CN114544675A - Band-pass light splitting X-ray optical system and film distribution determining method - Google Patents
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Abstract
The invention relates to an X-ray optical system with band-pass light splitting and a film distribution determining method, wherein the system comprises: a multilayer film subsystem; the multilayer film subsystem comprises a first reflecting mirror and a second reflecting mirror; the first reflector and the second reflector are both non-periodic multilayer film reflectors, and the reflection spectra of the first reflector and the second reflector are complementary; the first reflector and the second reflector adopt different film layer distribution; the positions of the first reflector and the second reflector are kept parallel, so that X-rays are taken as incident light rays to be sequentially incident to the first reflector and the second reflector, the grazing incidence angle of the first reflector is equal to that of the second reflector, and the reflected light rays passing through the second reflector are kept parallel to the incident light rays; the first mirror is used for suppressing low energy side lobes in the reflection spectrum and the second mirror is used for suppressing high energy side lobes in the reflection spectrum. On the premise of ensuring the resolution, the suppression efficiency of the side lobe is effectively improved.
Description
Technical Field
The invention relates to the technical field of precision optical systems, in particular to an X-ray optical system with band-pass light splitting and a film distribution determining method.
Background
X-ray spectral analysis is often applied to the fields of elemental analysis, plasma diagnosis, deep space astronomical detection and the like, and is an important research tool for subjects such as biology, materials, astronomy, physics, chemistry and the like. The X-ray spectral system is an essential component of the X-ray precision spectral analysis system, and the working performance mainly depends on the resolution and the sensitivity of the X-ray precision spectral analysis system. The conventional X-ray spectroscope comprises a filter disc, a crystal monochromator, a multilayer film and the like, wherein the filter disc divides a spectrum by utilizing the step change of refractive indexes of elements at the L or K absorption edge of the filter disc, and has the characteristic of simple and convenient preparation. However, the absorption edge of the filter is fixed, and the X-ray with energy higher than the L or K absorption edge cannot be effectively cut off; and the resolution is poor. The crystal monochromator has higher resolution and is a main light splitting device for hard X rays, but the crystal monochromator has fixed crystal face constant, low diffraction efficiency and poorer sensitivity. The multilayer film structure is a one-dimensional artificial crystal, and in the wave band from extreme ultraviolet to hard X-ray, the multilayer film fills the working wave band gap between the grating and the crystal of the traditional dispersion element, and has the advantages of high efficiency, stable performance and the like. The high energy synchrotron radiation source (CHESS) at Cornell university, USA, developed based on a W/C multilayer film, was applied to the CHESS A2 beam line, measuring up to 60% reflectance, with a luminous flux about 100 times higher than that of a Si crystal monochromator. In 2019, a wide-band multilayer film of Mo-Ka line is successfully realized by adopting a gradient Mo/Si multilayer film in an LLNL laboratory in the United states, the Mo-Ka line is expected to be applied to a national ignition device (NIF), and in addition, the multilayer film is used as a sectional mirror with an astronomical telescope Wolter configuration, can effectively improve the numerical aperture and the luminous flux, and is currently used for telescopes such as NuSTAR, SUMIT, InFOC mu S and the like.
The multilayer film spectroscope can be classified into a periodic multilayer film and a non-periodic multilayer film according to the film thickness distribution. The periodic thickness of the periodic multilayer film is a fixed value, and the position of the central wavelength has longer spatial coherence, so that the periodic multilayer film has the characteristics of high reflectivity and low half-height width, and is often applied to occasions requiring high resolution. But due to the constant period thickness, broadband and flat-band response cannot be realized. The film thickness of the non-periodic multilayer film is a variable, phase modulation in a certain wavelength range can be realized through the change of the periodic thickness, and the non-periodic multilayer film generally has wide-spectrum energy spectrum response. Meanwhile, the thickness distribution of the non-periodic multilayer film is variable, and the reflection spectral line can be artificially designed through optimization algorithm design.
The aperiodic multilayer film can realize flat spectral response in the neighborhood of the central spectral line through optimization algorithm design. But outside the effective region of the spectrum, a large amount of disordered side lobes appear due to phase mismatching, and the intensity and the resolution of the spectrum are reduced. In addition, interface roughness and interlayer diffusion will cause an increase in interface scattering and transmission, causing distortion and intensity reduction of the spectral pattern. The accuracy of the control of the film thickness will also affect the deviation of the reflection curve from the design pattern. The above factors will severely limit the performance of the aperiodic multilayer beamsplitter.
Disclosure of Invention
The invention aims to provide a band-pass light splitting X-ray optical system and a film distribution determining method, which can effectively improve the suppression efficiency of side lobes.
In order to achieve the purpose, the invention provides the following scheme:
the invention provides an X-ray optical system with band-pass light splitting, which comprises: a multilayer film subsystem; the multilayer film subsystem includes a first mirror and a second mirror;
the first reflector and the second reflector are both non-periodic multilayer film reflectors, and the reflection spectra of the first reflector and the second reflector are complementary; the first reflector and the second reflector adopt different film layer distribution; the positions of the first reflector and the second reflector are kept parallel, so that X-rays are taken as incident light rays to be sequentially incident to the first reflector and the second reflector, the grazing incidence angle of the first reflector is equal to that of the second reflector, and the reflected light rays passing through the second reflector are kept parallel to the incident light rays;
the first mirror is used for suppressing low-energy side lobes in the reflection spectrum, and the second mirror is used for suppressing high-energy side lobes in the reflection spectrum.
Optionally, the X-ray optical system further comprises:
the lead shell wraps the multilayer film subsystem and is used for shielding external stray light;
the beryllium window is arranged at the first opening and the second opening on the surface of the lead shell and is used for filtering the X-rays with low wave bands; the first opening is an opening formed in one end of the lead shell and is used as an inlet of X-rays which enter the multilayer film subsystem; the second opening is positioned at the other end of the lead shell and is opposite to the first opening, and the second opening is used as an outlet of the X-ray leaving the multilayer film subsystem.
Optionally, the first mirror and the second mirror are both plated on a silicon substrate with two different materials alternately distributed.
Optionally, the thickness of each of the first mirror and the second mirror is in a range of 1.6nm to 4.5 nm.
Optionally, the thickness of the lead shell is 5mm, and the thickness of the beryllium window is 50 μm.
Optionally, the inclination angles of the first mirror and the second mirror are both in the range of 0.6 ° to 1.5 °.
In order to achieve the above purpose, the invention also provides the following scheme:
the invention provides a method for determining the distribution of non-periodic multilayer film layers, which comprises the following steps:
respectively determining the film thickness distribution of the non-periodic multilayer film of the first reflector and the film thickness distribution of the non-periodic multilayer film of the second reflector by adopting a smooth gradient multilayer film method; the film thickness distribution represents the distribution condition of the thickness of each film of the non-periodic multilayer film;
determining an optimization function by adopting a simplex tuning method, and respectively optimizing the film thickness distribution of the first reflector and the film thickness distribution of the second reflector according to the optimization function to obtain the optimized film thickness distribution of the first reflector and the optimized film thickness distribution of the second reflector; when the optimization function is adopted to optimize the film thickness distribution of the first reflector, the suppression of low-energy side lobes in a reflection spectrum is realized; and when the second reflector is optimized by adopting an optimization function, the suppression of high-energy side lobes in the reflection spectrum is realized.
Optionally, the method further comprises:
determining a film thickness interval according to the maximum value and the minimum value of the film thickness; the maximum value of the film thickness is the maximum value of the film thicknesses of the first reflecting mirror and the second reflecting mirror; the minimum value of the film thicknesses is the minimum value of the film thicknesses of the first reflecting mirror and the second reflecting mirror;
preparing a plurality of periodic multilayer films with different film thicknesses within the range of the film thickness interval, and recording deposition time corresponding to different film thicknesses in the periodic multilayer films;
calibrating the thickness of the periodic multilayer film with different film thicknesses by using a grazing incidence X-ray reflection method;
and drawing a deposition rate curve of the non-periodic multilayer film according to the thickness and deposition time of each film layer in the periodic multilayer film after calibration, and determining the deposition rate when the non-periodic multilayer film is prepared.
Optionally, the method further comprises:
drawing a first relation curve according to the reflection spectrum of the first reflector, and drawing a second relation curve according to the reflection spectrum of the second reflector; the first relation curve is a relation curve of the central position angle of the first reflector and the reflectivity; the second relation curve is a relation curve of the central position angle of the second reflector and the reflectivity;
respectively characterizing the interface widths of the first reflector and the second reflector by using a grazing incidence X-ray reflection method, fitting the interface widths by using a Debye-Waller factor, and respectively determining the influence values of the interface widths on the reflectivity of the first reflector and the second reflector;
testing the first reflector by using a grazing incidence X-ray reflection method to obtain a third relation curve, and testing the second reflector by using the grazing incidence X-ray reflection method to obtain a fourth relation curve; the third relation curve is a relation curve of the angle of the center position of the reflection spectrum of the first reflector and the reflectivity of the first reflector; the fourth relation curve is a relation curve of the angle of the center position of the reflection spectrum of the second reflector and the reflectivity test;
and respectively comparing the peak positions and the peak heights of the first relation curve and the third relation curve, and the peak positions and the peak heights of the second relation curve and the fourth relation curve, and determining the integral deviation of the thicknesses of the film layers in the first reflecting mirror and the second reflecting mirror by combining the influence value of the interface width on the reflectivity of the first reflecting mirror and the influence value of the interface width on the reflectivity of the second reflecting mirror so as to adjust the deposition rate and optimize the thicknesses of the film layers according to the integral deviation.
According to the specific embodiment provided by the invention, the invention discloses the following technical effects:
the invention provides an X-ray optical system with band-pass light splitting and a film distribution determining method, wherein the system comprises: a multilayer film subsystem; the multilayer film subsystem includes a first mirror and a second mirror; the first reflector and the second reflector are both non-periodic multilayer film reflectors, and the reflection spectra of the first reflector and the second reflector are complementary; the first reflector and the second reflector adopt different film layer distribution; the positions of the first reflector and the second reflector are kept parallel, so that X-rays are taken as incident light rays to be sequentially incident to the first reflector and the second reflector, the grazing incidence angle of the first reflector is equal to that of the second reflector, and the reflected light rays passing through the second reflector are kept parallel to the incident light rays; the first mirror is used for suppressing low-energy side lobes in the reflection spectrum, and the second mirror is used for suppressing high-energy side lobes in the reflection spectrum. On the premise of ensuring the resolution, the suppression efficiency of the side lobe is effectively improved.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed to be used in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings without inventive exercise.
FIG. 1 is a schematic diagram of a system architecture of a bandpass spectroscopy X-ray optical system of the present invention;
FIG. 2 is a schematic structural view of a non-periodic multilayer film according to the present invention;
FIG. 3 is a film thickness distribution diagram for preparing an aperiodic multilayer film using W/Si;
FIG. 4 is a system output reflectance spectrum of the X-ray optical system of the present invention.
Description of the symbols:
the multilayer film subsystem-1, the first reflector-11, the second reflector-12, the lead shell-2 and the beryllium window-3.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The invention aims to provide a band-pass light splitting X-ray optical system and a film distribution determining method, which can effectively improve the suppression efficiency of side lobes.
In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in further detail below.
As shown in fig. 1, an X-ray optical system with bandpass spectroscopy according to the present invention includes: a multilayer film subsystem 1; the multilayer film subsystem comprises a first mirror 11 and a second mirror 12.
The first reflector 11 and the second reflector 12 are both non-periodic multilayer film reflectors, and the reflection spectra of the first reflector 11 and the second reflector 12 are complementary; the first reflector 11 and the second reflector 12 adopt different film layer distributions; the first reflector 11 and the second reflector 12 are positioned in parallel so that the X-ray is incident on the first reflector 11 and the second reflector 12 in sequence as an incident light, the grazing incidence angle of the first reflector 11 is equal to the grazing incidence angle of the second reflector 12, and the reflected light passing through the second reflector 12 is parallel to the incident light. The structural schematic diagram of the aperiodic multilayer film is shown in fig. 2, and the grazing incidence angle refers to an included angle between an incident ray and a mirror surface.
The first mirror 11 is used for suppressing low energy side lobes in the reflection spectrum, and the second mirror 12 is used for suppressing high energy side lobes in the reflection spectrum.
Further, the X-ray optical system further includes:
and the lead shell 2 wraps the multilayer film subsystem 1 and is used for shielding external stray light.
The beryllium window 3 is arranged at the first opening and the second opening on the surface of the lead shell 2 and is used for filtering the low-waveband X-rays; the first opening is an opening formed at one end of the lead shell 2 and is used as an inlet of X-rays which enter the multilayer film subsystem 1; the second opening is positioned at the other end of the lead shell 2 and is opposite to the first opening, and is used as an outlet of the X-ray leaving the multilayer film subsystem 1. Specifically, the beryllium window 3 is used for filtering low-energy X-rays below 2KeV, and a passage for cables and pipelines is arranged at the beryllium window 3.
Further, the X-ray optical system also comprises a rotating shaft platform. The first reflector 11 and the second reflector 12 are arranged on a rotating shaft platform, the parallel positions are kept, the included angle between the inclination angle of the mirror surface and the horizontal direction is 0.6-1.5 degrees, and the adjustment is carried out by the rotating shaft platform. The X-ray optical system is calibrated by using an interference method and a laser interferometer, a first reflecting mirror 11 or a second reflecting mirror 12 is arranged at the outlet end, and the inclination angle positions of the first reflecting mirror 11 and the second reflecting mirror 12 are adjusted by using the interference fringes of the laser light which returns and returns.
Further, the first mirror 11 and the second mirror 12 are both plated on a silicon substrate with two different materials alternately distributed. Wherein, the film material is determined by the refractive index and the absorption edge of the material, for example, the target energy point 8.04KeV adopts a W/Si multilayer film, namely, W and Si nanometer film layers are prepared on the substrate in turn and alternately; 9.67KeV Mo/Si multilayer films were used, i.e., Mo and Si nanolayer films were prepared in sequence and alternately on the substrate. Further, the first reflector 11 and the second reflector 12 may be made of different materials according to actual needs, and are not limited herein.
Preferably, the thickness of the film layer of the first mirror 11 and the second mirror 12 is in the range of 1.6nm to 4.5 nm.
Further, the thickness of the lead shell 2 is 5mm, and the thickness of the beryllium window 3 is 50 μm.
Preferably, the inclination angles of the first mirror 11 and the second mirror 12 are both in the range of 0.6-1.5 °.
In order to achieve the above object, the present invention further provides a method for determining the film layer distribution of an aperiodic multilayer film, comprising the steps of:
s1: respectively determining the film thickness distribution of the non-periodic multilayer film of the first reflector and the film thickness distribution of the non-periodic multilayer film of the second reflector by adopting a smooth gradient multilayer film method; the film thickness distribution represents the distribution of the thickness of each film of the non-periodic multilayer film.
S2: determining an optimization function by adopting a simplex tuning method, and respectively optimizing the film thickness distribution of the first reflector and the film thickness distribution of the second reflector according to the optimization function to obtain the optimized film thickness distribution of the first reflector and the optimized film thickness distribution of the second reflector; when the optimization function is adopted to optimize the film thickness distribution of the first reflector, the suppression of low-energy side lobes in a reflection spectrum is realized; and when the second reflector is optimized by adopting an optimization function, the suppression of high-energy side lobes in the reflection spectrum is realized. FIG. 3 is a film thickness distribution diagram of the non-periodic multilayer film prepared by W/Si according to the present invention; FIG. 4 is an output reflectance spectrum of an X-ray optical system.
Further, in order to accurately deposit the aperiodic multilayer film, the deposition rate is determined, and the method further comprises:
determining a film thickness interval according to the maximum value and the minimum value of the film thickness; the maximum value of the film thickness is the maximum value of the film thicknesses of the first reflecting mirror and the second reflecting mirror; the minimum value of the film thicknesses is the minimum value of the film thicknesses of the first reflector and the second reflector.
Preparing a plurality of periodic multilayer films with different film thicknesses within the range of the film thickness interval, and recording the deposition time corresponding to the different film thicknesses in the periodic multilayer films.
And calibrating the thickness of the periodic multilayer film with different film thicknesses by using a grazing incidence X-ray reflection method.
And drawing a deposition rate curve of the non-periodic multilayer film according to the thickness and deposition time of each film layer in the periodic multilayer film after calibration, and determining the deposition rate when the non-periodic multilayer film is prepared.
Further, the method further comprises:
drawing a first relation curve according to the reflection spectrum of the first reflector, and drawing a second relation curve according to the reflection spectrum of the second reflector; the first relation curve is a relation curve of the central position angle of the first reflector and the reflectivity; the second relation curve is a relation curve of the central position angle of the second reflector and the reflectivity.
Respectively characterizing the interface widths (non-ideal interfaces) of the first reflector and the second reflector by using a grazing incidence X-ray reflection method, fitting the interface widths by using a Debye-Waller factor, and respectively determining the influence values of the interface widths on the reflectivity of the first reflector and the second reflector, namely determining the influence of the non-ideal interfaces on the optical response of the non-periodic multilayer film caused by experiments, wherein the interface widths refer to the influence of a certain thickness of a film interface caused by diffusion or roughness on the reflectivity of the non-periodic multilayer film.
Testing the first reflector by using a grazing incidence X-ray reflection method to obtain a third relation curve, and testing the second reflector by using the grazing incidence X-ray reflection method to obtain a fourth relation curve; the third relation curve is a relation curve of the angle of the center position of the reflection spectrum of the first reflector and the reflectivity of the first reflector; the fourth relation curve is a relation curve of the angle of the center position of the reflection spectrum of the second reflector and the reflectivity test; the X-ray source in the grazing incidence X-ray reflection test is a Cu-Kalpha line, the wavelength is 0.154nm, and the test mode is a theta-2 theta linkage scanning mode.
And respectively comparing the peak positions and the peak heights of the first relation curve and the third relation curve, and the peak positions and the peak heights of the second relation curve and the fourth relation curve, and determining the integral deviation of the thicknesses of the film layers in the first reflector and the second reflector by combining the influence value of the interface width on the reflectivity of the first reflector and the influence value of the interface width on the reflectivity of the second reflector so as to adjust the deposition rate and optimize the thicknesses of the film layers according to the integral deviation.
Further, the average reflectivity, the flat band flatness and the side lobe suppression ratio of each band in the band pass interval are calculated to be used as evaluation indexes of the band-pass spectral X-ray optical system.
Wherein the flatness of the flat belt
Side lobe suppression ratio SRR ═ R0/RsAs an evaluation index of the system, wherein R0Is a target reflectance, RiFor actual reflectivity, m is the number of scattered points of the flat band, RsThe reflectivity of the highest side lobe.
The X-ray band-pass light splitting system adopted by the invention has the same light reflectivity for different wavelengths, so that relatively flat spectral response can be realized, and the extraction precision of the X-ray spectral signals can be improved.
The following are several specific examples of the present invention.
Example 1
The method for determining the film distribution of the non-periodic multilayer film is adopted, and an X-ray optical system working at a Cu-K alpha line of 8.05KeV and 1-degree glancing incidence is designed based on an X-ray band-pass light splitting system, wherein a W/Si multilayer film is adopted in the example, and the film thickness distribution is 1.6nm-4.5 nm.
Preparing a periodic multilayer film sample, wherein the film thickness is distributed between 1.6nm and 4.5nm, calibrating the thickness of the sample by using GIXRR, and performing linear fitting, wherein the film thickness error determined by a fitting curve is less than 1%.
The sample was characterized by a GIXRR for interfacial width of about 0.3 nm.
And calibrating the non-periodic multilayer film sample by using GIXRR, and performing thickness fitting by using a simplex tuning method, wherein the root mean square of the thickness error is less than 3%.
Calculated by Parratt recursion formula, the first reflector has a flat band width 560e, a full width at half maximum 924eV and a reflectivity of 56%.
Calculated by Parratt's recursion formula, the second mirror flat band width is 560eV, the half-height width is 972eV, and the reflectivity is 56%.
Calculated by a Parratt recursion formula, the combined flat band width of the first reflector and the second reflector is 560eV, the reflectivity is 31%, the response flatness is less than 0.1%, and the side lobe suppression ratio is higher than 10.41. Therefore, the multilayer film subsystem has good side lobe suppression ratio and response flatness.
Example 2
The method for determining the film distribution of the aperiodic multilayer film is adopted, and an X-ray optical system working at W-L alpha line of 9.67KeV and 1-degree glancing incidence is designed based on an X-ray band-pass light splitting system, wherein a Mo/Si multilayer film is adopted in the example, and the film thickness distribution is 1.6nm-4.5 nm.
Preparing a periodic multilayer film sample, wherein the film thickness is distributed between 1.6nm and 4.5nm, calibrating the thickness of the sample by using GIXRR, and performing linear fitting, wherein the film thickness error determined by a fitting curve is less than 1%.
The sample was characterized by a GIXRR for interfacial width of about 0.3 nm.
And calibrating the non-periodic multilayer film sample by using GIXRR, and performing thickness fitting by using a simplex tuning method, wherein the root mean square of the thickness error is less than 3%.
Calculated by Parratt recursion formula, the flat band width of the first reflector is 460eV, the half-height width is 813eV, and the reflectivity is 52%.
Calculated by Parratt recursion formula, the width of the second mirror flat band is 370eV, the half-height width is 775eV, and the reflectivity is 55%.
Calculated by a Parratt recursion formula, the combined flat band width is 370eV, the reflectivity is 28.6%, the response flatness is less than 0.1%, and the side lobe suppression ratio is higher than 9.55. Therefore, the multilayer film subsystem has good side lobe suppression ratio and response flatness.
Example 3
The method for determining the film distribution of the non-periodic multilayer film is adopted, and an X-ray optical system working at a Cu-K alpha line of 8.05KeV and 1-degree glancing incidence is designed based on an X-ray band-pass light splitting system, wherein a W/Si multilayer film is adopted in the example, and the film thickness distribution is 1.6nm-4.5 nm.
Preparing a periodic multilayer film sample, wherein the film thickness is distributed between 1.6nm and 4.5nm, calibrating the thickness of the sample by using GIXRR, and performing linear fitting, wherein the film thickness error determined by a fitting curve is less than 1%.
The sample was characterized by a GIXRR for interfacial width of about 0.3 nm.
And calibrating the non-periodic multilayer film sample by using GIXRR, and performing thickness fitting by using a simplex tuning method, wherein the root mean square of the thickness error is less than 3%.
Calculated by a Parratt recursion formula, when the rotation angle is 0.9 degrees, the central energy point is 9.07KeV, the flat band width is 640eV, the half-height width is 1090eV, and the reflectivity is 33%.
Calculated by a Parratt recursion formula, when the corner is 1 degree, the central energy point is positioned at 8.05KeV, the flat band width is 560eV, the half-height width is 920eV, and the reflectivity is 31%.
Calculated by a Parratt recursion formula, when the corner is 1.1 degrees, the central energy point is located at 7.45KeV, the flat band width is 420eV, the half height width is 880eV, and the reflectivity is 29%.
The embodiments in the present description are described in a progressive manner, each embodiment focuses on differences from other embodiments, and the same and similar parts among the embodiments are referred to each other.
The principles and embodiments of the present invention have been described herein using specific examples, which are provided only to help understand the method and the core concept of the present invention; meanwhile, for a person skilled in the art, according to the idea of the present invention, the specific embodiments and the application range may be changed. In view of the above, the present disclosure should not be construed as limiting the invention.
Claims (9)
1. A bandpass spectroscopic X-ray optical system, the X-ray optical system comprising: a multilayer film subsystem; the multilayer film subsystem includes a first mirror and a second mirror;
the first reflector and the second reflector are both non-periodic multilayer film reflectors, and the reflection spectra of the first reflector and the second reflector are complementary; the first reflector and the second reflector adopt different film layer distribution; the positions of the first reflector and the second reflector are kept parallel, so that X-rays are taken as incident light rays to be sequentially incident to the first reflector and the second reflector, the grazing incidence angle of the first reflector is equal to that of the second reflector, and the reflected light rays passing through the second reflector are kept parallel to the incident light rays;
the first mirror is used for suppressing low-energy side lobes in the reflection spectrum, and the second mirror is used for suppressing high-energy side lobes in the reflection spectrum.
2. The beam-splitting X-ray optical system of claim 1, further comprising:
the lead shell wraps the multilayer film subsystem and is used for shielding external stray light;
the beryllium window is arranged at the first opening and the second opening on the surface of the lead shell and is used for filtering the X-rays with low wave bands; the first opening is an opening formed in one end of the lead shell and is used as an inlet of X-rays which enter the multilayer film subsystem; the second opening is positioned at the other end of the lead shell and is opposite to the first opening, and the second opening is used as an outlet of the X-ray leaving the multilayer film subsystem.
3. The beam-splitting X-ray optical system of claim 1, wherein the first mirror and the second mirror are each coated on a silicon substrate with two different materials alternately disposed.
4. The beam-splitting X-ray optical system of claim 1, wherein the first and second mirrors each have a film thickness in a range of 1.6nm to 4.5 nm.
5. The beam-splitting X-ray optical system of claim 2, wherein the lead shell has a thickness of 5mm and the beryllium window has a thickness of 50 μ ι η.
6. The beam-splitting X-ray optical system of claim 1, wherein the first mirror and the second mirror each have a mirror surface tilt angle in the range of 0.6 ° to 1.5 °.
7. A method for determining the film distribution of an aperiodic multi-layer film, which is characterized by comprising the following steps:
determining the film thickness distribution of the non-periodic multilayer film based on the first reflector and the film thickness distribution of the non-periodic multilayer film based on the second reflector of claims 1-6 respectively by adopting a smooth gradient multilayer film method; the film thickness distribution represents the distribution condition of the thickness of each film of the non-periodic multilayer film;
determining an optimization function by adopting a simplex tuning method, and respectively optimizing the film thickness distribution of the first reflector and the film thickness distribution of the second reflector according to the optimization function to obtain the optimized film thickness distribution of the first reflector and the optimized film thickness distribution of the second reflector; when the optimization function is adopted to optimize the film thickness distribution of the first reflector, the suppression of low-energy side lobes in a reflection spectrum is realized; and when the second reflector is optimized by adopting an optimization function, the suppression of high-energy side lobes in the reflection spectrum is realized.
8. The method of determining aperiodic multilayer film layer distribution as recited in claim 7, further comprising:
determining a film thickness interval according to the maximum value and the minimum value of the film thickness; the maximum value of the film thickness is the maximum value of the film thicknesses of the first reflecting mirror and the second reflecting mirror; the minimum value of the film thicknesses is the minimum value of the film thicknesses of the first reflecting mirror and the second reflecting mirror;
preparing a plurality of periodic multilayer films with different film thicknesses within the range of the film thickness interval, and recording deposition time corresponding to different film thicknesses in the periodic multilayer films;
thickness calibration is carried out on the periodic multilayer films with different film thicknesses by using a grazing incidence X-ray reflection method;
and drawing a deposition rate curve of the non-periodic multilayer film according to the thickness and deposition time of each film layer in the periodic multilayer film after calibration, and determining the deposition rate when the non-periodic multilayer film is prepared.
9. The method of determining aperiodic multilayer film layer distribution as recited in claim 7, further comprising:
drawing a first relation curve according to the reflection spectrum of the first reflector, and drawing a second relation curve according to the reflection spectrum of the second reflector; the first relation curve is a relation curve of the central position angle of the first reflector and the reflectivity; the second relation curve is a relation curve of the central position angle of the second reflector and the reflectivity;
respectively characterizing the interface widths of the first reflector and the second reflector by using a grazing incidence X-ray reflection method, fitting the interface widths by using a Debye-Waller factor, and respectively determining the influence values of the interface widths on the reflectivity of the first reflector and the second reflector;
testing the first reflector by using a grazing incidence X-ray reflection method to obtain a third relation curve, and testing the second reflector by using the grazing incidence X-ray reflection method to obtain a fourth relation curve; the third relation curve is a relation curve of the angle of the center position of the reflection spectrum of the first reflector and the reflectivity of the first reflector; the fourth relation curve is a relation curve of the angle of the center position of the reflection spectrum of the second reflector and the reflectivity test;
and respectively comparing the peak positions and the peak heights of the first relation curve and the third relation curve, and the peak positions and the peak heights of the second relation curve and the fourth relation curve, and determining the integral deviation of the thicknesses of the film layers in the first reflecting mirror and the second reflecting mirror by combining the influence value of the interface width on the reflectivity of the first reflecting mirror and the influence value of the interface width on the reflectivity of the second reflecting mirror so as to adjust the deposition rate and optimize the thicknesses of the film layers according to the integral deviation.
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Application publication date: 20220527 |