X-ray metal ellipsoid focus lens and manufacturing method thereof

Abstract

The invention relates to the technical field of X-ray reflection optical device manufacturing, in particular to an X-ray metal ellipsoid focus lens and a manufacturing method thereof. The method comprises the following specific steps: determining the size, evaporating a conductive layer, electroplating a shell, dip-coating photoresist, evaporating a gold film, electroplating the shell, shearing and shaping, and demolding and cleaning to obtain the X-ray metal ellipsoid focus lens. According to the focusing lens, an ellipsoid-shaped precise mandrel is prepared through an electroplating method, the moving time and the current of a glass rod are controlled by quantitatively adjusting driving parts such as a stepping motor or an electric push rod so as to accurately control the thickness of electroplated nickel on the side face of the glass rod, and the X-ray metal ellipsoid focusing lens with the hundred-micron-scale diameter is manufactured. Gold is selected as a reflecting material, the reflectivity of X-rays on the gold surface is high, the critical angle of the grazing incidence angle of the X-rays is large, photons in a large solid angle can be collected, and high-intensity illumination is provided.

Description

Technical Field

[0001] The invention relates to the technical field of manufacturing X-ray reflection optical devices, and in particular to an X-ray metal ellipsoid focusing mirror and a manufacturing method thereof. Background Art

[0002] As a key X-ray optical device, the X-ray ellipsoid focusing mirror can focus the collected X-ray source to the micrometer scale, and has the advantages of no color difference and high efficiency. It has extremely high application value in many fields such as micro-focused X-ray fluorescence, micro-focused X-ray phase contrast imaging, X-ray diffraction measurement, full-field X-ray microscopy, and spectroscopy. The characteristic of this focusing mirror is that an ellipsoidal reflector is made on the inner surface of a tubular metal with a diameter of 100 microns, and the surface accuracy is at the level of 100 nanometers.

[0003] In the prior art, the University of Tokyo in Japan has developed a soft X-ray focusing mirror with a surface error height value of less than 30nm and a surface roughness of 0.2nm (MIMURAH, TAKEIY, KUMET, et al. Fabrication of a precise ellipsoidal mirror for soft x-ray nanofocusing [J]. Review of Scientific Instruments, 2018, 89 (9)). However, its inner surface diameter is 2mm or more, resulting in an illumination angle of the focus point of more than 10mrad, which does not meet the requirements for the development of desktop X-ray microscopes.

[0004] Xradia has developed a glass capillary lens that uses a glass wire drawing process to obtain a designed ellipsoidal surface by controlling the drawing speed and temperature (Zeng X, Duewer F, Feser M, et al. Ellipsoidal and parabolic glass capillaries as condensers for x-ray microscopes [J]. Applied optics, 2008, 47 (13): 2376-2381). However, the inner surface of the glass cannot be coated with a metal film, and the reflectivity of X-rays on the glass surface is low. The critical angle of the X-ray grazing incidence angle is small, and photons within a large solid angle cannot be collected, and higher intensity lighting cannot be provided.

[0005] Therefore, it is very necessary to provide an X-ray ellipsoid focusing mirror that can meet the development requirements of desktop X-ray microscopes and provide higher intensity illumination. Summary of the invention

[0006] In order to provide a high-throughput and small-size X-ray focusing mirror to meet the development requirements of desktop X-ray microscopes and provide higher intensity illumination, the present invention adopts the following technical solutions: In a first aspect, the present invention provides a method for manufacturing an X-ray metal ellipsoid focusing mirror, the specific steps are as follows: S1. Determine the size, and determine the length, diameter and thickness of the glass rod and the electroplated nickel according to the X-ray grazing angle, the photon collection solid angle and the ellipsoidal surface parameters of the metal ellipsoid focusing mirror; S2. Evaporation of conductive layer, the straightness is less than 1 A glass rod is placed in a vacuum coating machine, and a chromium film and a gold film are sequentially deposited on the outer surface of the glass rod; S3. Electroplating shell, the glass rod coated with chromium film and gold film in S2 is used as the cathode material, and the metal nickel is used as the anode material, and then the depth of the glass rod immersed in the electroplating solution and the residence time and current at different depths are controlled to obtain an ellipsoidal nickel electroplated shell of a predetermined thickness in S1 on the outer surface of the glass rod; S4 dip-coated photoresist, the glass rod electroplated with nickel shell in S3 is immersed in the photoresist, and then removed and baked to form a uniform organic film on the surface of the electroplated nickel shell of the glass rod; S5. Evaporating a gold film, after the glass rod in S4 is naturally cooled to room temperature, it is placed in a vacuum coating machine for spin coating, so that a layer of gold film is deposited on the outer surface of the organic film in S4; S6. Electroplating shell, placing the glass rod with the gold film deposited in S5 in the electroplating solution, electroforming a nickel shell on the outer surface of the gold film; S7. Shearing and shaping, cutting off the upper end of the ellipsoid area together with the excess glass rod, and then grinding the remaining effective ellipsoid area with sandpaper until it feels smooth; S8. Demolding and cleaning: placing the effective ellipsoid area polished in S7 in anhydrous acetone to dissolve the photoresist dip-coated in S4 until the glass rod core shaft can be pulled out of it, and then placing the ellipsoid part without the glass rod core shaft in anhydrous isopropanol for ultrasonic cleaning. After drying, the X-ray metal ellipsoid focusing mirror is obtained.

[0007] As an implementation manner, the thicknesses of the chromium film and the gold film in S2 are 5 nm and 30 nm, respectively.

[0008] As an implementation method, the thermal evaporation coating speed in S2 is 0.3 nm / s and the vacuum degree is 10 -4 Pa; During evaporation, the glass rod is placed horizontally and rotated at a speed of 300RPM under the action of a vacuum rotary motor.

[0009] As an implementation mode, the electroplating solution in S3 is a Watts plating solution, and the electroplating temperature is controlled at 55°C.

[0010] As an embodiment, the mass of the metal nickel in S3 is and plating time , current size The relationship is: ; in, is the relative atomic mass of nickel, ; is Faraday's constant, ; is Avogadro's constant, ; is the charge of the electron, .

[0011] As an implementation manner, the baking and shaping method in S4 is: placing the glass rod in an air cavity at a temperature of 100° C. and baking for 15 minutes.

[0012] The photoresist is MEGAPOSITSPR220-3.0, and the coating thickness is 2-4 .

[0013] As an implementation manner, the gold film deposition thickness in S5 is 100 nm, and the actual coating thickness during the coating process is the film thickness value measured by the coating machine divided by the π value.

[0014] As an embodiment, the nickel shell thickness in S6 is 100 .

[0015] As an implementation mode, the effective ellipsoid region in S8 is immersed in anhydrous acetone for more than 2 hours, and the ultrasonic cleaning time is 10 minutes.

[0016] In a second aspect, the present invention provides an X-ray metal ellipsoid focusing mirror, which is manufactured by the manufacturing method of the above-mentioned X-ray metal ellipsoid focusing mirror.

[0017] The advantages of the present invention are: 1. The present invention uses electroplating to prepare a precision mandrel with an ellipsoidal surface. By quantitatively adjusting driving parts such as a stepping motor or an electric push rod, the time and current of the glass rod movement are controlled to accurately control the thickness of the electroplated nickel on the side of the glass rod, and an X-ray metal ellipsoid focusing mirror with a diameter of hundreds of microns is produced, achieving a surface processing accuracy of hundreds of nanometers.

[0018] 2. The present invention uses photoresist lubrication technology as a release agent and provides an ultra-smooth inner surface for the X-ray ellipsoidal metal focusing mirror, thereby replacing the traditional polishing process and providing an excellent small-sized focusing light source.

[0019] 3. The X-ray ellipsoidal metal focusing mirror produced by the present invention uses gold as the reflective material. The reflectivity of X-rays on the gold surface is high, and the critical angle of the X-ray grazing incidence angle is large. It can collect photons within a large solid angle and provide high-intensity lighting. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] This specification includes the following drawings, which show the following contents: Figure 1 It is a schematic diagram of the manufacturing method and design process of the X-ray metal ellipsoid focusing mirror of the present invention; Figure 1 A is a schematic diagram of the vapor-deposited chromium film and gold film in S2 of the present invention; Figure 1 B is a schematic diagram of obtaining an ellipsoidal nickel-plated shell by electroplating a glass rod in S3 of the present invention; Figure 1 C is a schematic diagram of the photoresist lubricated reflective surface in S4 of the present invention; Figure 1 D is a schematic diagram of the gold film vapor deposition in S5 of the present invention; Figure 1 E is a schematic diagram of the electroformed nickel shell in S6 of the present invention; Figure 1 F is a schematic diagram of the glass rod being clamped and fixed before shearing in S7 of the present invention; Figure 1 G is a schematic diagram of removing the thinner end of the electroformed body and grinding and polishing in S7 of the present invention; Figure 1 H is a schematic diagram of removing the photoresist and pulling out the mandrel in S8 of the present invention to obtain a finished product of an X-ray metal ellipsoid focusing mirror; Figure 2 The surface shape of the X-ray metal ellipsoid focusing mirror measured by the high-resolution microscope of the present invention; Figure 2 A is the effective area ellipsoid profile of the X-ray metal ellipsoid focusing mirror of the present invention; Figure 2 B is a contour extraction diagram of the ellipsoidal contour of the effective area of ​​the X-ray metal ellipsoid focusing mirror of the present invention; Figure 2 C is a contour diagram of the starting area of ​​the effective area ellipsoid of the X-ray metal ellipsoid focusing mirror of the present invention; Figure 2 D is a contour extraction diagram of the contour of the starting point area of ​​the effective area ellipsoid of the X-ray metal ellipsoid focusing mirror of the present invention; Figure 3This is a scanning electron microscope image of the X-ray metal ellipsoid focusing mirror of the present invention; Figure 4 The test results of the X-ray metal ellipsoid focusing mirror of the present invention on the X-ray machine; Figure 4 A is a half-cut X-ray metal ellipsoid focusing mirror of the present invention; Figure 4 B is a complete X-ray metal ellipsoid focusing mirror of the present invention with a beam blocker; Figure 4 C is the test result of the X-ray metal ellipsoid focusing mirror alone of the present invention; Figure 4 D shows Figure 4 Three-dimensional graph of light intensity distribution in C; Figure 4 E is the annular beam after the X-ray metal ellipsoid focusing mirror of the present invention uses a small hole to shield the stray light; Figure 5 It is a schematic diagram of the test case structure layout; Figure 6 This is a schematic diagram of the assembly structure of the fixture and the X-ray metal ellipsoid focusing mirror of the present invention; Figure 6 A is the front view of the X-ray metal ellipsoid focusing mirror after it is placed in the fixture; Figure 6 B is a top view of the X-ray metal ellipsoid focusing mirror after it is placed in the fixture; In the figure, 1. glass rod; 2. clamp; 3. chromium film and gold film; 4. electroplating solution; 5. nickel electroplating; 6. driving part; 7. photoresist; 8. gold film; 9. nickel shell; 10. high-strength glue; 11. metal clamp; 12. X-ray metal ellipsoid focusing mirror. DETAILED DESCRIPTION

[0021] The following examples are used to illustrate the present invention but are not intended to limit the scope of the present invention.

[0022] like Figure 1-Figure 2 As shown, the present invention provides a method for manufacturing an X-ray metal ellipsoid focusing mirror, and the specific steps are as follows: S1. Determine the size, and determine the length, diameter and thickness of the glass rod and the electroplated nickel according to the X-ray grazing angle, the photon collection solid angle and the ellipsoidal surface parameters of the metal ellipsoid focusing mirror; S2. Evaporation of conductive layer, the straightness is less than 1 , diameter 150 The glass rod is placed in a vacuum coating machine, and a chromium film and a gold film are sequentially deposited on the outer surface of the glass rod. Figure 1 As shown in A; The thickness of the chromium film and the gold film are 5nm and 30nm respectively to ensure that the chromium film and the gold film have good adhesion stability and conductivity. At the same time, the vacuum degree can be controlled at 10 -4 Pa, the coating speed can be controlled at 0.3nm / s to ensure that the chromium film and the gold film have appropriate roughness, and further enhance the adhesion and adhesion stability of the chromium film and the gold film.

[0023] During evaporation, the fixture holds one end of the glass rod and places it on a vacuum rotary motor to rotate around the axis. The speed can be set to 300RPM. The axis of the glass rod is placed horizontally, and the side of the glass rod is evenly coated from bottom to top during the rotation of the glass rod.

[0024] S3. Electroplating shell, the glass rod coated with chromium film and gold film in S2 is used as the cathode material, and the metal nickel is used as the anode material, and then the depth of the glass rod immersed in the electroplating solution, the residence time at different depths and the current are controlled to obtain an ellipsoidal electroplated nickel shell of a predetermined thickness in S1 on the outer surface of the glass rod, such as Figure 1 As shown in B; The electroplating temperature can be set to 55°C, the anode material is nickel metal, and the electroplating solution can be Watts plating solution. Through a driving part, such as a stepper motor or an electric push rod, the glass rod clamped by the fixture is controlled to move downward in equal steps, and then the dwell time and current of each step are adjusted to control the thickness of the electroplated nickel shell on the surface of the glass rod to obtain an ellipsoidal surface.

[0025] And the quality of nickel metal and plating time , current size Relationship satisfaction ; in, is the relative atomic mass of nickel, ; is Faraday's constant, ; is Avogadro's constant, ; is the charge of the electron, .

[0026] Specifically in the electroplating process, the precise quality of the required nickel metal The calculation method is as follows: The X-ray metal ellipsoid focusing mirror with a plating length of L is divided into M steps of plating, L depends on the size of the collection solid angle during optical design, M can be 1000-3000, the step length of each step is L / M, and the plating step sequence is n, n=1,2,3,4...M.

[0027] At this time, the X-ray metal ellipsoid focusing mirror with a length of L is discretized into M positions, and the position sequence of each point is p, p = 1, 2, 3, 4... M. Therefore, the radius T of the ellipsoid cross section of each position point can be calculated according to the ellipse equation p , p=1,2,3,4…M.

[0028] The initial radius of the glass rod is r0, and the total thickness of nickel required for electroplating at each position point p is T p -r0. Then in the nth step of electroplating, the required electroplating thickness is t n T n -T n +1. After the nth step of electroplating, the current electroplated thickness at each position is recorded as Then the volume of the small cylinder at position p after the nth step of electroplating is It can be expressed as When performing n-step electroplating, the volume of the small cylinder at the pth position that needs to be increased in the nth step is Therefore, the total volume of the electroplating material needs to be increased to The total mass of electroplating material that needs to be added is M n =V n d, where d is the density of the electroplating material; Substituting the formula for the mass of metallic nickel, we get: Therefore, by controlling the product of current I and time t, the required quality of the electroplating material in the nth step can be accurately controlled.

[0029] Therefore, by precisely controlling the quality of metal nickel placement, electroplating current and time, the uniformity and smoothness of the ellipsoidal surface of the electroplated nickel shell can be ensured as much as possible.

[0030] S4. Dip-coat the photoresist, dip the glass rod with the nickel shell electroplated in S3 into the photoresist, and then take it out and bake it to form a uniform organic film on the surface of the nickel shell electroplated on the glass rod, such as Figure 1 As shown in C; Photoresist can be selected from MEGAPOSITSPR220-3.0, the dip coating thickness is 2-4 After the glass rod is dipped in photoresist, it can be transferred to a vacuum chamber and baked at 100°C for 15 minutes to form 2-4 The resulting uniform organic film makes the entire reflective surface as smooth as possible, which is also convenient for subsequent demoulding.

[0031] S5. Evaporation of gold film: After the glass rod in S4 is cooled to room temperature naturally, it is placed in a vacuum coating machine for spin coating, so that a layer of gold film is deposited on the outer surface of the organic film in S4. Figure 1 As shown in D; During evaporation, one end of the glass rod is clamped by a fixture and placed on a vacuum rotary motor to rotate around the axis. The axis of the glass rod is coaxial with the motor rotation axis. The speed can be set to 300RPM, and the axis of the glass rod is placed horizontally. During the rotation of the glass rod, the side of the glass rod is evenly coated from bottom to top, and a 100nm thick gold film is deposited on the photoresist surface in the effective ellipsoid area.

[0032] In the coating of rotating bodies, it should be noted that the actual coating thickness is the film thickness measurement reading in the coating machine divided by the π value. The equipment reading is for flat coating. Therefore, when we need to coat a 100nm thick gold film on the side of the ellipsoid rod, the equipment reading should be around 314nm.

[0033] S6. Electroplating shell: Place the glass rod with gold film deposited in S5 in the electroplating solution, and electroform a nickel shell on the outer surface of the gold film. Figure 1 As shown in E; the specific process of electroplating the nickel shell is the same as that of the S3 electroplating nickel shell, and will not be described in detail here.

[0034] S7. Shearing and shaping: fix the glass rod covered with nickel shell to the metal fixture with high-strength glue, so as to cut off the upper end of the ellipsoid area together with the excess glass rod, and then grind the remaining effective ellipsoid area with 2000-grit sandpaper until it feels smooth. Figure 1 F and Figure 1 As shown in G; like Figure 6 As shown, a semicircular hole is provided on the upper surface of the metal fixture, which can be used to place and fix the glass rod. The material of the metal fixture can be an aluminum plate, and the high-strength glue can be epoxy resin AB glue.

[0035] S8. Demolding and cleaning, soak the effective ellipsoid area polished in S7 in anhydrous acetone for more than 2 hours to dissolve the photoresist dip-coated in S4 until the glass rod core shaft can be pulled out of it. In this process, the photoresist is dissolved by anhydrous acetone to obtain an X-ray metal ellipsoid focusing mirror with a smooth inner surface and a reflective material of gold.

[0036] Then, the ellipsoid part without the glass rod core was placed in anhydrous isopropanol for ultrasonic cleaning for 10 minutes, and after drying, an X-ray metal ellipsoid focusing mirror was obtained. Figure 1 As shown in H.

[0037] The contour information of the X-ray metal ellipsoid focusing microscope image extracted by high-resolution microscope is as follows: Figure 2 shown.

[0038] The scanning electron microscope image of the manufactured X-ray metal ellipsoid focusing mirror is shown below: Figure 3 shown. Figure 3The figure shows the end with a larger diameter of the X-ray metal ellipsoid focusing mirror. It can be seen that there are some wrinkles on its inner surface. This is because the gold-plated film at the bottom causes part of the gold film on the nickel shell to move and deform during deposition, but it does not affect the use of the X-ray metal ellipsoid focusing mirror.

[0039] Test example: The focusing ability of the X-ray metal ellipsoid focusing mirror can be reflected by collecting the focused light spot after the X-ray machine irradiates the X-ray metal ellipsoid focusing mirror. In this experimental example, the focusing effect of the X-ray metal ellipsoid focusing mirror prepared in the above embodiment is measured. The specific measurement structure arrangement is as follows: Figure 5 shown.

[0040] The X-ray rotating ellipsoid focusing mirror is placed on a five-axis translation stage to measure the focusing effect. The designed length of the X-ray ellipsoid focusing mirror is 20 mm, the semi-major axis a=150 mm, the semi-minor axis b=0.4 mm, the X-ray machine is 12 mm away from the ellipsoid focusing mirror, and the detector is 268 mm away from the ellipsoid focusing mirror.

[0041] The X-ray machine is a Japanese Hamamatsu Photon L10101 micro-focus light source, with a voltage set at 40 kV and a current of 200 μA. The X-ray detector is composed of a scintillator, a visible light optical system and a cooling camera, with a single pixel spatial resolution of 5 , the number of pixels is 2048×2048, and the data readout bit is 16 bits. The detector can ensure high-resolution detection of the light spot.

[0042] Figure 4 A. Figure 4 B. Figure 4 C shows the test results of a half-cut X-ray metal ellipsoid focusing mirror, a complete X-ray metal ellipsoid focusing mirror with a beam blocker, and a single X-ray metal ellipsoid focusing mirror.

[0043] Figure 4 D shows Figure 4 The three-dimensional image of the intensity distribution of the focused light spot in C shows that the half-height width of the focused light spot is about 200. , achieving photon collection with a solid angle greater than 0.5mSr, and the total brightness within the spot is increased by more than 3 orders of magnitude.

[0044] This proves that the X-ray metal ellipsoid focusing mirror manufactured by the above embodiment can effectively improve the illumination intensity while meeting the small size requirement of a diameter of hundreds of microns.

[0045] Although the present invention has been described in detail above by general description and specific embodiments, it is obvious to those skilled in the art that some modifications or improvements can be made to the present invention. Therefore, these modifications or improvements made without departing from the spirit of the present invention all belong to the scope of protection claimed by the present invention.

Claims

1. A method for manufacturing an X-ray metal ellipsoid focusing mirror, characterized in that: The specific steps are as follows: S1. Determine the size, and determine the length, diameter and thickness of the glass rod and the electroplated nickel according to the X-ray grazing angle, the photon collection solid angle and the ellipsoidal surface parameters of the metal ellipsoid focusing mirror; S2. Evaporation of conductive layer, the straightness is less than 1 A glass rod is placed in a vacuum coating machine, and a chromium film and a gold film are sequentially deposited on the outer surface of the glass rod; S3. Electroplating shell, the glass rod coated with chromium film and gold film in S2 is used as the cathode material, and the metal nickel is used as the anode material, and then the depth of the glass rod immersed in the electroplating solution and the residence time and current at different depths are controlled to obtain an ellipsoidal nickel electroplated shell of a predetermined thickness in S1 on the outer surface of the glass rod; S4 dip-coated photoresist, the nickel-plated glass rod in S3 is immersed in the photoresist, and then removed and baked to form a uniform organic film on the surface of the nickel-plated shell of the glass rod; S5. Evaporating a gold film, after the glass rod in S4 is naturally cooled to room temperature, it is placed in a vacuum coating machine for spin coating, so that a layer of gold film is deposited on the outer surface of the organic film in S4; S6. Electroplating shell, placing the glass rod with the gold film deposited in S5 in the electroplating solution, electroforming a nickel shell on the outer surface of the gold film; S7. Shearing and shaping, cutting off the upper end of the ellipsoid area together with the excess glass rod, and then grinding the remaining effective ellipsoid area with sandpaper until it feels smooth; S8. Demolding and cleaning: placing the effective ellipsoid area polished in S7 in anhydrous acetone to dissolve the photoresist dip-coated in S4 until the glass rod core shaft can be pulled out of it, and then placing the ellipsoid part without the glass rod core shaft in anhydrous isopropanol for ultrasonic cleaning. After drying, the X-ray metal ellipsoid focusing mirror is obtained.

2. The method for manufacturing an X-ray metal ellipsoid focusing mirror according to claim 1, characterized in that: The thicknesses of the chromium film and the gold film in S2 are 5 nm and 30 nm respectively.

3. The method for manufacturing an X-ray metal ellipsoid focusing mirror according to claim 1, characterized in that: The thermal evaporation coating speed in S2 is 0.3nm / s and the vacuum degree is 10 -4 Pa; During evaporation, the glass rod is placed horizontally and rotated at a speed of 300RPM under the action of a vacuum rotary motor.

4. The method for manufacturing an X-ray metal ellipsoid focusing mirror according to claim 1, characterized in that: The electroplating solution in S3 is Watts plating solution, and the electroplating temperature is controlled at 55°C.

5. The method for manufacturing an X-ray metal ellipsoid focusing mirror according to claim 1, characterized in that: The mass of nickel metal described in S3 and plating time , current size The relationship is: ; in, is the relative atomic mass of nickel, ; is Faraday's constant, ; is Avogadro's constant, ; is the charge of the electron, .

6. The method for manufacturing an X-ray metal ellipsoid focusing mirror according to claim 1, characterized in that: The baking and shaping method in S4 is: placing the glass rod in an air cavity at a temperature of 100°C and baking for 15 minutes; The photoresist is MEGAPOSITSPR220-3.0, and the coating thickness is 2-4 .

7. The method for manufacturing an X-ray metal ellipsoid focusing mirror according to claim 1, characterized in that: The gold film deposition thickness described in S5 is 100 nm, and the actual coating thickness during the coating process is the film thickness value measured by the coating machine divided by the π value.

8. The method for manufacturing an X-ray metal ellipsoid focusing mirror according to claim 1, characterized in that: The thickness of the nickel shell in S6 is 100 .

9. The method for manufacturing an X-ray metal ellipsoid focusing mirror according to claim 1, characterized in that: The effective ellipsoid region in S8 is immersed in anhydrous acetone for more than 2 hours, and the ultrasonic cleaning time is 10 minutes.

10. X-ray metal ellipsoid focusing mirror, characterized in that: The X-ray metal ellipsoid focusing mirror is manufactured by the manufacturing method of any one of claims 1 to 9.

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