Design method of aperiodic two-channel multilayer mirror and aperiodic multilayer

Abstract

The application relates to the technical field of optical element manufacturing, in particular to a non-periodic double-channel multilayer film mirror and a design method of a non-periodic multilayer film, the non-periodic double-channel multilayer film mirror has a reflectivity of no less than 15.98% in a first wave band, the non-periodic double-channel multilayer film mirror has a reflectivity of no less than 27.11% in a second wave band, and the non-periodic double-channel multilayer film mirror comprises a substrate and a non-periodic multilayer film located on the substrate; the non-periodic multilayer film comprises titanium layers and aluminum layers arranged alternately, a layer in contact with the substrate is a titanium layer, and the topmost layer away from the substrate is a titanium layer, wherein the thickness of each titanium layer is different, and the thickness of each aluminum layer is different. The non-periodic double-channel multilayer film mirror provided in the embodiment can at least realize the improvement of reflectivity in two wave bands simultaneously.

Description

Technical Field

[0001] The present invention belongs to the technical field of optical element manufacturing, and in particular relates to a non-periodic double-channel multilayer film reflecting mirror and a design method of a non-periodic multilayer film. Background Art

[0002] Multilayer film mirrors can be used to achieve imaging of specific spectral lines (such as Fe-IX, Fe-XII, Fe XIV, Fe-XV and He-II) and are often used in space solar telescopes for corona research. However, current space solar telescopes usually include four areas, each with different reflectors. The reflectors in each area correspond to one spectral line, and their structure is relatively complex. If a reflector can be developed that can improve the reflection efficiency in two bands at the same time, it will significantly simplify the structure of the space solar telescope and reduce the payload mass, which is of great significance for rocket launches with limited space and payload. Summary of the Invention

[0003] In view of this, the present invention aims to provide a non-periodic dual-channel multilayer film reflector and a design method for a non-periodic multilayer film. The non-periodic dual-channel multilayer film reflector can at least achieve improved reflectivity in two bands at the same time.

[0004] To achieve the above object, the technical solution created by the present invention is implemented as follows:

[0005] On the one hand, the present invention provides a non-periodic dual-channel multilayer film reflector, including: the reflectivity of the non-periodic dual-channel multilayer film reflector in the first band is not less than 15.98%, the reflectivity of the non-periodic dual-channel multilayer film reflector in the second band is not less than 27.11%, and the non-periodic dual-channel multilayer film reflector includes: a substrate; a non-periodic multilayer film located on the substrate, the non-periodic multilayer film includes alternating titanium layers and aluminum layers, a layer in contact with the substrate is a titanium layer, and the top layer away from the substrate is a titanium layer, wherein the thickness of each titanium layer is different, and the thickness of each aluminum layer is different.

[0006] Furthermore, the first wavelength band is 17.1 nm and the second wavelength band is 19.5 nm.

[0007] Furthermore, the number of film layers of the non-periodic multilayer film is 57.

[0008] Furthermore, among the multiple titanium layers of the non-periodic multilayer film, the thickness of the smallest titanium layer is 10 angstroms, and the thickness of the largest titanium layer is 47.98 angstroms.

[0009] Furthermore, the thickness of the titanium layer arranged in a direction away from the substrate is: 43.44 angstroms, 15.54 angstroms, 47.98 angstroms, 47.95 angstroms, 47.63 angstroms, 26.88 angstroms, 10.18 angstroms, 37.05 angstroms, 15.69 angstroms, 17.18 angstroms, 40.85 angstroms, 43.25 angstroms, 31.03 angstroms, 10 angstroms, 38.12 angstroms, 10.03 angstroms, 12.36 angstroms, 33.61 angstroms, 38.81 angstroms, 34.73 angstroms, 26.56 angstroms, 10.19 angstroms, 10.01 angstroms, 14.39 angstroms, 32 angstroms, 33.85 angstroms, 32.29 angstroms, 10.1 angstroms and 10.23 angstroms.

[0010] Furthermore, among the multiple aluminum layers of the non-periodic multilayer film, the thickness of the smallest aluminum layer is 10.03 angstroms, and the thickness of the largest aluminum layer is 142.18 angstroms.

[0011] Furthermore, the thickness of the aluminum layer arranged in a direction away from the substrate is: 19.83 angstroms, 59.54 angstroms, 45.75 angstroms, 48.76 angstroms, 53.4 angstroms, 10.19 angstroms, 47.41 angstroms, 60.76 angstroms, 33.92 angstroms, 63.4 angstroms, 51.24 angstroms, 52.12 angstroms, 10.04 angstroms, 46.63 angstroms, 142.18 angstroms, 48.21 angstroms, 68.35 angstroms, 58.28 angstroms, 58.17 angstroms, 62.98 angstroms, 73.38 angstroms, 39.48 angstroms, 70.21 angstroms, 69.35 angstroms, 61.65 angstroms, 62.41 angstroms, 62.55 angstroms and 10.03 angstroms.

[0012] Another aspect of the present invention provides a method for designing a non-periodic multilayer film, comprising: providing an initial structure, the initial structure comprising a first periodic multilayer film and a second periodic multilayer film superimposed; optimizing the initial structure to obtain a non-periodic multilayer film, the non-periodic multilayer film having a reflectivity of not less than 15.98% in the first band, and a reflectivity of not less than 27.11% in the second band.

[0013] Furthermore, the central wavelength of the first-period multilayer film is 17.1 nm, the central wavelength of the second-period multilayer film is 19.5 nm, the first wavelength band is 17.1 nm, and the second wavelength band is 19.5 nm.

[0014] Furthermore, optimizing the initial structure includes: importing the initial structure into the IMD software, optimizing the number of periods of the first-period multilayer film through simulation, and optimizing the number of periods of the second-period multilayer film through simulation, to obtain a first-period multilayer film and a second-period multilayer film with a period number of 10, and making the theoretical reflectivity value of the initial structure at 17.1nm 12.4%, and the theoretical reflectivity value of the initial structure at 19.5nm 23.8%; then using a genetic algorithm to optimize the thickness of the first-period multilayer film and the thickness of the second-period multilayer film, respectively, so that the reflectivity of the initial structure at 17.1nm is 24.9%, and the reflectivity of the initial structure at 19.5nm is 19.0%; using the IMD software to optimize the number of film layers and the thickness of each film layer through a genetic algorithm to obtain a non-periodic multilayer film.

[0015] Compared with the prior art, the invention can achieve the following beneficial effects: the embodiment of the present invention adopts Ti / Al non-periodic multilayer film to form a non-periodic dual-channel multilayer film reflector, which can simultaneously improve the reflectivity in the two bands of 17.1nm and 19.5nm. The reflectivity at 17.1nm can reach 15.98%, and the reflectivity at 19.5nm can reach 27.11%. The application of the non-periodic dual-channel multilayer film reflector provided by the embodiment of the present invention in the structure of a space solar telescope is beneficial to reducing the weight and volume of the space solar telescope structure, and is of great significance for rocket launches with limited space and payload. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The accompanying drawings, which constitute part of the present invention, are intended to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are intended to explain the present invention and do not constitute an undue limitation of the present invention. In the accompanying drawings:

[0017] Figure 1 A schematic diagram illustrating the number of layers and the thickness of each layer of the non-periodic multilayer film according to an embodiment of the present invention;

[0018] Figure 2 A schematic diagram comparing the reflectivity of the non-periodic dual-channel multilayer film mirror described in an embodiment of the present invention before and after irradiation. DETAILED DESCRIPTION

[0019] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and do not constitute a limitation of the present invention.

[0020] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other.

[0021] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. In addition, the terms "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, features defined as "first", "second", etc. may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "multiple" means two or more.

[0022] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "installed," "connected," and "connected" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; and they can refer to internal connections between two components. Those skilled in the art can understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0023] The present invention will be described in detail below with reference to the accompanying drawings and in combination with embodiments.

[0024] On the one hand, the present invention provides a non-periodic dual-channel multilayer film reflector, including: the reflectivity of the non-periodic dual-channel multilayer film reflector in the first band is not less than 15.98%, the reflectivity of the non-periodic dual-channel multilayer film reflector in the second band is not less than 27.11%, and the non-periodic dual-channel multilayer film reflector includes: a substrate; a non-periodic multilayer film located on the substrate, the non-periodic multilayer film includes alternating titanium layers and aluminum layers, a layer in contact with the substrate is a titanium layer, and the top layer away from the substrate is a titanium layer, wherein the thickness of each titanium layer is different, and the thickness of each aluminum layer is different.

[0025] The titanium layer in contact with the substrate serves as a Ti seed layer, which can solve the problem of decreased reflectivity caused by the high surface roughness of the Al-containing multilayer film. That is, by first depositing a layer of Ti on the substrate, Al is easier to grow in layers when deposited on Ti. At the same time, the top Ti layer has a certain smoothing effect on the multilayer film, effectively reducing the surface roughness of the multilayer film and improving the reflectivity.

[0026] Furthermore, the first wavelength band is 17.1 nm and the second wavelength band is 19.5 nm.

[0027] For further reference, Figure 1 The number of film layers of the non-periodic multilayer film is 57.

[0028] Furthermore, among the multiple titanium layers of the non-periodic multilayer film, the thickness of the smallest titanium layer is 10 angstroms, and the thickness of the largest titanium layer is 47.98 angstroms.

[0029] For further reference, Figure 1 , the thickness of the titanium layer arranged in the direction away from the substrate is: 43.44 angstroms, 15.54 angstroms, 47.98 angstroms, 47.95 angstroms, 47.63 angstroms, 26.88 angstroms, 10.18 angstroms, 37.05 angstroms, 15.69 angstroms, 17.18 angstroms, 40.85 angstroms, 43.25 angstroms, 31.03 angstroms, 10 angstroms, 38.12 angstroms, 10.03 angstroms, 12.36 angstroms, 33.61 angstroms, 38.81 angstroms, 34.73 angstroms, 26.56 angstroms, 10.19 angstroms, 10.01 angstroms, 14.39 angstroms, 32 angstroms, 33.85 angstroms, 32.29 angstroms, 10.1 angstroms and 10.23 angstroms.

[0030] Furthermore, among the multiple aluminum layers of the non-periodic multilayer film, the thickness of the smallest aluminum layer is 10.03 angstroms, and the thickness of the largest aluminum layer is 142.18 angstroms.

[0031] For further reference, Figure 1 , the thickness of the aluminum layer arranged in the direction away from the substrate is: 19.83 angstroms, 59.54 angstroms, 45.75 angstroms, 48.76 angstroms, 53.4 angstroms, 10.19 angstroms, 47.41 angstroms, 60.76 angstroms, 33.92 angstroms, 63.4 angstroms, 51.24 angstroms, 52.12 angstroms, 10.04 angstroms, 46.63 angstroms, 142.18 angstroms, 48.21 angstroms, 68.35 angstroms, 58.28 angstroms, 58.17 angstroms, 62.98 angstroms, 73.38 angstroms, 39.48 angstroms, 70.21 angstroms, 69.35 angstroms, 61.65 angstroms, 62.41 angstroms, 62.55 angstroms and 10.03 angstroms.

[0032] It should be noted that the design and optimization of the non-periodic multilayer film involved in the present invention can be performed using IMD software to determine the optimal film system structure.

[0033] For the non-periodic dual-channel multilayer film reflector provided in the embodiment of the present invention, reflectivity measurements were performed at the U27 spectral radiation standard and metrology terminal station of the Hefei National Synchrotron Radiation Laboratory. An irradiation experiment was conducted at the Harbin Institute of Technology in China. The irradiation experiment used proton irradiation with an irradiation intensity of 100 keV and a dose of 7.832×10 14 p / cm2, the final measurement results show that the reference Figure 2 The reflectivity of the sample (non-periodic dual-channel multilayer film mirror) at the central wavelength of 17.1nm and 19.5nm is 15.98% and 27.11% respectively. After irradiation, the reflectivity of the sample decreases slightly to 14.29% and 25.14% respectively, and its radiation resistance is good.

[0034] The non-periodic dual-channel multilayer film reflector provided by the embodiment of the present invention can solve the problem that the reflector of the space solar telescope can only have a high reflectivity in a single band. The embodiment of the present invention uses the Ti / Al non-periodic multilayer film to achieve simultaneous improvement of the reflectivity in two bands. The reflectivity in the 17.1nm and 19.5nm bands can be simultaneously improved by only one reflector, which is of great significance for simplifying the structure of the space solar telescope and reducing the payload weight of the launch vehicle. The top titanium layer can well resist proton irradiation and adapt to the space working environment.

[0035] The non-periodic dual-channel multilayer film reflector provided by the embodiment of the present invention can be prepared by a DC magnetron sputtering coating machine. The background vacuum requirement before coating is less than 5×10-4Pa. The target material needs to be 99.99% pure Ti and 99.99% pure Al. The substrate can be a Si substrate. The root mean square roughness of the substrate surface is less than 0.2nm. During the sputtering process, 99.999% pure argon can be introduced to keep the working gas pressure at 0.1Pa. The deposition process is carried out without destroying the vacuum. During the preparation process, the deposition rates of Ti and Al can be respectively

[0036]

[0037] Another aspect of the present invention provides a method for designing a non-periodic multilayer film, comprising: providing an initial structure, the initial structure comprising a first periodic multilayer film and a second periodic multilayer film superimposed; optimizing the initial structure to obtain a non-periodic multilayer film, the non-periodic multilayer film having a reflectivity of not less than 15.98% in the first band, and a reflectivity of not less than 27.11% in the second band.

[0038] Furthermore, the central wavelength of the first-period multilayer film is 17.1 nm, the central wavelength of the second-period multilayer film is 19.5 nm, the first wavelength band is 17.1 nm, and the second wavelength band is 19.5 nm.

[0039] Further, the optimization of the initial structure includes: importing the initial structure into the IMD software, optimizing the period number of the first period multilayer film through simulation, and optimizing the period number of the second period multilayer film through simulation, so that the first period multilayer film and the second period multilayer film have a period number of 10, and the initial structure has a theoretical reflectivity value of 12.4% at 17.1 nm and a theoretical reflectivity value of 23.8% at 19.5 nm; and then the genetic algorithm is used to optimize the thickness of the first period multilayer film and the thickness of the second period multilayer film, so that the initial structure has a reflectivity of 24.9% at 17.1 nm and a reflectivity of 19.0% at 19.5 nm, and specifically, the maximum reflectivity at 17.1 nm and 19.5 nm is taken as the target, the incident angle relative to the normal is 5 degrees, and the minimum reflectivity at 18.1 nm is taken as the target, so as to realize high spectral selectivity near the two target wavelengths; and the genetic algorithm is used to optimize the layer number of the film layer of the initial structure and the thickness of each film layer by using the IMD software, so as to obtain the aperiodic multilayer film.

[0040] The design method of the aperiodic multilayer film provided by the application can be used for designing the aperiodic multilayer film of the aperiodic two-channel multilayer film mirror in the foregoing embodiments. The design method of the aperiodic multilayer film provided by the application first designs two Ti / Al periodic multilayer films. One Ti / Al periodic multilayer film is used to improve the reflectivity at 17.1 nm, and the other Ti / Al periodic multilayer film is used to improve the reflectivity at 19.5 nm. The period thicknesses of the two Ti / Al periodic multilayer films can be determined according to the Bragg diffraction formula. The optimal proportion of the two materials in the Ti / Al periodic multilayer film is determined according to the formula proposed by Vinogradov and Zeldovich, and the optimal proportion is used as the initial structure. Then the genetic algorithm is used to optimize and design the Ti / Al periodic multilayer film by using the IMD software. After the preliminary optimization is completed, the two Ti / Al periodic multilayer films are stacked to simultaneously improve the optimization targets of the two wave bands, and the thicknesses of the layers are simultaneously optimized, so as to obtain the final aperiodic multilayer film.

[0041] After the aperiodic multilayer film is designed, the aperiodic two-channel multilayer film mirror can be prepared by using a direct-current magnetron sputtering coating machine. The Ti / Al aperiodic multilayer film is deposited on a silicon substrate. The first layer and the top layer are both Ti. The Ti of the first layer serves as a seed layer, and the Ti of the last layer has a certain smoothing effect on the Al layer and also has a certain radiation resistance.

[0042] After the non-periodic dual-channel multilayer film mirror was prepared, its reflectivity was measured. It has high reflectivity in both bands, and irradiation experiments have verified that the non-periodic dual-channel multilayer film mirror has good anti-radiation properties and can be used in space payloads.

[0043] It should be understood that the various forms of the processes shown above can be used to reorder, add, or delete steps. For example, the steps described in the present disclosure can be performed in parallel, sequentially, or in a different order, as long as the desired results of the technical solutions disclosed in the present disclosure can be achieved. This is not limited herein.

[0044] The above specific embodiments do not limit the scope of protection of the present invention. Those skilled in the art will appreciate that various modifications, combinations, sub-combinations, and substitutions may be made based on design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention are intended to be included within the scope of protection of the present invention.

Claims

1. A non-periodic dual-channel multilayer film reflector, characterized in that: include: The reflectivity of the non-periodic dual-channel multi-layer film reflector in the first band is not less than 15.98%, and the reflectivity of the non-periodic dual-channel multi-layer film reflector in the second band is not less than 27.11%. The non-periodic dual-channel multi-layer film reflector includes: substrate; a non-periodic multilayer film on the substrate, the non-periodic multilayer film comprising alternating titanium layers and aluminum layers, wherein the layer in contact with the substrate is the titanium layer, and the topmost layer away from the substrate is the titanium layer, wherein the thickness of each titanium layer is different, and the thickness of each aluminum layer is different; The number of film layers of the non-periodic multilayer film is 57; The thickness of the titanium layer arranged in a direction away from the substrate is: 43.44 angstroms, 15.54 angstroms, 47.98 angstroms, 47.95 angstroms, 47.63 angstroms, 26.88 angstroms, 10.18 angstroms, 37.05 angstroms, 15.69 angstroms, 17.18 angstroms, 40.85 angstroms, 43.25 angstroms, 31.03 angstroms, 10 angstroms, 38.12 angstroms, 10.03 angstroms, 12.36 angstroms, 33.61 angstroms, 38.81 angstroms, 34.73 angstroms, 26.56 angstroms, 10.19 angstroms, 10.01 angstroms, 14.39 angstroms, 32 angstroms, 33.85 angstroms, 32.29 angstroms, 10.1 angstroms and 10.23 angstroms; The thickness of the aluminum layer arranged in the direction away from the substrate is: 19.83 angstroms, 59.54 angstroms, 45.75 angstroms, 48.76 angstroms, 53.4 angstroms, 10.19 angstroms, 47.41 angstroms, 60.76 angstroms, 33.92 angstroms, 63.4 angstroms, 51.24 angstroms, 52.12 angstroms, 10.04 angstroms, 46.63 angstroms, 142.18 angstroms, 48.21 angstroms, 68.35 angstroms, 58.28 angstroms, 58.17 angstroms, 62.98 angstroms, 73.38 angstroms, 39.48 angstroms, 70.21 angstroms, 69.35 angstroms, 61.65 angstroms, 62.41 angstroms, 62.55 angstroms and 10.03 angstroms.

2. The non-periodic dual-channel multilayer film reflector according to claim 1, characterized in that: The first wavelength band is 17.1 nm, and the second wavelength band is 19.5 nm.

3. A method for designing a non-periodic multilayer film, characterized in that: For designing the non-periodic multilayer film according to claim 1, the design method of the non-periodic multilayer film comprises: providing an initial structure, the initial structure comprising a first periodic multilayer film and a second periodic multilayer film superimposed; The initial structure is optimized to obtain a non-periodic multilayer film, wherein the reflectivity of the non-periodic multilayer film in the first band is not less than 15.98%, and the reflectivity of the non-periodic multilayer film in the second band is not less than 27.11%.

4. The method for designing a non-periodic multilayer film according to claim 3, wherein: The central wavelength of the first-period multilayer film is 17.1 nm, the central wavelength of the second-period multilayer film is 19.5 nm, the first wavelength band is 17.1 nm, and the second wavelength band is 19.5 nm.

5. The method for designing a non-periodic multilayer film according to claim 3, wherein: Optimizing the initial structure includes: Importing the initial structure into IMD software, optimizing the number of periods of the first-period multilayer film through simulation, and optimizing the number of periods of the second-period multilayer film through simulation, to obtain the first-period multilayer film and the second-period multilayer film each having a period number of 10, and making the theoretical reflectivity value of the initial structure at 17.1 nm be 12.4%, and the theoretical reflectivity value of the initial structure at 19.5 nm be 23.8%; Then, using a genetic algorithm, the thickness of the first period multilayer film and the thickness of the second period multilayer film are optimized respectively, so that the reflectivity of the initial structure at 17.1 nm is 24.9%, and the reflectivity of the initial structure at 19.5 nm is 19.0%; The number of film layers and the thickness of each film layer of the initial structure are optimized by genetic algorithm using IMD software to obtain the non-periodic multilayer film.

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