similar wavelengths (e.g., 8nm and 8.03nm) with different slit widths, the maximum permissible slit width can be intuitively determined while ensuring resolution (clearly separated light spots), thus achieving the optimal balance between resolution and luminous flux. Figure 6 As shown, by studying the diffraction effect of different grating line densities on the same wavelength (e.g., 13.5 nm), it was verified that high line density gratings can produce a larger diffraction angle, thus providing higher dispersion and theoretical resolution. The optimization process is an iterative loop, with the ultimate goal of enabling the system to resolve a minimum wavelength interval of 0.03 nm, as preset. Figure 7 The curve showing the variation of the RMS radius in the spectral direction with wavelength is a key basis for evaluating the optimization effect. The curve is generally flat and the value is small, indicating that the aberration of the system is well controlled in the whole band. The RMS radius is the smallest at 13.6nm, which means that the system has reached the optimal performance at this wavelength.

[0075] Finally, in step S700, the optimized parameter combination (such as a slit width of 0.05 mm, a specific variable spacing coefficient, and the optimal focal plane position of the detector) is used as a precise basis for guiding physical assembly and debugging. Figure 8 The actual measured spectrum of the strontium target shown demonstrates the accuracy and effectiveness of the simulation optimization results, with clearly separated spectral lines.

[0076] This embodiment significantly reduces the cost and time of physical trial and error by predicting and optimizing system performance in a virtual environment, ensuring that the final spectrometer can stably meet the design specifications and achieving a closed loop from theoretical design to high-performance physical realization.

[0077] The simulation optimization steps of the optical system of the present invention will be described in detail below with specific examples.

[0078] First, based on the Zemax optical simulation platform, a simulation model of the optical system of a broadband grating spectrometer was established. Initial parameters of the optical system, such as wavelength and aperture, were set, with the wavelength range selected as 5–20 nm and the aperture as 50 mm. A custom laminar flow pattern was used to replicate the diffraction grating surface. Using a custom DLL provided by Zemax as a template, the diffraction algorithm for the concave variable-spacing diffraction grating was written as a C++ program and a 64-bit DLL file was generated.

[0079] The specific steps are as follows: This model involves a pure reflection grating, therefore the transmission order is ignored. The basic equation for the light reflected by the diffraction grating is: ,in (Dimensionless integer) is a diffraction order. It's the wavelength. It is the spacing between continuous grooves or unit cells in a grating. It is the angle of incidence. It is the first The reflection angle of one diffraction order. With vacuum wavelength For different concepts, if the incident and reflected rays propagate through a medium with a refractive index n≠1, then The notation convention used is: the angle of incidence is positive, and the angle of reflection for the 0th order (specular reflection) is positive (…). The higher positive diffraction order is farther from the surface normal vector. In this model, the specified grating constant... Actually slightly smaller than the formula Used For concave gratings, the grating constant is interpreted as the projected distance between grooves in the tangent plane.

[0080] Given the data (coordinates, orientation angle) of the incident ray on the previous surface; for calculating the intersection point with the spherical substrate, the same analytical algorithm as the one used in Zemax's built-in sphere is employed to accurately calculate the intersection point of the ray with the spherical substrate without raster lines. The radial distance at the intersection point is calculated by determining the radial position and the grating's domain. and the boundary of the set effective area of ​​the grating (such as In comparison, the variable pitch characteristic of a grating is usually defined within the effective region, and the effective grating region processing is added (adding variable pitch phase, i.e., when...). This means that the light falls within the area affected by the grating lines; since the variable spacing coefficient of the variable-pitch grating introduces complex phase modulation (usually described by a higher-order polynomial), the optical path function is introduced to precisely analyze the intersection point: The corresponding equivalent height perturbation is: By using its tangent plane for local linearization approximation, and combining the equation of this tangent plane with the equation of the ray line, a set of simple linear equations can be solved to obtain the final estimated intersection point between the ray and the approximate grating surface. Nearby, The formula is as follows: In calculating the incident angle, a precise local incident angle is obtained by using the direction of the incident ray and the normal direction, and the reflection efficiency of the gold coating and the subsequent diffraction direction are evaluated using the built-in Fresnel formula. Finally, in calculating diffraction, the direction of the diffracted rays is calculated by applying rigorous diffraction equations (such as the grating equation) based on the variable spacing coefficient of the variable-spacing grating, the diffraction order, the wavelength, and the precise incident angle. However, the grating equation under grazing incidence requires special handling of coordinate transformations.

[0081] We use first-order diffraction light for detection, and take... And the angle of incidence Therefore, the expression for the center wavelength of the scattering center is: The grating's radius of curvature is 998.8 mm, which translates to 39.323 inches here. During the experimental measurement, the center wavelength of the measured spectrum is given by the microchannel plate (MCP) control software, and the step counter displays the number of spectrometer drums X [inch]. The MCP and CCD move along the track to the corresponding positions to perform the spectral measurement. Thus, by satisfying specific conditions (such as sufficiently accurate approximation of the tangent plane and reasonable selection of the prediction point), and avoiding time-consuming iterative calculations, we have achieved accurate tracking of the light path of a concave variable-pitch grating under grazing incidence conditions, with controllable error.

[0082] To perform ray tracing simulation for a particular type of grating, select this DLL in the sequence mode grating type in Zemax. The specific steps are as follows: Select "USERSURF" for surface type; select "Infinity" for thickness; set the corresponding parameters for the grating location in Zemax as "1, 222.654, 0.99863, 0.99263, 5E-03"; set the image plane at the paraxial focus, change the Solve type to "Marginal RayHeight", and adjust the thickness so that the edge ray height on the image plane is 0, which is the paraxial focus.

[0083] Modeling was performed in the sequential ray tracing mode of Zemax to simulate a wide-band grating spectrometer. In the Zemax data editing panel, parameters were entered: the radius of curvature of the grating (R), the distance from the grating to the slit (r1), the distance from the grating to the image plane (r2), and the glass material. Specific steps are as follows: the radius of curvature was set to "Infinity"; the distance from the grating to the slit was set to "237"; the distance from the grating to the image plane was set to "-235"; the glass type was set to "H-BK7"; and the grating beam-splitting coating was set to "Au".

[0084] Using COORDBRK ensures that the wavelength is incident on the grating surface at a predetermined angle of 87°. After setting the basic optical component parameters, adjustments are made sequentially based on the optical system principle of the concave variable-pitch grating. The diffraction patterns of the minimum and maximum wavelength beams are measured and received by a CCD detector, and corresponding parameters are set at multiple structural locations. The wavelength spacing is reduced to 0.03 nm, and the diffraction pattern is observed. Further optimization is performed by adjusting relevant functions in the evaluation function editor until the optical system can resolve a minimum wavelength spacing of 0.03 nm, thus initially achieving the simulation of the entire optical system.

[0085] The simulation diagram of the entire optical system is as follows: Figure 5 As shown, based on the optical path system simulation, the resolving power of the grating in this optical system can be analyzed. By changing a corresponding parameter according to actual needs and performing the simulation, the impact of that parameter on the overall resolving power of the optical system can be obtained, enabling the evaluation of system optimization and reliability.

[0086] Using the obtained grating recording parameters, the system was modeled and optimized in the optical design software Zemax, resulting in second-order diffraction patterns for six specific wavelengths in the 5-20 nm range, second-order diffraction patterns for wavelengths of 8 nm and 8.03 nm, and first-order diffraction patterns for wavelengths of 8 nm and 8.03 nm. Figure 6 It can be seen that when diffracting at wavelengths of 8 nm and 8.03 nm, the 8 nm and 8.03 nm diffraction spots in the second-order diffraction pattern are finer and more separated than those in the first-order diffraction pattern, resulting in better resolution. This indicates that higher-order diffraction can achieve better resolution. As shown in the figure, the spectrometer can resolve a minimum wavelength interval of 0.03 nm. The incident slit is placed at the focal plane of the grating, 235 mm from the light source. The system's object-side numerical aperture and field of view determine the size of the spot illuminating the slit, while the slit width determines the amount of light energy entering the system. During the simulation, we studied the changing trend of the diffraction pattern distribution of 8 nm and 8.03 nm light waves by changing the slit width in the Y direction. Figure 6 As shown. Among them, Figure 6 The widths of the slits in the Y direction corresponding to (a~c) are 0.2, 0.1, and 0.05 mm, respectively. (From...) Figure 6 It can be seen that when the slit width in the Y direction is 0.2 mm, the incident light, after diffraction and convergence by the grating, does not overlap but the resolution is poor. When the slit width is reduced to 0.1 mm, the two diffracted light spots become thinner and separate. When the slit width is further changed to make it smaller, the diffracted light spots become thinner and separate, and the spacing between the spots increases continuously, resulting in better and better resolution.

[0087] The grating line density N is inversely proportional to the grating constant d; the higher the grating line density, the lower the grating constant. Using gratings with line densities of 300, 600, and 1600 grooves / mm, diffraction of 13.5 nm light was performed. The optical path distribution of the first-order diffraction of 13.5 nm light is shown below. Figure 6 As shown. Observation Figure 6 It can be seen that for the same wavelength and the same order of diffraction, the diffraction angle gradually increases with the increase of grating line density. That is, under the same conditions, the smaller the grating constant, the larger the diffraction angle corresponding to the same wavelength.

[0088] Finally, after further optimization of the quality assessment parameters for spectral imaging, the following results were obtained. Figure 7 The figure shows the curve of the root mean square (RMS) radius of the spectral direction as a function of wavelength. Figure 7 It can be seen that for the structural design of this spectrometer system, the root mean square radius of the spectral direction reaches its minimum at a wavelength of 13.6 nm, that is, the system performance of the spectrometer is optimal at this wavelength.

[0089] Based on the optimization results of the above process, the experimental parameters were adjusted, and a laser plasma source (Sr plasma source) was used to generate extreme ultraviolet radiation in the 4~15nm wavelength range. The vacuum level inside the cavity was maintained at approximately 4×10⁻⁶ using a mechanical pump and a molecular pump assembly. - 4 Pa is used to reduce the impact of gas absorption on the optical signal; the rotating displacement stage is a triangular prism structure, with concave variable-spacing laminar flow replication diffraction gratings of 300 grooves / mm, 1200 grooves / mm and 2400 grooves / mm respectively mounted on the three sides, and the grating surface is coated with a 30nm gold film to enhance reflectivity; the slit width can be precisely adjusted in the range of 0.05~0.2mm, and the opening distance is controlled by a micrometer; a VID240-ZYLA-5.5-USB3 vacuum CCD detector is used, with a front-end coupled microchannel plate (MCP) for signal enhancement. The detector is mounted on a two-dimensional precision moving platform, which can move in the dispersion direction (Y-axis) and scanning direction (X-axis) to capture the complete spectral lines.

[0090] Under vacuum conditions, the spectrometer was calibrated using a standard extreme ultraviolet light source of known wavelength to ensure accurate correlation between the grating rotation angle and the detector position. The spectral emission of the strontium target surface within the range of 4–15 nm, as captured by the spectrometer, was successfully measured. Figure 8 As shown. Through actual testing, the compact broadband grating spectrometer of this invention meets the design specifications in terms of resolution, band coverage, and stability, with an actual resolution of 0.03 nm, consistent with the Zemax simulation results (…). Figure 5 (Consistent)

[0091] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A compact broadband grating spectrometer, characterized in that, include: A vacuum chamber (1) is provided with an entrance window and an exit window on its cavity wall. The entrance window and the exit window are arranged opposite to each other and are used to form the beginning and end of the optical path in the vacuum chamber (1), respectively. A slit assembly, fixed to the inside of the entrance window of the vacuum chamber (1), is used to form an entrance slit; A multi-grating tower assembly (2) is disposed in the vacuum chamber (1). The multi-grating tower assembly (2) includes a rotatable grating turret mechanism (21) and a plurality of grating mirrors (22) disposed on the grating turret mechanism (21). The plurality of grating mirrors (22) are concave variable-pitch diffraction gratings with different center line densities. The grating mirrors (22) switch between working and non-working positions as the grating turret mechanism (21) rotates. In the working position, the grating mirrors (22) are located on the optical path in the vacuum chamber (1). The grating mirrors (22) receive the light beam from the entrance window and disperse the light beam, reflecting it toward the exit window. The detector assembly (3) is movably connected to the outside of the exit window of the vacuum chamber (1) for receiving the spectral signal dispersed by the grating mirror (22) and forming a focus. The detector assembly (3) is coupled with a microchannel plate for enhancing the spectral signal.

2. The compact broadband grating spectrometer according to claim 1, characterized in that, The slit width of the slit assembly is adjustable. The slit assembly is mounted on a multi-degree-of-freedom adjustment bracket on the inner wall of the vacuum chamber (1). It is suitable for adjusting the angle of the slit assembly so that the incident beam emitted by the wide-band light source can irradiate the surface of the grating mirror (22) in the working position at an incident angle of 87° to 88.6°.

3. The compact broadband grating spectrometer according to claim 1, characterized in that, The grating turret mechanism (21) includes: A sealing flange (211) is connected to the vacuum chamber (1); The drive motor (212) is located outside the vacuum chamber (1), and the output shaft of the drive motor (212) passes through the sealing flange (211). A rotary displacement stage (213) is connected to the output shaft of the drive motor (212), and the rotary displacement stage (213) has a regular polyhedral structure. Multiple lens frames (214) are fixed to multiple sides of the circumferential direction of the rotary displacement stage (213) for detachably mounting the grating lens (22).

4. The compact broadband grating spectrometer according to claim 3, characterized in that, The rotary displacement stage (213) is a regular triangular prism structure. Three concave variable-pitch diffraction gratings with different center line densities are correspondingly mounted on the three sides of the rotary displacement stage (213) via the mirror frame (214). The rotary displacement stage (213) is adapted to be driven to rotate 120° or 240° by the drive motor (212) to switch one of the three concave variable-pitch diffraction gratings with different center line densities to the working position.

5. The compact broadband grating spectrometer according to claim 4, characterized in that, The center line densities of the three concave variable-pitch diffraction gratings are 300 grooves / mm, 1200 grooves / mm and 2400 grooves / mm, respectively, and are used to cover the long-wave, medium-wave and short-wave bands; the surfaces of the three concave variable-pitch diffraction gratings are all coated with a gold reflective layer.

6. The compact broadband grating spectrometer according to claim 1, characterized in that, The detector assembly (3) includes: A two-dimensional precision moving platform (31) is movably connected to the outside of the exit window of the vacuum chamber (1). The two-dimensional precision moving platform (31) is adapted to form a displacement change in a first direction that is close to or away from the vacuum chamber (1), and to form a displacement change in a second direction that is perpendicular to the first direction. A CCD detector is fixed on the two-dimensional precision moving platform (31) to receive the spectral signal dispersed by the grating mirror (22) and form a focus. The microchannel plate is coupled to the side of the CCD detector facing the vacuum chamber (1).

7. The compact broadband grating spectrometer according to claim 6, characterized in that, The two-dimensional precision moving platform (31) is provided with a receiving ring (32), and the CCD detector is installed on the side of the receiving ring (32) facing away from the vacuum chamber (1). The side of the receiving ring (32) facing the vacuum chamber (1) is connected to the exit window of the vacuum chamber (1) through a flexible corrugated tube (33).

8. The compact broadband grating spectrometer according to any one of claims 1 to 7, characterized in that, The vacuum chamber (1) includes a cylindrical stainless steel chamber (11), with a cover plate (12) installed at the top of the stainless steel chamber (11) and sealed by a rubber sealing ring (13); the multi-grating tower assembly (2) passes through the bottom of the stainless steel chamber (11); the entrance window and the exit window are provided on the side wall of the stainless steel chamber (11), and an observation window (14) and a vacuum transfer flange (15) are also provided on the side wall of the stainless steel chamber (11). The vacuum chamber (1) is connected to a vacuum pump group through the vacuum transfer flange (15).

9. A spectral measurement method, characterized in that, The spectral measurement method, applicable to the compact broadband grating spectrometer according to any one of claims 1 to 8, comprises: Start the vacuum pump unit to pump the air pressure inside the vacuum chamber (1) to a vacuum state; Based on the band information of the broadband light source, the multi-grating tower assembly (2) is driven to rotate, and the grating mirror (22) corresponding to the center line density is switched to the working position; The light emitted by the wideband light source is controlled to form a beam through the entrance window and slit assembly of the vacuum chamber (1) and irradiate the grating mirror (22) in the working position in a grazing incidence manner. After the beam is dispersed and focused by the grating mirror (22), it is directed toward the exit window of the vacuum chamber (1) to form a spectrum; The detector assembly (3) is controlled to move along the dispersion direction at the exit window of the vacuum chamber (1) so that the receiving surface of the detector assembly (3) coincides with the focusing position of the spectrum, thereby obtaining spectral data.

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