An ultrathin diamond clamping device

Abstract

The application discloses an ultrathin diamond clamping device, which comprises, from top to bottom, a graphite pressing block, a polycrystalline diamond limiting sheet, a polycrystalline diamond bottom sheet, a graphite bottom plate and graphite screws for fixing the above-mentioned elements; the polycrystalline diamond limiting sheet is provided with at least one rectangular notch, and the limiting groove for positioning the ultrathin diamond crystal sheet is formed by the rectangular notch and the polycrystalline diamond bottom sheet; the graphite pressing block covers the ultrathin diamond crystal sheet, the graphite screws pass through the graphite pressing block, the polycrystalline diamond limiting sheet and the polycrystalline diamond bottom sheet in sequence and are connected with the graphite bottom plate, the graphite pressing block is extruded by twisting the graphite screws, pressure is applied to the ultrathin diamond crystal sheet to realize clamping. According to the application, the ultrathin diamond clamping device has the advantages of low thermal load, small clamping stress, small radiation damage and the like, reliably supports the stable and efficient generation of the seed laser by the monochromator, and finally helps to realize the high-stability operation of the fully-coherent free electron laser.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of free electron laser self-seeding operation mode, and more particularly to an ultrathin diamond clamping device. BACKGROUND

[0002] X-ray free electron laser is the latest generation of X-ray source, which can produce super high brightness, ultra-short pulse coherent X-ray radiation, and is widely used in frontier scientific fields such as physics, chemistry, biology and materials. At present, the FEL device mainly adopts SASE operation mode, which has high brightness, high collimation, transverse coherence and many other advantages, and provides an irreplaceable tool for scientific research. Since SASE originates from electron noise, SASE-FEL has poor longitudinal coherence. Among the many schemes to improve the longitudinal coherence of FEL, self-seeding based on crystal monochromator has been proven and adopted, such as LCLS, PAL-XFEL, European-XFEL and SHINE devices. Unlike other monochromators, the self-seeding monochromator adopts an ultrathin diamond crystal based on forward Bragg diffraction monochromatic scheme.

[0003] The clamping device used in LCLS device (Design of a diamond-crystal monochromator for the LCLS hardx-ray self-seeding project, doi: 10.1088 / 1742-6596 / 425 / 5 / 052004) is made of graphite, which has low thermal conductivity and serious heat load problem. The clamping method is direct clamping, and the clamping force cannot be adjusted, and the crystal deformation affects the performance.

[0004] The clamping method of PAL-XFEL device (Diamond Double-Crystal System for a Forward Bragg Diffraction X-Ray Monochromator of the Self-Seeded PAL XFEL, doi: 10.18429 / JACoW-FEL2017-MOP001) is point contact, and the clamping spring is not fixed on the base plate, which is easy to fall off. The size of the clamping force needs to be achieved by replacing springs with different thicknesses, which is not convenient to adjust. There is no limiting groove, and the crystal is easy to move or even fall off.

[0005] The clamping device in the European-XFEL device (Status of the hard X-ray self-seeding setup at the european XFEL, doi:10.18429 / JACoW-FEL2019-TUP079) is made of metal, and has problems such as radiation safety, inconsistent thermal expansion coefficients, and low thermal conductivity.

[0006] The LCLS has a repetition frequency of 120 Hz, the PAL-XFEL has a repetition frequency of 60 Hz, and the repetition frequencies of the two devices are not high. The repetition frequency of the European-XFEL includes a pulse sequence repetition frequency and an intra-pulse sequence repetition frequency. The pulse sequence repetition frequency is 10 Hz, the intra-pulse sequence repetition frequency is 4.5 MHz, and the SHINE is 1 MHz. The SHINE device belongs to the ultra-high frequency. The European-XFEL uses a metal clamping device. The radiation problem is serious, and the motion mechanism of the crystal is often damaged due to the radiation problem and needs to be repaired.

[0007] In summary, the clamping device of the ultra-thin diamond crystal has the following problems: 1) the clamping device made of metal is easy to process, but the high-energy electron beam in the device is far away from the millimeter level, and the electron beam and the halo are easy to hit the metal, which causes radiation safety problems. In addition, the thermal expansion coefficient of the metal is different from that of the diamond, and the deformation of the clamping device easily affects the crystal lattice and even damages the crystal. 2) The contact area between the conventional clamping device and the ultra-thin diamond crystal is small, and the contact surface of the clamping device cannot be finely polished, which reduces the heat transfer efficiency of the crystal, and the crystal needs to bear a large amount of heat which cannot be conducted out in time and effectively, thereby affecting the performance of the crystal. 3) The ultra-thin crystal is sensitive to clamping force, and too small clamping force is difficult to keep the crystal stable, and too large clamping force is easy to damage the ultra-thin crystal or cause the performance of the crystal to decrease, and the size of the clamping force is not convenient to adjust.

[0008] Therefore, it is urgent to provide a new type of ultra-thin diamond clamping device which can overcome the above-mentioned defects, and has important significance for improving the stability of the self-seeding operation mode, especially for the operation in the direction of high repetition frequency. SUMMARY

[0009] The purpose of the present application is to provide an ultra-thin diamond clamping device, so as to solve the problems that the clamping device of the ultra-thin diamond crystal in the prior art causes the performance of the crystal to decrease due to factors such as radiation damage, thermal load, and clamping stress in the self-seeding operation mode, and the existing device often fails due to radiation damage and thermal load problems, and needs to be repaired and replaced out of vacuum, which greatly affects the stability of the free electron laser.

[0010] In order to solve the above technical problems, the following technical solutions are adopted in the present application:

[0011] The application provides an ultrathin diamond clamping device, which comprises, from top to bottom, a graphite pressing block, a polycrystalline diamond limiting sheet, a polycrystalline diamond bottom sheet, a graphite bottom plate and a graphite screw for fixation; at least one rectangular notch is arranged on the polycrystalline diamond limiting sheet, and the rectangular notch of the polycrystalline diamond limiting sheet and the upper surface of the polycrystalline diamond bottom sheet arranged below the polycrystalline diamond limiting sheet jointly form a limiting groove for positioning an ultrathin diamond crystal sheet; the graphite pressing block covers the ultrathin diamond crystal sheet, the graphite screw passes through the graphite pressing block, the polycrystalline diamond limiting sheet and the polycrystalline diamond bottom sheet in sequence and is connected with a threaded hole arranged on the graphite bottom plate, the graphite pressing block is deformed by twisting the graphite screw to press the graphite pressing block, pressure is applied to the ultrathin diamond crystal sheet to realize clamping, the graphite pressing block, the graphite bottom plate and the graphite screw are made of graphite, the polycrystalline diamond limiting sheet and the polycrystalline diamond bottom sheet are made of polycrystalline CVD diamond, and the ultrathin diamond crystal sheet is an HPHT ultrathin single crystal diamond sheet.

[0012] According to the application, the graphite pressing block, the graphite bottom plate and the graphite screw are all non-metal materials, so that secondary radiation generated under beam bombardment can be avoided; the polycrystalline diamond limiting sheet, the polycrystalline diamond bottom sheet and the ultrathin diamond crystal sheet have the same thermal expansion coefficient, so that thermal stress generated by temperature change can be reduced.

[0013] According to one preferred scheme of the application, the graphite pressing block has a reverse U-shaped structure, has a top portion provided with a through hole and two vertical arm portions extending downward, the rectangular notches are symmetrically arranged on both sides of the polycrystalline diamond limiting sheet along the length direction of the polycrystalline diamond limiting sheet, the size of the vertical arm portion of the graphite pressing block is matched with the size of the rectangular notch, so that the graphite pressing block only contacts the ultrathin diamond crystal sheet through the bottom surface of the vertical arm portion, and the polycrystalline diamond limiting sheet is avoided from being pressed.

[0014] According to one preferred scheme of the application, there are two graphite pressing blocks, and there are four graphite screws, each graphite pressing block is fixed by one graphite screw, and the graphite bottom plate is provided with four matched threaded holes.

[0015] According to one preferred scheme of the application, the polycrystalline diamond limiting sheet and the polycrystalline diamond bottom sheet are both provided with four through holes, the two through holes in the middle are used for fixing the graphite pressing block, and the two through holes on the outside are convenient for assembling and fixing the polycrystalline diamond limiting sheet and the polycrystalline diamond bottom sheet.

[0016] According to the application, the graphite screw, the graphite pressing block and the graphite bottom plate are cooperatively matched, the pressure is adjusted by rotating the graphite screw, the point contact is converted into the surface contact by the graphite pressing block, the pressure is reduced, and the crystal sheet is protected.

[0017] Preferably, the pressure exerted on the ultra-thin diamond crystal sheet after the graphite screw is twisted is within a preset clamping pressure range, which can ensure the stability of the ultra-thin diamond crystal sheet without causing damage. Preferably, the clamping force required by the ultra-thin diamond crystal sheet is about 0.01 N.

[0018] According to the present application, the polycrystalline diamond limiting sheet and the polycrystalline diamond bottom sheet are combined to form a limiting groove, which can meet the size requirements in the limiting groove, realize the complete limiting of the crystal sheet, meet the roughness requirements of the contact surface, and ensure the heat conduction efficiency.

[0019] Preferably, the groove width tolerance of the rectangular notch on the polycrystalline diamond limiting sheet is ±0.01 mm, and the groove depth tolerance is ±0.01 mm, so as to ensure the accurate fitting with the shape of the ultra-thin diamond crystal sheet.

[0020] Preferably, the thermal conductivity of the polycrystalline diamond limiting sheet and the polycrystalline diamond bottom sheet matches the thermal conductivity of the ultra-thin diamond crystal sheet, so as to improve the heat transfer efficiency of the ultra-thin diamond crystal sheet.

[0021] It should be known that the thermal conductivity coefficient of diamond is 2000-2200 W / (m·K), the thermal conductivity coefficient of graphite is 151 W / (m·K), the thermal conductivity coefficient of oxygen-free copper is (390-400) W / (m·K), and diamond is the material with the highest thermal conductivity in nature. Compared with the existing graphite clamping scheme and metal clamping scheme, the heat conduction efficiency of the diamond clamping of the present application can be improved by 5-15 times.

[0022] It should be particularly pointed out that if a limiting groove with a certain depth is directly added on a single piece of diamond, a laser cutting process needs to be used, which cannot guarantee the high precision of the cutting depth and is also difficult to effectively polish the surface of the limiting groove. The present application creatively solves the problems of cutting depth control and surface polishing by assembling and matching the polycrystalline diamond limiting sheet and the polycrystalline diamond bottom sheet, two independent components, to form a limiting groove. Specifically, the polycrystalline diamond limiting sheet and the polycrystalline diamond bottom sheet are first machined to a preset size, then a rectangular notch with high-precision size is formed on the polycrystalline diamond limiting sheet by laser direct cutting, and the surface of the polycrystalline diamond bottom sheet is polished to make the roughness of the contact surface reach 5 nm, and then the two independent elements are assembled together to finally construct a limiting groove with high size precision and highly polished surface, thereby realizing the stable clamping of the ultra-thin diamond crystal sheet and ensuring the effective contact area between the ultra-thin diamond crystal and the clamping device, and increasing the heat conduction capacity.

[0023] According to the present application, the ultra-thin diamond clamping device is particularly suitable for use in a monochromator in a free electron laser self-seeding operation mode to clamp the ultra-thin diamond crystal sheet as a core element of the monochromator.

[0024] Compared with the prior art, the ultrathin diamond clamping device provided by the application has the following advantages:

[0025] 1) The device as a whole adopts a non-metallic material, which can avoid secondary radiation when the electron beam group bombards the device, thereby reducing radiation damage;

[0026] 2) The polycrystalline diamond limiting sheet, the polycrystalline diamond bottom sheet and the ultrathin diamond crystal sheet are all diamond materials, which can ensure that the thermal expansion coefficients are consistent and have a high thermal conductivity, thereby reducing the influence of thermal load on the device;

[0027] 3) The diamond material is usually difficult to process, and the limiting groove is formed by assembling two polycrystalline CVD diamond components, which is convenient for processing and polishing, can ensure the size accuracy of the limiting groove, make the contact surface of the limiting groove and the ultrathin diamond crystal sheet smooth enough, and can increase the effective contact area of the polycrystalline diamond bottom sheet and the ultrathin diamond crystal sheet, which is beneficial to heat conduction;

[0028] 4) The graphite screws, the graphite pressing blocks and the graphite bottom plate are all graphite materials, which are relatively soft, the graphite pressing blocks are pressed by rotating the graphite screws to produce a certain deformation, and then a small pressure is applied on the ultrathin diamond crystal sheet, and this fixing mode can reduce the stress generated by direct clamping and protect the performance of the ultrathin diamond crystal sheet.

[0029] In summary, according to the ultrathin diamond clamping device provided by the application, the core technical problems of thermal load, clamping stress and radiation damage in the clamping process of the ultrathin diamond can be solved at the same time, which has the advantages of low thermal load, small clamping stress and small radiation damage, can effectively protect the stability of the device itself, reduce the failure rate and the frequency of downtime maintenance of the device, and can provide reliable support for the stable and efficient generation of seed laser by the monochromator, and ultimately help to realize the high-stability operation of the fully coherent free electron laser. BRIEF DESCRIPTION OF DRAWINGS

[0030] Figure 1 is an assembly schematic view of an ultrathin diamond clamping device according to a preferred embodiment of the application;

[0031] Figure 2 is an exploded view of the ultrathin diamond clamping device as shown in Figure 1 ;

[0032] Among them, the meanings of the reference signs are as follows:

[0033] 1: graphite screw; 2: graphite pressing block; 3: polycrystalline diamond limiting sheet; 4: polycrystalline diamond bottom sheet; 5: graphite bottom plate; 6: ultrathin diamond crystal sheet; 21: vertical arm part; 31: rectangular notch. DETAILED DESCRIPTION

[0034] The present application is further described in conjunction with the following examples. It should be understood that the following examples are merely illustrative of the present application and do not limit the scope of the application. Unless otherwise defined, the techniques used in the examples are conventional techniques used in the field, or are performed according to the manufacturer's instructions. The reagents and materials used in the examples are commercially available unless otherwise specified.

[0035] In the description of the present application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise" and the like indicate the orientation or positional relationship shown in the drawings based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application.

[0036] In conjunction with Figure 1 , Figure 2 The ultrathin diamond clamping device according to a preferred embodiment of the present application is shown in FIG. 1, which is used for clamping an ultrathin diamond crystal wafer 6 and mainly includes a graphite screw 1, a graphite pressing block 2, a polycrystalline diamond limiting sheet 3, a polycrystalline diamond bottom sheet 4, and a graphite bottom plate 5. The detailed structure is described as follows:

[0037] The polycrystalline diamond limiting sheet 3 is a long strip-shaped sheet, which is provided with four through holes in sequence along the length direction, and is provided with two symmetrical rectangular notches 31 on the sides. The polycrystalline diamond bottom sheet 4 is also a long strip-shaped sheet, which is provided with four through holes in sequence along the length direction.

[0038] The graphite pressing block 2 is two in total, which is in an inverted U-shaped structure, has a top portion provided with a through hole, and two vertical arm portions 21 extending downward on the sides. The graphite bottom plate 5 is provided with four threaded holes along the length direction. The graphite screw 1 is four in total, two of which are longer in size, and the other two are shorter in size.

[0039] In use, firstly, the polycrystalline diamond limiting sheet 3 and the polycrystalline diamond bottom sheet 4 are stacked from top to bottom, the rectangular notch 31 on the polycrystalline diamond limiting sheet 3 and the upper surface of the polycrystalline diamond bottom sheet 4 arranged below the polycrystalline diamond limiting sheet 3 together enclose a limiting groove for positioning the ultrathin diamond crystal sheet 6, the size of the limiting groove is equivalent to the size of the ultrathin diamond crystal sheet 6, so that when the ultrathin diamond crystal sheet 6 is placed in the limiting groove, the limiting groove can limit the displacement of the ultrathin diamond crystal sheet 6; then, the two shorter graphite screws 1 are sequentially threaded through the two through holes on the outer sides of the polycrystalline diamond limiting sheet 3 and the polycrystalline diamond bottom sheet 4, and are connected with the two threaded holes on the outer side of the graphite bottom plate 5, so that the polycrystalline diamond limiting sheet 3 and the polycrystalline diamond bottom sheet 4 are assembled and fixed; then, the graphite pressing block 2 is covered on the ultrathin diamond crystal sheet 6, the bottom surface of the vertical arm 21 of the graphite pressing block 2 completely and only abuts against the ultrathin diamond crystal sheet 6, and does not contact the polycrystalline diamond limiting sheet 3; then, the two longer graphite screws 1 are sequentially threaded through the through holes of the graphite pressing block 2, the middle two through holes on the polycrystalline diamond limiting sheet 3 and the polycrystalline diamond bottom sheet 4, and are connected with the middle two threaded holes of the graphite bottom plate 5, since the graphite material is soft, a certain deformation of the graphite pressing block 2 is generated by appropriately twisting the graphite screws 1 to press the graphite pressing block 2, and a small pressure is applied to the ultrathin diamond crystal sheet 6 to achieve clamping, and the fixing mode can greatly reduce the stress caused by direct clamping, and the performance of the crystal is not damaged. The device solves the clamping problem of the ultrathin diamond in the crystal monochromator in the free electron laser device under the self-seed operation mode.

[0040] According to the application, the graphite pressing block 2, the graphite bottom plate 5 and the graphite screws 1 are all non-metal materials, which can avoid secondary radiation under beam bombardment. The materials of the polycrystalline diamond limiting sheet 3, the polycrystalline diamond bottom sheet 4 and the ultrathin diamond crystal sheet 6 are all diamond, and the thermal expansion coefficients are consistent, so that the thermal stress generated by temperature change is greatly reduced.

[0041] According to the preferred embodiment, the graphite pressing block 2 is in an inverted U-shaped structure, has a top portion provided with a through hole and two vertical arms 21 extending downward from the two sides, and the rectangular notches 31 are symmetrically arranged along the length direction of the polycrystalline diamond limiting sheet 3, the size of the vertical arm 21 of the graphite pressing block is matched with the size of the rectangular notch 31, so that when the graphite pressing block 2 with the above structure is assembled with the polycrystalline diamond limiting sheet 3, the graphite pressing block 2 only contacts the ultrathin diamond crystal sheet 6 through the bottom surface of the vertical arm 21, avoids pressing the polycrystalline diamond limiting sheet 3, and ensures stable clamping of the ultrathin diamond crystal sheet 6.

[0042] Preferably, the clamping force required for the ultra-thin diamond crystal piece 6 is about 0.01 N. According to the embodiment, the pressure of about 0.01 N is applied to the ultra-thin diamond crystal piece 6 by twisting the graphite screw 1, so as to ensure that the ultra-thin diamond crystal piece 6 is stably clamped without causing any damage to the crystal.

[0043] According to the preferred embodiment, the size of the limiting groove formed by assembling the polycrystalline diamond limiting piece 3 and the polycrystalline diamond bottom piece 4 is adapted to the shape of the ultra-thin diamond crystal piece 6, and the contact surface of the limiting groove (i.e. the upper surface of the polycrystalline diamond bottom piece 4) needs to be precisely polished. It should be understood that the upper surface of the polycrystalline diamond bottom piece 4 is polished to be smooth enough, so as to increase the effective contact area of the polycrystalline diamond bottom piece 4 and the ultra-thin diamond crystal piece 6, and facilitate heat conduction.

[0044] Preferably, the groove width tolerance of the rectangular notch 31 on the polycrystalline diamond limiting piece 3 is ±0.01 mm, and the groove depth tolerance is ±0.01 mm, so as to ensure that the shape of the ultra-thin diamond crystal piece 6 is accurately adapted.

[0045] According to the preferred embodiment, the size of the limiting groove formed is 5.2 mm x 2 mm x 0.5 mm. The thickness of the polycrystalline diamond limiting piece 3 is 0.5 mm, and the thickness of the polycrystalline diamond bottom piece 4 is 1 mm. The contact surface of the limiting groove and the ultra-thin diamond crystal piece 6 is polished to have a roughness of 5 nm. The thickness of the ultra-thin diamond crystal piece 6 is 30 μm. However, it should be understood that the above experimental parameters are only used as examples and are not limited, and the above experimental parameters can be appropriately adjusted according to actual conditions in actual application.

[0046] In summary, the present application provides an ultra-thin diamond clamping device which can reduce radiation damage, reduce thermal load, facilitate processing and polishing, reduce clamping stress and avoid damage to the performance of the crystal.

[0047] The above description 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 the description of the present application fall within the scope of the claims of the present application. The present application is not described in detail, and is a conventional technical content.

Claims

1. An ultrathin diamond holding device for holding an ultrathin diamond crystal sheet, characterized by, The graphite pressing block, the polycrystalline diamond limiting sheet, the polycrystalline diamond bottom sheet and the graphite bottom plate are sequentially arranged from top to bottom, and graphite screws are used for fixation. At least one rectangular notch is arranged on the polycrystalline diamond limiting sheet, and the rectangular notch of the polycrystalline diamond limiting sheet and the upper surface of the polycrystalline diamond bottom sheet arranged below the polycrystalline diamond limiting sheet jointly enclose a limiting groove for positioning the ultrathin diamond crystal sheet. The graphite pressing block covers the ultrathin diamond crystal sheet, the graphite screws pass through the graphite pressing block, the polycrystalline diamond limiting sheet and the polycrystalline diamond bottom sheet in sequence, and are connected with the threaded holes arranged on the graphite bottom plate, the graphite pressing block is deformed by twisting the graphite screws to press the graphite pressing block, the ultrathin diamond crystal sheet is pressed to realize clamping. The graphite pressing block, the graphite bottom plate and the graphite screws are made of graphite, the polycrystalline diamond limiting sheet and the polycrystalline diamond bottom sheet are made of polycrystalline CVD diamond, and the ultrathin diamond crystal sheet is an HPHT ultrathin single crystal diamond sheet.

2. The ultrathin diamond holding device of claim 1, wherein, The graphite pressing block, the graphite bottom plate and the graphite screws are all non-metal materials to avoid secondary radiation caused by beam bombardment, and the polycrystalline diamond limiting sheet, the polycrystalline diamond bottom sheet and the ultrathin diamond crystal sheet have the same thermal expansion coefficient to reduce thermal stress caused by temperature change.

3. The ultrathin diamond holding device of claim 1, wherein, The graphite pressing block has a reverse U-shaped structure, has a top portion with a through hole and two vertical arm portions extending downward, the rectangular notches are symmetrically arranged on both sides of the polycrystalline diamond limiting sheet along the length direction, the size of the vertical arm portion of the graphite pressing block and the rectangular notch is matched, the graphite pressing block is in contact with the ultrathin diamond crystal sheet only through the bottom surface of the vertical arm portion, and the polycrystalline diamond limiting sheet is avoided from being pressed.

4. The ultrathin diamond holding device of claim 1, wherein, There are two graphite pressing blocks and four graphite screws, each graphite pressing block is fixed by one graphite screw, and the graphite bottom plate is provided with four matched threaded holes.

5. The ultrathin diamond holding device according to claim 4, wherein, The polycrystalline diamond limiting sheet and the polycrystalline diamond bottom sheet are provided with four through holes, the two middle through holes are used for fixing the graphite pressing block, and the two outer through holes are used for assembling and fixing the polycrystalline diamond limiting sheet and the polycrystalline diamond bottom sheet.

6. The ultrathin diamond holding device of claim 1, wherein, The pressure applied to the ultrathin diamond crystal sheet by the twisted graphite screws is in a preset clamping pressure range, and the preset clamping pressure range can ensure that the ultrathin diamond crystal sheet is stable and not damaged.

7. The ultrathin diamond chucking device of claim 1, wherein, The size of the limiting groove formed by assembling the polycrystalline diamond limiting sheet and the polycrystalline diamond bottom sheet is matched with the shape of the ultrathin diamond crystal sheet, and the contact surface of the limiting groove and the ultrathin diamond crystal sheet is precisely polished.

8. The ultrathin diamond chucking device of claim 1, wherein, The thermal conductivity of the polycrystalline diamond limiting sheet and the polycrystalline diamond bottom sheet is matched with the thermal conductivity of the ultrathin diamond crystal sheet to improve the heat transfer efficiency of the ultrathin diamond crystal sheet.

9. The ultrathin diamond chucking device of claim 1, wherein, The groove width tolerance of the rectangular notch on the polycrystalline diamond limiting sheet is ±0.01mm, and the groove depth tolerance is ±0.01mm, so as to ensure that the shape of the ultrathin diamond crystal sheet is accurately matched.

10. The ultrathin diamond chucking device of claim 1, wherein, The ultrathin diamond clamping device is used in a monochromator in a free electron laser self-seeding operation mode to clamp the ultrathin diamond crystal sheet as a core element of the monochromator.

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