CN113341492B

CN113341492B - Double-band-pass narrow-band optical filter for gas detection and manufacturing method thereof

Info

Publication number: CN113341492B
Application number: CN202110656250.0A
Authority: CN
Inventors: 刘文波; 武斌
Original assignee: Shenzhen Meisi Xianrui Electronic Co ltd
Current assignee: Shenzhen Meisi Xianrui Electronic Co ltd
Priority date: 2021-06-11
Filing date: 2021-06-11
Publication date: 2022-06-14
Anticipated expiration: 2041-06-11
Also published as: CN113341492A

Abstract

The invention discloses a dual-band-pass narrow-band optical filter for gas detection and a manufacturing method thereof. A dual-band-pass narrow-band filter for gas detection comprises a substrate, a main film system structure and a cut-off film system structure, wherein the main film system structure and the cut-off film system structure are respectively arranged on two sides of the substrate. High transmittance of wave bands with the central wavelength of 3.95um +/-20 nm and the central wavelength of 4.26um +/-20 nm is simultaneously realized on the same substrate, and the wave bands except for a pass band are cut off within 400-11000 nm. Thus, the central wavelength of 4.26um is used for testing CO₂Wavelength of concentration and center wavelength of 3.95um as reference wavelength to realize CO₂The data of concentration is corrected, and real CO can be obtained₂Concentration data.

Description

Double-band-pass narrow-band optical filter for gas detection and manufacturing method thereof

Technical Field

The invention belongs to the technical field of optical filters, and particularly relates to a dual-band-pass narrow-band optical filter for gas detection and a manufacturing method thereof.

Background

Carbon dioxide is a carbon oxide of the formula CO₂The water solution of the gas is colorless and tasteless or colorless and tasteless at normal temperature and slightly sour, and is also a common greenhouse gas which accounts for 0.03 to 0.04 percent of the total volume of the atmosphere, and a large amount of carbon dioxide can cause greenhouse effect and global warming; the demand for CO in the fields of metallurgy, automobile, indoor, medical treatment, environmental protection and the like₂The narrow-band filter is used as an important component of the sensor and is a key window for limiting the performance of the sensor, and the quality of the performance of the narrow-band filter directly influences the sensitivity and the accuracy of the sensor.

The prior art is a test CO consisting of 2 different bands (a narrowband filter with a central wavelength of 3.95um and a narrowband filter with a central wavelength of 4.26 um)₂A dual window sensor of concentration; one is as follows: 2 types of narrow-band filters with different wave bands need to be plated in the coating process, the coating cost is high, and the coating process is simple and easy to operateThe process debugging time is long; the packaging difficulty of the double-window sensor is higher, the efficiency is lower, and the manufacturing time is long.

Disclosure of Invention

In order to solve the problems and the defects of the prior art, the invention aims to provide a dual-band-pass narrow-band filter for gas detection and a manufacturing method thereof.

In order to achieve the above object, the present invention provides a dual-bandpass narrow-band filter for gas detection.

The technical scheme adopted by the invention is as follows:

a dual-band-pass narrow-band filter for gas detection comprises a substrate, a main film system structure and an interference cut-off film system structure, wherein the main film system structure and the interference cut-off film system structure are respectively arranged on two sides of the substrate;

the main membrane system structure adopts:

Sub/(0.5HL0.5H)⁶and/Air, wherein, Sub is the substrate, H is a quarter-wave optical thickness film layer of germanium, L is a quarter-wave optical thickness film layer of silicon monoxide, Air is Air, and the design wavelength is 3900 nm.

The interference cut-off film system structure adopts:

Sub/1.04(0.5HL0.5H)⁷ 1.7(0.5HL0.5H)⁷ 5.66(0.5LH0.5L)⁶and/Air, wherein, Sub is the substrate, H is a quarter-wave optical thickness film layer of germanium, L is a quarter-wave optical thickness film layer of silicon monoxide, and Air is Air, and the design wavelength is 1400 nm.

Furthermore, the main film system structure and the interference cut-off film system both use germanium and silicon monoxide as coating materials; the film layer adjacent to the substrate is a first layer, the first layer in the main film system structure is a germanium film layer, the last layer in the main film system structure is a germanium film layer, even layers are silicon monoxide film layers, and odd layers are germanium film layers; in the interference cut-off film system structure, the first layer is a germanium film layer, the last layer is a silicon monoxide film layer, even layers are silicon monoxide film layers, and odd layers are germanium film layers.

Further, the substrate may be one of single crystal silicon, sapphire, germanium, and calcium fluoride.

Further, the substrate is monocrystalline silicon with the diameter of 100mm and the thickness of 0.49 +/-0.02 mm.

The invention also provides a dual-band-pass narrow-band optical filter for gas detection and a manufacturing method thereof, wherein the manufacturing method comprises the following steps:

s1, cleaning the substrate by using an ultrasonic cleaner;

s2, placing the substrate into a clamp and placing the substrate into a vacuum cavity of a film coating machine, vacuumizing, and keeping the constant temperature for more than 30min, wherein the heating temperature of a film coating umbrella is 150 ℃ and the heating temperature of a light control sheet is 150 ℃;

s3, vacuumizing to 5.0X 10^-3Pa, carrying out pre-melting treatment on germanium film material particles;

s4, vacuumizing to 1.0X 10^-3Pa, bombarding the surface of the substrate for 10-15min by adopting a Hall ion source; starting film coating after the bombardment is finished;

s5, plating the 1 st film layer with the vacuum degree of 1.0 multiplied by 10^-3Pa, performing evaporation coating by an electron gun, wherein the evaporation rate is 6A/S;

s6, plating the 2 nd film layer with the vacuum degree of 1.0 multiplied by 10^-3Pa, preventing evaporation and thermal evaporation coating, wherein the evaporation rate is 15-20A/S;

s7, repeating S5 and S6 in sequence, plating the 3 rd to 47 th film layers of the main film system structure;

s8, cooling the optical filter coated with the 47 film layer of the main film system structure in a vacuum chamber for 1-2h, breaking the vacuum and taking out;

s9, repeating S1-S6 to complete the plating of the 42 layers of the interference cut-off film system structure;

and S10, breaking vacuum after cooling for 1-2h, and taking out the dual-band-pass narrow-band optical filter.

Further, in the steps S3-S10, the thickness and deposition rate of the film layer are controlled by indirect light control monitoring and quartz crystal monitoring.

Further, the method also comprises the step of carrying out adhesion verification on the plated dual-band-pass narrow-band filter.

Further, the adhesion test is a bagela film test: firstly, boiling for 2h, then soaking for 72h, and then carrying out a cold-hot cycle test and a salt spray test.

Further, the gas detection dual band pass narrowband filter was tested using a fourier infrared spectrometer.

Compared with the prior art, the invention has the beneficial effects that: the high transmissivity of wave bands with the central wavelength of 3.95um +/-20 nm and the central wavelength of 4.26um +/-20 nm is realized on the same substrate, the tolerance of the central wavelength is small, the cut-off of other wave bands except for a pass band within 400 plus 11000nm is less than 0.5 percent, the signal-to-noise ratio is improved, the test consistency is good, the accuracy is high, the film coating cost is saved, and the difficulty of sensor packaging is reduced; the double-bandpass narrow-band filter takes the central wavelength of 4.26um as the CO test₂Concentration wavelength and center wavelength of 3.95um as reference wavelength to realize CO₂The data of concentration is corrected, and real CO can be obtained₂Concentration data.

Drawings

Fig. 1 is a schematic structural diagram of a dual-bandpass narrow-band filter for gas detection according to embodiment 1 of the present invention;

FIG. 2 is a transmittance test spectrum of a primary film structure according to a second embodiment of the present invention;

FIG. 3 is a transmittance test spectrum of a second interference cut film system structure according to an embodiment of the present invention;

FIG. 4 is a graph showing the transmittance test patterns of the two sides of the dual-bandpass narrow-band filter according to the embodiment of the present invention.

Description of the reference numerals

1-substrate, 2-main film structure, 3-interference cut film structure.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and do not limit the invention.

The first embodiment is as follows:

an embodiment of the present invention provides a dual-band-pass narrow-band filter for gas detection, as shown in FIG. 1, the film structure is designed to satisfy the quarterA film system with wavelength optical thickness period symmetry (0.5HL0.5H)^SAnd (0.5LH0.5L)^SH is a quarter-wavelength optical thickness film layer of germanium, L is a quarter-wavelength optical thickness film layer of silicon monoxide, and S is the period number; the refractive index of germanium is 4.4, and the refractive index of silicon monoxide is 1.9.

The film coating device comprises a substrate 1, a main film system structure 2 and an interference stop film system 3, wherein the substrate 1 is positioned between a film layer of the main film system structure 2 and a film layer of the interference stop film system 3, and the film layer of the main film system structure 2 and the film layer of the interference stop film system 3 both use germanium and silicon monoxide as film coating materials; the substrate 1 may be one of single crystal silicon, sapphire, germanium, and calcium fluoride. The substrate 1 used in this example was a single crystal silicon having a diameter of 100mm and a thickness of 0.49. + -. 0.02 mm.

In this example 1, the main film system structure 2 employs:

G/(0.5HL0.5H)⁶/Air；

wherein G is monocrystalline 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 3900 nm.

The interference cut-off film system structure 3 adopts:

G/1.04(0.5HL0.5H)⁷ 1.7(0.5HL0.5H)⁷ 5.66(0.5LH0.5L)⁶/Air；

wherein G is monocrystalline 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 1400 nm.

The film layer adjacent to the substrate is a first layer, the first layer in the main film system structure film layer is a germanium film layer, the last layer is a germanium film layer, even layers are silicon monoxide film layers, and odd layers are germanium film layers; the first layer of the interference cut-off film system structure film layer is a germanium film layer, the last layer is a silicon monoxide film layer, even layers are silicon monoxide film layers, and odd layers are germanium film layers.

Thus, in the main film system structure film layer 2: the geometric thickness of the 1 st layer is 1175.84 nm; the geometric thickness of the 2 nd layer is 302.13 nm; the 3 rd layer has the geometric thickness of 999.52 nm; the geometric thickness of the 4 th layer is 401.76 nm; the 5 th layer has the geometric thickness of 892.02 nm; the 6 th layer has the geometric thickness of 496.11 nm; the 7 th layer has the geometric thickness of 414.26 nm; the geometric thickness of the 8 th layer is 637.26 nm; the 9 th layer has a geometric thickness of 188.61 nm; the 10 th layer has a geometric thickness of 480.18 nm; the geometric thickness of the 11 th layer is 214.56 nm; the geometric thickness of the 12 th layer is 175.24 nm; the geometric thickness of the 13 th layer is 104.31 nm; the geometric thickness of the 14 th layer is 700.14 nm; the geometric thickness of the 15 th layer is 220.88 nm; the 16 th layer has a geometric thickness of 468.58 nm; the geometric thickness of the 17 th layer is 215.90 nm; the 18 th layer has a geometric thickness of 1186.44 nm; the 19 th layer has a geometric thickness of 146.95 nm; the geometric thickness of the 20 th layer is 438.21 nm; the geometric thickness of the 21 st layer is 236.08 nm; the geometric thickness of the 22 nd layer is 654.32 nm; the geometric thickness of the 23 rd layer is 476.37 nm; the 24 th layer has a geometric thickness of 493.21 nm; the geometric thickness of the 25 th layer is 229.02 nm; the geometric thickness of the 26 th layer is 633.65 nm; the geometric thickness of the 27 th layer is 293.57 nm; the geometric thickness of the 28 th layer is 476.83 nm; the geometric thickness of the 29 th layer is 100.43 nm; the geometric thickness of the 30 th layer is 179.6 nm; the geometric thickness of the 31 st layer is 220.46 nm; the geometric thickness of the 32 nd layer is 501.88 nm; the geometric thickness of the 33 th layer is 205.84 nm; the 34 th layer has the geometric thickness of 1286.99 nm; the geometric thickness of the 35 th layer is 201.95 nm; the 36 th layer has a geometric thickness of 394 nm; the geometric thickness of the 37 th layer is 127.31 nm; the geometric thickness of the 38 th layer is 382.37 nm; the 39 th layer has a geometric thickness of 192.4 nm; the geometric thickness of the 40 th layer is 492.21 nm; the geometric thickness of the 41 st layer is 222.87 nm; the 42 th layer has a geometric thickness of 1191.05 nm; the 43 th layer has a geometric thickness of 121.45 nm; the geometric thickness of the 44 th layer is 703.46 nm; the geometric thickness of the 45 th layer is 236.75 nm; the geometric thickness of the 46 th layer is 1169.74 nm; the geometric thickness of the 47 th layer is 153.54 nm;

in the interference cut-off film system structure film layer 3: the geometric thickness of the 1 st layer is 65.08 nm; the geometric thickness of the 2 nd layer is 141.53 nm; the 3 rd layer has the geometric thickness of 108.85 nm; the geometric thickness of the 4 th layer is 193.53 nm; the 5 th layer has the geometric thickness of 67.98 nm; the geometric thickness of the 6 th layer is 230.76 nm; the geometric thickness of the 7 th layer is 72.9 nm; the geometric thickness of the 8 th layer is 224.18 nm; the geometric thickness of the 9 th layer is 87.92 nm; the 10 th layer has a geometric thickness of 142.18 nm; the geometric thickness of the 11 th layer is 117.18 nm; the geometric thickness of the 12 th layer is 146.48 nm; the geometric thickness of the 13 th layer is 83.65 nm; the geometric thickness of the 14 th layer is 236.15 nm; the geometric thickness of the 15 th layer is 61.58 nm; the 16 th layer has a geometric thickness of 406.54 nm; the geometric thickness of the 17 th layer is 84.64 nm; the 18 th layer has a geometric thickness of 360.26 nm; the 19 th layer has a geometric thickness of 82.92 nm; the geometric thickness of the 20 th layer is 402.94 nm; the geometric thickness of the 21 st layer is 132.66 nm; the geometric thickness of the 22 nd layer is 160.62 nm; the geometric thickness of the 23 rd layer is 192.07 nm; the 24 th layer has a geometric thickness of 381.77 nm; the geometric thickness of the 25 th layer is 56.66 nm; the geometric thickness of the 26 th layer is 451.21 nm; the geometric thickness of the 27 th layer is 132.57 nm; the geometric thickness of the 28 th layer is 313.82 nm; the geometric thickness of the 29 th layer is 91.12 nm; the geometric thickness of the 30 th layer is 349.7 nm; the geometric thickness of the 31 st layer is 506.17 nm; the geometric thickness of the 32 nd layer is 1082.94 nm; the geometric thickness of the 33 rd layer is 454.03 nm; the 34 th layer has the geometric thickness of 1072.78 nm; the geometric thickness of the 35 th layer is 474.3 nm; the 36 th layer geometric thickness is 1064.21 nm; the geometric thickness of the 37 th layer is 448.05 nm; the geometric thickness of the 38 th layer is 1077.17 nm; the 39 th layer has a geometric thickness of 480.36 nm; the geometric thickness of the 40 th layer is 1054.08 nm; the geometric thickness of the 41 st layer is 407 nm; the 42 th layer had a geometric thickness of 463.88 nm.

According to the dual-bandpass narrow-band filter for gas detection, high transmissivity of wave bands with central wavelengths of 3.95um +/-20 nm and 4.26um +/-20 nm is achieved on the same substrate, the central wavelength tolerance is small, the cut-offs of other wave bands except for a passband within 400-11000nm are all smaller than 0.5%, the signal-to-noise ratio is improved, the test consistency is good, the accuracy is high, the film coating cost is saved, and the difficulty of sensor packaging is reduced; the double-bandpass narrow-band filter takes the central wavelength of 4.26um as the CO test₂Concentration wavelength and center wavelength of 3.95um as reference wavelength to realize CO₂The data of concentration is corrected, and real CO can be obtained₂Concentration data.

The double-bandpass narrow-band filter can have a central wavelength of 3.95um +/-20 nm and a central wavelength of 4.26um +/-20 nm, and can also have a central wavelength of 2.78um and a central wavelength of 3.95um and the like.

Example two:

the second embodiment of the invention provides a manufacturing method of a dual-band-pass narrow-band optical filter for gas detection, which comprises the following steps:

s1, cleaning the substrate by using an ultrasonic cleaner;

s3, vacuumizing to 5.0X 10^-3Pa, carrying out pre-melting treatment on germanium film material particles, wherein the pre-melting aims at removing impurities on the surface of the film material and reducing the gas release of the film material;

s4, vacuumizing to 1.0X 10^-3Pa, bombarding the surface of the substrate for 10-15min by using a Hall ion source, wherein the bombarding aims at cleaning dust on the surface of the substrate and heating the substrate to enhance the adhesiveness of the substrate and the first layer of film; starting film coating after the bombardment is finished;

s5, plating the 1 st film layer with the vacuum degree of 1.0 multiplied by 10^-3Pa, evaporating and coating by an electron gun, wherein the evaporation rate is 6A/S, and the thickness and the deposition rate of the film layer are controlled by using indirect light control monitoring and quartz crystal monitoring methods in the deposition process;

s6, plating the 2 nd film layer with the vacuum degree of 1.0 multiplied by 10^-3Pa, evaporation-resistant thermal evaporation coating, wherein the evaporation rate is 15-20A/S, and the thickness and the deposition rate of the film layer are controlled by using indirect light control monitoring and quartz crystal monitoring methods in the deposition process;

s8, cooling the optical filter coated with the 47 film layer of the main film system structure in a vacuum chamber for 1-2h, breaking the vacuum and taking out; the test spectrum of the Fourier infrared spectrometer is shown in figure 2;

s10, breaking vacuum after cooling for 1-2h after plating, and taking out the double-band-pass narrow-band filter; the test spectrum of the Fourier infrared spectrometer is shown in FIG. 4;

in S3-S10, the thickness and deposition rate of each film layer are controlled by indirect light-operated monitoring and quartz crystal monitoring, so that the thickness of each film layer can be monitored more accurately, and the measured spectrum is basically close to the designed spectrum after the film layers are plated.

Further comprising: and (5) carrying out adhesion verification on the coated narrow-band filter.

The adhesion test of the filter included: and in the Baigela film test, boiling in water for 2h, soaking in water for 72h, performing a cold-hot cycle test, a salt spray test and the like, and if no film stripping occurs on the narrow-band optical filter, the film layer is not damaged.

The equipment used by the invention mainly comprises: the film plating machine is configured as follows: a telemark electron gun, a 10-position rotation steam resistance, a telemark ion source, a vacuum measurement system INFICON, an inlet 40-point light control, a 6-point crystal film thickness control, an Aike cold pump and the like; a Fourier transform infrared spectrometer; an ultrasonic cleaning machine; microscopes, and the like.

According to the manufacturing method of the dual-bandpass narrow-band filter for gas detection, high transmissivity of wave bands with central wavelengths of 3.95um +/-20 nm and 4.26um +/-20 nm is achieved on the same substrate, central wavelength tolerance is small, cutoff of other wave bands except for a pass band within 400 plus 11000nm is achieved, the cutoff is smaller than 0.5%, the signal-to-noise ratio is improved, the test consistency is good, the accuracy is high, the film coating cost is saved, and the difficulty of sensor packaging is reduced; the double-bandpass narrow-band filter takes the central wavelength of 4.26um as the CO test₂Wavelength of concentration and center wavelength of 3.95um as reference wavelength to realize CO₂The data of concentration is corrected, and real CO can be obtained₂Concentration data.

The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention are included in the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.

Claims

1. The dual-band-pass narrow-band filter for gas detection is characterized by comprising a substrate (1), a main film system structure (2) and an interference cut-off film system structure (3), wherein the main film system structure (2) and the interference cut-off film system structure (3) are respectively arranged on two sides of the substrate (1), the main film system structure (2) and the interference cut-off film system structure (3) both use germanium and silicon monoxide as coating materials, and a film layer adjacent to the substrate (1) is a first layer;

the main film system structure (2) adopts a structure with 47 layers of geometric thickness in total, the first layer in the main film system structure (2) is a germanium film layer, the last layer is a germanium film layer, even layers are silicon monoxide film layers, odd layers are germanium film layers, and the design wavelength is 3900 nm; in the main film system structure (2): the geometric thickness of the 1 st layer is 1175.84 nm; the geometric thickness of the 2 nd layer is 302.13 nm; the 3 rd layer has the geometric thickness of 999.52 nm; the geometric thickness of the 4 th layer is 401.76 nm; the 5 th layer has the geometric thickness of 892.02 nm; the 6 th layer has the geometric thickness of 496.11 nm; the 7 th layer has the geometric thickness of 414.26 nm; the geometric thickness of the 8 th layer is 637.26 nm; the 9 th layer has a geometric thickness of 188.61 nm; the 10 th layer has a geometric thickness of 480.18 nm; the geometric thickness of the 11 th layer is 214.56 nm; the geometric thickness of the 12 th layer is 175.24 nm; the geometric thickness of the 13 th layer is 104.31 nm; the geometric thickness of the 14 th layer is 700.14 nm; the geometric thickness of the 15 th layer is 220.88 nm; the 16 th layer has a geometric thickness of 468.58 nm; the geometric thickness of the 17 th layer is 215.90 nm; the 18 th layer has a geometric thickness of 1186.44 nm; the 19 th layer has a geometric thickness of 146.95 nm; the geometric thickness of the 20 th layer is 438.21 nm; the geometric thickness of the 21 st layer is 236.08 nm; the geometric thickness of the 22 nd layer is 654.32 nm; the geometric thickness of the 23 rd layer is 476.37 nm; the 24 th layer has a geometric thickness of 493.21 nm; the geometric thickness of the 25 th layer is 229.02 nm; the geometric thickness of the 26 th layer is 633.65 nm; the geometric thickness of the 27 th layer is 293.57 nm; the geometric thickness of the 28 th layer is 476.83 nm; the geometric thickness of the 29 th layer is 100.43 nm; the geometric thickness of the 30 th layer is 179.6 nm; the geometric thickness of the 31 st layer is 220.46 nm; the geometric thickness of the 32 nd layer is 501.88 nm; the geometric thickness of the 33 th layer is 205.84 nm; the 34 th layer has the geometric thickness of 1286.99 nm; the geometric thickness of the 35 th layer is 201.95 nm; the 36 th layer has a geometric thickness of 394 nm; the geometric thickness of the 37 th layer is 127.31 nm; the geometric thickness of the 38 th layer is 382.37 nm; the 39 th layer has a geometric thickness of 192.4 nm; the geometric thickness of the 40 th layer is 492.21 nm; the geometric thickness of the 41 st layer is 222.87 nm; the 42 th layer has a geometric thickness of 1191.05 nm; the 43 th layer has a geometric thickness of 121.45 nm; the geometric thickness of the 44 th layer is 703.46 nm; the geometric thickness of the 45 th layer is 236.75 nm; the geometric thickness of the 46 th layer is 1169.74 nm; the geometric thickness of the 47 th layer is 153.54 nm;

the interference cut-off film system structure (3) adopts a structure with 42 layers of geometric thickness in total, the first layer in the interference cut-off film system structure (3) is a germanium film layer, the last layer is a silicon monoxide film layer, the even layers are silicon monoxide film layers, the odd layers are germanium film layers, and the design wavelength is 1400 nm; in the interference cut film system structure (3): the geometric thickness of the 1 st layer is 65.08 nm; the geometric thickness of the 2 nd layer is 141.53 nm; the 3 rd layer has the geometric thickness of 108.85 nm; the geometrical thickness of the 4 th layer is 193.53 nm; the 5 th layer has the geometric thickness of 67.98 nm; the 6 th layer has the geometric thickness of 230.76 nm; the geometric thickness of the 7 th layer is 72.9 nm; the geometric thickness of the 8 th layer is 224.18 nm; the geometric thickness of the 9 th layer is 87.92 nm; the 10 th layer has a geometric thickness of 142.18 nm; the geometric thickness of the 11 th layer is 117.18 nm; the geometric thickness of the 12 th layer is 146.48 nm; the geometric thickness of the 13 th layer is 83.65 nm; the geometric thickness of the 14 th layer is 236.15 nm; the geometric thickness of the 15 th layer is 61.58 nm; the 16 th layer has a geometric thickness of 406.54 nm; the geometric thickness of the 17 th layer is 84.64 nm; the 18 th layer has a geometric thickness of 360.26 nm; the geometric thickness of the 19 th layer is 82.92 nm; the geometric thickness of the 20 th layer is 402.94 nm; the geometric thickness of the 21 st layer is 132.66 nm; the geometric thickness of the 22 nd layer is 160.62 nm; the geometric thickness of the 23 rd layer is 192.07 nm; the 24 th layer has a geometric thickness of 381.77 nm; the geometric thickness of the 25 th layer is 56.66 nm; the geometric thickness of the 26 th layer is 451.21 nm; the geometric thickness of the 27 th layer is 132.57 nm; the geometric thickness of the 28 th layer is 313.82 nm; the geometric thickness of the 29 th layer is 91.12 nm; the geometric thickness of the 30 th layer is 349.7 nm; the geometric thickness of the 31 st layer is 506.17 nm; the geometric thickness of the 32 nd layer is 1082.94 nm; the geometric thickness of the 33 th layer is 454.03 nm; the 34 th layer has the geometric thickness of 1072.78 nm; the geometric thickness of the 35 th layer is 474.3 nm; the 36 th layer geometric thickness is 1064.21 nm; the geometric thickness of the 37 th layer is 448.05 nm; the geometric thickness of the 38 th layer is 1077.17 nm; the 39 th layer has a geometric thickness of 480.36 nm; the geometric thickness of the 40 th layer is 1054.08 nm; the geometric thickness of the 41 st layer is 407 nm; the 42 th layer had a geometric thickness of 463.88 nm.

2. The dual bandpass narrowband filter for gas detection according to claim 1, wherein the substrate (1) is one of single crystal silicon, sapphire, germanium and calcium fluoride.

3. The dual bandpass narrowband filter for gas detection according to claim 2, wherein the substrate (1) is single-crystal silicon having a diameter of 100mm and a thickness of 0.49 ± 0.02 mm.

4. A method for manufacturing a dual-bandpass narrow-band filter for gas detection according to any one of claims 1 to 3, comprising the steps of:

s1, cleaning the substrate by using an ultrasonic cleaner;

s2, placing the substrate into a fixture and placing the fixture into a vacuum cavity of a coating machine, vacuumizing, and keeping the constant temperature for more than 30min, wherein the heating temperature of a coating umbrella is 150 ℃ and the heating temperature of a light control sheet is 150 ℃;

s9, repeating S1-S6 to complete the plating of the 42 film layers of the interference cut-off film system structure;

5. The method of claim 4, wherein in S3-S10, the thickness and deposition rate of the film are controlled by indirect light control monitoring and quartz crystal monitoring.

6. The method of claim 5, further comprising performing adhesion verification on the coated dual-bandpass narrowband filter.

7. The method of claim 6, wherein the adhesion test is a Poggera film test: firstly, boiling for 2h, then soaking for 72h, and then carrying out a cold-hot cycle test and a salt spray test.

8. The method of claim 7, wherein the dual bandpass narrowband filter for gas detection is tested using a Fourier Infrared spectrometer.