CN114496337A - Multilayer film laue lens and design method thereof - Google Patents
Multilayer film laue lens and design method thereof Download PDFInfo
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Abstract
The application discloses a multilayer film Laue lens and a design method thereof, wherein the lens comprises a substrate layer and a diffraction structure arranged on the substrate layer, the diffraction structure comprises a plurality of periods which are arranged in a laminated mode, each period comprises an absorption layer and a spacing layer which are arranged in a laminated mode, and the thickness of the period is gradually reduced from the direction close to the substrate layer to the direction far away from the substrate layer; the cross-sectional depth of each of the absorber and spacer layers is an optimum cross-sectional depth (1-modification parameter Q), wherein Q is any value between 0.4 and 1. According to the technical scheme provided by the embodiment of the application, the multilayer film Laue lens is modified, the structural error generated in the lens preparation process is compensated through modification, and the difference between the modified multilayer film Laue lens and an ideal electric field of the exit surface of the multilayer film Laue lens is reduced under the condition that other auxiliary optical elements are not needed, so that the focusing performance of the actually prepared multilayer film Laue lens is improved.
Description
Technical Field
The invention relates to the field of precision optical elements, in particular to a high-resolution X-ray micro-focusing element, and particularly relates to a multilayer film Laue lens and a design method thereof.
Background
The X-ray wave band covers the resonance line of most elements, has very high element sensitivity, has the characteristics of short wavelength, strong penetrability and the like, and can realize the nondestructive measurement of materials and biological cells, so that X-ray microscopy is an important research tool in the research fields of biology, medicine, materials, physics, chemistry and the like, and the size of an X-ray convergence light spot is directly related to the resolution and sensitivity of microscopic analysis. Because the refractive index n of the X-ray is close to 1, the diffraction type focusing element is more convenient to realize the X-ray focusing compared with a reflection type element and a refraction type element. The traditional zone plate can converge soft X-rays to tens of nanometers, but in a hard X-ray wave band, a larger height-to-width ratio is needed to realize ideal focusing, and the required height-to-width ratio is larger along with the increase of the X-ray energy, so that the traditional photoetching method is difficult to manufacture the zone plate capable of focusing to a smaller light spot.
To solve this problem, Argonne laboratory in 2004 in the united states proposed to plate a multilayer in a zone plate structure on a planar substrate in reverse order and then slice and polish it to a desired depth, which can achieve any aspect ratio. The new method is called Multilayer film Laue Lens (MLL), can obtain the focus below 1nm according to theoretical calculation, and is one of the most potential hard X-ray nanometer focusing elements at present. WSi adopted by Argonne national laboratory in 20062The inclined multilayer film Laue lens with the total thickness of 12.4 microns is prepared by the combination of the materials of the/Si, the focusing efficiency is 44% under the energy point of 19.5KeV, the size of a light spot is 30nm, and the focusing focal length is 4.72 mm; in 2012, U.S. Ray Conley et al completed the manufacture of low-error multilayer films in a newly-built high-precision film-plating laboratory, developed a stress-free micromachining technology of a diaphragm, realized the preparation of practical miniature lenses, one-dimensional focused light spot of 11nm, in 2015, Huang et al prepared wedge-shaped MLL with a pore diameter of 31 μm and a focal length of 3.2mm, obtained 25.6nm of one-dimensional focused light spot in 14.6keV test of an U.S. APS light source, and diffraction efficiency of 27%.
However, in the actual manufacturing process, there is a certain difference between the actual sputtering rate and the calibrated sputtering rate due to the systematic random error, and the long-time plating may bring regular drift of the sputtering rate, both of them may bring structural error to the finally manufactured multilayer film laue lens, so that the structure thereof deviates from the ideal structure, and further due to the influence of the structural error, the electric field of the actual multilayer film laue lens on the exit surface deviates greatly from the electric field of the ideal multilayer film laue lens on the exit surface, which finally affects the optical performance thereof, and reduces the diffraction efficiency and the focusing resolution thereof, usually, an additional optical element such as a phase shift sheet is needed to compensate, but this may increase the debugging work of the whole system, and is not favorable for the application of the multilayer film laue lens on different systems.
Disclosure of Invention
In view of the above-described deficiencies or inadequacies in the prior art, it would be desirable to provide a multilayer film laue lens and method of designing the same.
In a first aspect, there is provided a multilayer film Laue lens comprising a substrate layer and a diffractive structure disposed on the substrate layer, the diffractive structure comprising a plurality of periods arranged in a stack, each period comprising an absorbing layer and a spacer layer in a stack,
the thickness of the period is gradually reduced from the direction close to the substrate layer to the direction far away from the substrate layer;
the cross-sectional depth of each of the absorber and spacer layers is an optimum cross-sectional depth (1-modification parameter Q), wherein Q is any value between 0.4 and 1.
In a second aspect, there is provided a method of designing the multilayer film laue lens, comprising the steps of:
determining a diffraction structure, wherein the depth of the diffraction structure is an optimal section depth, and the optimal section depth corresponds to an optimal electric field distribution;
forming an actual diffraction structure on the substrate layer, wherein the electric field distribution of the formed actual diffraction structure is actual electric field distribution;
modifying the shape of the absorption layer and the spacing layer in the diffraction structure, calculating the actual electric field distribution of the modified emergent surface until the error between the actual electric field distribution and the optimal electric field distribution is within a set range, and determining a modification parameter Q;
and etching the emergent surface of the diffraction structure according to the shape modification parameter Q, wherein the etching depth is the optimal section depth.
According to the technical scheme provided by the embodiment of the application, the multilayer film Laue lens is modified, the error compensation of the prepared lens structure is realized through modification, and the difference between the lens structure and the ideal electric field of the exit surface of the multilayer film Laue lens is reduced under the condition that other auxiliary optical elements are not needed, so that the focusing performance of the actually prepared multilayer film Laue lens is improved.
Drawings
Other features, objects and advantages of the present application will become more apparent upon reading of the following detailed description of non-limiting embodiments thereof, made with reference to the accompanying drawings in which:
FIG. 1 is a schematic view of a prior art multilayer film Laue lens construction;
FIG. 2 is a schematic view of an ideal multilayer film Laue lens and a practically produced multilayer film Laue lens;
FIG. 3 is a schematic view of a multi-layer Laue lens structure according to the present embodiment;
FIG. 4 is the exit electric field of the multilayer film Laue lens of this embodiment at the optimum cross-sectional depth;
FIG. 5 is a graph showing the intensity distribution near the focal point when focusing is achieved in the multilayer film Laue lens provided in the present embodiment; wherein, a graph a is a multilayer film Laue lens with an ideal structure, a graph b is a multilayer film Laue lens with an actual structure containing errors, and a graph c is a multilayer film Laue lens with an actual structure after modification;
FIG. 6 is a graph showing the normalized electric field intensity curve at the focal plane of the multilayer film Laue lens in this embodiment compared with the ideal case;
fig. 7 is a modification of the multi-layer film laue lens provided in this example.
Detailed Description
The present application will be described in further detail with reference to the drawings and examples. It is to be understood that the specific embodiments described herein are merely illustrative of the relevant invention and not restrictive of the invention. It should be noted that, for convenience of description, only the portions related to the present invention are shown in the drawings.
It should be noted that the embodiments and features of the embodiments in the present application may be combined with each other without conflict. The present application will be described in detail below with reference to the embodiments with reference to the attached drawings.
The Laue lens is a linear zone plate with a multilayer film structure, the existing Laue lens is generally formed by alternately plating two materials with different atomic numbers on the surface of a substrate layer, the plated structure is a diffraction structure, specifically, as shown in figure 1, a material with a high atomic number forms an absorption layer, a material with a low atomic number forms a spacing layer, and one absorption layer and the spacing layer adjacent to the absorption layer are used as a film layer period; forming a coordinate system in the Laue lens structure, wherein the formed diffraction structure has an incident surface and an exit surface, the length of the diffraction structure along the Z-axis is the sectional depth, the thickness shown by Dn in the figure refers to the thickness of different periods, the layer at the maximum position of the X-axis is the outermost layer of the diffraction structure, the thickness of the outermost layer is Drout, rnAnd indicating the position radius of the nth film layer, wherein each lens structure has the film layer number, the film layer thickness and the film layer section depth which are theoretically calculated when being prepared, and the theoretically calculated section depth is the optimal section depth. According to the theoretical parameters, the corresponding multilayer film Laue lens is prepared, in the actual preparation process, the actual sputtering rate and the calibrated sputtering rate have certain difference due to systematic random errors, regular drift of the sputtering rate can be brought by long-time plating, structural errors are generated on the prepared multilayer film Laue lens, an actual structure as shown in figure 2 is formed, and the condition that each film layer is not arranged according to the rule that the thickness is gradually reduced can exist in the actual structure, so that the optical performance of the multilayer film Laue lens is influenced.
Referring to fig. 3, the present embodiment provides a multilayer film laue lens, including a substrate layer 10 and a diffraction structure 20 disposed on the substrate layer 10, wherein the diffraction structure 20 includes a plurality of periods disposed in a stacked manner, each of the periods includes an absorption layer and a spacer layer disposed in a stacked manner,
the thickness of the period gradually decreases from the direction close to the substrate layer 10 to the direction far away from the substrate layer 10;
the cross-sectional depth of each of the absorber and spacer layers is an optimum cross-sectional depth (1-modification parameter Q), wherein Q is any value between 0.4 and 1.
The multilayer film laue lens provided by the embodiment comprises a substrate layer 10 and a diffraction structure 20 arranged on the substrate layer 10, wherein the diffraction structure 20 comprises a plurality of absorption layers and spacing layers, the periodic thickness of the diffraction structure 20 is gradually reduced, the cross-sectional depths of the absorption layers and the spacing layers in the diffraction structure 20, namely the lengths of the diffraction structure 20 on the Z axis, are the optimal cross-sectional depths (1-modification parameters Q), wherein Q is the degree of etching the current layer structure, Q is generally any value between 0.4 and 1, and 1 is not etched at all; the compensation of errors generated on the manufactured lens structure is realized by modifying the corresponding absorption layer and the corresponding spacing layer and adjusting the section depth of the absorption layer and the spacing layer, and the difference between the absorption layer and the electric field of the ideal multi-layer film Laue lens emergent surface 2 is reduced under the condition that other auxiliary optical elements are not needed, so that the focusing performance of the actually manufactured multi-layer film Laue lens is improved.
Further, the optimal section depth is the depth of the diffraction structure 20 corresponding to the maximum value of the diffraction efficiency of the multilayer film laue lens.
The optimal cross-sectional depth in the above embodiment is the depth of the diffraction structure 20 corresponding to the maximum diffraction efficiency of the lens, and specifically, the optimal cross-sectional depth Zopt with the maximum efficiency may be selected according to an efficiency curve of the negative first-order diffraction efficiency varying with the depth, and the specific steps will be described in detail below.
Firstly, determining the total film thickness, the periodic thickness Drout of the outermost film layer and the total film layer number of the lens according to the application requirements of the lens;
determining the periodic thickness of each film layer at the incident surface 1;
calculating a curve eta-1 (Z) of-1 order diffraction efficiency changing with the cross-sectional depth Z according to the wavelength lambda of incident light, the focal length f of the lens-1 order diffraction light and the number of film layers, and obtaining the optimal cross-sectional depth Zopt;
wherein, the thickness of each film layer is calculated by the following formula:
Dn＝fλ/rn；
wherein D isnThe period thickness of the nth film layer is shown, f is the focal length of the lens-1 order diffracted light, and lambda is the wavelength of incident light;
wherein, the position radius r of the nth film layernCalculated by the following formula:
rn＝nfλ+n2λ2/4。
further, the thickness of the absorption layer and the spacing layer in each period is the same.
The diffraction structure 20 includes a plurality of periods, and the thickness of the two layer structures is the same in each film layer period, wherein the material of the absorption layer may be WSi2Or Nb, the material of the spacing layer can be Si or Al, wherein the material with a large absorption coefficient is used as an absorption layer, and the absorption coefficient of the opposite spacing layer is smaller than that of the absorption layer.
Further, the diffraction structure 20 includes an incident surface 1 and an exit surface 2 which are oppositely arranged, and end faces of the plurality of absorption layers and the plurality of spacer layers at the incident surface 1 are located on the same plane.
Further, the error between the actual electric field distribution and the optimal electric field distribution of the exit surface 2 of the multilayer film laue lens is within a set range.
As shown in fig. 3, the lens structure provided in this embodiment has the structure of the exit surface 2 with different layers, which is mainly to realize that the error between the actual electric field distribution of the exit surface 2 of the multi-layer laue lens is small and the error is adjusted to an acceptable range, so that only the exit surface 2 of the lens structure needs to be adjusted, and thus, the structure as shown in fig. 2 is finally formed, the end surfaces of the entrance surface 1 of the lens structure are located on the same plane and are generally perpendicular to the substrate layer 10, and because the cross-sectional depths of different layers are different, the end surfaces of the exit surface 2 are also not located on the same plane, and the error between the actual electric field distribution and the optimal electric field distribution of the exit surface 2 is ensured to be within a set range.
The present embodiment also provides a method for designing a multilayer-film laue lens, including the following steps:
determining a diffraction structure, wherein the depth of the diffraction structure is an optimal section depth, and the optimal section depth corresponds to an optimal electric field distribution;
forming an actual diffraction structure on the base layer 10, wherein an electric field distribution of the formed actual diffraction structure is an actual electric field distribution;
modifying the shape of the absorption layer and the spacing layer in the actual diffraction structure, calculating the actual electric field distribution of the modified emergent surface 2 until the error between the actual electric field distribution and the optimal electric field distribution is within a set range, and determining a modification parameter Q;
and etching the emergent surface 2 of the actual diffraction structure according to the shape modification parameter Q, wherein the etching depth is the optimal section depth x shape modification parameter Q.
The preparation method provided in the embodiment firstly determines the corresponding diffraction structure, the determined diffraction structure has the optimal section depth, and the emergent surface electric field distribution corresponding to the corresponding optimal section depth is the optimal electric field distribution which is the theoretical target to be reached by the prepared lens structure;
the corresponding actual diffraction structure is prepared on the substrate layer 10 according to the diffraction structure determined by theory, and the prepared lens structure has a certain systematic random deviation between the actual sputtering rate and the calibrated sputtering rate, and the regular drift of the sputtering rate can be brought by the long-time plating, and a certain error can exist in the finally actually prepared multilayer film Laue lens, as shown in figure 4, figure 4 shows the emergent electric field of the multilayer film Laue lens at the optimal section depth, wherein the black line is an ideal case, and the gray line is a case in an actual structure, therefore, it is necessary to measure the actually prepared lens structure, compare the measured actual electric field distribution diagram with the theoretical electric field distribution, i.e. the optimal electric field distribution diagram, the difference between the actual electric field distribution and the theoretical electric field distribution is reduced by adjusting the prepared lens structure.
Optionally, the shaping the absorption layer and the spacer layer in the actual diffraction structure includes:
dividing the actual diffraction structure into N parts with equal intervals or equal film quantity, wherein each part of the actual diffraction structure corresponds to one shape modification parameter Q;
and optimizing the N modification parameters simultaneously.
The actually prepared multilayer film Laue lens is subdivided in an equidistant or equal-film mode along the X direction in the picture 2 and divided into N parts, each part of structure is provided with a modification parameter Q, the variation range of the modification parameter is 0.4-1, and due to the strong electric field coupling effect among different layer structures, when a single substructure is artificially and simply optimized, all coupling factors can not be considered, some unexpected variation can be introduced into the emergent electric fields of adjacent substructures, and the optimal effect can not be achieved, so that the N modification parameters are simultaneously optimized by using a genetic algorithm, and finally the emergent electric field of the modified multilayer film Laue lens at the Zopt position is approximately the same as the emergent electric field of the ideal multilayer film Laue lens at the optimal depth Zopt position.
Wherein, N is 65-70% of the number of the film layers. In the multilayer film Laue lens, the film layer which contributes greatly to the focusing effect is the film layer with smaller thickness, so in order to save the process step of modification, only the film layer structure with larger effect is modified, wherein the number of the film layers is 65-70 percent, and preferably, N which accounts for 70 percent of the number of the film layers is set from the film layer at the outermost layer of the lens; n can be arranged at equal intervals, or the number of the film layers can be equal, preferably the film layers can be equal, and each film layer is used as one part for calculation and shape correction;
after the N modification parameters are simultaneously optimized by adopting the genetic algorithm, the modification parameter Q is determined, and the error between the actual electric field distribution and the optimal electric field distribution after modification is determined to be within a set range, because the etching precision in the prior art is generally 50 nanometers, the error between the actual electric field distribution and the optimal electric field distribution is preferably set to be +/-0.1 pi according to the etching precision, and the error between the actual electric field distribution and the optimal electric field distribution can be further reduced according to the development of the etching precision;
subsequently, the exit surface 2 of the actual diffraction structure is etched according to the shape modification parameters calculated by the genetic algorithm, which includes:
and etching the emergent surface 2 of the actual diffraction structure one by one according to the number N of the actual diffraction structure and the shape modification parameter Q corresponding to the number N.
The etching of the actual diffraction structure is related to the parts of the actual diffraction structure, each part of the actual diffraction structure corresponds to one modification parameter Q, the corresponding parts of the film layer are etched on the emergent surface 2 of the actual diffraction structure, and the optimal depth of the etched section is the modification parameter Q.
Therefore, the etched multi-layer Laue lens compensates the electric field change of the emergent surface 2 caused by the structural error without other auxiliary optical elements, thereby improving the focusing performance of the actually prepared multi-layer film Laue lens.
Optionally, the determining the diffraction structure includes the following steps:
determining the total film thickness, the periodic thickness Drout of the outermost film layer and the total film layer number of the lens according to the application requirement of the lens;
determining the periodic thickness of each film layer at the incident surface 1;
and calculating a curve eta-1 (Z) of the-1 st order diffraction efficiency changing with the section depth Z according to the wavelength lambda of the incident light, the focal length f of the lens-1 st order diffraction light and the number of film layers to obtain the optimal section depth Zopt.
In the above steps, firstly, a diffraction structure is determined, and the total film thickness of the lens, the periodic thickness Drout of the outermost film and the total film layer number are determined according to the application requirements of the lens;
the outermost layer thickness is determined by the following formula:
Δ — 1.22Drout, where Δ is the spatial resolution required to be achieved by the lens;
the total number of film layers was determined by the following formula:
Nmax＝fλ/(4*Drout2)；
the total thickness can be obtained through the total layer number;
the subsequent determination of the periodic thickness of the individual film layers at the entry face 1 comprises the following steps:
obtaining the position radius r of the nth film layer by the following formulan：
rn＝nfλ+n2λ2/4；
Wherein n is the number of films outward from the substrate, f is the focal length of the lens-1 order diffracted light, and lambda is the wavelength of incident light;
obtaining the periodic thickness D of the nth film layer based on the position radius of the nth film layern：
Dn＝fλ/rn；
Then calculating a curve eta-1 of the-1-order diffraction efficiency changing along with the depth Z by using a Takagi-Taupin theory in diffraction dynamics; selecting the optimal section depth Zopt with the maximum efficiency according to the calculated efficiency curve eta-1, and calculating the emergent electric field Eopt of the ideal multilayer film Laue lens at the optimal section depth Zopt; the actual lens preparation is then carried out on the basis of the optimal section depth value Zopt.
In this embodiment, a specific embodiment is preferably given, assuming that the incident light energy E is 20keV, the required focusing resolution is 25nm, the selected focal length is 3mm, the total film thickness is 10 μm, the outermost layer thickness is 10nm according to the coating capability and the resolution requirement, and the total number of layers is 500 according to the calculation.
Determining a diffraction structure according to the company in the step;
calculating a curve eta-1 (z) of the negative 1-order diffraction efficiency changing along with the depth z by utilizing a Takagi-Taupin theory;
selecting the optimal depth Zopt with the maximum efficiency as 6 mu m according to the diffraction curve eta-1 (z);
calculating the electric field distribution of the exit surface 2 of the Laue lens with the ideal structure according to the optimal depth Zopt, and recording the electric field distribution as Eopt; according to the actually measured structure and the same method, the electric field distribution of the exit surface 2 of the multilayer film Laue lens with the actual structure is calculated and is recorded as Eopt'.
Subdividing the multilayer film Laue lens with an actual structure into a certain number of substructures along the X direction, setting the subdivision number to be 350, subdividing according to each layer of structure, and etching the structure in the Z direction;
setting the modification parameter as Q, wherein the variation range is 0.4-1, and 1 is complete etching. Due to the fact that strong electric field coupling effect exists among different substructures, when a single substructure is artificially and simply optimized, all coupling factors cannot be considered, some unexpected changes can be introduced to emergent electric fields of adjacent substructures, and the optimal effect cannot be achieved, therefore, N shape modification parameters are optimized simultaneously by using a genetic algorithm, the optimization result is preferably as shown in fig. 7, wherein the parameters of shape modification needed by each layer of structure are shown, the abscissa is the number of layers, and the ordinate is the shape modification parameters.
After optimization, kirchhoff-fresnel diffraction integration is utilized to obtain light intensity distribution on an image surface, the focusing resolution of the lens after shape modification is 26nm, the ideal focusing resolution is 25nm, the focusing resolution under an actual structure is 39nm, as shown in fig. 5 and 6, normalized distribution curves of electric field intensities at three focal planes in fig. 6 are respectively structures which are actually prepared according to calculation parameters under a theoretical ideal condition and are obtained after shape modification and etching of an actual Laue lens structure, wherein the structure provided in the embodiment after shape modification and etching is closer to the curve under the theoretical ideal condition;
the Laue lens is approximately the same as an ideal type in focusing resolution after being modified, and is far superior to the Laue lens in an actual structure in focusing resolution, and the fact that the single-order diffraction Laue lens can effectively compensate the difference of an electric field on the emergent surface 2 caused by structural errors under the actual condition without the help of any additional optical element is shown.
It will be understood that any orientation or positional relationship indicated above with respect to the terms "central," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," etc., is based on the orientation or positional relationship shown in the drawings and is for convenience in describing and simplifying the invention, and does not indicate or imply that the referenced device or element must have a particular orientation, be constructed and operated in a particular orientation, and is therefore not to be considered limiting; the terms "inner and outer" refer to the inner and outer relative to the profile of the respective component itself. Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature.
Spatially relative terms, such as "above … …," "above … …," "above … … surface," "above," and the like, may be used herein for ease of description to describe one device or feature's spatial relationship to another device or feature as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if a device in the figures is turned over, devices described as "above" or "on" other devices or configurations would then be oriented "below" or "under" the other devices or configurations. Thus, the exemplary term "above … …" can include both an orientation of "above … …" and "below … …". The device may also be oriented 90 degrees or at other orientations and the spatially relative descriptors used herein interpreted accordingly.
It should be noted that unless expressly stated or limited otherwise, the terms "mounted," "connected," and "connected" are to be construed broadly and include, for example, fixed or removable connections or integral connections; can be mechanically or electrically connected; either directly or indirectly through intervening media, either internally or in any other relationship. The specific meaning of the above terms in the present application can be understood by those of ordinary skill in the art as appropriate.
The above description is only a preferred embodiment of the application and is illustrative of the principles of the technology employed. It will be appreciated by a person skilled in the art that the scope of the invention as referred to in the present application is not limited to the embodiments with a specific combination of the above-mentioned features, but also covers other embodiments with any combination of the above-mentioned features or their equivalents without departing from the inventive concept. For example, the above features may be replaced with (but not limited to) features having similar functions disclosed in the present application.
Claims (10)
1. A multilayer film Laue lens comprising a substrate layer and a diffractive structure disposed on the substrate layer, the diffractive structure comprising a plurality of periods arranged in a stack, each period comprising an absorbing layer and a spacer layer in a stack,
the thickness of the period is gradually reduced from the direction close to the substrate layer to the direction far away from the substrate layer;
the cross-sectional depth of each of the absorber and spacer layers is an optimum cross-sectional depth (1-modification parameter Q), wherein Q is any value between 0.4 and 1.
2. The multilayer film laue lens of claim 1, wherein the optimal cross-sectional depth is a depth of a diffraction structure corresponding to a maximum value of a diffraction efficiency of the multilayer film laue lens.
3. The multilayer film laue lens of claim 1, wherein the absorber layer and the spacer layer thickness in each of the periods are the same.
4. The multilayer film laue lens of claim 1, wherein the diffractive structure comprises oppositely disposed entrance and exit faces, and wherein the end faces of the plurality of absorbing layers and the spacer layer at the entrance face lie in the same plane.
5. The multilayer film laue lens of claim 1, wherein an error between an actual electric field distribution and an optimal electric field distribution of an exit surface of the multilayer film laue lens is within a set range.
6. A method of designing a multilayer film Laue lens as claimed in any one of claims 1 to 5, comprising the steps of:
determining a diffraction structure, wherein the depth of the diffraction structure is an optimal section depth, and the optimal section depth corresponds to an optimal electric field distribution;
forming an actual diffraction structure on the base layer, the electric field distribution of the actual diffraction structure being formed as an actual electric field distribution,
modifying the shape of the absorption layer and the spacing layer in the actual diffraction structure, calculating the actual electric field distribution of the modified emergent surface until the error between the actual electric field distribution and the optimal electric field distribution is within a set range, and determining a modification parameter Q;
and etching the emergent surface of the actual diffraction structure according to the shape modification parameter Q, wherein the etching depth is the optimal section depth.
7. The design method of claim 6, wherein the shaping the absorption layer and the spacer layer in the actual diffractive structure comprises:
dividing the actual diffraction structure into N parts with equal intervals or equal film quantity, wherein each part of the actual diffraction structure corresponds to one shape modification parameter Q;
and optimizing the N modification parameters simultaneously.
8. The design method of claim 7, wherein N is 65% -70% of the number of film layers.
9. The design method of claim 6, wherein the etching the exit surface of the actual diffraction structure according to the modification parameter Q comprises:
and etching the emergent surface of the actual diffraction structure in parts by parts according to the part N of the actual diffraction structure and the shape modification parameter Q corresponding to the part N.
10. The design method of claim 6, wherein said determining a diffractive structure comprises the steps of:
determining the total film thickness, the periodic thickness Drout of the outermost film layer and the total film layer number of the lens according to the application requirement of the lens;
determining the periodic thickness of each film layer at the incident surface;
and calculating a curve eta-1 (Z) of the-1 st order diffraction efficiency changing with the section depth Z according to the wavelength lambda of the incident light, the focal length f of the lens-1 st order diffraction light and the number of film layers to obtain the optimal section depth Zopt.
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN117575901A (en) * | 2024-01-11 | 2024-02-20 | 浙江大学杭州国际科创中心 | X-ray phase contrast micro-splicing method and system based on multilayer film Laue lens |
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2022
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN117575901A (en) * | 2024-01-11 | 2024-02-20 | 浙江大学杭州国际科创中心 | X-ray phase contrast micro-splicing method and system based on multilayer film Laue lens |
| CN117575901B (en) * | 2024-01-11 | 2024-05-07 | 浙江大学杭州国际科创中心 | X-ray phase contrast micro-splicing method and system based on multilayer film Laue lens |
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