Dual-bandpass filter and method for making the same

Abstract

The present invention discloses a dual-bandpass filter and a manufacturing method thereof, wherein the dual-bandpass filter comprises a film system structure satisfying a λ / 4 periodic symmetry (0.5HL0.5H) S and (0.5LH0.5L) S , where λ is the central wavelength, H is the λ / 4 layer of germanium, L is the λ / 4 layer of zinc sulfide, and S is the period number. The dual-bandpass filter of the present invention has a film system structure that satisfies the λ / 4 periodic symmetry (0.5HL0.5H) S and (0.5LH0.5L) S , germanium and zinc sulfide are selected as the coating materials to form a dual-bandpass filter, so that only one filter can be used to achieve high transmittance in two specific bands, and the remaining bands are cut off. In the gas infrared detection system, two absorption peaks of the same gas or absorption peaks of different gases can be detected at the same time, effectively improving the sensitivity of the system.

Description

Technical Field

[0001] The invention belongs to the technical field of optical coating, and in particular relates to a dual-bandpass filter and a manufacturing method thereof. Background Art

[0002] With the development of infrared detection technology, the application of gas infrared thermal imaging detection technology in the field of gas detection is becoming more and more extensive. Infrared filter is one of the core components of gas infrared detection system. Its filtering performance plays a huge role in the detection system and is the key to determine the detection effect.

[0003] However, in the field of gas infrared thermal imaging detection, the existing methane gas infrared thermal imaging detection system can only detect a single infrared characteristic absorption peak of methane, and there is also interference from other gas absorption peaks. Summary of the invention

[0004] In order to solve the above problems, the present invention provides a dual-bandpass filter, which can achieve high transmittance in two specific bands with only one filter and cut off the remaining bands. In the gas infrared detection system, two absorption peaks of the same gas or absorption peaks of different gases can be detected simultaneously, effectively improving the sensitivity of the system.

[0005] Another object of the present invention is to provide a method for manufacturing a dual-bandpass filter.

[0006] The technical solution adopted by the present invention is:

[0007] A dual-bandpass filter, the film structure is a film system that satisfies the λ / 4 periodic symmetry (0.5HL0.5H) S and (0.5LH0.5L) S , where λ is the central wavelength, H is the λ / 4 layer of germanium, L is the λ / 4 layer of zinc sulfide, and S is the period number.

[0008] Preferably, the film system of the front surface film layer adopts:

[0009] G / 0.63(0.5HL0.5H) 12 (0.5HL0.5H) 12 3.08(0.5LH0.5L) 12 / Air;

[0010] Among them, G is single crystal silicon, H is a λ / 4 layer of germanium, L is a λ / 4 layer of zinc sulfide, and Air is air.

[0011] Preferably, the film system of the rear surface film layer adopts:

[0012] G / 4H(0.5HL0.5H) 18 / Air;

[0013] Among them, G is single crystal silicon, H is a λ / 4 layer of germanium, L is a λ / 4 layer of zinc sulfide, and Air is air.

[0014] Preferably, it comprises a substrate, a front surface film layer and a rear surface film layer, wherein the substrate is located between the front surface film layer and the rear surface film layer, and the front surface film layer and the rear surface film layer are both coated with germanium and zinc sulfide;

[0015] The film layer adjacent to the substrate is the first layer, the first layer of the front surface film layer is a zinc sulfide film layer, the last layer is a zinc sulfide film layer, the even-numbered layers are all germanium film layers, and the odd-numbered layers are all zinc sulfide film layers; the first layer of the rear surface film layer is a zinc sulfide film layer, the last layer is a zinc sulfide film layer, the even-numbered layers are all germanium film layers, and the odd-numbered layers are all zinc sulfide film layers.

[0016] Preferably, the substrate is one of single crystal silicon, germanium and calcium fluoride.

[0017] Preferably, the central wavelength includes a combination of a mid-wave infrared band and a far-wave infrared band.

[0018] Another technical solution of the present invention is achieved in this way:

[0019] A method for manufacturing the dual-bandpass filter comprises the following steps:

[0020] S1, using ultrasonic cleaning substrate;

[0021] S2, placing the substrate, germanium film material particles and zinc sulfide film material particles into a vacuum chamber and evacuating the chamber, without baking during the coating process;

[0022] S3, vacuum pumped to 8.0×10 -3 Pa, pre-melting the germanium film material particles and the zinc sulfide film material particles to obtain pre-melted germanium and zinc sulfide;

[0023] S4, vacuum pumped to 1.5×10 -3 Pa, bombarding the surface of the substrate with an ion source for 20-30 minutes to obtain a bombarded substrate;

[0024] S5, at a vacuum degree of 1.0×10 -2 Pa, using a zinc sulfide ion source assisted deposition technique to plate a first zinc sulfide film layer on the front surface of the bombarded substrate obtained in S4, to obtain a substrate having the first zinc sulfide film layer on the front surface;

[0025] S6, at a vacuum degree of 1.0×10 -2Pa, using a germanium ion source assisted deposition technique to plate a second germanium film layer on the front surface of the substrate having the first zinc sulfide film layer on the front surface obtained in S5, to obtain a substrate having the second germanium film layer on the front surface;

[0026] S7, repeating S5 and S6 in sequence to plate the 3rd to 73rd film layers on the front surface;

[0027] S8, cooling the filter with the 73-layer film on the front surface in a vacuum chamber for 1-2 hours and then taking it out;

[0028] S9, repeat S1-S6 to complete the plating of 49 layers of film layers on the rear surface film layer;

[0029] S10. After plating, cool for 1-2 hours and then take it out.

[0030] Preferably, in S3-S6, the ion-assisted deposition is specifically: bombarding the film material with an electron gun while bombarding the deposited ions on the surface of the substrate with an ion beam; and determining the thickness of the film layer with a quartz crystal monitoring method.

[0031] Preferably, the method further comprises: verifying the adhesion of the plated dual-bandpass filter.

[0032] Preferably, the adhesion verification of the dual-bandpass filter includes: a Begla film test, first boiling in water for 2 hours, then immersing in water for 72 hours, and then performing a hot and cold cycle test and a salt spray test. If the dual-bandpass filter does not delaminate, it means that the film layer is not damaged.

[0033] Compared with the prior art, the dual-bandpass filter of the present invention has a film system structure that satisfies the λ / 4 periodic symmetry (0.5HL0.5H) S and (0.5LH0.5L) S , germanium and zinc sulfide are selected as coating materials to form a dual-bandpass filter, so that only one filter can be used to achieve high transmittance in two specific bands, and the remaining bands are cut off. In the gas infrared detection system, two absorption peaks of the same gas or absorption peaks of different gases can be detected at the same time, effectively improving the sensitivity of the system. It can also be used in security monitoring, machine vision inspection, intelligent transportation, drone monitoring and other fields. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 is a schematic structural diagram of a dual-bandpass filter provided by Example 1 of the present invention;

[0035] Figure 2 is a spectral transmittance curve of a front surface film layer of a method for manufacturing a dual-bandpass filter provided in Example 2 of the present invention;

[0036] Figure 3is a spectral transmittance curve of a rear surface film layer of a method for manufacturing a dual-bandpass filter provided in Example 2 of the present invention;

[0037] Figure 4 It is a spectral transmittance curve of a 3.43 μm and 6.53 μm dual-bandpass filter according to a method for manufacturing a dual-bandpass filter provided in Example 2 of the present invention.

[0038] Description of Reference Numerals

[0039] 1-substrate, 2-front surface film layer, 3-back surface film layer. DETAILED DESCRIPTION

[0040] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0041] Example 1

[0042] Embodiment 1 of the present invention provides a dual-bandpass filter, such as Figure 1 As shown, the film system structure satisfies the λ / 4 periodic symmetry (0.5HL0.5H) S and (0.5LH0.5L) S , where λ is the central wavelength, H is the λ / 4 layer of germanium, L is the λ / 4 layer of zinc sulfide, and S is the period number;

[0043] It includes a substrate 1, a front surface film layer 2 and a rear surface film layer 3, wherein the substrate 1 is located between the front surface film layer 2 and the rear surface film layer 3, and the front surface film layer 2 and the rear surface film layer 3 are both coated with germanium and zinc sulfide;

[0044] The film layer adjacent to the substrate 1 is the first layer, the first layer of the front surface film layer 2 is a zinc sulfide film layer, the last layer is a zinc sulfide film layer, the even-numbered layers are all germanium film layers, and the odd-numbered layers are all zinc sulfide film layers; the first layer of the rear surface film layer 3 is a zinc sulfide film layer, the last layer is a zinc sulfide film layer, the even-numbered layers are all germanium film layers, and the odd-numbered layers are all zinc sulfide film layers.

[0045] In this way, the film system structure satisfies the λ / 4 periodic symmetry (0.5HL0.5H) S and (0.5LH0.5L) S, germanium and zinc sulfide are selected as coating materials, and a dual-bandpass filter is composed of a substrate, a front surface film layer and a rear surface film layer, so that only one filter can be used to achieve high transmittance in two specific bands, and the remaining bands are cut off. In the gas infrared detection system, two absorption peaks of the same gas or absorption peaks of different gases can be detected simultaneously, effectively improving the sensitivity of the system. The dual-bandpass filter of the present invention has a central wavelength of 3.43μm and 6.53μm, a peak transmittance Tp≥75%, a bandwidth of 120±20nm and 200±30nm, 0.4-10μm (except the passband), Tavg<0.5%, and can be used for methane gas detection.

[0046] The film system of the front surface film layer 2 adopts:

[0047] G / 0.63(0.5HL0.5H) 12 (0.5HL0.5H) 12 3.08(0.5LH0.5L) 12 / Air;

[0048] Among them, G is single crystal silicon, H is a λ / 4 layer of germanium, L is a λ / 4 layer of zinc sulfide, and Air is air.

[0049] The film system of the rear surface film layer 3 is:

[0050] G / 4H(0.5HL0.5H) 18 / Air;

[0051] Among them, G is single crystal silicon, H is a λ / 4 layer of germanium, L is a λ / 4 layer of zinc sulfide, and Air is air.

[0052] Thus, in the front surface film layer 2: the geometric thickness of the first layer is 68.48nm; the geometric thickness of the second layer is 92.97nm; the geometric thickness of the third layer is 164.33nm; the geometric thickness of the fourth layer is 93.92nm; the geometric thickness of the fifth layer is 168.10nm; the geometric thickness of the sixth layer is 92.77nm; the geometric thickness of the seventh layer is 200.12nm; the geometric thickness of the eighth layer is 121.37nm; the geometric thickness of the ninth layer is 212.30nm; the geometric thickness of the tenth layer is 107.92nm; the geometric thickness of the eleventh layer is 179.02nm; the geometric thickness of the twelfth layer is 92.12nm; the geometric thickness of the thirteenth layer is 197.03nm; the geometric thickness of the fourteenth layer is 97.88nm; The geometric thickness of the 15th layer is 168.42nm; the geometric thickness of the 16th layer is 91.63nm; the geometric thickness of the 17th layer is 165.82nm; the geometric thickness of the 18th layer is 79.72nm; the geometric thickness of the 19th layer is 84.95nm; the geometric thickness of the 20th layer is 73.26nm; the geometric thickness of the 21st layer is 171.68nm; the geometric thickness of the 22nd layer is 84.81nm; the geometric thickness of the 23rd layer is 174.39nm; the geometric thickness of the 24th layer is 92.08nm; the geometric thickness of the 25th layer is 307.10nm; the geometric thickness of the 26th layer is 112.44nm; the geometric thickness of the 27th layer is 335.21nm; the geometric thickness of the 28th layer is 130.75nm; the geometric thickness of the 2 The geometric thickness of the 9th layer is 327.00nm; the geometric thickness of the 30th layer is 124.56nm; the geometric thickness of the 31st layer is 368.34nm; the geometric thickness of the 32nd layer is 120.72nm; the geometric thickness of the 33rd layer is 318.15nm; the geometric thickness of the 34th layer is 164.69nm; the geometric thickness of the 35th layer is 252.14nm; the geometric thickness of the 36th layer is 168.23nm; the geometric thickness of the 37th layer is 273.59nm; the geometric thickness of the 38th layer is 171.40nm; the geometric thickness of the 39th layer is 242.18nm; the geometric thickness of the 40th layer is 170.80nm; the geometric thickness of the 41st layer is 318.57nm; the geometric thickness of the 42nd layer is 117.98nm m; the geometric thickness of the 43rd layer is 343.60nm; the geometric thickness of the 44th layer is 174.50nm; the geometric thickness of the 45th layer is 190.48nm; the geometric thickness of the 46th layer is 187.36nm; the geometric thickness of the 47th layer is 377.83nm; the geometric thickness of the 48th layer is 76.91nm; the geometric thickness of the 49th layer is 348.34nm; the geometric thickness of the 50th layer is 551.26nm; the geometric thickness of the 51st layer is 1030.47nm; the geometric thickness of the 52nd layer is 488.13nm; the geometric thickness of the 53rd layer is 938.66nm; the geometric thickness of the 54th layer is 466.81nm; the geometric thickness of the 55th layer is 949.02nm; the geometric thickness of the 56th layer is 469.07nm; the 57th layer has a geometric thickness of 914.17nm; the 58th layer has a geometric thickness of 461.29nm; the 59th layer has a geometric thickness of 939.91nm; the 60th layer has a geometric thickness of 460.47nm; the 61st layer has a geometric thickness of 914.50nm; the 62nd layer has a geometric thickness of 464.38nm; the 63rd layer has a geometric thickness of 932.68nm; the 64th layer has a geometric thickness of 457.36nm; the 65th layer has a geometric thickness of The geometric thickness of the 66th layer is 466.21nm; the geometric thickness of the 67th layer is 924.05nm; the geometric thickness of the 68th layer is 459.13nm; the geometric thickness of the 69th layer is 944.74nm; the geometric thickness of the 70th layer is 475.38nm; the geometric thickness of the 71st layer is 927.16nm; the geometric thickness of the 72nd layer is 456.90nm; the geometric thickness of the 73rd layer is 461.03nm;.

[0053] In the back surface film layer 3: the geometric thickness of the first layer is 319.4nm; the geometric thickness of the second layer is 42.65nm; the geometric thickness of the third layer is 216.63nm; the geometric thickness of the fourth layer is 119.8nm; the geometric thickness of the fifth layer is 614.87nm; the geometric thickness of the sixth layer is 306.83nm; the geometric thickness of the seventh layer is 430.48nm; the geometric thickness of the eighth layer is 80.47nm; the geometric thickness of the ninth layer is 73.89nm; the geometric thickness of the tenth layer is 174.16nm; the geometric thickness of the eleventh layer is 631.13nm; the geometric thickness of the twelfth layer is 276.38nm; the geometric thickness of the thirteenth layer is The geometric thickness of the 14th layer is 253.26nm; the geometric thickness of the 15th layer is 600.66nm; the geometric thickness of the 16th layer is 281.39nm; the geometric thickness of the 17th layer is 564.86nm; the geometric thickness of the 18th layer is 273.54nm; the geometric thickness of the 19th layer is 572.56nm; the geometric thickness of the 20th layer is 195.12nm; the geometric thickness of the 21st layer is 167.25nm; the geometric thickness of the 22nd layer is 84.08nm; the geometric thickness of the 23rd layer is 266.29nm; the geometric thickness of the 24th layer is 103.13nm; the geometric thickness of the 25th layer is 19 3.41nm; the 26th layer has a geometric thickness of 265.39nm; the 27th layer has a geometric thickness of 560.06nm; the 28th layer has a geometric thickness of 272.58nm; the 29th layer has a geometric thickness of 460.27nm; the 30th layer has a geometric thickness of 142.35nm; the 31st layer has a geometric thickness of 159.92nm; the 32nd layer has a geometric thickness of 63.16nm; the 33rd layer has a geometric thickness of 1014.38nm; the 34th layer has a geometric thickness of 231.47nm; the 35th layer has a geometric thickness of 251.62nm; the 36th layer has a geometric thickness of 81.56nm; the 37th layer has a geometric thickness of 187.7 4nm; the geometric thickness of the 38th layer is 134.68nm; the geometric thickness of the 39th layer is 388.56nm; the geometric thickness of the 40th layer is 36.21nm; the geometric thickness of the 41st layer is 551.35nm; the geometric thickness of the 42nd layer is 386.51nm; the geometric thickness of the 43rd layer is 258.19nm; the geometric thickness of the 44th layer is 123.45nm; the geometric thickness of the 45th layer is 310.28nm; the geometric thickness of the 46th layer is 31.96nm; the geometric thickness of the 47th layer is 977.54nm; the geometric thickness of the 48th layer is 240.51nm; the geometric thickness of the 49th layer is 1010.8nm;

[0054] The equipment used in the present invention mainly includes: a coating machine configured as follows: 2 sets of electron guns, VEECO MarkⅡ ion source, vacuum measurement system INFICON, 6-point crystal film thickness control, IC6, equipped with a cold pump, etc.; a Fourier transform infrared spectrometer; an ultrasonic cleaning machine; a microscope, etc.

[0055] The substrate 1 is one of single crystal silicon, germanium and calcium fluoride.

[0056] In this way, the substrate 1 is one of single crystal silicon, germanium and calcium fluoride, all of which can be used as a substrate for a dual-bandpass filter.

[0057] The central wavelength includes a combination of a mid-wave infrared band and a far-wave infrared band.

[0058] In this way, the combination band including the mid-wave infrared band and the far-wave infrared band through the central wavelength can be applied to a variety of different band combinations and has a wide range of applications.

[0059] The central wavelengths are 3.43 μm and 6.53 μm, or 3.31 μm and 7.66 μm, and the half bandwidths are 120 nm and 200 nm, or 3.1 μm and 4.01 μm, or 10 μm and 10.56 μm.

[0060] The dual-bandpass filter of the present invention has a film system structure that satisfies the λ / 4 periodic symmetry (0.5HL0.5H) S and (0.5LH0.5L) S , germanium and zinc sulfide are selected as coating materials, and the substrate, front surface film layer and back surface film layer form a double-bandpass filter. Therefore, only one filter can be used to achieve high transmittance in two specific bands, and the remaining bands are cut off. In the gas infrared detection system, two absorption peaks of the same gas or absorption peaks of different gases can be detected at the same time, effectively improving the sensitivity of the system.

[0061] Example 2

[0062] like Figure 2-4 As shown, Embodiment 2 of the present invention provides a method for manufacturing the dual-bandpass filter, comprising the following steps:

[0063] S1, using ultrasonic cleaning substrate;

[0064] S2, placing the substrate, germanium film material particles and zinc sulfide film material particles into a vacuum chamber and evacuating the chamber, without baking during the coating process (i.e., using a cold plating method);

[0065] S3, vacuum pumped to 8.0×10 -3 Pa, pre-melting the germanium film material particles and the zinc sulfide film material particles to obtain pre-melted germanium and zinc sulfide, wherein the purpose of pre-melting is to remove impurities on the film material surface and reduce the outgassing of the film material;

[0066] S4, vacuum pumped to 1.5×10 -3Pa, bombarding the substrate surface with an ion source for 20-30 minutes to obtain a bombarded substrate, wherein the bombardment is to clean the substrate surface and heat the substrate to enhance adhesion with the first film;

[0067] S5, coating the first film layer, the vacuum degree is 1.0×10-2Pa, the film is evaporated by electron gun, the evaporation rate is 15A / S, the ion source is assisted by deposition, and the thickness of the first ZnS film is determined by quartz crystal monitoring method;

[0068] S6, coating the second film layer, the vacuum degree is 1.0×10-2Pa, the film is evaporated by electron gun, the evaporation rate is 6A / S, the deposition is assisted by ion source, and the thickness of the second germanium film is determined by quartz crystal monitoring method;

[0069] S7, repeating S5 and S6 in sequence to plate the 3rd to 73rd film layers on the front surface;

[0070] S8, cooling the filter with the 73-layer film on the front surface in a vacuum chamber for 1-2 hours and then taking it out;

[0071] S9, repeat S1-S6 to complete the plating of 49 layers of film layers on the rear surface film layer;

[0072] S10. After plating, cool for 1-2 hours and then take it out.

[0073] Thus, a single crystal silicon material with a diameter of 25 μm and a thickness of 0.625 μm is used as a substrate after ultrasonic cleaning, and a multi-layer dielectric film is deposited on the substrate in a high vacuum. The dielectric film materials of the coating layer are Ge and ZnS. The film system of the front surface film layer 2 is: G / 0.63 (0.5HL0.5H) 12 (0.5HL0.5H) 12 3.08(0.5LH0.5L) 12 / Air, in this embodiment, the thickness of each film layer in the film system is optimized to achieve the following functions: the two peak transmittances of the filter Tp ≥ 75%, the bandwidth is 120 ± 20nm and 200 ± 30nm, 0.4-10μm (except the passband), Tavg < 0.5%. Wherein, the coating adopts a vacuum thermal evaporation thin film deposition method.

[0074] Among them, because the coating machine cavity is equipped with a heating system with a temperature of 0-300°C, different baking temperatures are generally set according to different products and coating materials. Zinc sulfide film material is a sublimation material. If the temperature is too high, it will decompose into zinc oxide or zinc hydroxide impurities, affecting the surface quality of the film layer. Therefore, this application adopts cold plating without heating.

[0075] In S3-S6, the ion-assisted deposition specifically includes: bombarding the film material with an electron gun while bombarding the deposited ions on the surface of the substrate with an ion beam; and determining the thickness of the film layer with a quartz crystal monitoring method.

[0076] In this way, through ion-assisted deposition: while the film material is bombarded with an electron gun, the deposited ions on the surface of the substrate are bombarded with an ion beam to improve the density of the film layer.

[0077] The method also includes: verifying the adhesion of the dual-bandpass filter after coating. The adhesion verification of the dual-bandpass filter includes: a Begla film test, first boiling it in water for 2 hours, then immersing it in water for 72 hours, and then performing a hot and cold cycle test and a salt spray test. If the dual-bandpass filter does not show any film peeling, it means that the film layer is not damaged.

[0078] In this way, the reliability of the dual-bandpass filter was verified and tested through the adhesion test of the Beggella film.

[0079] The method for manufacturing a dual-bandpass filter of the present invention comprises: a film system structure satisfying a λ / 4 periodic symmetry (0.5HL0.5H) S and (0.5LH0.5L) S , germanium and zinc sulfide are selected as coating materials, and the substrate, front surface film layer and back surface film layer form a double-bandpass filter. Therefore, only one filter can be used to achieve high transmittance in two specific bands, and the remaining bands are cut off. In the gas infrared detection system, two absorption peaks of the same gas or absorption peaks of different gases can be detected at the same time, effectively improving the sensitivity of the system.

[0080] The above is only a preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed by the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A dual-bandpass filter, characterized in that: It comprises a substrate (1), a front surface film layer (2) and a rear surface film layer (3), wherein the substrate (1) is located between the front surface film layer (2) and the rear surface film layer (3), and the front surface film layer (2) and the rear surface film layer (3) are both coated with germanium and zinc sulfide; The film layer adjacent to the substrate (1) is the first layer, the first layer of the front surface film layer (2) is a zinc sulfide film layer, the last layer is a zinc sulfide film layer, the even-numbered layers are all germanium film layers, and the odd-numbered layers are all zinc sulfide film layers; the first layer of the rear surface film layer (3) is a zinc sulfide film layer, the last layer is a zinc sulfide film layer, the even-numbered layers are all germanium film layers, and the odd-numbered layers are all zinc sulfide film layers; In the front surface film layer (2): the geometric thickness of the first layer is 68.48nm; the geometric thickness of the second layer is 92.97nm; the geometric thickness of the third layer is 164.33nm; the geometric thickness of the fourth layer is 93.92nm; the geometric thickness of the fifth layer is 168.10nm; the geometric thickness of the sixth layer is 92.77nm; the geometric thickness of the seventh layer is 200.12nm; the geometric thickness of the eighth layer is 121.37nm; the geometric thickness of the ninth layer is 212.30nm; the geometric thickness of the tenth layer is 107.92nm; the geometric thickness of the eleventh layer is 179.02nm; the geometric thickness of the twelfth layer is 92.12nm; the geometric thickness of the thirteenth layer is 197.03nm; the geometric thickness of the fourteenth layer is 97.88nm; The geometric thickness of the 15th layer is 168.42nm; the geometric thickness of the 16th layer is 91.63nm; the geometric thickness of the 17th layer is 165.82nm; the geometric thickness of the 18th layer is 79.72nm; the geometric thickness of the 19th layer is 84.95nm; the geometric thickness of the 20th layer is 73.26nm; the geometric thickness of the 21st layer is 171.68nm; the geometric thickness of the 22nd layer is 84.81nm; the geometric thickness of the 23rd layer is 174.39nm; the geometric thickness of the 24th layer is 92.08nm; the geometric thickness of the 25th layer is 307.10nm; the geometric thickness of the 26th layer is 112.44nm; the geometric thickness of the 27th layer is 335.21nm; the geometric thickness of the 28th layer is 130.75nm; the geometric thickness of the 29th layer is The geometric thickness of the layer is 327.00nm; the geometric thickness of the 30th layer is 124.56nm; the geometric thickness of the 31st layer is 368.34nm; the geometric thickness of the 32nd layer is 120.72nm; the geometric thickness of the 33rd layer is 318.15nm; the geometric thickness of the 34th layer is 164.69nm; the geometric thickness of the 35th layer is 252.14nm; the geometric thickness of the 36th layer is 168.23nm; the geometric thickness of the 37th layer is 273.59nm; the geometric thickness of the 38th layer is 171.40nm; the geometric thickness of the 39th layer is 242.18nm; the geometric thickness of the 40th layer is 170.80nm; the geometric thickness of the 41st layer is 318.57nm; the geometric thickness of the 42nd layer is 117.98nm ; The geometric thickness of the 43rd layer is 343.60nm; the geometric thickness of the 44th layer is 174.50nm; the geometric thickness of the 45th layer is 190.48nm; the geometric thickness of the 46th layer is 187.36nm; the geometric thickness of the 47th layer is 377.83nm; the geometric thickness of the 48th layer is 76.91nm; the geometric thickness of the 49th layer is 348.34nm; the geometric thickness of the 50th layer is 551.26nm; the geometric thickness of the 51st layer is 1030.47nm; the geometric thickness of the 52nd layer is 488.13nm; the geometric thickness of the 53rd layer is 938.66nm; the geometric thickness of the 54th layer is 466.81nm; the geometric thickness of the 55th layer is 949.02nm; the geometric thickness of the 56th layer is 469.07nm; the 57th layer has a geometric thickness of 914.17nm; the 58th layer has a geometric thickness of 461.29nm; the 59th layer has a geometric thickness of 939.91nm; the 60th layer has a geometric thickness of 460.47nm; the 61st layer has a geometric thickness of 914.50nm; the 62nd layer has a geometric thickness of 464.38nm; the 63rd layer has a geometric thickness of 932.68nm; the 64th layer has a geometric thickness of 457.36nm; the 65th layer has a geometric thickness of The geometric thickness of the 66th layer is 466.21nm; the geometric thickness of the 67th layer is 924.05nm; the geometric thickness of the 68th layer is 459.13nm; the geometric thickness of the 69th layer is 944.74nm; the geometric thickness of the 70th layer is 475.38nm; the geometric thickness of the 71st layer is 927.16nm; the geometric thickness of the 72nd layer is 456.90nm; the geometric thickness of the 73rd layer is 461.03nm;. In the back surface film layer (3): the first layer has a geometric thickness of 319.4 nm; the second layer has a geometric thickness of 42.65 nm; the third layer has a geometric thickness of 216.63 nm; the fourth layer has a geometric thickness of 119.8 nm; the fifth layer has a geometric thickness of 614.87 nm; the sixth layer has a geometric thickness of 306.83 nm; the seventh layer has a geometric thickness of 430.48 nm; the eighth layer has a geometric thickness of 80.47 nm; the ninth layer has a geometric thickness of 73.89 nm; the tenth layer has a geometric thickness of 174.16 nm; the eleventh layer has a geometric thickness of 631.13 nm; the twelfth layer has a geometric thickness of 276.38 nm; the thirteenth layer has a geometric thickness of The thickness of the 14th layer is 253.26nm; the geometric thickness of the 15th layer is 600.66nm; the geometric thickness of the 16th layer is 281.39nm; the geometric thickness of the 17th layer is 564.86nm; the geometric thickness of the 18th layer is 273.54nm; the geometric thickness of the 19th layer is 572.56nm; the geometric thickness of the 20th layer is 195.12nm; the geometric thickness of the 21st layer is 167.25nm; the geometric thickness of the 22nd layer is 84.08nm; the geometric thickness of the 23rd layer is 266.29nm; the geometric thickness of the 24th layer is 103.13nm; the geometric thickness of the 25th layer is 1 93.41nm; the 26th layer has a geometric thickness of 265.39nm; the 27th layer has a geometric thickness of 560.06nm; the 28th layer has a geometric thickness of 272.58nm; the 29th layer has a geometric thickness of 460.27nm; the 30th layer has a geometric thickness of 142.35nm; the 31st layer has a geometric thickness of 159.92nm; the 32nd layer has a geometric thickness of 63.16nm; the 33rd layer has a geometric thickness of 1014.38nm; the 34th layer has a geometric thickness of 231.47nm; the 35th layer has a geometric thickness of 251.62nm; the 36th layer has a geometric thickness of 81.56nm; the 37th layer has a geometric thickness of 187. 74nm; the geometric thickness of the 38th layer is 134.68nm; the geometric thickness of the 39th layer is 388.56nm; the geometric thickness of the 40th layer is 36.21nm; the geometric thickness of the 41st layer is 551.35nm; the geometric thickness of the 42nd layer is 386.51nm; the geometric thickness of the 43rd layer is 258.19nm; the geometric thickness of the 44th layer is 123.45nm; the geometric thickness of the 45th layer is 310.28nm; the geometric thickness of the 46th layer is 31.96nm; the geometric thickness of the 47th layer is 977.54nm; the geometric thickness of the 48th layer is 240.51nm; the geometric thickness of the 49th layer is 1010.8nm.

2. The dual-bandpass filter according to claim 1, characterized in that: The substrate (1) is one of single crystal silicon, germanium and calcium fluoride.

3. The dual-bandpass filter according to claim 1, characterized in that: The central wavelength of the dual-bandpass filter includes a combination of a mid-wave infrared band and a far-wave infrared band.

4. A method for manufacturing a dual-bandpass filter according to any one of claims 1 to 3, characterized in that: The steps include: S1, using ultrasonic cleaning substrate; S2, placing the substrate, germanium film material particles and zinc sulfide film material particles into a vacuum chamber and evacuating the chamber, without baking during the coating process; S3, vacuum pumped to 8.0×10 -3 Pa, pre-melting the germanium film material particles and the zinc sulfide film material particles to obtain pre-melted germanium and zinc sulfide; S4, vacuum pumped to 1.5×10 -3 Pa, bombarding the surface of the substrate with an ion source for 20-30 minutes to obtain a bombarded substrate; S5, at a vacuum degree of 1.0×10 -2 Pa, using ion source assisted deposition technology to plate a first zinc sulfide film layer on the front surface of the bombarded substrate obtained in S4, to obtain a substrate having the first zinc sulfide film layer on the front surface; S6, at a vacuum degree of 1.0×10 -2 Pa, using a germanium ion source assisted deposition technique to plate a second germanium film layer on the front surface of the substrate having the first zinc sulfide film layer on the front surface obtained in S5, to obtain a substrate having the second germanium film layer on the front surface; S7, repeating S5 and S6 in sequence to plate the 3rd to 73rd film layers on the front surface; S8, cooling the filter with the 73-layer film on the front surface in a vacuum chamber for 1-2 hours and then taking it out; S9, repeat S1-S6 to complete the plating of 49 layers of film layers on the rear surface film layer; S10. After plating, cool for 1-2 hours and then take it out.

5. The method for manufacturing a dual-bandpass filter according to claim 4, characterized in that: In S3-S6, the ion source assisted deposition technology is specifically: while bombarding the film material with an electron gun, bombarding the deposited ions on the surface of the substrate with an ion beam; and determining the thickness of the film layer with a quartz crystal monitoring method.

6. The method for manufacturing a dual-bandpass filter according to claim 5, characterized in that: Also includes: The adhesion of the plated dual-bandpass filter was verified.

7. The method for manufacturing a dual-bandpass filter according to claim 6, characterized in that: The adhesion verification of the dual-bandpass filter includes: a Begla film test, first boiling in water for 2 hours, then immersing in water for 72 hours, and then performing a hot and cold cycle test and a salt spray test. If the dual-bandpass filter does not delaminate, it means that the film layer is not damaged.

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