A narrow band filter and its preparation method

Abstract

The present invention discloses a narrow-band filter and a preparation method thereof. Among them, for the narrow-band filter, its film system structure is a film system that satisfies λ / 4 periodic symmetry (0.5HL0.5H)<supgt;S< / supgt> and (0.5LH0.5L)<supgt;S< / supgt>, where λ is the wavelength, H is a λ / 4 optical thickness layer of germanium, L is a λ / 4 optical thickness layer of silicon monoxide, and S is the number of periods. By adopting a film system structure that satisfies λ / 4 periodic symmetry (0.5HL0.5H)<supgt;S< / supgt> and (0.5LH0.5L)<supgt;S< / supgt>, and selecting germanium and silicon monoxide as coating materials to form the narrow-band filter, the narrow-band filter has the characteristics of high transmittance, small tolerance of the center wavelength, can greatly improve the signal-to-noise ratio, good test consistency, and high accuracy.

Description

Technical Field

[0001] The invention belongs to the technical field of infrared optical coating, and in particular relates to a narrow-band filter and a preparation method thereof. Background Art

[0002] Carbon dioxide is a carbon oxide with the chemical formula CO2. It is a colorless and odorless gas at room temperature. It is also a common greenhouse gas, accounting for 0.03-0.04% of the total volume of the atmosphere. A large amount of carbon dioxide will lead to the greenhouse effect and global warming. In metallurgy, automobiles, indoors, medical treatment, environmental protection, etc., the concentration of CO2 needs to be quantitatively detected and controlled. Therefore, it is of great practical value to develop sensors with stable performance, high sensitivity and accuracy. As an important component of the sensor, the narrowband filter is a key window that limits the performance of the sensor. The quality of its performance directly affects the sensitivity and accuracy of the sensor.

[0003] According to information retrieval, the main technical problems of this type of filters currently commonly available on the market are: too large a central wavelength tolerance, poor test accuracy, easy signal drowning, not conducive to high-concentration measurement, and poor signal-to-noise ratio. Summary of the invention

[0004] In order to solve the above problems, the purpose of the present invention is to provide a narrow-band filter for CO2 gas sensor which has high transmittance, small central wavelength tolerance, can greatly improve the signal-to-noise ratio, has good consistency and high accuracy.

[0005] The present invention also aims to provide a method for manufacturing the above narrow-band filter.

[0006] To achieve the above object, the technical solution of the present invention is implemented as follows: a narrow-band filter for a CO2 gas sensor, whose film system structure satisfies the λ / 4 periodic symmetry (0.5HL0.5H) S and (0.5LH0.5L) S , where λ is the wavelength, H is the λ / 4 optical thickness layer of germanium, L is the λ / 4 optical thickness layer of silicon monoxide, and S is the number of periods.

[0007] Preferably, the narrowband filter comprises a substrate, a main film structure layer and an interference cut-off film structure layer, wherein the substrate is located between the main film structure layer and the interference cut-off film structure layer, and the main film structure layer and the interference cut-off film structure layer are both coated with germanium and silicon monoxide;

[0008] Preferably, the film layer adjacent to the substrate is the first layer, the first layer in the main film system structure layer is a silicon monoxide film layer, the last layer is a silicon monoxide film layer, the even-numbered layers are all germanium film layers, and the odd-numbered layers are all silicon monoxide film layers; the first layer in the interference cutoff film system structure layer is a silicon monoxide film layer, the last layer is a silicon monoxide film layer, the even-numbered layers are all germanium film layers, and the odd-numbered layers are all silicon monoxide film layers.

[0009] Preferably, the structure of the main film structure layer is:

[0010] G / (0.5HL0.5H) 6 1.5(0.5HL0.5H) 6 2.15(0.5LH0.5L) 7 3.88(0.5LH0.5L) 7 / Air;

[0011] Wherein, G is single crystal silicon, H is a germanium film layer with an optical thickness of λ / 4, L is a silicon monoxide film layer with an optical thickness of λ / 4, Air is air, and λ is 1300 to 1500 nm.

[0012] Preferably, the structure of the interference cutoff film structure layer (3) is:

[0013] G / (0.5HL0.5H) 7 / Air;

[0014] Wherein, G is single crystal silicon, H is a germanium film layer with an optical thickness of λ / 4, L is a silicon monoxide film layer with an optical thickness of λ / 4, Air is air, and λ is 8400 to 8600 nm.

[0015] Preferably, the substrate may be one of single crystal silicon, sapphire, germanium and calcium fluoride.

[0016] Another technical solution of the present invention is achieved as follows: a method for manufacturing a narrow-band filter comprises the following steps:

[0017] S1, cleaning the substrate using an ultrasonic cleaning machine;

[0018] S2, placing the substrate into a vacuum chamber and evacuating the chamber;

[0019] S3, vacuum pumped to 5.0×10 -3 Pa, pre-melting the germanium film material particles;

[0020] S4, vacuum pumped to 1.0×10 -3 Pa, bombarding the substrate surface with an ion source for 10 to 15 minutes to obtain a bombarded substrate;

[0021] S5, at a vacuum degree of 1.0×10-3 Pa, using vacuum evaporation coating technology to deposit a first SiO film layer on one side surface of the bombarded substrate obtained in S4;

[0022] S6, at a vacuum degree of 1.0×10 -3 Pa, using vacuum evaporation coating technology to deposit a second germanium film layer on the surface of the first silicon oxide film layer away from the substrate;

[0023] S7, repeating S5 and S6 in sequence to plate the 3rd to 53rd film layers in the main film system structure layer 2;

[0024] S8, cooling the filter after coating the 53rd film layer of the main film system structure layer in a vacuum chamber for 1-2 hours, breaking the vacuum and taking it out;

[0025] S9, repeat S1-S6 to complete the plating of the 1st to 19th film layers of the interference cutoff film structure layer;

[0026] S10. After the plating is completed and cooled for 1-2 hours, the vacuum is broken and the narrow-band filter is taken out.

[0027] Preferably, in S5, the evaporation rate during the deposition process using the vacuum evaporation coating technology is 15-25A / S; in S6, the evaporation rate during the deposition process using the vacuum evaporation coating technology is 6A / S.

[0028] Preferably, in S5-S6, the thickness of the film layer and the deposition rate are controlled by light-controlled monitoring and quartz crystal monitoring methods, so that the thickness of the film layer can be monitored more accurately.

[0029] Preferably, the method further comprises: verifying the adhesion of the plated narrow-band filter by using a Beggstra film test.

[0030] Preferably, the specific method for verifying adhesion is: boiling in water for 2 hours, immersing in water for 72 hours, hot and cold cycle test and salt spray test, etc. If the narrow-band filter does not peel off, it means that the film layer is not damaged.

[0031] Compared with the prior art, the present invention adopts a film system structure that satisfies the λ / 4 periodic symmetry (0.5HL0.5H) S and (0.5LH0.5L) S The narrow-band filter is made of germanium and silicon monoxide as the coating material. It has high transmittance and small central wavelength tolerance, which can greatly improve the signal-to-noise ratio, and has good test consistency and high accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 is a schematic structural diagram of a narrow-band filter provided by Embodiment 1 of the present invention;

[0033] Figure 2 is a spectral transmittance curve of the main film system structure in the narrow-band filter obtained in Example 2 of the present invention;

[0034] Figure 3 is a spectral transmittance curve of the interference cutoff film system structure in the narrow-band filter obtained in Example 2 of the present invention;

[0035] Figure 4 This is the double-sided coating spectral transmittance curve of the narrow-band filter obtained in Example 2 of the present invention.

[0036] In the figure, 1. substrate, 2. main film structure layer, 3. interference cutoff film structure layer. DETAILED DESCRIPTION

[0037] 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.

[0038] Example 1

[0039] Embodiment 1 of the present invention provides a narrow-band filter for a CO2 gas sensor, such as Figure 1 As shown, the film structure satisfies the λ / 4 periodic symmetry (0.5HL0.5H) S and (0.5LH0.5L) S , where λ is the wavelength, H is the λ / 4 optical thickness layer of germanium, L is the λ / 4 optical thickness layer of silicon monoxide, and S is the number of periods.

[0040] After adopting the above scheme, the film system structure is adopted to satisfy the periodic symmetry of the λ / 4 optical thickness (0.5HL0.5H) S and (0.5LH0.5L) S , and a narrow-band filter made of germanium and silicon monoxide as the coating material is selected, which has the characteristics of high transmittance, small central wavelength tolerance, can greatly improve the signal-to-noise ratio, good test consistency and high accuracy; in addition, the central wavelength of the mid- and far-infrared narrow-band filter is 4.26μm±20nm, the peak transmittance Tp≥88%, the bandwidth is 180±20nm, 400~11200nm (except the passband), Tavg<0.5%, and can be used for CO2 gas detection more accurately.

[0041] Furthermore, if Figure 1As shown, the narrowband filter includes a substrate 1, a main film structure layer 2 and an interference cutoff film structure layer 3, wherein the substrate 1 is located between the main film structure layer 2 and the interference cutoff film structure layer 3, and both the main film structure layer 2 and the interference cutoff film structure layer 3 are coated with germanium and silicon monoxide.

[0042] Furthermore, the film layer adjacent to the substrate 1 is the first layer, the first layer in the main film system structure layer 2 is a silicon monoxide film layer, the last layer is a silicon monoxide film layer, the even-numbered layers are all germanium film layers, and the odd-numbered layers are all silicon monoxide film layers; the first layer in the interference cutoff film system structure layer 3 is a silicon monoxide film layer, the last layer is a silicon monoxide film layer, the even-numbered layers are all germanium film layers, and the odd-numbered layers are all silicon monoxide film layers.

[0043] By adopting a narrow-band filter composed of a substrate, a main film structure layer 2 and an interference cutoff film structure layer 3, and both the main film structure layer 2 and the interference cutoff film structure layer 3 are coated with germanium and silicon monoxide, it has the characteristics of high transmittance, small central wavelength tolerance, greatly improving the signal-to-noise ratio, good test consistency and high accuracy.

[0044] Furthermore, the structure of the main film structure layer 2 is:

[0045] G / (0.5HL0.5H) 6 1.5(0.5HL0.5H) 6 2.15(0.5LH0.5L) 7 3.88(0.5LH0.5L) 7 / Air;

[0046] Wherein, G is single crystal silicon, H is a quarter wavelength optical thickness film layer of germanium, L is a quarter wavelength optical thickness film layer of silicon monoxide, Air is air, and the design wavelength is preferably 1400 nm.

[0047] Furthermore, the structure of the interference cutoff film structure layer 3 is:

[0048] G / (0.5HL0.5H) 7 / Air;

[0049] Wherein, G is single crystal silicon, H is a quarter wavelength optical thickness film layer of germanium, L is a quarter wavelength optical thickness film layer of silicon monoxide, Air is air, and the design wavelength is preferably 8500 nm.

[0050] Thus, in the main film structure layer 2: the geometric thickness of the first layer is 180.84nm; the geometric thickness of the second layer is 82.9nm; the geometric thickness of the third layer is 162.76nm; the geometric thickness of the fourth layer is 82.15nm; the geometric thickness of the fifth layer is 179.84nm; the geometric thickness of the sixth layer is 72.55nm; the geometric thickness of the seventh layer is 187.82nm; the geometric thickness of the eighth layer is 81.77nm; the geometric thickness of the ninth layer is 155.64nm; the geometric thickness of the tenth layer is 85.58nm; the geometric thickness of the eleventh layer is 175.74nm; the geometric thickness of the twelfth layer is 82.63nm; the geometric thickness of the thirteenth layer is The geometric thickness of the 14th layer is 137.37nm; the geometric thickness of the 15th layer is 276.26nm; the geometric thickness of the 16th layer is 118.45nm; the geometric thickness of the 17th layer is 249.6nm; the geometric thickness of the 18th layer is 142.25nm; the geometric thickness of the 19th layer is 277.44nm; the geometric thickness of the 20th layer is 117.17nm; the geometric thickness of the 21st layer is 271.29nm; the geometric thickness of the 22nd layer is 126.69nm; the geometric thickness of the 23rd layer is 299.65nm; the geometric thickness of the 24th layer is 134.44nm; the geometric thickness of the 25th layer is 369.42nm; the geometric thickness of the 26th layer is 176.23nm; the geometric thickness of the 27th layer is 142.25nm; the geometric thickness of the 28th layer is 289.66nm; the geometric thickness of the 14th layer is 137.37nm; the geometric thickness of the 15th layer is 276.26nm; the geometric thickness of the 26th layer is 176.23nm; The geometric thickness of the 27th layer is 399.07nm; the geometric thickness of the 28th layer is 184.42nm; the geometric thickness of the 29th layer is 405.9nm; the geometric thickness of the 30th layer is 183.56nm; the geometric thickness of the 31st layer is 406.25nm; the geometric thickness of the 32nd layer is 180.49nm; the geometric thickness of the 33rd layer is 402.17nm; the geometric thickness of the 34th layer is 173.58nm; the geometric thickness of the 35th layer is 374.93nm; The geometric thickness of the 36th layer is 170.24nm; the geometric thickness of the 37th layer is 400.94nm; the geometric thickness of the 38th layer is 116.58nm; the geometric thickness of the 39th layer is 352.25nm; the geometric thickness of the 40th layer is 313.85nm; the geometric thickness of the 41st layer is 713.31nm; the geometric thickness of the 42nd layer is 322.43nm; the geometric thickness of the 43rd layer is 711nm; the geometric thickness of the 44th layer is 316.23nm; The geometric thickness of the 45th layer is 712.13nm; the geometric thickness of the 46th layer is 329.44nm; the geometric thickness of the 47th layer is 838.19nm; the geometric thickness of the 48th layer is 323.71nm; the geometric thickness of the 49th layer is 695.64nm; the geometric thickness of the 50th layer is 314.01nm; the geometric thickness of the 51st layer is 750.99nm; the geometric thickness of the 52nd layer is 354.68nm; the geometric thickness of the 53rd layer is 356.14nm;

[0051] In the interference cutoff film structure layer 3: the geometric thickness of the first layer is 112.3nm; the geometric thickness of the second layer is 84.12nm; the geometric thickness of the third layer is 1227.67nm; the geometric thickness of the fourth layer is 512.97nm; the geometric thickness of the fifth layer is 1217.52nm; the geometric thickness of the sixth layer is 484.83nm; the geometric thickness of the seventh layer is 1041.4nm; the geometric thickness of the eighth layer is 483.37nm; the geometric thickness of the ninth layer is 1199.84nm; the geometric thickness of the tenth layer is 1303.3nm; the geometric thickness of the ninth layer is 1199.84nm; the geometric thickness of the ninth layer is 1303.3 ... The geometric thickness of the layer is 484.92nm; the geometric thickness of the 11th layer is 1039.56nm; the geometric thickness of the 12th layer is 483.15nm; the geometric thickness of the 13th layer is 1224.48nm; the geometric thickness of the 14th layer is 500.92nm; the geometric thickness of the 15th layer is 925.04nm; the geometric thickness of the 16th layer is 66.7nm; the geometric thickness of the 17th layer is 94.5nm; the geometric thickness of the 18th layer is 299.91nm; the geometric thickness of the 19th layer is 539.42nm;

[0052] The equipment used in the present invention mainly includes: the coating machine is configured as follows: telemark electron gun, 10-bit rotary resist, telemark ion source, vacuum measurement system INFICON, 40-point light control, 6-point crystal film thickness control, Aifak cold pump, etc.; Fourier transform infrared spectrometer; ultrasonic cleaning machine; microscope, etc.

[0053] Furthermore, the substrate 1 is one of single crystal silicon, sapphire, germanium and calcium fluoride.

[0054] In this way, the substrate 1 is one of single crystal silicon, sapphire, germanium and calcium fluoride, all of which can be used as a substrate for a narrow-band filter.

[0055] Embodiment 1 of the present invention adopts a mid-to-far infrared narrow-band filter composed of a substrate 1, a main film structure layer 2 and an interference cut-off film structure layer 3, and the film structure of the narrow-band filter is selected to satisfy the λ / 4 periodic symmetry (0.5HL0.5H) S and (0.5LH0.5L) S , and germanium and silicon monoxide are selected as coating materials to make the main film structure layer 2 and the interference cutoff film structure layer 3, so that the narrow-band filter has the characteristics of high transmittance, small central wavelength tolerance, greatly improved signal-to-noise ratio, good test consistency and high accuracy.

[0056] Example 2

[0057] like Figure 2-4 As shown, Embodiment 2 of the present invention provides a method for manufacturing the narrow-band filter described in Embodiment 1, comprising the following steps:

[0058] S1, cleaning substrate 1 using an ultrasonic cleaning machine;

[0059] S2, loading the substrate 1 into a fixture and placing it into a vacuum chamber and evacuating the chamber. During the evacuation process, the heating temperature of the coating umbrella is 150° C., the heating temperature of the light control sheet is 150° C., and the temperature is kept constant for more than 30 minutes;

[0060] S3, vacuum pumped to 5.0×10 -3 Pa, pre-melting the germanium film particles, the purpose of pre-melting is to remove impurities on the surface of the film material and reduce the outgassing of the film material;

[0061] S4, vacuum pumped to 1.0×10 -3 Pa, bombarding the surface of the substrate 1 for 10 to 15 minutes using a Hall ion source to obtain a bombarded substrate; the purpose of the bombardment is to clean all dust on the surface of the substrate 1 and to heat to increase the adhesion between the substrate 1 and the first coating;

[0062] S5, at a vacuum degree of 1.0×10 -3 Pa, a first SiO film layer is deposited on one side of the bombarded substrate obtained in S4 by using a vacuum evaporation coating technology (barrier thermal evaporation coating technology); wherein the evaporation rate during the deposition process using the vacuum evaporation coating technology is 15-25A / S; and during the deposition process, the thickness of the film layer and the deposition rate are controlled by light control monitoring and quartz crystal monitoring methods, so that the thickness of the film layer can be more accurately monitored;

[0063] S6, at a vacuum degree of 1.0×10 -3 Pa, a second germanium film layer is deposited on the surface of the first SiO film layer away from the substrate 1 by using a vacuum evaporation coating technology (electron gun evaporation coating technology); wherein the evaporation rate during the deposition process using the vacuum evaporation coating technology is 6A / S; and during the deposition process, the thickness of the film layer and the deposition rate are controlled by using a light control monitoring and a quartz crystal monitoring method, so that the thickness of the film layer can be more accurately monitored;

[0064] S7, repeating S5 and S6 in sequence to plate the 3rd to 53rd film layers of the main film system structure;

[0065] S8, cooling the filter with 53 layers of the main film structure layer in a vacuum chamber for 1-2 hours and then breaking the vacuum to take it out;

[0066] S9, repeat S1-S6 to complete the plating of 19 film layers of the interference cutoff film structure;

[0067] S10. After the plating is completed and cooled for 1-2 hours, the vacuum is broken and the narrow-band filter is taken out.

[0068] Thus, a single crystal silicon material with a diameter of 100 mm and a thickness of 0.49 ± 0.02 mm is used as substrate 1 after being cleaned by an ultrasonic cleaning machine, and a multi-layer dielectric film is evaporated on substrate 1. The dielectric film materials of the coating layer are germanium and silicon monoxide. The film system of the main film structure layer 2 is: G / (0.5HL0.5H) 6 1.5(0.5HL0.5H) 6 2.15(0.5LH0.5L) 7 3.88(0.5LH0.5L) 7 / Air, interference cut-off film structure film layer 2 film system adopts: G / (0.5HL0.5H) 7 / Air, in this embodiment, the thickness of each film layer in the film system is optimized to achieve the following functions: the central wavelength is 4.26um±20nm, the peak transmittance Tp≥88%, the bandwidth is 180±20nm, 400-11200 (except the passband), Tavg<0.5%. Wherein, the coating adopts a vacuum thermal evaporation thin film deposition method.

[0069] Furthermore, the method also includes: using a Beggella film test to verify the adhesion of the plated narrow-band filter.

[0070] Furthermore, the specific method for verifying adhesion is: boiling in water for 2 hours, immersing in water for 72 hours, hot and cold cycle test and salt spray test, etc. If the narrow-band filter does not peel off, it means that the film layer is not damaged.

[0071] The narrowband filter obtained by the manufacturing method in Example 2 of the present invention makes the film system structure of the narrowband filter a film system (0.5HL0.5H) that satisfies the λ / 4 periodic symmetry. S and (0.5LH0.5L) S The narrow-band filter composed of a substrate 1, a main film structure layer 2 and an interference cutoff film structure layer 3 has the characteristics of high transmittance, small central wavelength tolerance, greatly improved signal-to-noise ratio, good test consistency and high accuracy.

[0072] 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 narrow band filter for a CO2 gas sensor, characterized in that: The narrowband optical filter comprises a substrate (1), a main film system structure layer (2) and an interference cut-off film system structure layer (3), wherein the substrate (1) is located between the main film system structure layer (2) and the interference cut-off film system structure layer (3), and the main film system structure layer (2) and the interference cut-off film system structure layer (3) are both coated with germanium and silicon monoxide; The film layer adjacent to the substrate (1) is the first layer; the first layer of the main film system structure layer (2) is a silicon monoxide film layer, the last layer is a silicon monoxide film layer, the even-numbered layers are all germanium film layers, and the odd-numbered layers are all silicon monoxide film layers; the first layer of the interference cutoff film system structure layer (3) is a silicon monoxide film layer, the last layer is a silicon monoxide film layer, the even-numbered layers are all germanium film layers, and the odd-numbered layers are all silicon monoxide film layers; in the main film system structure layer (2): the geometric thickness of the first layer is 180.84nm; the geometric thickness of the second layer is 82.9nm; the geometric thickness of the third layer is 1 The geometric thickness of the 4th layer is 82.15nm; the geometric thickness of the 5th layer is 179.84nm; the geometric thickness of the 6th layer is 72.55nm; the geometric thickness of the 7th layer is 187.82nm; the geometric thickness of the 8th layer is 81.77nm; the geometric thickness of the 9th layer is 155.64nm; the geometric thickness of the 10th layer is 85.58nm; the geometric thickness of the 11th layer is 175.74nm; the geometric thickness of the 12th layer is 82.63nm; the geometric thickness of the 13th layer is 289.66nm; the geometric thickness of the 14th layer is 137 .37nm; the geometric thickness of the 15th layer is 276.26nm; the geometric thickness of the 16th layer is 118.45nm; the geometric thickness of the 17th layer is 249.6nm; the geometric thickness of the 18th layer is 142.25nm; the geometric thickness of the 19th layer is 277.44nm; the geometric thickness of the 20th layer is 117.17nm; the geometric thickness of the 21st layer is 271.29nm; the geometric thickness of the 22nd layer is 126.69nm; the geometric thickness of the 23rd layer is 299.65nm; the geometric thickness of the 24th layer is 134.44nm; the geometric thickness of the 25th layer is 369.42nm; the geometric thickness of the 26th layer is 176.23nm; the geometric thickness of the 27th layer is 399.07nm; the geometric thickness of the 28th layer is 184.42nm; the geometric thickness of the 29th layer is 405 .9nm; the geometric thickness of the 30th layer is 183.56nm; the geometric thickness of the 31st layer is 406.25nm; the geometric thickness of the 32nd layer is 180.49nm; the geometric thickness of the 33rd layer is 402.17nm; the geometric thickness of the 34th layer is 173.58nm; the geometric thickness of the 35th layer is 374.93nm; the geometric thickness of the 36th layer is 170.24nm; the geometric thickness of the 37th layer is 400.94nm; the geometric thickness of the 38th layer is 116.58nm; the geometric thickness of the 39th layer is 352.25nm; the geometric thickness of the 40th layer is 313.85nm; the geometric thickness of the 41st layer is 713.31nm; the geometric thickness of the 42nd layer is 322 .43nm; the geometric thickness of the 43rd layer is 711nm; the geometric thickness of the 44th layer is 316 .23nm; the geometric thickness of the 45th layer is 712.13nm; the geometric thickness of the 46th layer is 329.44nm; the geometric thickness of the 47th layer is 838.19nm; the geometric thickness of the 48th layer is 323.71nm; the geometric thickness of the 49th layer is 695.64nm; the geometric thickness of the 50th layer is 314.01nm; the geometric thickness of the 51st layer is 750.99nm; the geometric thickness of the 52nd layer is 354.68nm; the geometric thickness of the 53rd layer is 356.14nm; in the interference cutoff film structure layer (3): the geometric thickness of the 1st layer is 112.3nm; the geometric thickness of the 2nd layer is 84.12nm; the geometric thickness of the 3rd layer is 1227.67nm; the geometric thickness of the 4th layer is 512.97nm; the geometric thickness of the 5th layer is 1217.52nm; the geometric thickness of the 6th layer is 484.83nm; the geometric thickness of the 7th layer is 1 041.4nm; the 8th layer has a geometric thickness of 483.37nm; the 9th layer has a geometric thickness of 1199.84nm; the 10th layer has a geometric thickness of 484.92nm; the 11th layer has a geometric thickness of 1039.56nm; the 12th layer has a geometric thickness of 483.15nm; the 13th layer has a geometric thickness of 1224.48nm; the 14th layer has a geometric thickness of 500.92nm; the 15th layer has a geometric thickness of 925.04nm; the 16th layer has a geometric thickness of 66.7nm; the 17th layer has a geometric thickness of 94.5nm; the 18th layer has a geometric thickness of 299.91nm; and the 19th layer has a geometric thickness of 539.42nm. .

2. A narrowband filter according to claim 1, characterized in that: The substrate (1) may be one of single crystal silicon, sapphire, germanium and calcium fluoride.

3. A method for manufacturing a narrow-band filter according to claim 1 or 2, characterized in that: The steps include: S1, cleaning the substrate (1) using an ultrasonic cleaning machine; S2, placing the substrate (1) into a vacuum chamber and evacuating the chamber; S3, vacuum pumped to 5.0×10 -3 Pa, pre-melting the germanium film particles; S4, vacuum pumped to 1.0×10 -3 Pa, bombarding the surface of the substrate (1) with an ion source for 10 to 15 minutes to obtain a bombarded substrate; S5, at a vacuum degree of 1.0×10 -3 Pa, using vacuum evaporation coating technology to deposit a first SiO film layer on one side surface of the bombarded substrate obtained in S4; S6, at a vacuum degree of 1.0×10 -3 Pa, using vacuum evaporation coating technology to deposit a second germanium film layer on the surface of the first silicon oxide film layer away from the substrate; S7, repeating S5 and S6 in sequence to plate the 3rd to 53rd film layers in the main film system structure layer (2); S8, cooling the filter after coating the 53rd film layer of the main film system structure layer in a vacuum chamber for 1-2 hours, breaking the vacuum and taking it out; S9, repeat S1-S6 to complete the plating of the 1st to 19th film layers of the interference cutoff film structure layer; S10. After the plating is completed and cooled for 1-2 hours, the vacuum is broken and the narrow-band filter is taken out.

4. A narrowband filter according to claim 3, characterized in that: In S5, the evaporation rate during the deposition process using the vacuum evaporation coating technology is 15-25A / S; in S6, the evaporation rate during the deposition process using the vacuum evaporation coating technology is 6A / S.

5. The method for manufacturing a narrow-band filter according to claim 3, characterized in that: In S5-S6, the thickness of the film layer and the deposition rate are controlled by light-controlled monitoring and quartz crystal monitoring methods, so that the thickness of the film layer can be monitored more accurately.

6. A method for manufacturing a narrow-band filter according to any one of claims 3 to 5, characterized in that: The method also includes: using a Begger film test to verify the adhesion of the plated narrow-band filter.

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