CN114755821A - Partition calculation method for diffraction efficiency of Fresnel zone plate - Google Patents
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Abstract
The invention provides a partition calculation method for the diffraction efficiency of a Fresnel zone plate, which is characterized in that the structure of the Fresnel zone plate is determined based on the application requirement of the Fresnel zone plate; approximating the annular grating of the Fresnel zone plate to a two-dimensional linear grating, and taking the total width of a pair of adjacent zones as the period of the approximate linear grating; calculating the diffraction efficiency of the two-dimensional linear grating with different periods, and drawing a relation curve between the diffraction efficiency and the ring bandwidth according to the diffraction efficiency of each ring of the Fresnel zone plate with different ring bandwidth; dividing the Fresnel zone plate into a plurality of areas according to the fluctuation degree of the diffraction efficiency of different ring bandwidth degrees; calculating the sum of diffraction efficiencies of all the areas; and calculating the overall diffraction efficiency of the whole structure of the Fresnel zone plate according to the sum of the diffraction efficiencies of the regions. The method solves the technical problems of large error and calculation amount in the prior art when the diffraction efficiency of the Fresnel zone plate is calculated, especially when the number of rings is large and the variation of the ring bandwidth is obvious.
Description
Technical Field
The invention relates to the technical field of optical devices, in particular to a partition calculation method for the diffraction efficiency of a Fresnel zone plate.
Background
The X-ray microscopic imaging technology has the advantages of high resolution, small damage to a sample and the like, provides a new visual field for human observation, is widely applied to various industries such as bioscience, material detection and the like, and becomes one of the most powerful tools for obtaining the internal three-dimensional structure of the sample under the high resolution. The Fresnel zone plate is a key device of an X-ray microscopic imaging system, and the internal appearance of a sample is obtained by using the change of the phase after X-rays penetrate through the sample. Resolution and diffraction efficiency are the most important parameters of a fresnel zone plate. Resolution is proportional to the outermost ring width, representing the smallest dimension that can be imaged; diffraction efficiency is the ratio of diffracted light energy to incident light energy, and determines the focusing or imaging quality of the device. Optimizing device performance by calculating the diffraction efficiency of the Fresnel zone plate with a high-resolution structure has been a difficulty in the field of Fresnel zone plates.
The method for calculating the diffraction efficiency of the Fresnel zone plate mainly depends on a complex amplitude superposition method and a coupled wave theory. The complex amplitude superposition method analyzes by using a diffraction integral zone plate transmittance function or superposing diffraction fields of all circular rings of a zone plate, has high calculation speed, but when the width of the outermost ring of the Fresnel zone plate is small, the volume effect cannot be ignored, and the complex amplitude superposition method is difficult to accurately analyze the zone plate. The finite difference method of the time domain is based on the propagation process of the electromagnetic waves through the hard X-ray FZP by recursion of Maxwell equation sets in the time domain, but the application of the finite difference method is seriously hindered by the extremely small grid requirement and huge calculation amount of the hard X-ray frequency band. According to the coupled wave theory, the Fresnel zone plate is approximated to a plurality of small linear gratings, and then all the linear grating diffraction fields are vector-superposed to obtain the diffraction efficiency of the Fresnel zone plate. The method has larger error and calculation amount when analyzing devices with more ring numbers and obvious ring bandwidth change, and the calculation efficiency is not high. Therefore, a precise and rapid method for calculating the diffraction efficiency of the fresnel zone plate is needed to provide a theoretical analysis basis for analyzing and optimizing the diffraction characteristics of the fresnel zone plate with any structure.
The prior art at least has the following technical problems:
in the prior art, when the diffraction efficiency of the Fresnel zone plate is calculated, especially when the number of rings is large and the variation of the ring bandwidth is obvious, the technical problems of large error and calculation amount exist.
Disclosure of Invention
The embodiment of the application provides a partition calculation method for the diffraction efficiency of a Fresnel zone plate, and solves the technical problems of large errors and calculation amount in the prior art when the diffraction efficiency of the Fresnel zone plate is calculated, especially when the number of rings is large and the variation of the ring bandwidth is obvious.
In view of the foregoing problems, an embodiment of the present application provides a method for calculating the diffraction efficiency of a fresnel zone plate in a partitioned manner, where the method includes: determining the structure of the Fresnel zone plate based on the application requirement of the Fresnel zone plate; approximating the ring grating of the Fresnel zone plate to a two-dimensional linear grating, and taking the total width of a pair of adjacent zones as the period of the approximate linear grating; calculating the diffraction efficiency of the two-dimensional linear grating with different periods, and drawing a relation curve between the diffraction efficiency and the ring bandwidth according to the diffraction efficiency of each ring of the Fresnel zone plate with different ring bandwidth; dividing the Fresnel zone plate into a plurality of areas according to the fluctuation degree of the diffraction efficiency of different ring bandwidth degrees; calculating the sum of diffraction efficiencies of all the areas; and calculating the overall diffraction efficiency of the whole structure of the Fresnel zone plate according to the sum of the diffraction efficiencies of the regions.
Preferably, the determining the structure of the fresnel zone plate based on the application requirement of the fresnel zone plate includes: determining the required resolution and focal length according to the application requirements of the Fresnel zone plate; taking certain light source energy as a main application light source, and calculating by combining the required resolution and focal length through a coupled wave theory to obtain the thickness, the width and the material of the Fresnel zone plate; and determining the optimal thickness, the annular belt width and the optimal material of the Fresnel zone plate according to the thickness, the annular belt width and the material of the Fresnel zone plate.
Preferably, the applied light source energy is 0.1-20 keV.
Preferably, the thickness of the fresnel zone plate is a thickness value corresponding to the maximum diffraction efficiency.
Preferably, the thickness of the annular belt is satisfied
Wherein n is the number of rings and λ is the wavelengthF is the focal length of the Fresnel zone plate, and the ring number n and the wavelength lambda are uniquely determined by the energy of the light source.
Preferably, the dividing the fresnel zone plate into a plurality of regions according to the fluctuation degree of the diffraction efficiencies of different ring bandwidth degrees includes: the diffraction efficiency fluctuation of the area is not more than 1%, and the average fluctuation value is not more than one thousandth, wherein the average fluctuation value is obtained by the following formula: the average fluctuation value (fluctuation value zone number)/total zone number is calculated.
Preferably, the calculating the sum of diffraction efficiencies of the regions includes: obtaining a preset standard of the number of rings; obtaining the annulus diffraction efficiency of the preset number of rings in each area according to the preset standard of the number of rings; taking the bad zone diffraction efficiency of the preset ring number of each area as an average value of the diffraction efficiency of the area; obtaining the number of zone belts; and calculating to obtain the sum of the regional diffraction efficiencies according to the mean value of the regional diffraction efficiencies and the number of the regional zones.
Preferably, the obtaining the annulus diffraction efficiency of the preset number of rings in each area according to the preset number of rings standard includes: obtaining the width of the area ring belt; determining a diffraction efficiency calculation method according to the width of the area ring band; and calculating to obtain the zone diffraction efficiency of the preset number of rings in the area according to the diffraction efficiency calculation method.
Preferably, the determining a diffraction efficiency calculation method according to the width of the area ring band includes: when the width of the area ring band is 0-25nm, the diffraction efficiency calculation method is a coupling wave theory calculation method; and when the width of the area annular band is 25-100nm, the diffraction efficiency calculation method is a complex amplitude superposition method.
Preferably, the calculating the global diffraction efficiency of the whole structure of the fresnel zone plate according to the sum of the diffraction efficiencies of the regions includes: and calculating the global diffraction efficiency of the whole structure with different thicknesses according to the sum of the diffraction efficiencies of the areas by taking the number of the ring zones as the weight.
One or more technical solutions in the embodiments of the present application at least have one or more of the following technical effects:
the embodiment of the application provides a partition calculation method for the diffraction efficiency of a Fresnel zone plate, which comprises the following steps: determining the structure of the Fresnel zone plate based on the application requirement of the Fresnel zone plate; approximating the annular grating of the Fresnel zone plate to a two-dimensional linear grating, and taking the total width of a pair of adjacent zones as the period of the approximate linear grating; calculating the diffraction efficiency of the two-dimensional linear grating with different periods, and drawing a relation curve between the diffraction efficiency and the ring bandwidth according to the diffraction efficiency of each ring of the Fresnel zone plate with different ring bandwidth; dividing the Fresnel zone plate into a plurality of areas according to the fluctuation degree of diffraction efficiency of different ring bandwidth degrees; calculating the sum of diffraction efficiency of each area; and calculating the overall diffraction efficiency of the whole structure of the Fresnel zone plate according to the sum of the diffraction efficiencies of the areas. The diffraction characteristics of the Fresnel zone plate are analyzed based on a strict coupled wave theory, the diffraction efficiency of any zone of the Fresnel zone plate is accurately obtained, and the zone calculation is carried out on the Fresnel zone plate with more rings, so that the calculation efficiency is improved while the high-precision calculation result is ensured, and the technical problems of large errors and calculation amount in the prior art when the diffraction efficiency of the Fresnel zone plate is calculated, particularly when the number of rings is more and the width of the ring changes obviously are solved. The Fresnel zone plate is partitioned, the diffraction efficiencies of different areas of the Fresnel zone plate under given light source energy are calculated by using a strict coupled wave theory and are superposed, the diffraction efficiency of the Fresnel zone plate with any resolution can be accurately obtained, the application range is wide, the diffraction efficiency of the Fresnel zone plate with any ring number and any resolution can be calculated, the diffraction characteristics can be analyzed, and the technical effect of optimizing the device structure is facilitated.
The foregoing description is only an overview of the technical solutions of the present invention, and the embodiments of the present invention are described below in order to make the technical means of the present invention more clearly understood and to make the above and other objects, features, and advantages of the present invention more clearly understandable.
Drawings
Fig. 1 is a schematic flow chart of a method for calculating the diffraction efficiency of a fresnel zone plate according to an embodiment of the present disclosure;
FIG. 2 shows Al with a resolution of 12.2nm in an embodiment of the present invention2O3/HfO2A schematic diagram of the change of the number of rings of each zone section of the Fresnel zone plate;
FIG. 3 shows Al with a resolution of 12.2nm in an embodiment of the present invention2O3/HfO2A relation curve chart between the minimum zone number of the Fresnel zone plate and the width of the outermost ring;
FIG. 4 shows Al with a resolution of 12.2nm in an embodiment of the present application2O3/HfO2And (3) a trend comparison graph of the relation between the diffraction efficiency and the thickness of the Fresnel zone plate.
Detailed Description
The embodiment of the application provides a partition calculation method for the diffraction efficiency of a Fresnel zone plate, and the technical problems of large errors and large calculation amount exist in the prior art when the diffraction efficiency of the Fresnel zone plate is calculated, especially when the number of rings is large and the variation of the ring bandwidth is obvious.
The technical scheme provided by the invention has the following general idea:
determining the structure of the Fresnel zone plate based on the application requirement of the Fresnel zone plate; approximating the ring grating of the Fresnel zone plate to a two-dimensional linear grating, and taking the total width of a pair of adjacent zones as the period of the approximate linear grating; calculating the diffraction efficiency of the two-dimensional linear grating with different periods, and drawing a relation curve between the diffraction efficiency and the ring bandwidth according to the diffraction efficiency of each ring of the Fresnel zone plate with different ring bandwidth; dividing the Fresnel zone plate into a plurality of areas according to the fluctuation degree of the diffraction efficiency of different ring bandwidth degrees; calculating the sum of diffraction efficiencies of all the areas; and calculating the overall diffraction efficiency of the whole structure of the Fresnel zone plate according to the sum of the diffraction efficiencies of the regions. The Fresnel zone plate is partitioned, the diffraction efficiencies of different areas of the Fresnel zone plate under given light source energy are calculated by using a strict coupled wave theory and are superposed, the diffraction efficiency of the Fresnel zone plate with any resolution can be accurately obtained, the application range is wide, the diffraction efficiency of the Fresnel zone plate with any ring number and any resolution can be calculated, the diffraction characteristics can be analyzed, and the technical effect of optimizing the device structure is facilitated.
The technical solutions of the present invention are described in detail below with reference to the accompanying drawings and specific embodiments, and it should be understood that the specific features in the embodiments and examples are described in detail in the technical solutions of the present invention, but not limited to the technical solutions of the present invention, and the technical features in the embodiments and examples may be combined with each other without conflict.
Example one
Fig. 1 is a schematic flow chart of a method for calculating the diffraction efficiency of a fresnel zone plate in a partitioned manner in the embodiment of the present application. As shown in fig. 1, an embodiment of the present application provides a method for calculating the diffraction efficiency of a fresnel zone plate in a partitioned manner, where the method includes:
step S100: and determining the structure of the Fresnel zone plate based on the application requirement of the Fresnel zone plate.
Further, step S100: the determining the structure of the Fresnel zone plate based on the application requirement of the Fresnel zone plate comprises the following steps: determining required resolution and focal length according to the application requirements of the Fresnel zone plate; taking certain light source energy as a main application light source, and calculating by combining the required resolution and focal length through a coupled wave theory to obtain the thickness, the width and the material of the Fresnel zone plate; and determining the optimal thickness, the ring width and the optimal material of the Fresnel zone plate according to the thickness, the ring width and the material of the Fresnel zone plate.
Further, the energy of the applied light source is 0.1-20 keV.
Further, the thickness of the fresnel zone plate is a corresponding thickness value when the diffraction efficiency is maximum.
Further, the thickness of the annular belt is satisfied
Wherein n is the number of rings,Lambda is the wavelength, f is the focal length of the Fresnel zone plate, and the number of rings n and the wavelength lambda are uniquely determined by the energy of the light source.
Specifically, the structure of the fresnel zone plate is determined based on the application requirements of the fresnel zone plate. And taking the energy of a certain light source as a main application light source, and calculating the optimal thickness, the width and the optimal material of the Fresnel zone plate by combining the required resolution and focal length through a coupled wave theory. The optimal thickness is the thickness value corresponding to the maximum diffraction efficiency, and the width of the ring band satisfies
Wherein n represents the number of rings, the wavelength is lambda, and is uniquely determined by the energy of the light source; and f is the focal length of the Fresnel zone plate. Further, the energy of the applied light source is 0.1 to 20keV, preferably 10 keV. The desired resolution is 10-200nm, preferably 12 nm. The focal length is 1-20mm, preferably 16 mm. The thickness is 1-15 μm, preferably 4.5 μm. The Fresnel zone plate is made of Al 2O3/HfO2、Al2O3/Ir、Al2O3/Ta2O5And SiO2/HfO2Preferably, the material is Al2O3/HfO2. For example, a multi-layer Fresnel zone plate is used as an analysis sample, and the resolution is 12.2nm of Al2O3/HfO2Fresnel zone plate, Al2O3And HfO2As a multilayer film material, the wavelength of incident light is 0.155nm, the required resolution is 12.2nm, and the required focal length is 16 mm. The resolution of the fresnel zone plate and the outermost ring width satisfy δ of 1.22 Δ rN, and thus the formula can obtain the outermost ring width of the fresnel zone plate of 10 nm.
Step S200: and approximating the annular grating of the Fresnel zone plate to a two-dimensional linear grating, and taking the total width of a pair of adjacent zones as the period of the approximate linear grating.
Specifically, a ring grating of the fresnel zone plate is approximated to a two-dimensional linear grating, and the total width of a pair of adjacent zones is taken as the period of the approximated grating, phenanthreneThe zone diffraction efficiency of a niell zone plate is equal to the diffraction efficiency of an approximate grating. Also takes a multilayer Fresnel zone plate as an analysis sample, Al2O3And HfO2As a multilayer film material, Al2O3As grating light-transmitting material, with HfO2As an opaque material. The total width of the ring zones of two adjacent materials is used as the grating period.
Step S300: and calculating the diffraction efficiency of the two-dimensional linear grating with different periods, and drawing a relation curve between the diffraction efficiency and the ring bandwidth according to the diffraction efficiency of each ring of the Fresnel zone plate with different ring bandwidth.
Specifically, the diffraction efficiency of the two-dimensional grating with different periods is calculated, the diffraction efficiency of each ring of the Fresnel zone plate corresponding to different ring bandwidth is calculated, and a relation curve between the diffraction efficiency and the ring bandwidth is drawn. The width of the different annular belts is changed from 0 according to a certain step length, the range of the width of the annular belts is 0 to 200nm, and the range of the step length is 0.01 to 5 nm. Preferably, the loop bandwidth is selected to be 0-50nm, and the loop bandwidth variation step size is 0.05 nm.
Step S400: and dividing the Fresnel zone plate into a plurality of areas according to the fluctuation degree of the diffraction efficiency of different ring bandwidth degrees.
Further, step S400: dividing the Fresnel zone plate into a plurality of areas according to the fluctuation degree of the diffraction efficiency of different ring bandwidth degrees, including: the diffraction efficiency fluctuation of the area is not more than 1%, and the average fluctuation value is not more than one thousandth, wherein the average fluctuation value is obtained by the following formula: the average fluctuation value (fluctuation value zone number)/total zone number is calculated.
Specifically, a part of zone with small diffraction efficiency fluctuation is used as a region, so that the zone of the Fresnel zone plate is divided into a plurality of regions, the Fresnel zone plate is divided into a plurality of regions according to the fluctuation degree of the diffraction efficiency of different zone bandwidths, the diffraction efficiency fluctuation of the zone in each region is extremely small and is not more than 1%, and the average fluctuation value is not more than one thousandth. Taking a multilayer Fresnel zone plate as an analysis sample, and averaging a fluctuation value (fluctuation value zone band number) according to a formula ) The number of total areas is calculated, and the number of required divided areas is 244 in this embodiment. Al with a resolution of 12.2nm as shown in FIG. 22O3/HfO2The number of rings in each zone section of the Fresnel zone plate is changed.
Step S500: and calculating the sum of diffraction efficiencies of the areas.
Further, the calculating the sum of diffraction efficiencies of the regions includes: obtaining a preset standard of the number of rings; obtaining the annulus diffraction efficiency of the preset number of rings in each area according to the preset standard of the number of rings; taking the bad zone diffraction efficiency of the preset ring number of each area as an average value of the diffraction efficiency of the area; obtaining the number of zone belts; and calculating to obtain the sum of the regional diffraction efficiencies according to the mean value of the regional diffraction efficiencies and the number of the regional zones.
Further, the obtaining the annulus diffraction efficiency of the preset number of rings in each area according to the preset number of rings standard includes: obtaining the width of the area ring belt; determining a diffraction efficiency calculation method according to the width of the area ring band; and calculating to obtain the zone diffraction efficiency of the preset number of rings in the area according to the diffraction efficiency calculation method.
Further, the method for determining the diffraction efficiency according to the width of the area ring band includes: when the width of the area ring band is 0-25nm, the diffraction efficiency calculation method is a coupling wave theory calculation method; and when the width of the area annular band is 25-100nm, the diffraction efficiency calculation method is a complex amplitude superposition method.
Specifically, since the number of rings in each region is very large, and there may be tens of rings and hundreds of rings … …, if the diffraction efficiency of each ring is calculated, a large diffraction efficiency is brought, and since the diffraction efficiency fluctuation in each region is small, one of the rings is selected as a representative, and the diffraction efficiency of the ring is used as the average value of the region, and specifically which ring is selected as the representative of the region, the average value of the diffraction efficiencies of the region may be set by itself, but it is necessary to unify these valuesThe value is conveniently taken, preferably, the minimum ring or the maximum ring is selected for setting, and then the sum of diffraction efficiency of the region is calculated according to the number of the rings in the region. When calculating the diffraction efficiency, selecting an algorithm according to the width of the ring bandwidth, wherein the diffraction efficiency calculation method can only be a coupling wave theoretical calculation method when the width of the ring bandwidth is 0-25 nm; when the width of the area annular band is 25-100nm, the diffraction efficiency calculation method can be a complex amplitude superposition method. As shown in FIG. 3, the resolution of Al in the present example is 12.2nm 2O3/HfO2The relationship curve between the minimum zone number of the Fresnel zone plate and the width of the outermost ring.
Step S600: and calculating the overall diffraction efficiency of the whole structure of the Fresnel zone plate according to the sum of the diffraction efficiencies of the regions.
Further, the calculating the overall diffraction efficiency of the whole structure of the fresnel zone plate according to the sum of the diffraction efficiencies of the regions includes: and calculating the global diffraction efficiency of the whole structure with different thicknesses according to the sum of the diffraction efficiencies of the areas by taking the number of the ring zones as the weight.
Specifically, the global diffraction efficiency of the whole structure with different thicknesses is calculated by taking the number of the ring zones as weight according to a calculation formula
And calculating the global diffraction efficiency, wherein n is the number of the divided areas, and the thickness change of the Fresnel zone plate can be considered. The relationship between diffraction efficiency and thickness is shown in FIG. 4, where FIG. 4 is a graph comparing the trend of the relationship between diffraction efficiency and thickness in each algorithm, and is calculated according to the complex amplitude superposition method, the coupled wave grating approximation method, and the embodiment of the present invention, and the resolution is 12.2nm for Al at 8keV2O3/HfO2A plot of fresnel zone plate diffraction efficiency versus thickness. By analyzing the diffraction characteristics of the Fresnel zone plate based on the strict coupled wave theory, the method of the embodiment of the application realizes the accurate obtaining of the diffraction efficiency of any zone of the Fresnel zone plate; by carrying out partition calculation on the Fresnel zone plate with a large number of rings, high precision is ensured The calculation efficiency is improved while the calculation result is calculated, so that the technical problems of large errors and calculation amount in the prior art when the diffraction efficiency of the Fresnel zone plate is calculated, particularly when the number of rings is large and the variation of the ring bandwidth is obvious are solved. The Fresnel zone plate is partitioned, the diffraction efficiencies of different areas of the Fresnel zone plate under given light source energy are calculated by using a strict coupled wave theory and are superposed, the diffraction efficiency of the Fresnel zone plate with any resolution can be accurately obtained, the application range is wide, the diffraction efficiency of the Fresnel zone plate with any ring number and any resolution can be calculated, the diffraction characteristics can be analyzed, and the technical effect of optimizing the device structure is facilitated.
One or more technical solutions in the embodiments of the present application at least have one or more of the following technical effects:
the embodiment of the application provides a partition calculation method for the diffraction efficiency of a Fresnel zone plate, which comprises the following steps: determining the structure of the Fresnel zone plate based on the application requirement of the Fresnel zone plate; approximating the ring grating of the Fresnel zone plate to a two-dimensional linear grating, and taking the total width of a pair of adjacent zones as the period of the approximate linear grating; calculating the diffraction efficiency of the two-dimensional linear grating with different periods, and drawing a relation curve between the diffraction efficiency and the ring bandwidth according to the diffraction efficiency of each ring of the Fresnel zone plate with different ring bandwidth; dividing the Fresnel zone plate into a plurality of areas according to the fluctuation degree of the diffraction efficiency of different ring bandwidth degrees; calculating the sum of diffraction efficiencies of all the areas; and calculating the overall diffraction efficiency of the whole structure of the Fresnel zone plate according to the sum of the diffraction efficiencies of the regions. The method comprises the steps of analyzing the diffraction characteristics of the Fresnel zone plate based on a strict coupled wave theory, accurately obtaining the diffraction efficiency of any zone of the Fresnel zone plate, and carrying out zone calculation on the Fresnel zone plate with a large number of rings to ensure that the calculation efficiency is improved while a high-precision calculation result is ensured, so that the technical problems of large errors and calculation amount existing in the prior art when the diffraction efficiency of the Fresnel zone plate is calculated, particularly when the number of rings is large and the variation of the ring bandwidth is obvious are solved. The Fresnel zone plate is partitioned, the diffraction efficiencies of different areas of the Fresnel zone plate under given light source energy are calculated by using a strict coupled wave theory and are superposed, the diffraction efficiency of the Fresnel zone plate with any resolution can be accurately obtained, the application range is wide, the diffraction efficiency of the Fresnel zone plate with any ring number and any resolution can be calculated, the diffraction characteristics can be analyzed, and the technical effect of optimizing the device structure is facilitated.
While preferred embodiments of the present invention have been described, additional variations and modifications in those embodiments may occur to those skilled in the art once they learn of the basic inventive concepts. Therefore, it is intended that the appended claims be interpreted as including preferred embodiments and all such alterations and modifications as fall within the scope of the invention.
It will be apparent to those skilled in the art that various changes and modifications may be made in the embodiments of the present application without departing from the spirit and scope of the embodiments of the present application. Thus, if such modifications and variations of the embodiments of the present application fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to encompass such modifications and variations.
Claims (10)
1. A partition calculation method for the diffraction efficiency of a Fresnel zone plate is characterized by comprising the following steps:
determining the structure of the Fresnel zone plate based on the application requirement of the Fresnel zone plate;
approximating the ring grating of the Fresnel zone plate to a two-dimensional linear grating, and taking the total width of a pair of adjacent zones as the period of the approximate linear grating;
calculating the diffraction efficiency of the two-dimensional linear grating with different periods, and drawing a relation curve between the diffraction efficiency and the ring bandwidth according to the diffraction efficiency of each ring of the Fresnel zone plate with different ring bandwidth;
Dividing the Fresnel zone plate into a plurality of areas according to the fluctuation degree of the diffraction efficiency of different ring bandwidth degrees;
calculating the sum of diffraction efficiency of each area;
and calculating the overall diffraction efficiency of the whole structure of the Fresnel zone plate according to the sum of the diffraction efficiencies of the regions.
2. The method of claim 1, wherein determining the structure of the fresnel zone plate based on the application requirements of the fresnel zone plate comprises:
determining required resolution and focal length according to the application requirements of the Fresnel zone plate;
taking certain light source energy as a main application light source, and calculating by combining the required resolution and focal length through a coupled wave theory to obtain the thickness, the width and the material of the Fresnel zone plate;
and determining the optimal thickness, the ring width and the optimal material of the Fresnel zone plate according to the thickness, the ring width and the material of the Fresnel zone plate.
3. The method of claim 2, wherein the applied light source energy is from 0.1 keV to 20 keV.
4. The method of claim 2, wherein the thickness of the fresnel zone plate is a thickness value corresponding to a maximum diffraction efficiency.
5. The method of claim 2, wherein the annulus thickness is sufficient to provide for 
Wherein n is the number of rings, λ is the wavelength, f is the focal length of the fresnel zone plate, and the number of rings n and the wavelength λ are uniquely determined by the energy of the light source.
6. The method of claim 1, wherein the dividing the fresnel zone plate into zones according to the fluctuation degree of diffraction efficiency of different ring bandwidth degrees comprises:
the diffraction efficiency fluctuation of the area is not more than 1%, and the average fluctuation value is not more than one thousandth, wherein the average fluctuation value is obtained by the following formula: the average fluctuation value (fluctuation value zone number)/total zone number is calculated.
7. The method of claim 1, wherein calculating the sum of diffraction efficiencies for each region comprises:
obtaining a preset standard of the number of rings;
obtaining the annulus diffraction efficiency of the preset number of rings in each area according to the preset standard of the number of rings;
taking the bad zone diffraction efficiency of the preset ring number of each area as an average value of the diffraction efficiency of the area;
obtaining the number of zone belts;
and calculating to obtain the sum of the regional diffraction efficiencies according to the mean value of the regional diffraction efficiencies and the number of the regional zones.
8. The method of claim 7, wherein obtaining the annulus diffraction efficiency for a predetermined number of rings in each ring number of the plurality of zones according to the predetermined criteria for ring number comprises:
Obtaining the width of the area ring belt;
determining a diffraction efficiency calculation method according to the width of the area ring band;
and calculating to obtain the zone diffraction efficiency of the preset number of rings in the area according to the diffraction efficiency calculation method.
9. The method of claim 8, wherein determining a diffraction efficiency calculation based on the zone annulus width comprises:
when the width of the area ring band is 0-25nm, the diffraction efficiency calculation method is a coupling wave theory calculation method;
and when the width of the area annular band is 25-100nm, the diffraction efficiency calculation method is a complex amplitude superposition method.
10. The method according to claim 1, wherein the calculating the global diffraction efficiency of the entire structure of the fresnel zone plate according to the sum of the diffraction efficiencies of the regions comprises:
and calculating the global diffraction efficiency of the whole structure with different thicknesses according to the sum of the diffraction efficiencies of the areas by taking the number of the ring zones as the weight.
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