CN114755821B - Partition calculation method for diffraction efficiency of Fresnel zone plate - Google Patents
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Abstract
The application provides a partition calculation method of diffraction efficiency of a Fresnel zone plate, which is used for determining the structure of the Fresnel zone plate based on the application requirement of the Fresnel zone plate; the annular grating of the Fresnel zone plate is approximately a two-dimensional linear grating, and the total width of a pair of adjacent zones is taken as the period of the approximately linear grating; calculating diffraction efficiency of two-dimensional linear gratings with different periods, and drawing a relation curve between the diffraction efficiency and the zone width according to the diffraction efficiency of each ring of the Fresnel zone plate with different zone widths; dividing the Fresnel zone plate into a plurality of areas according to the fluctuation degree of diffraction efficiency of different zone widths; calculating diffraction efficiency sum of each area; and calculating the global diffraction efficiency of the whole structure of the Fresnel zone plate according to the diffraction efficiency sum of each region. The technical problems of larger error 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 belt is obviously changed, are solved.
Description
Technical Field
The application relates to the technical field of optical devices, in particular to a partition calculation method for diffraction efficiency of a Fresnel zone plate.
Background
The X-ray microscopic imaging technology has the advantages of high resolution, small damage to the sample and the like, provides a new view field for human observation things, 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 three-dimensional structure inside the sample at high resolution. The Fresnel zone plate is a key device of an X-ray microscopic imaging system, and the appearance inside the sample is obtained by utilizing 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 the energy of diffracted light to the energy of incident light, which determines the focusing or imaging quality of the device. Optimizing device performance by calculating fresnel zone plate diffraction efficiency for high resolution structures 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 an overlapping amplitude superposition method and a coupled wave theory. The complex amplitude superposition method is used for analyzing the diffraction fields of all rings of the diffraction integral zone plate through the transmittance function of the diffraction integral zone plate or superposing the diffraction fields of all rings of the zone plate, so that the calculation speed is high, however, when the width of the outermost ring of the Fresnel zone plate is smaller, the body effect cannot be ignored, and at the moment, the complex amplitude superposition method is difficult to accurately analyze the zone plate. The time domain finite difference method is based on the recursion simulation of the propagation process of electromagnetic waves in the time domain by the Maxwell equation set through the hard X-ray FZP, but the application of the method is seriously hindered by the extremely small grid requirement and huge calculation amount of the hard X-ray frequency band. The coupled wave theory approximates the Fresnel zone plate to a plurality of small linear gratings, and then vectors are added to all diffraction fields of the linear gratings to obtain the diffraction efficiency of the Fresnel zone plate. The method has larger error and calculated amount when analyzing devices with more rings and obvious ring width change, and has low calculation efficiency. Therefore, an accurate and rapid calculation method of the diffraction efficiency of the Fresnel zone plate is needed to provide theoretical analysis basis for analysis and optimization of diffraction characteristics of the Fresnel zone plate with any structure.
The prior art has at least the following technical problems:
in the prior art, when the diffraction efficiency of the Fresnel zone plate is calculated, the technical problems of larger error and calculation amount exist especially when the number of rings is more and the width of the ring belt is obviously changed.
Disclosure of Invention
The embodiment of the application provides a partition calculation method for diffraction efficiency of a Fresnel zone plate, which solves the technical problems of larger 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 more and the width of an annular belt is obviously changed.
In view of the above problems, an embodiment of the present application provides a method for calculating a zone of diffraction efficiency of a fresnel zone plate, where the method includes: determining the structure of a 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 diffraction efficiency of the two-dimensional linear gratings in different periods, and drawing a relation curve between the diffraction efficiency and the zone width according to the diffraction efficiency of each ring of the Fresnel zone plate with different zone widths; dividing the Fresnel zone plate into a plurality of areas according to the fluctuation degree of diffraction efficiency of different zone widths; calculating diffraction efficiency sum of each area; and calculating the global diffraction efficiency of the whole structure of the Fresnel zone plate according to the diffraction efficiency sum of each region.
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 the energy of a certain light source as a main application light source, and obtaining the thickness, the girdle width and the material of the Fresnel zone plate by combining the coupling wave theory with the required resolution and focal length calculation; and determining the optimal thickness, the annular zone width and the optimal material of the Fresnel zone plate according to the thickness, the annular zone width and the material of the Fresnel zone plate.
Preferably, the applied light source energy is 0.1-20keV.
Preferably, the thickness of the fresnel zone plate is the thickness value corresponding to the maximum diffraction efficiency.
Preferably, the thickness of the endless belt satisfiesWherein 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.
Preferably, the dividing the fresnel zone plate into a plurality of areas according to the fluctuation degree of diffraction efficiency of different zone widths includes: the diffraction efficiency of the region fluctuates by no more than 1%, and the average fluctuation value does not exceed one thousandth, wherein the average fluctuation value passes through the formula: average fluctuation value= (fluctuation value×zone number)/total zone number.
Preferably, the calculating the diffraction efficiency sum of each region includes: obtaining a preset ring number standard; obtaining the ring zone diffraction efficiency of the preset ring number in each zone according to the ring number preset standard; taking the zone diffraction efficiency of the preset number of rings of each zone as a zone diffraction efficiency average value; obtaining the zone number; and calculating to obtain the area diffraction efficiency sum according to the area diffraction efficiency mean value and the area zone number.
Preferably, the obtaining the ring diffraction efficiency of the preset ring number in the ring number of each region according to the preset ring number standard includes: obtaining the zone width; determining a diffraction efficiency calculation method according to the zone width; and calculating and obtaining the annular zone diffraction efficiency of the preset annular number in the regional annular number according to the diffraction efficiency calculation method.
Preferably, the method for determining diffraction efficiency according to the zone width includes: when the zone width is 0-25nm, the diffraction efficiency calculation method is a coupled wave theory calculation method; when the zone width is 25-100nm, the diffraction efficiency calculation method is an overlapping amplitude 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 areas includes: and calculating the global diffraction efficiency of the whole structure with different thicknesses according to the diffraction efficiency sum of each region by taking the ring belt number as a weight.
The above 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 of diffraction efficiency of a Fresnel zone plate, which comprises the following steps: determining the structure of a 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 diffraction efficiency of the two-dimensional linear gratings in different periods, and drawing a relation curve between the diffraction efficiency and the zone width according to the diffraction efficiency of each ring of the Fresnel zone plate with different zone widths; dividing the Fresnel zone plate into a plurality of areas according to the fluctuation degree of diffraction efficiency of different zone widths; calculating diffraction efficiency sum of each area; and calculating the global diffraction efficiency of the whole structure of the Fresnel zone plate according to the diffraction efficiency sum of each region. The diffraction characteristics of the Fresnel zone plate are analyzed based on a strict coupling wave theory, the diffraction efficiency of any zone of the Fresnel zone plate is accurately obtained, and the Fresnel zone plate with more rings is subjected to zone calculation, so that the calculation efficiency is improved while the high-precision calculation result is ensured, and the technical problems of larger errors and calculation amount in the prior art when the diffraction efficiency of the Fresnel zone plate is calculated, particularly in the case of devices with more rings and obvious zone width change, are solved. The method achieves the technical effects that the diffraction efficiency of the Fresnel zone plate with any resolution can be accurately obtained by partitioning the Fresnel zone plate, calculating the diffraction efficiency of different areas of the Fresnel zone plate under the given light source energy by utilizing the strict coupled wave theory and superposing the diffraction efficiency, the method has a wide application range, can calculate the diffraction efficiency of the Fresnel zone plate with any number of rings and any resolution, analyzes the diffraction characteristics, and is beneficial to optimizing the device structure.
The foregoing description is only an overview of the present application, and is intended to be implemented in accordance with the teachings of the present application in order that the same may be more clearly understood and to make the same and other objects, features and advantages of the present application more readily apparent.
Drawings
Fig. 1 is a flow chart of a partition calculation method of diffraction efficiency of a fresnel zone plate according to an embodiment of the present application;
FIG. 2 shows Al with a resolution of 12.2nm in the first embodiment of the application 2 O 3 /HfO 2 A ring number change schematic diagram of each ring zone section of the Fresnel zone plate;
FIG. 3 shows Al with a resolution of 12.2nm in the first embodiment of the application 2 O 3 /HfO 2 A graph of the relationship between the minimum zone number and the outermost annular width of the Fresnel zone plate;
FIG. 4 shows a resolution of 12.2nm in accordance with an embodiment of the present applicationAl of (2) 2 O 3 /HfO 2 And a relation trend comparison graph 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 diffraction efficiency of a Fresnel zone plate, which has the technical problems of larger error and calculation amount when calculating the diffraction efficiency of the Fresnel zone plate, especially when devices with more rings and obvious ring width change in the prior art.
The technical scheme provided by the application has the following overall thought:
determining the structure of a 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 diffraction efficiency of the two-dimensional linear gratings in different periods, and drawing a relation curve between the diffraction efficiency and the zone width according to the diffraction efficiency of each ring of the Fresnel zone plate with different zone widths; dividing the Fresnel zone plate into a plurality of areas according to the fluctuation degree of diffraction efficiency of different zone widths; calculating diffraction efficiency sum of each area; and calculating the global diffraction efficiency of the whole structure of the Fresnel zone plate according to the diffraction efficiency sum of each region. The method achieves the technical effects that the diffraction efficiency of the Fresnel zone plate with any resolution can be accurately obtained by partitioning the Fresnel zone plate, calculating the diffraction efficiency of different areas of the Fresnel zone plate under the given light source energy by utilizing the strict coupled wave theory and superposing the diffraction efficiency, the method has a wide application range, can calculate the diffraction efficiency of the Fresnel zone plate with any number of rings and any resolution, analyzes the diffraction characteristics, and is beneficial to optimizing the device structure.
The following detailed description of the technical solutions of the present application will be given by way of the accompanying drawings and specific embodiments, and it should be understood that the specific features of the embodiments and embodiments of the present application are detailed descriptions of the technical solutions of the present application, and not limiting the technical solutions of the present application, and that the embodiments and technical features of the embodiments of the present application may be combined with each other without conflict.
Example 1
Fig. 1 is a flow chart of a partition calculation method of diffraction efficiency of a fresnel zone plate in an embodiment of the present application. As shown in fig. 1, an embodiment of the present application provides a method for calculating a zone of diffraction efficiency of a fresnel zone plate, where the method includes:
step S100: the structure of the Fresnel zone plate is determined based on the application requirements 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 the required resolution and focal length according to the application requirements of the Fresnel zone plate; taking the energy of a certain light source as a main application light source, and obtaining the thickness, the girdle width and the material of the Fresnel zone plate by combining the coupling wave theory with the required resolution and focal length calculation; and determining the optimal thickness, the annular zone width and the optimal material of the Fresnel zone plate according to the thickness, the annular zone width and the material of the Fresnel zone plate.
Further, the applied light source energy is 0.1-20keV.
Further, the thickness of the fresnel zone plate is a thickness value corresponding to the maximum diffraction efficiency.
Further, the thickness of the annular band satisfiesWherein 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 annular width and the optimal material of the Fresnel zone plate by combining the required resolution and the required focal length through the coupled wave theory. The optimal thickness is the thickness value corresponding to the maximum diffraction efficiency, and the width of the annular band meets the following conditionsWherein n is substituted byThe number of the meter rings, the wavelength lambda, is uniquely determined by the energy of the light source; f is the focal length of the fresnel zone plate. Further, the applied light source energy is 0.1-20keV, preferably 10keV. The required resolution is 10-200nm, preferably 12nm. The focal length is 1-20mm, preferably 16mm. The thickness is 1-15 μm, preferably 4.5 μm. The Fresnel zone plate is made of Al 2 O 3 /HfO 2 、Al 2 O 3 /Ir、Al 2 O 3 /Ta 2 O 5 And SiO 2 /HfO 2 Preferably the material is selected from Al 2 O 3 /HfO 2 . For example, a multilayer film Fresnel zone plate is used as an analysis sample, and the resolution of Al is 12.2nm 2 O 3 /HfO 2 Fresnel zone plate, al 2 O 3 And HfO 2 As a multilayer film material, the wavelength of incident light was 0.155nm, the required resolution was 12.2nm, and the required focal length was 16mm. The resolution and the outermost ring width of the Fresnel zone plate meet delta=1.22DeltarN, so that the outermost ring width of the Fresnel zone plate can be obtained by the formula to be 10nm.
Step S200: the annular grating of the Fresnel zone plate is approximately a two-dimensional linear grating, and the total width of a pair of adjacent zones is taken as the period of the approximately linear grating.
Specifically, the annular grating of the fresnel zone plate is approximated as a two-dimensional linear grating, and the total width of a pair of adjacent zones is taken as the period of the approximated grating, and the zone diffraction efficiency of the fresnel zone plate is equal to the diffraction efficiency of the approximated grating. Also taking a multilayer film Fresnel zone plate as an analysis sample, al 2 O 3 And HfO 2 As a multilayer film material, al 2 O 3 As grating light-transmitting material, hfO is adopted 2 As an opaque material. The total width of the annular bands of two adjacent materials is used as the grating period.
Step S300: and calculating diffraction efficiency of the two-dimensional linear gratings in different periods, and drawing a relation curve between the diffraction efficiency and the zone width according to the diffraction efficiency of each ring of the Fresnel zone plate with different zone widths.
Specifically, the diffraction efficiency of the two-dimensional grating in different periods is calculated, the diffraction efficiency of each ring of the Fresnel zone plate corresponding to different zone widths is calculated, and a relation curve between the diffraction efficiency and the zone width is drawn. The different zones are formed by changing the zone width from 0 according to a certain step length, the zone width ranges from 0 to 200nm, and the step length ranges from 0.01 to 5nm. Preferably, the zone width is selected to be 0-50nm, and the zone width variation step is 0.05nm.
Step S400: and dividing the Fresnel zone plate into a plurality of areas according to the fluctuation degree of diffraction efficiency of different zone widths.
Further, step S400: dividing the Fresnel zone plate into a plurality of areas according to the fluctuation degree of diffraction efficiency of different zone widths, wherein the Fresnel zone plate comprises: the diffraction efficiency of the region fluctuates by no more than 1%, and the average fluctuation value does not exceed one thousandth, wherein the average fluctuation value passes through the formula: average fluctuation value= (fluctuation value×zone number)/total zone number.
Specifically, a part of zones with small diffraction efficiency fluctuation are used as one zone, the zone of the Fresnel zone plate is divided into a plurality of zones, the Fresnel zone plate is divided into a plurality of zones according to the fluctuation degree of diffraction efficiency of different zone widths, the diffraction efficiency fluctuation of the zone in each zone is extremely small and not more than 1%, and the average fluctuation value is not more than one thousandth. The number of the required dividing regions in this embodiment is 244, which is calculated by using the fresnel zone plate of the multilayer film as an analysis sample according to the formula average fluctuation value= (fluctuation value×number of zone bands)/total number of zones. As shown in FIG. 2, al with a resolution of 12.2nm 2 O 3 /HfO 2 The number of rings of each zone section of the fresnel zone plate varies.
Step S500: the diffraction efficiency sum of each region was calculated.
Further, the calculating the diffraction efficiency sum of each area includes: obtaining a preset ring number standard; obtaining the ring zone diffraction efficiency of the preset ring number in each zone according to the ring number preset standard; taking the bad band diffraction efficiency of the preset ring number of each region as a region diffraction efficiency average value; obtaining the zone number; and calculating to obtain the area diffraction efficiency sum according to the area diffraction efficiency mean value and the area zone number.
Further, the obtaining the ring zone diffraction efficiency of the preset ring number in the ring number of each region according to the preset ring number standard includes: obtaining the zone width; determining a diffraction efficiency calculation method according to the zone width; and calculating and obtaining the annular zone diffraction efficiency of the preset annular number in the regional annular number according to the diffraction efficiency calculation method.
Further, the method for determining diffraction efficiency according to the zone width comprises the following steps: when the zone width is 0-25nm, the diffraction efficiency calculation method is a coupled wave theory calculation method; when the zone width is 25-100nm, the diffraction efficiency calculation method is an overlapping amplitude method.
Specifically, since the number of rings in each region is very large, it is possible that tens of rings and hundreds of rings … … bring about a large diffraction efficiency when calculating the diffraction efficiency of each ring, since the diffraction efficiency in each region fluctuates little, one ring is selected as a representative, the diffraction efficiency of the ring is used as the average value of the region, which ring is specifically selected as the representative of the region, and the diffraction efficiency of the region is selected as the average value of the diffraction efficiency of the region. When diffraction efficiency calculation is carried out, algorithm selection is carried out according to the width of the ring belt, and when the width of the ring belt is 0-25nm, the diffraction efficiency calculation method can only be a coupled wave theory calculation method; when the zone width is 25-100nm, the diffraction efficiency calculation method may be an overlapping amplitude method. As shown in FIG. 3, al with a resolution of 12.2nm is used in the embodiment of the application 2 O 3 /HfO 2 The relationship between the minimum zone number and the outermost ring width of the Fresnel zone plate.
Step S600: and calculating the global diffraction efficiency of the whole structure of the Fresnel zone plate according to the diffraction efficiency sum of each region.
Further, 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 areas includes: and calculating the global diffraction efficiency of the whole structure with different thicknesses according to the diffraction efficiency sum of each region by taking the ring belt number as a weight.
Specifically, global diffraction efficiency of the whole structure with different thicknesses is calculated by taking the ring band number as a weight, and the calculation formula is used for calculating the diffraction efficiencyAnd 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, FIG. 4 is a graph showing the comparison of diffraction efficiency and thickness, calculated according to the complex amplitude superposition method, coupled wave grating approximation, and the embodiment of the present application, for Al with a resolution of 12.2nm at 8keV 2 O 3 /HfO 2 And (3) a relation diagram between the diffraction efficiency and the thickness of the Fresnel zone plate. The diffraction characteristics of the Fresnel zone plate are analyzed based on the strict coupled wave theory by the method provided by the embodiment of the application, so that the diffraction efficiency of any zone of the Fresnel zone plate is accurately obtained; the Fresnel zone plate with more rings is subjected to partition calculation, so that the calculation efficiency is improved while the high-precision calculation result is ensured, and the technical problems of larger error and calculation amount in the prior art when the diffraction efficiency of the Fresnel zone plate is calculated, particularly when the Fresnel zone plate with more rings and obvious change of the annular band width is realized. The method achieves the technical effects that the diffraction efficiency of the Fresnel zone plate with any resolution can be accurately obtained by partitioning the Fresnel zone plate, calculating the diffraction efficiency of different areas of the Fresnel zone plate under the given light source energy by utilizing the strict coupled wave theory and superposing the diffraction efficiency, the method has a wide application range, can calculate the diffraction efficiency of the Fresnel zone plate with any number of rings and any resolution, analyzes the diffraction characteristics, and is beneficial to optimizing the device structure.
The above 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 of diffraction efficiency of a Fresnel zone plate, which comprises the following steps: determining the structure of a 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 diffraction efficiency of the two-dimensional linear gratings in different periods, and drawing a relation curve between the diffraction efficiency and the zone width according to the diffraction efficiency of each ring of the Fresnel zone plate with different zone widths; dividing the Fresnel zone plate into a plurality of areas according to the fluctuation degree of diffraction efficiency of different zone widths; calculating diffraction efficiency sum of each area; and calculating the global diffraction efficiency of the whole structure of the Fresnel zone plate according to the diffraction efficiency sum of each region. The diffraction characteristics of the Fresnel zone plate are analyzed based on a strict coupling wave theory, the diffraction efficiency of any zone of the Fresnel zone plate is accurately obtained, and the Fresnel zone plate with more rings is subjected to zone calculation, so that the calculation efficiency is improved while the high-precision calculation result is ensured, and the technical problems of larger errors and calculation amount in the prior art when the diffraction efficiency of the Fresnel zone plate is calculated, particularly in the case of devices with more rings and obvious zone width change, are solved. The method achieves the technical effects that the diffraction efficiency of the Fresnel zone plate with any resolution can be accurately obtained by partitioning the Fresnel zone plate, calculating the diffraction efficiency of different areas of the Fresnel zone plate under the given light source energy by utilizing the strict coupled wave theory and superposing the diffraction efficiency, the method has a wide application range, can calculate the diffraction efficiency of the Fresnel zone plate with any number of rings and any resolution, analyzes the diffraction characteristics, and is beneficial to optimizing the device structure.
While preferred embodiments of the present application 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. It is therefore intended that the following claims be interpreted as including the preferred embodiments and all such alterations and modifications as fall within the scope of the application.
It will be apparent to those skilled in the art that various modifications and variations can be made to the embodiments of the present application without departing from the spirit or scope of the embodiments of the application. Thus, if such modifications and variations of the embodiments of the present application fall within the scope of the claims and the equivalents thereof, the present application is also intended to include such modifications and variations.
Claims (8)
1. The method for calculating the diffraction efficiency of the Fresnel zone plate in a partitioned mode is characterized by comprising the following steps of:
determining the structure of a 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 diffraction efficiency of the two-dimensional linear gratings in different periods, and drawing a relation curve between the diffraction efficiency and the zone width according to the diffraction efficiency of each ring of the Fresnel zone plate with different zone widths;
dividing the Fresnel zone plate into a plurality of areas according to the fluctuation degree of diffraction efficiency of different zone widths;
calculating diffraction efficiency sum of each area;
calculating the global diffraction efficiency of the whole structure of the Fresnel zone plate according to the diffraction efficiency sum of each region;
the determining the structure of the fresnel zone plate based on the application requirement of the fresnel zone plate comprises the following steps:
determining the required resolution and focal length according to the application requirements of the Fresnel zone plate;
taking the energy of a certain light source as a main application light source, and obtaining the thickness, the girdle width and the material of the Fresnel zone plate by combining the coupling wave theory with the required resolution and focal length calculation;
determining the optimal thickness, the annular zone width and the optimal material of the Fresnel zone plate according to the thickness, the annular zone width and the material of the Fresnel zone plate;
wherein, the fresnel zone plate is divided into a plurality of areas according to the fluctuation degree of diffraction efficiency of different zone widths, comprising:
the diffraction efficiency of the region fluctuates by no more than 1%, and the average fluctuation value does not exceed one thousandth, wherein the average fluctuation value passes through the formula: average fluctuation value= (fluctuation value×zone number)/total zone number.
2. The method of claim 1, wherein the applied light source energy is 0.1 to 20keV.
3. The method of claim 1, wherein the thickness of the fresnel zone plate is a thickness value corresponding to a maximum diffraction efficiency.
4. The method of claim 1, wherein the annulus thickness is such thatWherein 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.
5. The method of claim 1, wherein said calculating the diffraction efficiency sum for each region comprises:
obtaining a preset ring number standard;
obtaining the ring zone diffraction efficiency of the preset ring number in each zone according to the ring number preset standard;
taking the zone diffraction efficiency of the preset number of rings of each zone as a zone diffraction efficiency average value;
obtaining the zone number;
and calculating to obtain the area diffraction efficiency sum according to the area diffraction efficiency mean value and the area zone number.
6. The method of claim 5, wherein obtaining the zone diffraction efficiency for the preset number of rings in each zone according to the preset number of rings criteria comprises:
obtaining the zone width;
determining a diffraction efficiency calculation method according to the zone width;
and calculating and obtaining the annular zone diffraction efficiency of the preset annular number in the regional annular number according to the diffraction efficiency calculation method.
7. The method of claim 6, wherein said determining a diffraction efficiency calculation method based on said zone annulus width comprises:
when the zone width is 0-25nm, the diffraction efficiency calculation method is a coupled wave theory calculation method;
when the zone width is 25-100nm, the diffraction efficiency calculation method is an overlapping amplitude method.
8. The method of claim 1, wherein calculating the global diffraction efficiency of the entire structure of the fresnel zone plate based on 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 diffraction efficiency sum of each region by taking the ring belt number as a weight.
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