Double-multilayer-film monochromator of light beam line

Abstract

The invention provides a double-multilayer-film monochromator of a light beam line. The double-multilayer-film monochromator comprises two reflecting mirrors located on the same horizontal light path, a main shaft driving and supporting system, two reflecting mirror tables installed on the main shaft driving and supporting system and used for installing the two reflecting mirrors, and a water cooling system connected with the two reflecting mirrors. And a W / Si multilayer film and a Ru / C multilayer film which are separated from each other are plated on the reflecting surface of each reflecting mirror. The monochromator can provide micron-scale focusing light spots which are high in flux, wide in energy coverage range and extremely high in stability, compared with a liquid nitrogen cooling circulation system, the water cooling circulation system is adopted, the stability of the light spots is greatly improved, meanwhile, compared with a liquid nitrogen cooling scheme, the water cooling design is simpler, and more expenditure can be saved.

Description

TECHNICAL FIELD

[0001] The present application relates to a double multilayer film monochromator of a beamline. BACKGROUND

[0002] Synchrotron radiation light has become a powerful experimental tool for studying physics, chemistry, materials, energy, life and many other fields due to its high brightness, good collimation, wide energy range, strong stability and many other excellent characteristics. As the core equipment on the beamline of the synchrotron radiation source, the main function of the monochromator is to decompose the synchrotron radiation light into monochromatic light of different wavelengths.

[0003] Nowadays, the various needs of scientific research users for the experimental device of the beamline station are constantly increasing, for example, they hope that the beamline station can provide higher flux of light beams, the energy selection range of the line station is more extensive, and the micron-scale focused light spot has extremely high stability. Therefore, it is very important to design a new type of high-flux monochromator.

[0004] At present, the monochromators used in various lines of domestic synchrotron radiation devices are mainly crystal monochromators. The light transmission efficiency of this type of monochromator is relatively low, and it cannot meet the flux demand for some experimental stations that require high-flux light beams.

[0005] In recent years, with the development of X-ray multilayer film technology, synchrotron radiation monochromators based on periodic multilayer film mirrors have been widely used. Multilayer film monochromators generally use two types of mirror materials, and the periodic multilayer film structure formed by the alternating stacking of the two types of mirror materials has similar optical properties to crystals. The bandwidth of the multilayer film monochromator is 1-2 orders of magnitude larger than that of the crystal monochromator, and the reflectivity is high. Therefore, the light transmission efficiency of the multilayer film monochromator is more than several dozen times higher than that of the crystal monochromator, and it can provide higher photon flux.

[0006] In order to enable the line station to provide a wider energy range, some light source lines have deposited two / multiple sets of multilayer films with different structural materials on the mirror substrate to form two / multiple channels. These different combination structure channels work in different energy intervals. For example, the TopoTomo line station of the ANKA light source in Germany uses W / Si and Pd / B4C double-channel multilayer films; the TOMCAT line station of the Swiss light source uses Ru / C and W / Si double-channel multilayer films, and the Ru / C and W / Si multilayer films work in the 6-22 keV and 22-45 keV energy ranges, respectively.

[0007] With the development of the experiment of the user of the synchrotron radiation, the user has higher and higher requirements for the photon flux of the synchrotron radiation line. Generally, the photon flux of the beam line is improved from two aspects. The first method is to improve the brightness of the light source itself, which is less feasible and requires huge investment for the existing light source equipment. The other method is to design the light path on the beam line station to improve the photon flux per unit area at the sample point. The latter is relatively easy to realize and can meet the requirements of high-quality experiments.

[0008] In addition, since the monochromator is the core component of the beam line to provide high-flux and high-monochromatic light beams, its stability is very important, which determines the stability of the user light and the accuracy of the experiment. In order to improve the stability of the monochromator, the monochromator needs to be considered from the aspects of suppressing temperature drift, reducing the degree of freedom of crystal adjustment, increasing the inherent frequency of the adjustment machine, etc. Generally, since the energy of the synchrotron light is mainly deposited in the first crystal of the monochromator, it causes a high thermal load on the crystal, generates a large temperature gradient in the crystal, and causes thermal deformation of the crystal. The thermal deformation will make the reflected light deviate from the intended direction, greatly reducing the performance of the crystal monochromator. A large thermal stress can even damage the optical elements.

[0009] Therefore, it is necessary to develop a new type of double multilayer film monochromator to further improve the light transmission efficiency and reflection efficiency, and provide a micron-scale light beam with high flux and high stability. SUMMARY

[0010] The purpose of the present application is to provide a double multilayer film monochromator of a beam line, which has the advantages of high light transmission efficiency, high reflection efficiency, suppression of high-order harmonics, good stability, etc.

[0011] In order to achieve the above purpose, the present application provides a double multilayer film monochromator of a beam line, characterized in that it comprises two reflecting mirrors in the same horizontal light path, a main shaft driving and supporting system, two mirror tables mounted on the main shaft driving and supporting system for mounting the two reflecting mirrors, and a water cooling system connected with the first reflecting mirror and the second reflecting mirror; the reflecting surface of each reflecting mirror is coated with spaced W / Si multilayer film and Ru / C multilayer film.

[0012] The Ru / C multilayer film and the W / Si multilayer film work in the energy range of 5-18 keV and 18-25 keV, respectively; the period number of the W / Si multilayer film is 70, the period number of the Ru / C multilayer film is 100, and the average period thickness of the W / Si multilayer film and the Ru / C multilayer film is 3.06 nm.

[0013] The base of the reflecting mirror is a plane mirror made of single crystal Si or fused SiO2.

[0014] The two mirrors in the same horizontal light path include a first mirror and a second mirror downstream of the first mirror; the first mirror and the second mirror are in the same horizontal plane, and the reflecting surfaces of the first mirror and the second mirror are parallel to each other; the normal direction of the first mirror points to the storage ring of the beam line, and the normal direction of the second mirror is opposite to that of the first mirror.

[0015] The main shaft driving and supporting system provides stable support for the mirror body table, and is provided with a manual adjusting device and first and second motors; the manual adjusting device is used for adjusting the position and posture of the Bragg rotation axis of the first mirror and the second mirror; and the first and second motors are used for adjusting the Bragg angle of the first mirror and the second mirror around the Bragg rotation axis respectively.

[0016] The main shaft driving and supporting system further comprises a third motor and a slide rail, which are used for driving the second mirror to translate along the incident direction of the X-ray, so that the second mirror can make necessary translational motion in the light path direction relative to the first mirror.

[0017] The water cooling system comprises cooling pipelines of the bases of the first mirror and the second mirror, and the cooling pipelines of the first mirror and the second mirror are independent of each other.

[0018] The reflecting surfaces of the first mirror and the second mirror are both provided with temperature sensors; and a Compton shielding device is arranged upstream of the first mirror.

[0019] The double multilayer film monochromator of the beam line further comprises a vacuum system, which comprises a vacuum cavity, a cavity supporting system for supporting the vacuum cavity, and a water cooling circulation device connected with the water cooling system, an electrical driving device connected with the motors of the main shaft driving and supporting system, and a mechanical transmission device connected with the manual adjusting device of the main shaft driving and supporting system.

[0020] The vacuum cavity is fixed on a natural marble base for isolating the vibration transmitted from the ground to the monochromator; and the vacuum cavity is sealed by aluminum wires.

[0021] Compared with the traditional crystal monochromator, the multilayer film monochromator has the advantages of high light transmission efficiency, high reflection efficiency, and suppression of high-order harmonics.

[0022] The monochromator can provide a micron-scale focused light spot with high flux, wide energy coverage range and extremely high stability, wherein the water cooling circulation system is adopted, and the stability of the light spot is greatly improved compared with the liquid nitrogen cooling circulation system; and the water cooling design is simpler than the liquid nitrogen cooling scheme, and can save more funds. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 is a schematic diagram of the principle of a horizontal reflective double multilayer film monochromator.

[0024] Figure 2 is a schematic diagram of the crystal and its coating of a double multilayer film monochromator.

[0025] Figure 3 is a three-dimensional diagram of the inside of a double multilayer film monochromator.

[0026] Figure 4 is a top view of the inside of a double multilayer film monochromator.

[0027] Figure 5 is a front view of the external cavity design of a double multilayer film monochromator, showing the vacuum system.

[0028] Figure 6 is a top view of the external cavity design of a double multilayer film monochromator.

[0029] Figure 7A is a curve graph of the surface deformation in the meridional normal direction of a water-cooled multilayer film monochromator DMM1.

[0030] Figure 7B is a curve graph of the surface slope in the meridional normal direction of a water-cooled multilayer film monochromator DMM1.

[0031] Figure 8 is a curve graph of the residual surface slope in the meridional normal direction of a water-cooled multilayer film monochromator DMM1.

[0032] Figure 9 is a curve graph of the residual surface deformation after deducting the circular arc background.

[0033] Figure 10 is a graph of the photon flux result when the 2mrad surface error is directly input by the shadow software. DETAILED DESCRIPTION

[0034] The application will be further described below in conjunction with specific embodiments. It should be understood that the following embodiments are only used to illustrate the application and are not used to limit the scope of the application.

[0035] As shown in Figure 1 and Figure 2 is a schematic diagram of a double multilayer film monochromator (DMM) of a beamline of the application. The double multilayer film monochromator is used for an insert light source (such as an undulator), adopts a horizontal reflection mode, and adopts a water-cooled cooling method to obtain high stability. The function of the double multilayer film monochromator is to select and transmit the required X-ray photon energy from the continuous spectrum of the synchrotron light, and also allows white light to pass through the inside thereof.

[0036] The double multilayer monochromator adopts a horizontal reflection mode, and includes two mirrors (i.e., a first mirror 10 and a second mirror 20 downstream of the first mirror 10) in the same horizontal light path, so as to balance the convenience of energy adjustment and the stability of a light spot.

[0037] The reflective surfaces of each mirror are coated with spaced-apart W / Si multilayers 11 and Ru / C multilayers 12 to realize double-channel multilayers. In this embodiment, the energy range covered by the double multilayer monochromator is 5-25 keV to meet the scientific objectives of the beamline station and the characteristics of the light source. For this energy requirement, the mirrors use W / Si multilayers and Ru / C multilayers, in which the Ru / C multilayers and the W / Si multilayers work in the energy ranges of 5-18 keV and 18-25 keV, respectively, to meet the coating requirements of different energies and balance the load. In other embodiments, the Ru / C multilayers can be replaced by Pd / B4C multilayers.

[0038] The regions of the W / Si multilayers and the Ru / C multilayers are spaced apart by less than 3 mm. In addition, the double multilayer monochromator (DMM) can also be removed from the light path to provide a white light mode in which the double multilayer monochromator directly outputs high-flux quasi-monochromatic light instead of monochromatic light, i.e., 0.1 mrad (H) x 0.05 mrad (V) white light is output through the double multilayer monochromator. To provide the white light mode, the double multilayer monochromator does not require special structures, but only needs to be removed from the light path in this state (bypass state).

[0039] Both the W / Si multilayers and the Ru / C multilayers are obtained by a coating deposition process. After the coating deposition process is completed, the root mean square values of the film thickness errors of the W / Si multilayers are 0.30% and 0.19%, respectively, and the root mean square values of the film thickness errors of the Ru / C multilayers are 0.39% and 0.20%, respectively. In this embodiment, the number of periods of the W / Si multilayers is 70, and the number of periods of the Ru / C multilayers is 100. The average period thickness of the W / Si multilayers and the Ru / C multilayers is 3.06 nm.

[0040] As Figure 1 and Figure 2As shown in the figure, in the embodiment, the base of the mirror adopts a plane mirror of single crystal Si material with a size of 350 mm x 60 mm x 50 mm; the length and width of the W / Si multilayer film and the Ru / C multilayer film are 320 mm and 20 mm respectively. In other embodiments, the base of the mirror can have other sizes, for example, the length is at least 330 mm, the length is limited to less than 500 mm considering the rotation of the blocked light beam, the width is 60 mm considering the spot projection and the engineering cost, and the thickness is 50 mm considering the structural strength and the cost. The material of the base of the mirror can be fused SiO2 in addition to single crystal Si, but the structural strength of fused SiO2 will be reduced, and the performance is not as good as that of the single crystal Si plane mirror.

[0041] Figure 1 The spatial position relationship of the two mirrors adopted by the double multilayer film monochromator of the beamline of the application and the definition of the coordinate of each motion axis are shown. Figure 1 As shown in the figure, the two mirrors of the double multilayer film monochromator are a first mirror 10 and a second mirror 20.

[0042] The first mirror 10 and the second mirror 20 are in the same horizontal plane, and the reflecting surfaces of the first mirror 10 and the second mirror 20 are parallel to each other. The normal direction of the first mirror 10 points to the storage ring of the beamline, and the normal direction of the second mirror 20 is opposite to that of the first mirror 10, so that the direction of the X-rays reflected by the first mirror 10 gradually approaches the direction of the storage ring, and the direction of the X-rays reflected by the second mirror 20 gradually deviates from the direction of the storage ring. In addition, the grazing angle of the X-rays when they are incident on the first mirror 10 is 22.7-8.3 mrad. For example, during the switching of the energy from 10 keV to 25 keV, the grazing incidence angle changes from 22.7 to 8.3 mrad.

[0043] As shown in the figure, Figure 1 , Figure 3 and Figure 4 The double multilayer film monochromator of the beamline includes a first mirror 10 and a second mirror 20, a main shaft driving and supporting system 30, two mirror tables 40 mounted on the main shaft driving and supporting system 30, and a water cooling system 50 connected with the first mirror 10 and the second mirror 20, and a vacuum system 60. Figure 5 , Figure 6 ).

[0044] The main shaft driving and supporting system 30 provides stable support for the mirror body table 40 and is provided with a manual adjusting device for adjusting the position and posture of the Bragg rotation axis of the first mirror 10 and the second mirror 20 (such as the inclination angle of the Bragg rotation axis relative to the light beam line) and first and second motors for adjusting the Bragg angle of the first mirror 10 and the second mirror 20 around the Bragg rotation axis, respectively.

[0045] Monochromatic light is obtained by adjusting the Bragg angle of the first mirror 10 and the second mirror 20 around the Bragg rotation axis, and when the Bragg angle θ is changed, it can be ensured that the reflecting surfaces of the first mirror 10 and the second mirror 20 are parallel to each other.

[0046] The Bragg rotation axis of the first mirror 10 should coincide with the center of the reflecting surface of the first mirror 10 and be perpendicular to the incident direction of the X-rays, so that the incident light always hits the center of the reflecting surface of the first mirror 10 after the first mirror 10 rotates.

[0047] Within the working range of the Bragg angle, the monochromatic light passing through the double multilayer film monochromator (DMM) has a fixed horizontal offset relative to the incident synchrotron light in the vertical direction. Therefore, the main shaft driving and supporting system 30 further comprises a third motor 31 and a slide rail 32 for driving the second mirror 20 to translate along the incident direction of the X-rays, so that the second mirror 20 can make necessary translational motion in the optical path direction relative to the first mirror 10.

[0048] In addition, the first, second and third motors are provided with cooling devices, which are connected with the motors by copper metal for heat conduction to avoid the heat generated by the operation of the motors to reduce the performance of the monochromator and cause the temperature change of the entire mechanical system. The copper metal is in direct contact with the water cooling system 50 described in detail below to achieve heat conduction. In addition, in order to reduce the heat flow from the motors to the mechanical components, a coupling and a gasket are provided between the first, second and third motors and the mirror table 40 for thermal protection.

[0049] The mirror table 40 is used to mount the first mirror 10 and the second mirror 20, and high-precision fixation is used to ensure the accuracy of switching and adjustment of the two first mirrors 10 and the second mirror 20.

[0050] The water cooling system 50 is used to cool the first mirror 10 and the second mirror 20, so that the water cooling system cools the first mirror 10 and the second mirror 20, reduces temperature drift while taking away the heat, ensures that the multilayer film of the first mirror 10 and the second mirror 20 has the same period thickness, and further ensures that the multilayer film interface and the reflecting surface structure are stable, and the surface is not damaged or the film layer is not separated from the substrate due to thermal strain. The maximum heat load and the heat load density on the reflecting surface of the first mirror 10 are 161 W and 3.8 W / mm 2 , respectively, and about 161 W of heat load needs to be absorbed, so water cooling is needed to release the absorbed photon energy; the second mirror 20 also needs to be water-cooled to improve system stability.

[0051] The water cooling system 50 includes cooling pipes passing through the substrates of the first mirror 10 and the second mirror 20. Specifically, the cooling pipes are shown by the orange copper pipes in Figure 3 , which directly contact the multilayer film substrate for heat conduction, and the inside of the cooling pipes has circulating water for cooling. The cooling pipes of the first mirror 10 and the second mirror 20 are independent of each other, so that the cooling water of the second mirror 20 needs to have a cooling pipe independent of the cooling water of the first mirror 10. Therefore, in the two states of the monochromator turning on or off the light or switching the energy, the exiting light can reach the DMM stability requirement within thirty minutes.

[0052] The reflecting surfaces of the first mirror 10 and the second mirror 20 are provided with temperature sensors to detect the surface temperature of the crystal. The upstream of the first mirror 10 is provided with a Compton shielding device for preventing tangential high-energy radiation of the electron beam and protecting all light-sensitive elements from scattering, and the Compton shielding device itself also needs to have constant temperature protection. The Compton shielding device is generally a metal baffle designed and processed according to the actual light path for shielding high-energy X-ray scattering.

[0053] Figure 5 and Figure 6 are the front view and the top view of the external cavity of the double multilayer film monochromator, respectively. The vacuum system 60 includes a vacuum cavity 61 accommodating the first mirror 10, the second mirror 20, the spindle drive and support system 30, the mirror table 40, and the water cooling system 50, and a cavity support system 62 for supporting the vacuum cavity 61. The vacuum system 60 further includes a water cooling circulation device connected with the water cooling system 50, an electrical drive device connected with the motor of the spindle drive and support system 30, and a mechanical transmission device connected with the manual adjustment device of the spindle drive and support system 30, which are arranged outside the vacuum cavity 61.

[0054] In the embodiment, the vacuum cavity 61 is a vacuum mirror box, which is fixed on a natural marble base for isolating the vibration transmitted from the ground to the monochromator. The vacuum cavity 61 is sealed with aluminum wires to provide an ultra-high vacuum environment for the DMM.

[0055] In the on-off light or switching energy state of the monochromator, the exiting light can reach the following index capacity within thirty minutes: the exiting light angle stability (RMS) is less than 50 nrad (rms, 10min, <100Hz) in the vertical direction and less than 100 nrad (rms, 10min, <100Hz) in the horizontal direction.

[0056] Through calculation simulation, by selecting the performance index under the condition of different plating layer materials, periods, thicknesses and other parameters, the performance index meets the requirements of beamline reflectivity, energy resolution and energy range. The main performance index of the double multilayer film monochromator of the beamline is shown in Table 1.

[0057] Table 1: Main parameters and performance index of the double multilayer film monochromator of the beamline

[0058] The double multilayer film monochromator of the beamline of the application is combined with the water-cooling cooling scheme, so that the beamline station can provide a micron-scale focused light spot with high flux, wide energy coverage range and extremely high stability. In the actual manufacturing process, the installation of the two mirrors is very important, and the influence of the mechanism on the deformation and slope error of the mirror during operation should be minimized. The local flatness, overall flatness and local slope error must be strictly controlled to meet the requirements of the beamline focusing point light spot size, energy range, energy resolution and photon flux parameters.

[0059] The accuracy and small roughness of the surface shape processing are the key indicators for the mirror to achieve good working condition. These are the key points of the design of the monochromator. The water-cooling cooling scheme can make the stability of the multilayer film monochromator reach a very high level. When the monochromator is adjusted to the required energy point, the exiting light angle stability (RMS) of the monochromator is less than 50 nrad (rms, 10min, <100Hz) in the vertical direction and less than 100 nrad (rms, 10min, <100Hz) in the horizontal direction.

[0060] The traditional double crystal monochromator can also provide X-rays with a relatively wide energy range, but the photon flux thereof will decrease by 1-2 orders of magnitude compared with the multilayer film monochromator. There are many factors affecting the stability of the monochromator exit beam, and the position and attitude changes of some optical elements in the working environment will cause the offset of the exit spot, such as the vibration caused by the fluid movement in the cooling system, the vibration transmitted by the foundation, the interference of the driving motor, the temperature drift, etc. Among them, the temperature drift is the most critical factor to improve the stability of the monochromator, because the deformation of the first crystal caused by thermal radiation is very large. In order to meet the heat release requirement, many monochromator designs use a liquid nitrogen cooling circulation system to stabilize the deformation of the monochromator crystal. The double multilayer film monochromator of the beamline of the present application adopts water cooling, which can provide an X-ray beam with high flux, wide energy selection range and extremely high stability.

[0061] To solve the problem of high heat load of the crystal, the existing solutions mainly include: (1) cooling the optical elements (such as the first mirror 10 and the second mirror 20) with a low-temperature coolant, and the commonly used coolants are water, liquid nitrogen, liquid gallium, etc.; (2) increasing the cooling area of the optical element; (3) using a material with high thermal conductivity and low expansion coefficient (such as silicon crystal, diamond) to make the optical element. The present application considers these three conditions at the same time. First, the water cooling circulation system is adopted, which can greatly improve the stability of the spot compared with the liquid nitrogen cooling circulation system, and the water cooling design is also simpler than the liquid nitrogen cooling scheme, which can save a lot of funds. Secondly, water cooling also has a large cooling area like liquid nitrogen, and in addition, the first mirror 10 and the second mirror 20 adopt a single crystal silicon substrate, which has the advantages of high thermal conductivity and low expansion coefficient.

[0062] The conventional cooling measure for the multilayer film monochromator is a liquid nitrogen cooling system, and a water cooling scheme cannot meet the cooling requirement. This is because the conventional water cooling cannot meet the power density requirement of the multilayer film monochromator. After calculation, the heat load of the first multilayer film of the monochromator is 161W, and if the multilayer film is used in the maximum magnetic field intensity mode (k=1.876, E=10.57keV), the maximum heat load power density reaches 1.9W / mm 2 .

[0063] The application realizes the first water-cooled multilayer film monochromator for an insertion light source (such as an undulator). Various measures are taken to realize the successful application of water cooling. Specifically, to realize the application of water cooling, the water-cooled multilayer film monochromator of the application can absorb energy through the externally added CVD diamond absorption sheet. The CVD diamond absorption sheet is arranged at the front end of the double multilayer film monochromator of the entire beam line, which can absorb part of the light source radiant power without significantly affecting the light flux. At the same time, the water-cooled multilayer film monochromator of the application controls the waveband range, and when working at an energy of 10-25 keV, different CVD diamond absorption sheets are inserted for thermal irradiation attenuation to avoid the failure of traditional water cooling to meet the standard. In addition, when using the monochromator of the application, attention should also be paid to the surface error introduced by the excessively high power density, and the conventional beam line design cannot meet the requirements (such as the super-ring plane mirror). After careful calculation, the application simulates the surface change curve caused by temperature change, and then designs a KB mirror system with variable surface downstream of the multilayer film monochromator to compensate for the surface change caused by temperature change. Through these designs, the water cooling scheme can be applied, otherwise it cannot meet the requirements. After the actual operation of the subsequent equipment, the stability and various indicators of the equipment are very excellent.

[0064] In the present embodiment, when the water cooling scheme is adopted, the design index parameter is a 1-micron focused light spot, and the photon energy is 12 keV. At this time, the surface deformation and surface error curve of the water-cooled multilayer film monochromator DMM1 obtained by FEA analysis are as shown in Figure 7A and Figure 7B , wherein Figure 7A shows the surface deformation curve (unit: mm) of the meridional normal direction of the water-cooled multilayer film monochromator DMM1, Figure 7B shows the surface slope curve (unit: mrad) of the meridional normal direction of the water-cooled multilayer film monochromator DMM1, and the overall RMS surface slope is 9.7 mrad. Although the overall RMS surface is 9.7 mrad, the curve is relatively smooth and approximates a circular arc, so by deducting a suitable circular arc background, the overall residual surface curve error can reach 1.6 mrad (RMS), as shown in Figure 8 . Figure 8 is the residual surface slope curve (unit: mrad) of the meridional normal direction of the water-cooled multilayer film monochromator DMM1. In the present embodiment, after performing the mode of deducting a circular arc background with a radius of 4500 m, the residual surface deformation curve after deducting the circular arc background is as shown in Figure 9The residual surface deformation can be compensated by the pre-focusing KB mirror bending radius from 2800m to 2497m, which can focus the light spot to the accurate secondary light source point position, and obtain the required light spot size and flux. The KB mirror is bendable, on the one hand, according to the surface deformation and radius compensation calculation caused by heat, the KB mirror bending range needs to meet the maximum thermal deformation compensation requirement, on the other hand, there is an observation system (another patent device) at the secondary light source point, which can observe the light spot size, and by adjusting the KB mirror bending radius at the secondary light source point to obtain the minimum light spot size, the compensation is completed.

[0065] Figure 10 The shadow software directly inputs the 2mrad surface error to generate the photon flux result, and the 1micron focal spot photon flux 1612 (a.u.) is obtained by tracing. According to the light source point and the transmission efficiency of each optical element, the 12keV photon flux of 1micron light spot at the sample is 2.91´10 12 phs / s, which is close to the photon flux 2.97´10 12 phs / s directly simulated by the software directly simulating the 2mrad surface error. Therefore, the surface error obtained by the FEA analysis is close to the surface error obtained by the simulation.

[0066] The monochromator of the present application can provide a micron-scale focused light spot with high flux, wide energy coverage range and extremely high stability. The water-cooling circulation system is used, which can greatly improve the stability of the light spot compared with the liquid nitrogen cooling circulation system. At the same time, the water-cooling design is also simpler than the liquid nitrogen cooling scheme, which can save a lot of funds.

[0067] The above is only a preferred embodiment of the present application, and is not intended to limit the scope of the present application. The above embodiment of the present application can be variously changed. Any simple, equivalent changes and modifications made according to the content of the claims and description of the present application fall within the scope of protection of the present application. The present application is not described in detail, which is a conventional technical content.

Claims

1. A double multilayer film monochromator for a beamline, characterized in that, The two mirrors in the same horizontal light path, the main shaft driving and supporting system, the two mirror tables mounted on the main shaft driving and supporting system for mounting the two mirrors, and the water cooling system connected with the two mirrors; the reflecting surface of each mirror is coated with spaced W / Si multilayer film and Ru / C multilayer film.

2. The dual multilayer film monochromator of a beamline according to claim 1, wherein, The Ru / C multilayer film and the W / Si multilayer film work in the energy bands of 5-18 keV and 18-25 keV, respectively. The W / Si multilayer film has 70 periods, and the Ru / C multilayer film has 100 periods, and the average period thickness of the W / Si multilayer film and the Ru / C multilayer film is 3.06 nm.

3. The dual multilayer film monochromator of a beamline of claim 1, wherein, The base of the mirror is a plane mirror made of single crystal Si or fused SiO2.

4. The dual multilayer film monochromator of a beamline of claim 1, wherein, The two mirrors in the same horizontal light path include a first mirror and a second mirror downstream of the first mirror. The first mirror and the second mirror are in the same horizontal plane, and the reflecting surfaces of the first mirror and the second mirror are parallel to each other; the normal direction of the first mirror points to the storage ring of the beamline, and the normal direction of the second mirror is opposite to that of the first mirror.

5. The dual multilayer film monochromator of a beamline according to claim 4, wherein, The main shaft driving and supporting system provides stable support for the mirror body table, and is provided with a manual adjusting device and first and second motors; the manual adjusting device is used to adjust the position and attitude of the Bragg rotation axis of the first mirror and the second mirror, and the first and second motors are used to adjust the Bragg angle of the first mirror and the second mirror around the Bragg rotation axis, respectively.

6. The dual multilayer film monochromator of a beamline of claim 5, wherein, The main shaft driving and supporting system further includes a third motor and a slide rail, which are used to drive the second mirror to translate along the incident direction of the X-ray, so that the second mirror can make necessary translational motion in the light path direction relative to the first mirror.

7. The dual multilayer film monochromator of a beamline of claim 5, wherein, The water cooling system includes cooling pipelines of the bases of the first mirror and the second mirror, and the cooling pipelines of the first mirror and the second mirror are independent of each other.

8. The dual multilayer film monochromator of a beamline of claim 4, wherein, The reflecting surfaces of the first mirror and the second mirror are both provided with temperature sensors. A Compton shielding device is mounted upstream of the first mirror.

9. The dual multilayer film monochromator of a beamline of claim 1, wherein, A vacuum system is further included, which includes a vacuum cavity, a cavity supporting system for supporting the vacuum cavity, and a water cooling circulation device connected with the water cooling system, an electrical driving device connected with the motors of the main shaft driving and supporting system, and a mechanical transmission device connected with the manual adjusting device of the main shaft driving and supporting system, which are arranged outside the vacuum cavity.

10. The dual multilayer film monochromator of a beamline of claim 9, wherein, The vacuum cavity is fixed on a natural marble base for isolating the vibration transmitted from the ground to the monochromator; the vacuum cavity is sealed with aluminum wire.

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