Tunable multi-wavelength laser protective film for space solar cells

Abstract

A tunable multi-wavelength laser protection film for space solar cells is used on the surface of the protective glass cover of space solar cells. It reflects high-energy lasers of a specific wavelength and transmits the working wavelength of the solar cell panel to achieve the purpose of laser protection. The basic film system structure is: #imgabs0# where S represents the substrate, A represents the incident medium, H represents the n and L n Respectively represent different high and low refractive index materials with an optical thickness of one quarter of the central wavelength, a1, b1 to a n ,b n is the low refractive index material coefficient, x1 to x n is the optical thickness coefficient of the reflection cavity in each protection band, m1 to m n The present invention realizes the spatial protection of multiple laser bands by using the superposition combination of multiple reflection cavities without affecting the working efficiency of solar cells. The protection method used is universal for the design of linear laser protection windows of different working bands and multiple laser protection bands.

Description

Technical Field

[0001] The invention belongs to the technical field of space optical films and relates to a laser protective film for space solar cell panels. Background Art

[0002] Laser weapons play a vital role in modern warfare. The blinding attack and thermal damage of laser weapons on satellites make the research of anti-laser damage film a key issue. The triple-junction gallium arsenide solar cells on satellites have the characteristics of high conversion efficiency and strong radiation resistance. In recent years, they have been used as the main power system. Studies have shown that when 8W / cm 2 When a 1315nm continuous laser with high power density irradiates a triple-junction gallium arsenide solar cell for 60 seconds, its electrical performance drops by 70%. At the same time, the optical window detection sensitivity on the satellite is high, which is the weak link of the satellite system and also faces serious threats. Therefore, in order to ensure the reliable implementation of satellite missions, it is urgent to increase efforts to carry out laser threat assessment, study efficient protection strategies and protection technologies, and realize on-orbit applications as soon as possible.

[0003] At present, for laser protection of solar panels, Shanghai Aerospace Equipment Manufacturing Factory uses SiO 2 and VO 2 As a protective layer, MgF 2 As an anti-reflection layer, the visible light transmittance is about 60% under normal conditions, and the infrared band transmittance is 65% to 80%. The test results of the laser protection equivalent test show that the damage threshold of silicon cells is increased by 3 to 4 times after the protective film is protected, but the protective film will seriously affect the working efficiency of silicon cells. The U.S. Army Natick Research Center has developed a combined layered structure protective mirror, which uses the reflection attenuation of a specific wavelength laser by a multi-layer dielectric film to achieve laser protection effect. It can protect three types of lasers at 532nm, 694nm and 1064nm. The reflectivity of the protection band is 99.99%, and the visible light transmittance is 73%, but it cannot be used for space solar cell protection. Jiang Yugang and others from Tianjin Jinhang Technical Physics Institute plated a multilayer film on both sides of the absorption substrate to achieve high reflection of 0.532, 1.064, 1.315, 2.7, and 3.8μm wavelengths, high transmittance of 0.55-0.8μm and 1.55μm bands, and achieved multi-band protection and high transmittance in the 1.55μm working band. The disadvantage is that it cannot be used for space solar cell protection. There are reports abroad using Rugate filters to achieve dual-wavelength protection of 532 and 1064nm, but the disadvantage is that the transmittance of the solar cell working band is low and the Rugate filter is difficult to manufacture.

[0004] From this point of view, the current means of protecting solar panels have the disadvantages of fewer protection bands, non-tunability, and poor compatibility of working bands. Therefore, it is necessary to develop a tunable laser protection film that can protect against multi-band high-energy lasers without losing the original working performance of the protection device. This will have important application prospects in fields such as satellite security. Summary of the invention

[0005] The purpose of the present invention is to provide a multi-wavelength laser protection film for space solar cells based on the principle of reflecting specific laser wavelengths. By combining a protective substrate with a linear laser protection film, a film that needs to protect a specific band is plated to achieve high transmittance in the working band of space solar cells and low transmittance in the band of strong laser weapons, thereby meeting the needs of normal operation of space solar cells and protection against strong laser weapons.

[0006] In order to solve the above technical problems, the present invention provides a tunable multi-wavelength laser protective film for space solar cells, which is a thin film deposited on the surface of the solar cell glass cover, and its basic film system structure is:

[0007]

[0008] Where S represents the substrate, A represents the incident medium, and H n and L n They represent different high and low refractive index materials with an optical thickness of one quarter of the central wavelength, a 1 ,b 1 to a n ,b n is the low refractive index material coefficient, x 1 to x n is the optical thickness coefficient of the reflection cavity in each protection band, m 1 To m n is the period number of the reflection cavity in each protection band, x 1 The value of m is 0.8~1.2, 1 The value of is between 15 and 25. 0 Used to compress the spectral folds in the long-wave band, the high refractive index material layer H 0 With H 1 For the same high refractive index material. is the reflection cavity of the selected nth guard band, used to compress the spectral short-band fold a n ,b n is the optical thickness coefficient of the low refractive index material in the reflection cavity, and a is required n +b n =1, n≥1, the preferred value of n is less than 7. n is the optical thickness coefficient of the nth protection band reflection cavity, x nThe value is the ratio of the center wavelength of the nth protection band to the center wavelength of the first protection band, m n is the period number of the reflection cavity in the nth protection band, and its size determines the reflectivity of the reflection cavity. n The value of is between 15 and 25. n and L n The ratio of the refractive index will determine the reflection bandwidth of the reflection cavity. The larger the ratio, the larger the reflection bandwidth, and the smaller the ratio, the smaller the reflection bandwidth.

[0009] Compared with the prior art, the tunable multi-wavelength laser protection film for space solar cells provided by the present invention can realize multi-band solar cell laser protection under the premise of ensuring the photoelectric efficiency of space solar cells by superimposing selected reflection cavities of different bands and compressing the folds of the transmission spectrum sidebands. It has universal applicability for the design of linear laser protection films with different working bands and different protection laser bands applied in optical windows. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 Diagram of the structure of tunable multi-wavelength laser protective film for space solar cells.

[0011] Figure 2 K9 glass transmittance curve.

[0012] Figure 3 Al 2 O 3 、SiO 2 Refractive index curve.

[0013] Figure 4 Optimize the film system theory to design the transmittance curve. DETAILED DESCRIPTION

[0014] In order to make the purpose, content, and advantages of the present invention more clear, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments.

[0015] Reference Figure 1 As shown in the figure, the thin film deposited on the surface of the solar cell glass cover has the following basic film structure:

[0016]

[0017] Among them, S represents the substrate, A represents the incident medium, and H n and L n They represent different high and low refractive index materials with an optical thickness of one quarter of the central wavelength, x n (a n L n H n b n L n) is the selected reflection cavity of the nth guard band, which is used to compress the spectral short-wave band fold a n ,b n is the optical thickness coefficient of the low refractive index material in the reflection cavity, and a n +b n =1,n≥1,x n is the optical thickness coefficient of the reflection cavity in the nth protection band, m n is the period number of the reflection cavity in the nth protection band, and the high refractive index material layer H 0 With H 1 For the same high refractive index material.

[0018] According to the requirements of the reflection band, Al 2 O 3 and SiO 2 The optical constants are imported into the thin film design software. n 、m n 、a n 、b n value, calculate the transmittance curve, and then select the appropriate x according to the preset index requirements n 、m n 、a n 、b n value.

[0019] Among them, K9 glass is selected as the substrate.

[0020] The following design is based on the working bands of space solar cells: 0.3-1.05μm, 1.1-1.3μm, 1.35-1.8μm transmission and 1.064μm, 1.315μm strong laser protection as examples. The design steps are as follows:

[0021] According to the design requirements of the dual-band protection window, the schematic diagram of the linear laser protection film window structure is as follows: Figure 1 As shown in Figure 1, K9 glass is selected as the substrate. Its 0.3-1.8μm transmittance curve is as follows Figure 2 shown.

[0022] Al 2 O 3 、SiO 2 The optical constants are imported into the thin film design software, and the relationship between the refractive index and wavelength is as follows: Figure 3 shown.

[0023] Import the K9 parameters and the dual-band linear laser protection film basic film system into the film design software. The reference wavelength is 1.064μm, and the basic film system structure is:

[0024] S / H(0.5LH0.5L) 20 1.235(0.5LH0.5L)20 / A

[0025] Wherein, A represents the incident medium, which is air in this embodiment, and the final structure is a fully optimized structure.

[0026] like Figure 4 As shown, the designed dual-band linear laser protection film window achieves low transmittance of strong lasers in the 1.064 and 1.315μm bands within the space solar cell working band of 0.3-1.8μm, and high transmittance in the remaining bands, which not only meets the high transmittance of the solar cell working band, but also can protect against the attack of strong laser weapons.

[0027] The above is only a preferred embodiment of the present invention. It should be noted that, for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention, such as selecting more x n 、m n Value, for working in a wide band and in different optical windows, utilizing the principle of reflecting specific laser wavelengths and compressing the spectral folds of the transmitted band, multi-band and high-reflection protection is performed while taking into account the original working performance. These improvements and deformations should also be regarded as the scope of protection of the present invention.

Claims

1. A tunable multi-wavelength laser protective film for space solar cells, characterized in that: The basic film structure of the thin film deposited on the surface of the solar cell glass cover is: Among them, S represents the substrate, A represents the incident medium, and H n and L n They represent different high and low refractive index materials with an optical thickness of one quarter of the central wavelength, x n (a n L n H n b n L n ) is the reflection cavity of the selected nth guard band, which is used to compress the spectral short-wave band fold a n ,b n is the optical thickness coefficient of the low refractive index material in the reflection cavity, and a n +b n =1,n≥1,x n is the optical thickness coefficient of the reflection cavity in the nth protection band, m n is the period number of the nth protection band reflection cavity, and the high refractive index material layers H0 and H1 are made of the same high refractive index material.

2. The tunable multi-wavelength laser protective film for space solar cells according to claim 1, characterized in that: The high refractive index material layer H0 is used to compress the spectral folds in the long-wave band.

3. The tunable multi-wavelength laser protective film for space solar cells according to claim 1, characterized in that: The value of x1 is between 0.8 and 1.2, and the value of m1 is between 15 and 25.

4. The tunable multi-wavelength laser protective film for space solar cells according to claim 1, characterized in that: x n The value is the ratio of the center wavelength of the nth protection band to the center wavelength of the first protection band, m n is the period number of the reflection cavity in the nth protection band, and its size determines the reflectivity of the reflection cavity. n The value is between 15 and 25.

5. The tunable multi-wavelength laser protective film for space solar cells according to claim 1, characterized in that: The nth reflection cavity H n and L n The ratio of the refractive index will determine the reflection bandwidth of the reflection cavity. The larger the ratio, the larger the reflection bandwidth, and the smaller the ratio, the smaller the reflection bandwidth.

6. The tunable multi-wavelength laser protective film for space solar cells according to claim 1, characterized in that: n is less than 7.

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