Aperiodic dual-channel multilayer film reflector and design method of aperiodic multilayer film

Abstract

The invention relates to the technical field of optical element manufacturing, in particular to an aperiodic dual-channel multilayer film reflector and a design method of an aperiodic multilayer film, the reflectivity of the aperiodic dual-channel multilayer film reflector at a first wave band is not less than 15.98%, the reflectivity of the aperiodic dual-channel multilayer film reflector at a second wave band is not less than 27.11%, and the reflectivity of the aperiodic dual-channel multilayer film reflector at a third wave band is not less than 15.98%. The aperiodic dual-channel multilayer film reflector comprises a substrate; the aperiodic multilayer film is located on the substrate and comprises titanium layers and aluminum layers, the titanium layers and the aluminum layers are alternately arranged, the layer in contact with the substrate is the titanium layer, the topmost layer away from the substrate is the titanium layer, the thicknesses of the titanium layers are different, and the thicknesses of the aluminum layers are different. According to the aperiodic dual-channel multilayer film reflector provided by the embodiment of the invention, the reflectivity can be improved at least in two wave bands at the same time.

Description

Technical Field

[0001] The 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 reflectors 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] On the other hand, the present invention provides a design method for a non-periodic multilayer film, including: providing an initial structure, the initial structure including a first periodic multilayer film and a second periodic multilayer film superimposed on each other; optimizing the initial structure to obtain a non-periodic multilayer film, 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%.

[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, the initial structure is optimized including: 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 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 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 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 non-periodic dual-channel multilayer film reflector provided by the embodiment of the invention is applied to the structure of a space solar telescope, which is beneficial to reducing the weight and volume of the structure of the space solar telescope, and is of great significance for rocket launches with limited space and payload. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The drawings constituting part of the present invention are used to provide a further understanding of the present invention. The exemplary embodiments and descriptions of the present invention are used to explain the present invention and do not constitute an improper limitation on the present invention. In the drawings:

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

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

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

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

[0021] In the description of the 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", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the drawings, and are only for the convenience of describing the 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 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 technical features indicated. Therefore, the features defined as "first", "second", etc. may explicitly or implicitly include one or more of the features. In the description of the invention, unless otherwise specified, the meaning of "multiple" is two or more.

[0022] In the description of the invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installation", "connection" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the invention can be understood according to 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, which effectively reduces the surface roughness of the multilayer film and improves 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 by 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 measurement was carried out at the U27 spectral radiation standard and metrology terminal station of the Hefei National Synchrotron Radiation Laboratory, and irradiation experiments were carried out 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 reflector) 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 in 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 realizes the improvement of reflectivity in two bands at the same time through the Ti / Al non-periodic multilayer film, and realizes the improvement of reflectivity in the two bands of 17.1nm and 19.5nm at the same time through 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 resist proton irradiation well and adapt to the space working environment.

[0035] The non-periodic dual-channel multilayer film reflector provided in 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 gas 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] On the other hand, the present invention provides a design method for a non-periodic multilayer film, including: providing an initial structure, the initial structure including a first periodic multilayer film and a second periodic multilayer film superimposed on each other; optimizing the initial structure to obtain a non-periodic multilayer film, 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%.

[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] Furthermore, the initial structure is optimized including: importing the initial structure into the IMD software, optimizing the number of periods of the first period multilayer film by simulation, and optimizing the number of periods of the second period multilayer film by simulation, to obtain the first period multilayer film and the second period multilayer film with the number of periods being 10, and making the theoretical reflectivity value of the initial structure at 17.1nm to be 12.4%, and the theoretical reflectivity value of the initial structure at 19.5nm to be 23.8%; then optimizing the thickness of the first period multilayer film and the second period multilayer film by using a genetic algorithm, 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%, specifically, with the maximum reflectivity at 17.1nm and 19.5nm as the target, the incident angle relative to the normal is 5 degrees, and the minimum reflectivity at 18.1nm is the target, and high spectral selectivity is achieved near the two target wavelengths; using the IMD software to optimize the number of film layers and the thickness of each film layer of the initial structure by a genetic algorithm to obtain a non-periodic multilayer film.

[0040] The present invention provides a method for designing a non-periodic multilayer film, which can be used to design the non-periodic multilayer film of the non-periodic dual-channel multilayer film reflector in the aforementioned embodiment. The present invention provides a method for designing a non-periodic multilayer film, which first designs two Ti / Al periodic multilayer films, one Ti / Al periodic multilayer film is used to improve the reflectivity at 17.1nm, and the other Ti / Al periodic multilayer film is used to improve the reflectivity at 19.5nm. The periodic thickness of the two Ti / Al periodic multilayer films can be determined according to the Bragg diffraction formula, and then according to the formula proposed by Vinogradov and Zeldovich The optimal ratio of the two materials in the Ti / Al periodic multilayer film is determined and used as the initial structure. The Ti / Al periodic multilayer film is then optimized using a genetic algorithm using IMD software. After the preliminary optimization, two Ti / Al periodic multilayer films are superimposed to simultaneously improve the optimization targets of the two bands, and the thickness of each layer is simultaneously optimized to obtain the final non-periodic multilayer film.

[0041] After the non-periodic multilayer film design is completed, a non-periodic dual-channel multilayer film reflector can be prepared using a DC magnetron sputtering coating machine. Ti / Al non-periodic multilayer films are deposited on a silicon substrate. The first layer and the top layer are both Ti. The first layer of Ti serves as a seed layer, and the last layer of Ti has a certain smoothing effect on the Al layer and has certain radiation resistance.

[0042] After the non-periodic dual-channel multilayer film mirror was prepared, its reflectivity was measured, and it had high reflectivity in both bands. Irradiation experiments also proved that the non-periodic dual-channel multilayer film mirror had good anti-radiation properties and could be used in space payloads.

[0043] It should be understood that the various forms of processes shown above can be used to reorder, add or delete steps. For example, the steps described in the disclosure of the present invention can be performed in parallel, sequentially or in different orders, as long as the desired results of the technical solution disclosed in the present invention can be achieved, and this document does not limit this.

[0044] The above specific implementations do not constitute a limitation on the protection scope of the present invention. It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and substitutions can be made according to design requirements and other factors. Any modification, equivalent substitution and improvement made within the spirit and principle of the present invention should be included in the protection scope 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 located on the substrate, the non-periodic multilayer film includes alternately arranged titanium layers and aluminum layers, the 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.

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. The non-periodic dual-channel multilayer film reflector according to claim 1, characterized in that: The number of film layers of the non-periodic multilayer film is 57.

4. The non-periodic dual-channel multilayer film reflector according to claim 3, characterized in that: 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.

5. The non-periodic dual-channel multilayer film reflector according to claim 4, characterized in that: 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.

6. The non-periodic dual-channel multilayer film reflector according to claim 3, characterized in that: 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.

7. The non-periodic dual-channel multilayer film reflector according to claim 6, characterized in that: The thickness of the aluminum layers arranged in sequence 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.

8. A method for designing a non-periodic multilayer film, characterized in that: include: Providing an initial structure, the initial structure comprising a first period multilayer film and a second period multilayer film stacked; The initial structure is optimized to obtain a non-periodic multilayer film, wherein the reflectivity of the non-periodic multilayer film in the first waveband is not less than 15.98%, and the reflectivity of the non-periodic multilayer film in the second waveband is not less than 27.11%.

9. The method for designing a non-periodic multilayer film according to claim 8, characterized in that: 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.

10. The method for designing a non-periodic multilayer film according to claim 8, characterized in that: Optimizing the initial structure includes: Importing the initial structure into IMD software, optimizing the period number of the first period multilayer film by simulation, and optimizing the period number of the second period multilayer film by simulation, obtaining the first period multilayer film and the second period multilayer film both having 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, the thickness of the first period multilayer film and the thickness of the second period multilayer film are optimized by using a genetic algorithm, 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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