Method for depositing a dual-band film system on a calcium fluoride substrate

Abstract

A method for preparing a dual-band film system deposited on a calcium fluoride substrate includes the following steps: cleaning a lens; placing it in a tooling fixture; cleaning with an ion source; depositing a Y₂O₃ film layer on the first surface; depositing a first ZnSe film layer; depositing a first YbF₃ film layer; depositing a second ZnSe film layer; depositing a second YbF₃ film layer; depositing a third ZnSe film layer; depositing a third YbF₃ film layer; depositing a fourth ZnSe film layer; depositing a fourth YbF₃ film layer; depositing a fifth ZnSe film layer; depositing a fifth YbF₃ film layer; depositing a sixth ZnSe film layer; and depositing... The sixth YbF3 film layer; the first ZnS film layer; the seventh YbF3 film layer; the second ZnS film layer; the lens is removed; preparation for the second side; the lens is placed in the tooling fixture; ion source cleaning; the Y2O3 film layer is deposited on the second side; the first ZnSe film layer is deposited; the first YbF3 film layer is deposited; the second ZnSe film layer is deposited; the second YbF3 film layer is deposited; the third ZnSe film layer is deposited; the third YbF3 film layer is deposited; the first ZnS film layer is deposited; the fourth YbF3 film layer is deposited; the second ZnS film layer is deposited; the lens is removed.

Description

Technical Field

[0001] This disclosure relates to the field of optical coating, and more specifically to a method for preparing a dual-band film system deposited on a calcium fluoride substrate. Background Technology

[0002] Calcium fluoride (CaF2) windows, with a spectral range of 200-8000 nm covering the visible and infrared bands, are widely used in excimer lasers, infrared optics, ultraviolet optical equipment, high-energy detectors, industrial instrument windows, and scientific research experiments, making them an ideal material for optical systems. As their applications become more widespread and the requirements for coatings become more stringent, further development of coating systems on calcium fluoride substrates is needed. Summary of the Invention

[0003] In view of the problems existing in the background art, the purpose of this disclosure is to provide a method for preparing a dual-band film system deposited on a calcium fluoride substrate, which can meet the requirements of an average reflectance of more than 97% in the 930-1050nm laser band at a 45° angle and an average reflectance of less than 6% in the 2-5μm infrared band.

[0004] Therefore, a method for preparing a dual-band film system deposited on a calcium fluoride substrate includes the following steps:

[0005] S1, the surface of the co-plating sheet, which serves as the calcium fluoride base for the lens, and the product are cleaned. The thickness of the co-plating sheet is 0.9-1.5mm.

[0006] S2, Place the cleaned lens into the fixture, and hang the fixture with the lens in it into the cavity of the vacuum coating machine. The temperature of the cavity is set to 180±1℃.

[0007] S3, the vacuum coating machine starts pumping vacuum, and the vacuum level reaches 1.5×10. -3 Pa, turn on the auxiliary coating ion source of the vacuum coating machine for cleaning. The cleaning time is 6 minutes. The anode voltage of the ion source is 220V, the anode current is 1.2-1.5A, and the emitter current is 1.3-1.5A.

[0008] S4. Maintaining the aforementioned vacuum level, deposit a Y2O3 film on the first surface of the lens. The deposition rate of the Y2O3 film is 0.3 nm / s, and the thickness of the Y2O3 film is controlled to be 15 nm ± 1 nm. Ion source-assisted evaporation is used. After the Y2O3 film is deposited, the temperature of the cavity drops to 150 ± 1 °C.

[0009] S5, a first ZnSe film is deposited on the deposited Y2O3 film. The deposition rate of the first ZnSe film is 0.8 nm / s, and the thickness of the first ZnSe film is controlled to be 35 nm ± 2 nm. Ion source assisted evaporation.

[0010] S6, deposit a first YbF3 film on the deposited first ZnSe film. The deposition rate of the first YbF3 film is 0.6 nm / s, and the thickness of the first YbF3 film is controlled to be 384 nm ± 5 nm. Ion source assisted deposition.

[0011] S7, a second ZnSe film is deposited on the first YbF3 film layer by vapor deposition. The deposition rate of the second ZnSe film layer is 0.8 nm / s, and the film thickness of the second ZnSe film layer is controlled to be 65 nm ± 3 nm. Ion source assisted vapor deposition.

[0012] S8, a second YbF3 film is deposited on the deposited second ZnSe film. The deposition rate of the second YbF3 film is 0.6 nm / s, and the film thickness of the second YbF3 film is controlled to be 219 nm ± 5 nm. Ion source assisted evaporation.

[0013] S9, a third ZnSe film is deposited on the deposited second YbF3 film. The deposition rate of the third ZnSe film is 0.8 nm / s, and the thickness of the third ZnSe film is controlled to be 135 nm ± 5 nm. Ion source assisted evaporation.

[0014] S10, deposit a third YbF3 film on the deposited third ZnSe film. The deposition rate of the third YbF3 film is 0.6 nm / s, and the thickness of the third YbF3 film is controlled to be 176 nm ± 5 nm. Ion source assisted deposition.

[0015] S11, a fourth ZnSe film is deposited on the deposited third YbF3 film. The deposition rate of the fourth ZnSe film is 0.8 nm / s, and the film thickness of the fourth ZnSe film is controlled to be 165.7 nm ± 5 nm. Ion source assisted evaporation.

[0016] S12, deposit a fourth YbF3 film on the deposited fourth ZnSe film. The deposition rate of the fourth YbF3 film is 0.6 nm / s, and the thickness of the fourth YbF3 film is controlled to be 93.2 nm ± 4 nm. Ion source assisted deposition.

[0017] S13, a fifth ZnSe film is deposited on the deposited fourth YbF3 film. The deposition rate of the fifth ZnSe film is 0.8 nm / s, and the film thickness of the fifth ZnSe film is controlled to be 169 nm ± 5 nm. Ion source assisted evaporation.

[0018] S14, deposit a fifth YbF3 film on the deposited fifth ZnSe film. The deposition rate of the fifth YbF3 film is 0.6 nm / s, and the thickness of the fifth YbF3 film is controlled to be 148 nm ± 4 nm. Ion source assisted evaporation.

[0019] S15, a sixth ZnSe film is deposited on the fifth YbF3 film. The deposition rate of the sixth ZnSe film is 0.8 nm / s, and the film thickness of the sixth ZnSe film is controlled to be 134.4 nm ± 5 nm. Ion source assisted evaporation.

[0020] S16, deposit a sixth YbF3 film on the deposited sixth ZnSe film. The deposition rate of the sixth YbF3 film is 0.6 nm / s, and the thickness of the sixth YbF3 film is controlled to be 152.7 nm ± 4 nm. Ion source assisted evaporation.

[0021] S17, deposit the first ZnS film on the deposited sixth YbF3 film layer. The deposition rate of the first ZnS film layer is 0.8 nm / s, and the film thickness of the first ZnS film layer is controlled to be 66.4 nm ± 3 nm. Ion source assisted evaporation.

[0022] S18, a seventh YbF3 film layer is deposited on the first ZnS film layer. The deposition rate of the seventh YbF3 film layer is 0.6 nm / s, and the film thickness of the seventh YbF3 film layer is controlled to be 342 nm ± 5 nm. Ion source assisted evaporation.

[0023] S19, a second ZnS film is deposited on the seventh YbF3 film layer. The deposition rate of the second ZnS film layer is 0.8 nm / s, and the film thickness of the second ZnS film layer is controlled to be 65 nm ± 3 nm. Ion source assisted evaporation.

[0024] S20, after the second ZnS film layer is deposited, wait for the cavity to cool to below 90-100℃ and then take out the lens with the first film layer deposited.

[0025] S21, the surface of the calcium fluoride substrate used as the first coated lens and the product are cleaned in preparation for the second coating.

[0026] S22, Place the cleaned lens into the fixture, and hang the fixture with the lens in it into the cavity of the vacuum coating machine. The temperature of the cavity is set to 180±1℃.

[0027] S23, the vacuum coating machine starts vacuuming, and the vacuum level reaches 1.5×10⁻⁶. -3 Pa, turn on the auxiliary coating ion source of the vacuum coating machine for cleaning. The cleaning time is 6 minutes. The anode voltage of the ion source is 220V, the anode current is 1.2-1.5A, and the emitter current is 1.3-1.5A.

[0028] S24, maintaining the aforementioned vacuum level, deposit a Y2O3 film on the second surface of the lens. The deposition rate of the Y2O3 film is 0.3 nm / s, and the thickness of the Y2O3 film is controlled to be 15 nm ± 1 nm. Ion source assisted deposition. After the Y2O3 film is deposited, the temperature of the cavity drops to 150 ± 1 °C.

[0029] S25, a first ZnSe film is deposited on the deposited Y2O3 film. The deposition rate of the first ZnSe film is 0.8 nm / s, and the thickness of the first ZnSe film is controlled to be 53 nm ± 2 nm. Ion source assisted evaporation.

[0030] S26, deposit a first YbF3 film on the deposited first ZnSe film. The deposition rate of the first YbF3 film is 0.6 nm / s, and the thickness of the first YbF3 film is controlled to be 286 nm ± 5 nm. Ion source assisted deposition.

[0031] S27, a second ZnSe film is deposited on the first YbF3 film layer by vapor deposition. The deposition rate of the second ZnSe film layer is 0.8 nm / s, and the film thickness of the second ZnSe film layer is controlled to be 193 nm ± 5 nm. Ion source assisted vapor deposition.

[0032] S28, a second YbF3 film is deposited on the deposited second ZnSe film. The deposition rate of the second YbF3 film is 0.6 nm / s, and the thickness of the second YbF3 film is controlled to be 112.5 nm ± 5 nm. Ion source assisted deposition.

[0033] S29, a third ZnSe film is deposited on the deposited second YbF3 film. The deposition rate of the third ZnSe film is 0.8 nm / s, and the thickness of the third ZnSe film is controlled to be 412 nm ± 5 nm. Ion source assisted evaporation.

[0034] S30, a third YbF3 film is deposited on the deposited third ZnSe film. The deposition rate of the third YbF3 film is 0.6 nm / s, and the thickness of the third YbF3 film is controlled to be 89.4 nm ± 4 nm. Ion source assisted evaporation.

[0035] S31, a first ZnS film is deposited on the deposited third YbF3 film. The deposition rate of the first ZnS film is 0.8 nm / s, and the thickness of the first ZnS film is controlled to be 238.4 nm ± 5 nm. Ion source assisted evaporation.

[0036] S32, a fourth YbF3 film layer is deposited on the first ZnS film layer. The deposition rate of the fourth YbF3 film layer is 0.6 nm / s, and the film thickness of the fourth YbF3 film layer is controlled to be 381.3 nm ± 5 nm. Ion source assisted evaporation.

[0037] S33, a second ZnS film is deposited on the deposited fourth YbF3 film. The deposition rate of the second ZnS film is 0.8 nm / s, and the thickness of the second ZnS film is controlled to be 60 nm ± 3 nm. Ion source assisted evaporation.

[0038] S34, after the second ZnS film is deposited, wait for the cavity to cool to below 90-100℃ and then take out the lens with the second film deposited.

[0039] The beneficial effects of this disclosure are as follows.

[0040] In the method for preparing a dual-band film system deposited on a calcium fluoride substrate disclosed herein, a Y₂O₃ film with a thickness of 15 nm ± 1 nm, a first ZnSe film with a thickness of 35 nm ± 2 nm, a first YbF₃ film with a thickness of 384 nm ± 5 nm, a second ZnSe film with a thickness of 65 nm ± 3 nm, a second YbF₃ film with a thickness of 219 nm ± 5 nm, a third ZnSe film with a thickness of 135 nm ± 5 nm, and a 17 nm thick film are deposited on the first surface of the calcium fluoride substrate used as a lens and the surface of the product. The following are examples of ZnS films: a third YbF3 film with a thickness of 6 nm ± 5 nm, a fourth ZnSe film with a thickness of 165.7 nm ± 5 nm, a fourth YbF3 film with a thickness of 93.2 nm ± 4 nm, a fifth ZnSe film with a thickness of 169 nm ± 5 nm, a fifth YbF3 film with a thickness of 148 nm ± 4 nm, a sixth ZnSe film with a thickness of 134.4 nm ± 5 nm, a sixth YbF3 film with a thickness of 152.7 nm ± 4 nm, a first ZnS film with a thickness of 66.4 nm ± 3 nm, and a third ZnS film with a thickness of 342 nm ± 5 nm. The film consists of 16 layers, including a 5nm thick seventh YbF3 layer and a 65nm±3nm thick second ZnS layer. On the second surface, there are also 15nm±1nm thick Y2O3 layers, a 53nm±2nm thick first ZnSe layer, a 286nm±5nm thick first YbF3 layer, a 193nm±5nm thick second ZnSe layer, a 112.5nm±5nm thick second YbF3 layer, a 412nm±5nm thick third ZnSe layer, and an 89.4nm thick layer. The substrate consists of 10 layers: a third YbF3 layer with a thickness of ±4 nm, a first ZnS layer with a thickness of 238.4 nm ± 5 nm, a fourth YbF3 layer with a thickness of 381.3 nm ± 5 nm, and a second ZnS layer with a thickness of 60 nm ± 3 nm. Based on the reflectance tests of the substrate in the 930-1050 nm laser band at a 45° angle and the 2-5 μm infrared band, the average reflectance in the 930-1050 nm laser band at a 45° angle is above 97%, while the average reflectance in the 2-5 μm infrared band is less than 6%. In other words, it exhibits high reflectance in the 930-1050 nm range and low reflectance in the 2-5 μm range. The calcium fluoride substrate, along with the films on both surfaces, meets the reflectance requirements for both upper and lower wavelengths. Attached Figure Description

[0041] Figure 1 This is a schematic diagram of the calcium fluoride substrate and the film layers on both sides, according to the method for preparing a dual-band film system deposited on a calcium fluoride substrate according to the present disclosure.

[0042] Figure 2 This is a graph showing the reflectance of the coated substrate in the 930-1050nm laser band at a 45° angle, after coating in Example 1.

[0043] Figure 3 This is a curve showing the reflectance of the coated substrate in the infrared 2-5μm region at a 45° laser angle after coating in Example 1.

[0044] Figure 4 This is a photograph of the coated substrate of Example 1 after a water immersion test.

[0045] Figure 5 This is a photograph of the coated substrate of Comparative Example 1 after a water immersion test.

[0046] Figure 6 This is a photograph of the coated substrate of Comparative Example 2 after a water immersion test. Detailed Implementation

[0047] The accompanying drawings illustrate embodiments of this disclosure, and it will be understood that the disclosed embodiments are merely examples of this disclosure, which can be implemented in various forms. Therefore, the specific details disclosed herein should not be construed as limiting, but are intended only as the basis for the claims and as an illustrative basis to teach those skilled in the art how to implement this disclosure in various ways.

[0048] [Preparation method of dual-band film system deposited on calcium fluoride substrate]

[0049] Reference Figure 1 The method for preparing a dual-band film system deposited on a calcium fluoride substrate according to this disclosure includes the following steps:

[0050] S1, the surface of the co-plating sheet, which serves as the calcium fluoride base for the lens, and the product are cleaned. The thickness of the co-plating sheet is 0.9-1.5mm.

[0051] S2, Place the cleaned lens into the fixture, and hang the fixture with the lens in it into the cavity of the vacuum coating machine. The temperature of the cavity is set to 180±1℃.

[0052] S3, the vacuum coating machine starts pumping vacuum, and the vacuum level reaches 1.5×10. -3Pa, turn on the auxiliary coating ion source of the vacuum coating machine for cleaning. The cleaning time is 6 minutes. The anode voltage of the ion source is 220V, the anode current is 1.2-1.5A, and the emitter current is 1.3-1.5A.

[0053] S4. Maintaining the aforementioned vacuum level, deposit a Y2O3 film on the first surface of the lens. The deposition rate of the Y2O3 film is 0.3 nm / s, and the thickness of the Y2O3 film is controlled to be 15 nm ± 1 nm. Ion source-assisted evaporation is used. After the Y2O3 film is deposited, the temperature of the cavity drops to 150 ± 1 °C.

[0054] S5, a first ZnSe film is deposited on the deposited Y2O3 film. The deposition rate of the first ZnSe film is 0.8 nm / s, and the thickness of the first ZnSe film is controlled to be 35 nm ± 2 nm. Ion source assisted evaporation.

[0055] S6, deposit a first YbF3 film on the deposited first ZnSe film. The deposition rate of the first YbF3 film is 0.6 nm / s, and the thickness of the first YbF3 film is controlled to be 384 nm ± 5 nm. Ion source assisted deposition.

[0056] S7, a second ZnSe film is deposited on the first YbF3 film layer by vapor deposition. The deposition rate of the second ZnSe film layer is 0.8 nm / s, and the film thickness of the second ZnSe film layer is controlled to be 65 nm ± 3 nm. Ion source assisted vapor deposition.

[0057] S8, a second YbF3 film is deposited on the deposited second ZnSe film. The deposition rate of the second YbF3 film is 0.6 nm / s, and the film thickness of the second YbF3 film is controlled to be 219 nm ± 5 nm. Ion source assisted evaporation.

[0058] S9, a third ZnSe film is deposited on the deposited second YbF3 film. The deposition rate of the third ZnSe film is 0.8 nm / s, and the thickness of the third ZnSe film is controlled to be 135 nm ± 5 nm. Ion source assisted evaporation.

[0059] S10, deposit a third YbF3 film on the deposited third ZnSe film. The deposition rate of the third YbF3 film is 0.6 nm / s, and the thickness of the third YbF3 film is controlled to be 176 nm ± 5 nm. Ion source assisted deposition.

[0060] S11, a fourth ZnSe film is deposited on the deposited third YbF3 film. The deposition rate of the fourth ZnSe film is 0.8 nm / s, and the film thickness of the fourth ZnSe film is controlled to be 165.7 nm ± 5 nm. Ion source assisted evaporation.

[0061] S12, deposit a fourth YbF3 film on the deposited fourth ZnSe film. The deposition rate of the fourth YbF3 film is 0.6 nm / s, and the thickness of the fourth YbF3 film is controlled to be 93.2 nm ± 4 nm. Ion source assisted deposition.

[0062] S13, a fifth ZnSe film is deposited on the deposited fourth YbF3 film. The deposition rate of the fifth ZnSe film is 0.8 nm / s, and the film thickness of the fifth ZnSe film is controlled to be 169 nm ± 5 nm. Ion source assisted evaporation.

[0063] S14, deposit a fifth YbF3 film on the deposited fifth ZnSe film. The deposition rate of the fifth YbF3 film is 0.6 nm / s, and the thickness of the fifth YbF3 film is controlled to be 148 nm ± 4 nm. Ion source assisted evaporation.

[0064] S15, a sixth ZnSe film is deposited on the fifth YbF3 film. The deposition rate of the sixth ZnSe film is 0.8 nm / s, and the film thickness of the sixth ZnSe film is controlled to be 134.4 nm ± 5 nm. Ion source assisted evaporation.

[0065] S16, deposit a sixth YbF3 film on the deposited sixth ZnSe film. The deposition rate of the sixth YbF3 film is 0.6 nm / s, and the thickness of the sixth YbF3 film is controlled to be 152.7 nm ± 4 nm. Ion source assisted evaporation.

[0066] S17, deposit the first ZnS film on the deposited sixth YbF3 film layer. The deposition rate of the first ZnS film layer is 0.8 nm / s, and the film thickness of the first ZnS film layer is controlled to be 66.4 nm ± 3 nm. Ion source assisted evaporation.

[0067] S18, a seventh YbF3 film layer is deposited on the first ZnS film layer. The deposition rate of the seventh YbF3 film layer is 0.6 nm / s, and the film thickness of the seventh YbF3 film layer is controlled to be 342 nm ± 5 nm. Ion source assisted evaporation.

[0068] S19, a second ZnS film is deposited on the seventh YbF3 film layer. The deposition rate of the second ZnS film layer is 0.8 nm / s, and the film thickness of the second ZnS film layer is controlled to be 65 nm ± 3 nm. Ion source assisted evaporation.

[0069] S20, after the second ZnS film layer is deposited, wait for the cavity to cool to below 90-100℃ and then take out the lens with the first film layer deposited.

[0070] S21, the surface of the calcium fluoride substrate used as the first coated lens and the product are cleaned in preparation for the second coating.

[0071] S22, Place the cleaned lens into the fixture, and hang the fixture with the lens in it into the cavity of the vacuum coating machine. The temperature of the cavity is set to 180±1℃.

[0072] S23, the vacuum coating machine starts vacuuming, and the vacuum level reaches 1.5×10⁻⁶. -3 Pa, turn on the auxiliary coating ion source of the vacuum coating machine for cleaning. The cleaning time is 6 minutes. The anode voltage of the ion source is 220V, the anode current is 1.2-1.5A, and the emitter current is 1.3-1.5A.

[0073] S24, maintaining the aforementioned vacuum level, deposit a Y2O3 film on the second surface of the lens. The deposition rate of the Y2O3 film is 0.3 nm / s, and the thickness of the Y2O3 film is controlled to be 15 nm ± 1 nm. Ion source assisted deposition. After the Y2O3 film is deposited, the temperature of the cavity drops to 150 ± 1 °C.

[0074] S25, a first ZnSe film is deposited on the deposited Y2O3 film. The deposition rate of the first ZnSe film is 0.8 nm / s, and the thickness of the first ZnSe film is controlled to be 53 nm ± 2 nm. Ion source assisted evaporation.

[0075] S26, deposit a first YbF3 film on the deposited first ZnSe film. The deposition rate of the first YbF3 film is 0.6 nm / s, and the thickness of the first YbF3 film is controlled to be 286 nm ± 5 nm. Ion source assisted deposition.

[0076] S27, a second ZnSe film is deposited on the first YbF3 film layer by vapor deposition. The deposition rate of the second ZnSe film layer is 0.8 nm / s, and the film thickness of the second ZnSe film layer is controlled to be 193 nm ± 5 nm. Ion source assisted vapor deposition.

[0077] S28, a second YbF3 film is deposited on the deposited second ZnSe film. The deposition rate of the second YbF3 film is 0.6 nm / s, and the thickness of the second YbF3 film is controlled to be 112.5 nm ± 5 nm. Ion source assisted deposition.

[0078] S29, a third ZnSe film is deposited on the deposited second YbF3 film. The deposition rate of the third ZnSe film is 0.8 nm / s, and the thickness of the third ZnSe film is controlled to be 412 nm ± 5 nm. Ion source assisted evaporation.

[0079] S30, a third YbF3 film is deposited on the deposited third ZnSe film. The deposition rate of the third YbF3 film is 0.6 nm / s, and the thickness of the third YbF3 film is controlled to be 89.4 nm ± 4 nm. Ion source assisted evaporation.

[0080] S31, a first ZnS film is deposited on the deposited third YbF3 film. The deposition rate of the first ZnS film is 0.8 nm / s, and the thickness of the first ZnS film is controlled to be 238.4 nm ± 5 nm. Ion source assisted evaporation.

[0081] S32, a fourth YbF3 film layer is deposited on the first ZnS film layer. The deposition rate of the fourth YbF3 film layer is 0.6 nm / s, and the film thickness of the fourth YbF3 film layer is controlled to be 381.3 nm ± 5 nm. Ion source assisted evaporation.

[0082] S33, a second ZnS film is deposited on the deposited fourth YbF3 film. The deposition rate of the second ZnS film is 0.8 nm / s, and the thickness of the second ZnS film is controlled to be 60 nm ± 3 nm. Ion source assisted evaporation.

[0083] S34, after the second ZnS film is deposited, wait for the cavity to cool to below 90-100℃ and then take out the lens with the second film deposited.

[0084] In the method for preparing a dual-band film system deposited on a calcium fluoride substrate disclosed herein, a Y₂O₃ film with a thickness of 15 nm ± 1 nm, a first ZnSe film with a thickness of 35 nm ± 2 nm, a first YbF₃ film with a thickness of 384 nm ± 5 nm, a second ZnSe film with a thickness of 65 nm ± 3 nm, a second YbF₃ film with a thickness of 219 nm ± 5 nm, a third ZnSe film with a thickness of 135 nm ± 5 nm, and a 17 nm thick film are deposited on the first surface of the calcium fluoride substrate used as a lens and the surface of the product. The following are examples of ZnS films: a third YbF3 film with a thickness of 6 nm ± 5 nm, a fourth ZnSe film with a thickness of 165.7 nm ± 5 nm, a fourth YbF3 film with a thickness of 93.2 nm ± 4 nm, a fifth ZnSe film with a thickness of 169 nm ± 5 nm, a fifth YbF3 film with a thickness of 148 nm ± 4 nm, a sixth ZnSe film with a thickness of 134.4 nm ± 5 nm, a sixth YbF3 film with a thickness of 152.7 nm ± 4 nm, a first ZnS film with a thickness of 66.4 nm ± 3 nm, and a third ZnS film with a thickness of 342 nm ± 5 nm. The film consists of 16 layers, including a 5nm thick seventh YbF3 layer and a 65nm±3nm thick second ZnS layer. On the second surface, there are also 15nm±1nm thick Y2O3 layers, a 53nm±2nm thick first ZnSe layer, a 286nm±5nm thick first YbF3 layer, a 193nm±5nm thick second ZnSe layer, a 112.5nm±5nm thick second YbF3 layer, a 412nm±5nm thick third ZnSe layer, and an 89.4nm thick layer. The substrate consists of 10 layers: a third YbF3 layer with a thickness of ±4 nm, a first ZnS layer with a thickness of 238.4 nm ± 5 nm, a fourth YbF3 layer with a thickness of 381.3 nm ± 5 nm, and a second ZnS layer with a thickness of 60 nm ± 3 nm. Based on the reflectance tests of the substrate in the 930-1050 nm laser band at a 45° angle and the 2-5 μm infrared band, the average reflectance in the 930-1050 nm laser band at a 45° angle is above 97%, while the average reflectance in the 2-5 μm infrared band is less than 6%. In other words, it exhibits high reflectance in the 930-1050 nm range and low reflectance in the 2-5 μm range. The calcium fluoride substrate, along with the films on both surfaces, meets the reflectance requirements for both upper and lower wavelengths.

[0085] In one example, in steps S1 and S21, the thickness of the plating sheet is 1.0 mm.

[0086] In one example, in steps S1 and S21, the lens surface is cleaned using ultrasound or by hand.

[0087] In one example, in steps S3 and S23, the anode current is 1.2A and the emitter current is 1.5A.

[0088] In one example, in steps S3 and S23, the ion source is a Hall ion source.

[0089] In one example, in step S4, the thickness of the Y2O3 film is controlled to be 15 nm; in step S5, the thickness of the first ZnSe film is controlled to be 35 nm; in step S6, the thickness of the first YbF3 film is controlled to be 384 nm; in step S7, the thickness of the second ZnSe film is controlled to be 65 nm; in step S8, the thickness of the second YbF3 film is controlled to be 219 nm; in step S9, the thickness of the third ZnSe film is controlled to be 135 nm; and in step S10, the thickness of the third YbF3 film is controlled to be 176 nm. In step S11, the thickness of the fourth ZnSe film is controlled to be 165.7 nm; in step S12, the thickness of the fourth YbF3 film is controlled to be 93.2 nm; in step S13, the thickness of the fifth ZnSe film is controlled to be 169 nm; in step S14, the thickness of the fifth YbF3 film is controlled to be 148 nm; in step S15, the thickness of the sixth ZnSe film is controlled to be 134.4 nm; in step S16, the thickness of the sixth YbF3 film is controlled to be 152.7 nm; in step S17, the thickness of the first ZnSe film is controlled to be 165.7 nm. The thickness of the first YbF3 film is 66.4 nm; in step S18, the thickness of the seventh YbF3 film is controlled to be 342 nm; in step S19, the thickness of the second ZnS film is controlled to be 65 nm; in step S20, the cavity is cooled to 60°C; in step S24, the thickness of the Y2O3 film is controlled to be 15 nm; in step S25, the thickness of the first ZnSe film is controlled to be 53 nm; in step S26, the thickness of the first YbF3 film is controlled to be 286 nm; in step S27, the thickness of the second ZnSe film is controlled to be 193 nm. m; In step S28, the thickness of the second YbF3 film is controlled to be 112.5 nm; In step S29, the thickness of the third ZnSe film is controlled to be 412 nm; In step S30, the thickness of the third YbF3 film is controlled to be 89.4 nm; In step S31, the thickness of the first ZnS film is controlled to be 238.4 nm; In step S32, the thickness of the fourth YbF3 film is controlled to be 381.3 nm; In step S33, the thickness of the second ZnS film is controlled to be 60 nm; In step S34, the cavity is cooled to 60°C.

[0090] In one example, in steps S4, S6, S8, S10, S12, S14, S16, S18, S24, S26, S28, S30, and S32, a neutralizer is provided for the ion source. The parameters of the neutralizer are: neutralization current of 0.5A, neutralizing gas is formed by argon, and the flow rate of the neutralizing gas is 10 sccm. The anode voltage of the ion source is 160V, the anode current is 1.6A, argon and oxygen are used as working gases, the flow rate of argon is 20 sccm, and the flow rate of oxygen is 80 sccm.

[0091] In one example, in steps S5, S7, S9, S11, S13, S15, S17, S19, S25, S27, S29, S31, and S33, a neutralizer is provided for the ion source. The parameters of the neutralizer are: neutralization current of 0.5A, neutralization gas is formed by argon, and the flow rate of the neutralization gas is 8 sccm. The anode voltage of the ion source is 120V, the anode current is 1.2A, argon is used as the working gas, and the flow rate of the argon gas is 100 sccm.

[0092] In one example, in steps S4 and S24, the vapor deposition is performed using electron beam evaporation; in steps S5 to S19 and steps S25 to S33, the vapor deposition is performed using resistance heating evaporation.

[0093] [test]

[0094] Example 1

[0095] The method for preparing a dual-band film system deposited on a calcium fluoride substrate comprises the following steps:

[0096] S1, the surface of the co-plating sheet, which serves as the calcium fluoride base for the lens, and the product are cleaned using ultrasonic cleaning. The thickness of the co-plating sheet is 1.0 mm.

[0097] S2, Place the cleaned lens into the fixture, and hang the fixture with the lens in it into the cavity of the vacuum coating machine. The temperature of the cavity is set to 180℃. The vacuum coating machine is a Hall ion source with a neutralizer manufactured and sold by Chengdu Xiwoke Vacuum Technology Co., Ltd. The Hall ion source with a neutralizer was purchased from Boton Optoelectronics Technology Co., Ltd.

[0098] S3, the vacuum coating machine starts pumping vacuum, and the vacuum level reaches 1.5×10. -3 Pa, turn on the ion source of the auxiliary coating of the vacuum coating machine for cleaning. The cleaning time is 6 minutes. The anode voltage of the ion source is 220V, the anode current is 1.2A, and the emitter current is 1.5A. Argon is used as the working gas.

[0099] S4. Maintaining the aforementioned vacuum level, deposit a Y2O3 film on the first surface of the lens. The deposition rate of the Y2O3 film is 0.3 nm / s, and the thickness of the Y2O3 film is controlled to be 15 nm. Ion source-assisted evaporation is used, and electron beam evaporation is employed. After the Y2O3 film is deposited, the temperature of the cavity is reduced to 150°C.

[0100] S5, a first ZnSe film is deposited on the deposited Y2O3 film. The deposition rate of the first ZnSe film is 0.8 nm / s, and the thickness of the first ZnSe film is controlled to be 35 nm. Ion source assisted evaporation is used, and resistance heating evaporation is employed for the evaporation.

[0101] S6, deposit a first YbF3 film on the deposited first ZnSe film. The deposition rate of the first YbF3 film is 0.6 nm / s, and the thickness of the first YbF3 film is controlled to be 384 nm. Ion source assisted evaporation is used, and resistance heating evaporation is employed.

[0102] S7, a second ZnSe film is deposited on the first YbF3 film layer by vapor deposition. The deposition rate of the second ZnSe film layer is 0.8 nm / s, and the film thickness of the second ZnSe film layer is controlled to be 65 nm. Ion source assisted vapor deposition is used, and resistance heating evaporation is employed for vapor deposition.

[0103] S8, a second YbF3 film is deposited on the deposited second ZnSe film. The deposition rate of the second YbF3 film is 0.6 nm / s, and the thickness of the second YbF3 film is controlled to be 219 nm. Ion source assisted evaporation is used, and resistance heating evaporation is employed.

[0104] S9, a third ZnSe film is deposited on the deposited second YbF3 film. The deposition rate of the third ZnSe film is 0.8 nm / s, and the film thickness of the third ZnSe film is controlled to be 135 nm. Ion source assisted evaporation is used, and resistance heating evaporation is used for evaporation.

[0105] S10, a third YbF3 film is deposited on the deposited third ZnSe film. The deposition rate of the third YbF3 film is 0.6 nm / s, and the thickness of the third YbF3 film is controlled to be 176 nm. Ion source assisted evaporation is used, and resistance heating evaporation is employed.

[0106] S11, a fourth ZnSe film is deposited on the deposited third YbF3 film. The deposition rate of the fourth ZnSe film is 0.8 nm / s, and the film thickness of the fourth ZnSe film is controlled to be 165.7 nm. Ion source assisted evaporation is used, and resistance heating evaporation is used for evaporation.

[0107] S12, a fourth YbF3 film is deposited on the deposited fourth ZnSe film. The deposition rate of the fourth YbF3 film is 0.6 nm / s, and the thickness of the fourth YbF3 film is controlled to be 93.2 nm. Ion source assisted evaporation is used, and resistance heating evaporation is employed.

[0108] S13, a fifth ZnSe film is deposited on the fourth YbF3 film. The deposition rate of the fifth ZnSe film is 0.8 nm / s, and the film thickness of the fifth ZnSe film is controlled to be 169 nm. Ion source assisted evaporation is used, and resistance heating evaporation is used for evaporation.

[0109] S14, deposit a fifth YbF3 film on the deposited fifth ZnSe film. The deposition rate of the fifth YbF3 film is 0.6 nm / s, and the thickness of the fifth YbF3 film is controlled to be 148 nm. Ion source assisted evaporation and resistance heating evaporation are used for evaporation.

[0110] S15, a sixth ZnSe film is deposited on the fifth YbF3 film. The deposition rate of the sixth ZnSe film is 0.8 nm / s, and the film thickness of the sixth ZnSe film is controlled to be 134.4 nm. Ion source assisted evaporation is used, and resistance heating evaporation is used for evaporation.

[0111] S16, a sixth YbF3 film layer is deposited on the deposited sixth ZnSe film layer. The deposition rate of the sixth YbF3 film layer is 0.6 nm / s, and the film thickness of the sixth YbF3 film layer is controlled to be 152.7 nm. Ion source assisted evaporation is used, and resistance heating evaporation is used for evaporation.

[0112] S17, the first ZnS film layer is deposited on the deposited sixth YbF3 film layer. The deposition rate of the first ZnS film layer is 0.8 nm / s, and the film thickness of the first ZnS film layer is controlled to be 66.4 nm. Ion source assisted evaporation is used, and resistance heating evaporation is used for evaporation.

[0113] S18, a seventh YbF3 film layer is deposited on the first ZnS film layer. The deposition rate of the seventh YbF3 film layer is 0.6 nm / s, and the film thickness of the seventh YbF3 film layer is controlled to be 342 nm. Ion source assisted evaporation and resistance heating evaporation are used for evaporation.

[0114] S19, a second ZnS film layer is deposited on the seventh YbF3 film layer. The deposition rate of the second ZnS film layer is 0.8 nm / s, and the film thickness of the second ZnS film layer is controlled to be 65 nm. Ion source assisted evaporation is used, and resistance heating evaporation is employed for the evaporation.

[0115] S20, after the second ZnS film layer is deposited, wait for the cavity to cool to 60°C and then take out the lens with the first film layer deposited.

[0116] S21, the surface of the calcium fluoride substrate used as the first coated lens and the product are cleaned in preparation for the second coating.

[0117] S22, Place the cleaned lens into the fixture, and hang the fixture with the lens in it into the cavity of the vacuum coating machine. The temperature of the cavity is set to 180℃.

[0118] S23, the vacuum coating machine starts vacuuming, and the vacuum level reaches 1.5×10⁻⁶. -3 Pa, turn on the ion source of the auxiliary coating of the vacuum coating machine for cleaning. The cleaning time is 6 minutes. The anode voltage of the ion source is 220V, the anode current is 1.2A, and the emitter current is 1.5A. Argon is used as the working gas.

[0119] S24, maintaining the aforementioned vacuum level, deposit a Y2O3 film on the second surface of the lens. The deposition rate of the Y2O3 film is 0.3 nm / s, and the thickness of the Y2O3 film is controlled to be 15 nm ± 1 nm. Ion source assisted evaporation is used, and electron beam evaporation is employed. After the Y2O3 film is deposited, the temperature of the cavity is reduced to 150°C.

[0120] S25, a first ZnSe film layer is deposited on the deposited Y2O3 film layer. The deposition rate of the first ZnSe film layer is 0.8 nm / s, and the film thickness of the first ZnSe film layer is controlled to be 53 nm. Ion source assisted evaporation is used, and resistance heating evaporation is employed for the evaporation.

[0121] S26, deposit a first YbF3 film on the deposited first ZnSe film. The deposition rate of the first YbF3 film is 0.6 nm / s, and the thickness of the first YbF3 film is controlled to be 286 nm. Ion source assisted evaporation is used, and resistance heating evaporation is employed for the evaporation.

[0122] S27, a second ZnSe film is deposited on the first YbF3 film layer. The deposition rate of the second ZnSe film layer is 0.8 nm / s, and the film thickness of the second ZnSe film layer is controlled to be 193 nm. Ion source assisted evaporation is used, and resistance heating evaporation is employed for the evaporation.

[0123] S28, a second YbF3 film layer is deposited on the deposited second ZnSe film layer. The deposition rate of the second YbF3 film layer is 0.6 nm / s, and the film thickness of the second YbF3 film layer is controlled to be 112.5 nm. Ion source assisted evaporation is used, and resistance heating evaporation is used for evaporation.

[0124] S29, a third ZnSe film is deposited on the deposited second YbF3 film. The deposition rate of the third ZnSe film is 0.8 nm / s, and the film thickness of the third ZnSe film is controlled to be 412 nm. Ion source assisted evaporation is used, and resistance heating evaporation is used for evaporation.

[0125] S30, a third YbF3 film is deposited on the deposited third ZnSe film. The deposition rate of the third YbF3 film is 0.6 nm / s, and the thickness of the third YbF3 film is controlled to be 89.4 nm. Ion source assisted evaporation is used, and resistance heating evaporation is used for evaporation.

[0126] S31, a first ZnS film is deposited on the deposited third YbF3 film. The deposition rate of the first ZnS film is 0.8 nm / s, and the thickness of the first ZnS film is controlled to be 238.4 nm. Ion source assisted evaporation is used, and resistance heating evaporation is employed.

[0127] S32, a fourth YbF3 film layer is deposited on the first ZnS film layer. The deposition rate of the fourth YbF3 film layer is 0.6 nm / s, and the film thickness of the fourth YbF3 film layer is controlled to be 381.3 nm. Ion source assisted evaporation and resistance heating evaporation is used for evaporation.

[0128] S33, a second ZnS film is deposited on the deposited fourth YbF3 film. The deposition rate of the second ZnS film is 0.8 nm / s, and the thickness of the second ZnS film is controlled to be 60 nm. Ion source assisted evaporation is used, and resistance heating evaporation is employed.

[0129] S34, After the second ZnS film layer is deposited, wait for the cavity to cool to 60°C and then take out the lens with the second film layer deposited.

[0130] in,

[0131] In steps S4, S6, S8, S10, S12, S14, S16, S18, S24, S26, S28, S30, and S32, a neutralizer is provided for the ion source. The parameters of the neutralizer are: neutralization current of 0.5A, neutralization gas is formed by argon, and the flow rate of the neutralization gas is 10 sccm. The anode voltage of the ion source is 160V, the anode current is 1.6A, argon and oxygen are used as working gases, the flow rate of argon is 20 sccm, and the flow rate of oxygen is 80 sccm.

[0132] In steps S5, S7, S9, S11, S13, S15, S17, S19, S25, S27, S29, S31, and S33, a neutralizer is provided for the ion source. The parameters of the neutralizer are: neutralization current of 0.5A, neutralization gas is generated by argon, and the flow rate of the neutralization gas is 8 sccm. The anode voltage of the ion source is 120V, the anode current is 1.2A, argon is used as the working gas, and the flow rate of the argon gas is 100 sccm.

[0133] Comparative Example 1

[0134] Except for the cavity temperature being set to 150°C in steps S2 and S22, the rest is the same as in Example 1. That is, in Comparative Example 1, the cavity temperature remains unchanged from step S2 to step S4, and the cavity temperature remains unchanged from step S22 to step S24.

[0135] Comparative Example 2

[0136] Except for replacing Y2O3 with ZnS in steps S4 and S24, using resistance heating for evaporation, and changing the deposition rate to 0.8 nm / s, everything else is the same as in Example 1. That is, in Comparative Example 2, the layer directly adjacent to the calcium fluoride substrate is changed.

[0137] Figure 2 This is a graph showing the reflectance of the coated substrate in the 930-1050nm laser band at a 45° angle, after coating in Example 1. Figure 3 This is a graph showing the reflectance of the coated substrate of Example 1 in the 2-5μm infrared band at a 45° laser angle. The reflectance of the coated substrate of Example 1 was tested in the 930-1050nm laser band at a 45° angle and the 2-5μm infrared band. The average reflectance in the 930-1050nm laser band at a 45° angle was above 97%, while the average reflectance in the 2-5μm infrared band was less than 6%. In other words, it exhibits high reflectance in the 930-1050nm range and low reflectance in the 2-5μm range, meaning the calcium fluoride substrate and the coating systems on both surfaces meet the reflectance requirements for both bands.

[0138] Figure 4 This is a photograph of the coated substrate of Example 1 after a water immersion test. Figure 5 This is a photograph of the coated substrate of Comparative Example 1 after a water immersion test. Figure 6 This is a photograph of the coated substrate of Comparative Example 2 after a water immersion test. The coated substrates prepared in Example 1, Comparative Example 1, and Comparative Example 2, along with the film systems coated on both sides, were subjected to a water immersion test using tap water for 10 minutes. The film system of the coated substrate in Example 1 did not show any film detachment, while the film systems of Comparative Example 1 and Comparative Example 2 showed film detachment.

[0139] Several exemplary embodiments have been described in detail above, but this document is not intended to limit itself to the explicitly disclosed combinations. Therefore, unless otherwise stated, the various features disclosed herein can be combined to form several other combinations, which are not shown for simplicity.

Claims

1. A method for preparing a dual-band film system deposited on a calcium fluoride substrate, characterized in that, Including the following steps: S1, the surface of the co-plating sheet, which serves as the calcium fluoride base for the lens, and the product are cleaned. The thickness of the co-plating sheet is 0.9-1.5mm. S2, Place the cleaned lens into the fixture, and hang the fixture with the lens in it into the cavity of the vacuum coating machine. The temperature of the cavity is set to 180±1℃. S3, the vacuum coating machine starts pumping vacuum, and the vacuum level reaches 1.5×10. -3 Pa, turn on the auxiliary coating ion source of the vacuum coating machine for cleaning. The cleaning time is 6 minutes. The anode voltage of the ion source is 220V, the anode current is 1.2-1.5A, and the emitter current is 1.3-1.5A. S4. Maintaining the aforementioned vacuum level, deposit a Y2O3 film on the first surface of the lens. The deposition rate of the Y2O3 film is 0.3 nm / s, and the thickness of the Y2O3 film is controlled to be 15 nm ± 1 nm. Ion source-assisted evaporation is used. After the Y2O3 film is deposited, the temperature of the cavity drops to 150 ± 1 °C. S5, deposit a first ZnSe film on the deposited Y2O3 film. The deposition rate of the first ZnSe film is 0.8 nm / s, and the thickness of the first ZnSe film is controlled to be 35 nm ± 2 nm. Ion source assisted evaporation. S6, deposit a first YbF3 film on the deposited first ZnSe film. The deposition rate of the first YbF3 film is 0.6 nm / s, and the thickness of the first YbF3 film is controlled to be 384 nm ± 5 nm. Ion source assisted deposition. S7, a second ZnSe film is deposited on the first YbF3 film layer by vapor deposition. The deposition rate of the second ZnSe film layer is 0.8 nm / s, and the film thickness of the second ZnSe film layer is controlled to be 65 nm ± 3 nm. Ion source assisted vapor deposition. S8, a second YbF3 film is deposited on the deposited second ZnSe film. The deposition rate of the second YbF3 film is 0.6 nm / s, and the film thickness of the second YbF3 film is controlled to be 219 nm ± 5 nm. Ion source assisted evaporation. S9, a third ZnSe film is deposited on the deposited second YbF3 film. The deposition rate of the third ZnSe film is 0.8 nm / s, and the thickness of the third ZnSe film is controlled to be 135 nm ± 5 nm. Ion source assisted evaporation. S10, deposit a third YbF3 film on the deposited third ZnSe film. The deposition rate of the third YbF3 film is 0.6 nm / s, and the thickness of the third YbF3 film is controlled to be 176 nm ± 5 nm. Ion source assisted deposition. S11, a fourth ZnSe film is deposited on the deposited third YbF3 film. The deposition rate of the fourth ZnSe film is 0.8 nm / s, and the film thickness of the fourth ZnSe film is controlled to be 165.7 nm ± 5 nm. Ion source assisted evaporation. S12, deposit a fourth YbF3 film on the deposited fourth ZnSe film. The deposition rate of the fourth YbF3 film is 0.6 nm / s, and the thickness of the fourth YbF3 film is controlled to be 93.2 nm ± 4 nm. Ion source assisted deposition. S13, a fifth ZnSe film is deposited on the deposited fourth YbF3 film. The deposition rate of the fifth ZnSe film is 0.8 nm / s, and the film thickness of the fifth ZnSe film is controlled to be 169 nm ± 5 nm. Ion source assisted evaporation. S14, deposit a fifth YbF3 film on the deposited fifth ZnSe film. The deposition rate of the fifth YbF3 film is 0.6 nm / s, and the thickness of the fifth YbF3 film is controlled to be 148 nm ± 4 nm. Ion source assisted evaporation. S15, a sixth ZnSe film is deposited on the fifth YbF3 film. The deposition rate of the sixth ZnSe film is 0.8 nm / s, and the film thickness of the sixth ZnSe film is controlled to be 134.4 nm ± 5 nm. Ion source assisted evaporation. S16, deposit a sixth YbF3 film on the deposited sixth ZnSe film. The deposition rate of the sixth YbF3 film is 0.6 nm / s, and the thickness of the sixth YbF3 film is controlled to be 152.7 nm ± 4 nm. Ion source assisted evaporation. S17, deposit the first ZnS film on the deposited sixth YbF3 film layer. The deposition rate of the first ZnS film layer is 0.8 nm / s, and the film thickness of the first ZnS film layer is controlled to be 66.4 nm ± 3 nm. Ion source assisted evaporation. S18, a seventh YbF3 film layer is deposited on the first ZnS film layer. The deposition rate of the seventh YbF3 film layer is 0.6 nm / s, and the film thickness of the seventh YbF3 film layer is controlled to be 342 nm ± 5 nm. Ion source assisted evaporation. S19, a second ZnS film is deposited on the seventh YbF3 film layer. The deposition rate of the second ZnS film layer is 0.8 nm / s, and the film thickness of the second ZnS film layer is controlled to be 65 nm ± 3 nm. Ion source assisted evaporation. S20, after the second ZnS film layer is deposited, wait for the cavity to cool to below 100°C and then take out the lens with the first film layer deposited. S21, the surface of the calcium fluoride substrate used as the first coated lens and the product are cleaned in preparation for the second coating. S22, Place the cleaned lens into the fixture, and hang the fixture with the lens in it into the cavity of the vacuum coating machine. The temperature of the cavity is set to 180±1℃. S23, the vacuum coating machine starts vacuuming, and the vacuum level reaches 1.5×10⁻⁶. -3 Pa, turn on the auxiliary coating ion source of the vacuum coating machine for cleaning. The cleaning time is 6 minutes. The anode voltage of the ion source is 220V, the anode current is 1.2-1.5A, and the emitter current is 1.3-1.5A. S24, maintaining the aforementioned vacuum level, deposit a Y2O3 film on the second surface of the lens. The deposition rate of the Y2O3 film is 0.3 nm / s, and the thickness of the Y2O3 film is controlled to be 15 nm ± 1 nm. Ion source assisted deposition. After the Y2O3 film is deposited, the temperature of the cavity drops to 150 ± 1 °C. S25, a first ZnSe film is deposited on the deposited Y2O3 film. The deposition rate of the first ZnSe film is 0.8 nm / s, and the thickness of the first ZnSe film is controlled to be 53 nm ± 2 nm. Ion source assisted evaporation. S26, deposit a first YbF3 film on the deposited first ZnSe film. The deposition rate of the first YbF3 film is 0.6 nm / s, and the thickness of the first YbF3 film is controlled to be 286 nm ± 5 nm. Ion source assisted deposition. S27, a second ZnSe film is deposited on the first YbF3 film layer by vapor deposition. The deposition rate of the second ZnSe film layer is 0.8 nm / s, and the film thickness of the second ZnSe film layer is controlled to be 193 nm ± 5 nm. Ion source assisted vapor deposition. S28, a second YbF3 film is deposited on the deposited second ZnSe film. The deposition rate of the second YbF3 film is 0.6 nm / s, and the thickness of the second YbF3 film is controlled to be 112.5 nm ± 5 nm. Ion source assisted deposition. S29, a third ZnSe film is deposited on the deposited second YbF3 film. The deposition rate of the third ZnSe film is 0.8 nm / s, and the thickness of the third ZnSe film is controlled to be 412 nm ± 5 nm. Ion source assisted evaporation. S30, a third YbF3 film is deposited on the deposited third ZnSe film. The deposition rate of the third YbF3 film is 0.6 nm / s, and the thickness of the third YbF3 film is controlled to be 89.4 nm ± 4 nm. Ion source assisted evaporation. S31, a first ZnS film is deposited on the deposited third YbF3 film. The deposition rate of the first ZnS film is 0.8 nm / s, and the thickness of the first ZnS film is controlled to be 238.4 nm ± 5 nm. Ion source assisted evaporation. S32, a fourth YbF3 film layer is deposited on the first ZnS film layer. The deposition rate of the fourth YbF3 film layer is 0.6 nm / s, and the film thickness of the fourth YbF3 film layer is controlled to be 381.3 nm ± 5 nm. Ion source assisted evaporation. S33, a second ZnS film is deposited on the deposited fourth YbF3 film. The deposition rate of the second ZnS film is 0.8 nm / s, and the thickness of the second ZnS film is controlled to be 60 nm ± 3 nm. Ion source assisted evaporation. S34, after the second ZnS film layer is deposited, wait for the cavity to cool to below 100°C and then take out the lens with the second film layer deposited.

2. The method for preparing a dual-band film system deposited on a calcium fluoride substrate according to claim 1, characterized in that, In steps S1 and S21, the thickness of the substrate is 1.0 mm.

3. The method for preparing a dual-band film system deposited on a calcium fluoride substrate according to claim 1, characterized in that, In steps S1 and S21, the lens surface is cleaned using ultrasonic waves or by hand.

4. The method for preparing a dual-band film system deposited on a calcium fluoride substrate according to claim 1, characterized in that, In steps S3 and S23, the anode current is 1.2A and the emitter current is 1.5A.

5. The method for preparing a dual-band film system deposited on a calcium fluoride substrate according to claim 1, characterized in that, In steps S3 and S23, the ion source is a Hall ion source.

6. The method for preparing a dual-band film system deposited on a calcium fluoride substrate according to claim 1, characterized in that, In step S4, the thickness of the Y2O3 film is controlled to be 15 nm; In step S5, the thickness of the first ZnSe film is controlled to be 35 nm; In step S6, the thickness of the first YbF3 film is controlled to be 384 nm; In step S7, the thickness of the second ZnSe film is controlled to be 65 nm; In step S8, the thickness of the second YbF3 film is controlled to be 219 nm; In step S9, the thickness of the third ZnSe film is controlled to be 135 nm; In step S10, the thickness of the third YbF3 film is controlled to be 176 nm; In step S11, the thickness of the fourth ZnSe film is controlled to be 165.7 nm; In step S12, the thickness of the fourth YbF3 film is controlled to be 93.2 nm; In step S13, the thickness of the fifth ZnSe film is controlled to be 169 nm; In step S14, the thickness of the fifth YbF3 film is controlled to be 148 nm; In step S15, the thickness of the sixth ZnSe film is controlled to be 134.4 nm; In step S16, the thickness of the sixth YbF3 film is controlled to be 152.7 nm; In step S17, the thickness of the first ZnS film is controlled to be 66.4 nm; In step S18, the thickness of the seventh YbF3 film is controlled to be 342 nm; In step S19, the thickness of the second ZnS film is controlled to be 65 nm; In step S20, the cavity is cooled to 60°C; In step S24, the thickness of the Y2O3 film is controlled to be 15 nm; In step S25, the thickness of the first ZnSe film is controlled to be 53 nm; In step S26, the thickness of the first YbF3 film is controlled to be 286 nm; In step S27, the thickness of the second ZnSe film is controlled to be 193 nm; In step S28, the thickness of the second YbF3 film is controlled to be 112.5 nm; In step S29, the thickness of the third ZnSe film is controlled to be 412 nm; In step S30, the thickness of the third YbF3 film is controlled to be 89.4 nm; In step S31, the thickness of the first ZnS film is controlled to be 238.4 nm; In step S32, the thickness of the fourth YbF3 film is controlled to be 381.3 nm; In step S33, the thickness of the second ZnS film is controlled to be 60 nm; In step S34, the cavity is cooled to 60°C.

7. The method for preparing a dual-band film system deposited on a calcium fluoride substrate according to claim 1, characterized in that, In steps S4, S6, S8, S10, S12, S14, S16, S18, S24, S26, S28, S30, and S32, a neutralizer is provided for the ion source. The parameters of the neutralizer are: neutralization current of 0.5A, neutralization gas is formed by argon, and the flow rate of the neutralization gas is 10 sccm. The anode voltage of the ion source is 160V, the anode current is 1.6A, and argon and oxygen are used as working gases, with an argon flow rate of 20 sccm and an oxygen flow rate of 80 sccm.

8. The method for preparing a dual-band film system deposited on a calcium fluoride substrate according to claim 1, characterized in that, In steps S5, S7, S9, S11, S13, S15, S17, S19, S25, S27, S29, S31, and S33, a neutralizer is provided for the ion source. The parameters of the neutralizer are: neutralization current of 0.5A, neutralization gas is generated by argon, and the flow rate of the neutralization gas is 8 sccm. The anode voltage of the ion source is 120V, the anode current is 1.2A, argon is used as the working gas, and the flow rate of the argon gas is 100 sccm.

9. The method for preparing a dual-band film system deposited on a calcium fluoride substrate according to claim 1, characterized in that, In steps S4 and S24, electron beam evaporation is used for vapor deposition; In steps S5 to S19 and steps S25 to S33, the vapor deposition is performed using resistance heating evaporation.

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