CN215219220U - Narrow-band filter - Google Patents

Abstract

The utility model discloses a narrow-band filter, the structure of the membrane system is the membrane system (0.5HL0.5H) satisfying the lambda/4 periodic symmetry^SAnd (0.5LH0.5L)^SWherein, λ is wavelength, H is optical thickness layer of λ/4 of germanium, L is optical thickness layer of λ/4 of silicon monoxide, and S is period number. The utility model adopts the membrane system structure to satisfy lambda/4 periodic symmetry (0.5HL0.5H)^SAnd (0.5LH0.5L)^SAnd the narrow-band filter is formed by selecting germanium and silicon monoxide as coating materials, has high transmissivity and small central wavelength tolerance, can greatly improve the signal-to-noise ratio, and is tested IGood sexual feeling and high accuracy.

Description

Narrow-band filter

Technical Field

The utility model belongs to the technical field of infrared optical coating, concretely relates to narrowband optical filter.

Background

Carbon dioxide is a carbon oxide of the formula CO₂The gas is colorless and tasteless at normal temperature and is common greenhouse gas, accounting for 0.03-0.04% of the total volume of the atmosphere, and a large amount of carbon dioxide can cause greenhouse effectGlobal warming; the requirement for CO in 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.

According to data retrieval, the optical filters commonly found in the market mainly exist: the central wavelength tolerance is too large, the test accuracy is poor, signal flooding is easy to generate, high-concentration measurement is not facilitated, and the signal-to-noise ratio is poor.

SUMMERY OF THE UTILITY MODEL

In order to solve the above problems, an object of the present invention is to provide a CO filter with high transmittance, small central wavelength tolerance, greatly improved signal-to-noise ratio, good consistency and high accuracy₂A narrowband filter for a gas sensor.

An object of the present invention is to provide a manufacturing method of the above narrow band filter.

In order to achieve the above purpose, the technical scheme of the utility model is realized like this: a narrow band filter for CO₂A gas sensor having a membrane system structure satisfying lambda/4 periodic symmetry (0.5HL0.5H)^SAnd (0.5LH0.5L)^SWherein, λ is wavelength, H is optical thickness layer of λ/4 of germanium, L is optical thickness layer of λ/4 of silicon monoxide, and S is period number.

Preferably, the narrowband filter comprises a substrate, a main film system structure layer and an interference cut-off film system structure layer, wherein the substrate is positioned between the main film system structure layer and the interference cut-off film system structure layer, and the main film system structure layer and the interference cut-off film system structure layer both use germanium and silicon monoxide as coating materials;

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

Preferably, the structure of the main film structure layer adopts:

G/(0.5HL0.5H)⁶1.5(0.5HL0.5H)⁶2.15(0.5LH0.5L)⁷3.88(0.5LH0.5L)⁷/Air；

wherein G is monocrystalline silicon, H is a lambda/4 optical thickness film layer of germanium, L is a lambda/4 optical thickness film layer of silicon monoxide, Air is Air, and lambda is 1300-1500 nm.

Preferably, the interference cut-off film system structure layer (3) adopts the following structure:

G/(0.5HL0.5H)⁷/Air；

wherein G is monocrystalline silicon, H is a lambda/4 optical thickness film layer of germanium, L is a lambda/4 optical thickness film layer of silicon monoxide, Air is Air, and lambda is 8400-8600 nm.

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

Compared with the prior art, the utility model adopts the membrane system structure to satisfy the lambda/4 periodic symmetry (0.5HL0.5H)^SAnd (0.5LH0.5L)^SMoreover, the narrow-band optical filter formed by selecting germanium and silicon monoxide as coating materials has the characteristics of high transmissivity, small central wavelength tolerance, great improvement of signal-to-noise ratio, good test consistency and high accuracy.

Drawings

Fig. 1 is a schematic structural diagram of a narrowband optical filter provided in embodiment 1 of the present invention;

fig. 2 is a spectral transmittance curve of a main film structure in a narrowband filter obtained in example 2 of the present invention;

fig. 3 is a spectral transmittance curve of an interference cut film system structure in a narrow band pass filter obtained in example 2 of the present invention;

fig. 4 is a spectrum transmittance curve of the double-sided coating film of the narrow-band filter obtained in example 2 of the present invention.

In the figure, 1, a substrate, 2, a main film system structure layer, and 3, an interference cut film system structure layer.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in 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 are not intended to limit the invention.

An embodiment of the utility model provides a narrowband filter for CO₂A gas sensor, as shown in FIG. 1, has a membrane system structure satisfying lambda/4 periodic symmetry (0.5HL0.5H)^SAnd (0.5LH0.5L)^SWherein, λ is wavelength, H is optical thickness layer of λ/4 of germanium, L is optical thickness layer of λ/4 of silicon monoxide, and S is period number.

After adopting the scheme, the film system (0.5HL0.5H) which satisfies lambda/4 optical thickness period symmetry is adopted by adopting the film system structure^SAnd (0.5LH0.5L)^SThe narrow-band optical filter formed by selecting germanium and silicon monoxide as coating materials has the characteristics of high transmissivity, small central wavelength tolerance, high signal-to-noise ratio, good test consistency and high accuracy; in addition, the center wavelength of the middle and far infrared narrow-band filter is 4.26 mu m +/-20 nm, the peak transmittance Tp is more than or equal to 88 percent, the bandwidth is 180 +/-20 nm, 400-11200 nm (except for a pass band), Tavg is less than 0.5 percent, and the filter can be more accurately used for CO₂And (5) detecting gas.

Further, as shown in fig. 1, the narrow-band filter includes a substrate 1, a main film system structure layer 2 and an interference cut-off film system structure layer 3, 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 both use germanium and silicon monoxide as coating materials.

Further, the film layer adjacent to the substrate 1 is a first layer, the first layer in the main film structure layer 2 is a silicon monoxide film layer, the last layer is a silicon monoxide film layer, even layers are germanium film layers, and odd layers are silicon monoxide film layers; in the interference cut-off film system structure layer 3, the first layer is a silicon monoxide film layer, the last layer is a silicon monoxide film layer, the even layers are germanium film layers, and the odd layers are silicon monoxide film layers.

By adopting the narrow-band optical filter which is composed of the substrate, the main film system structure layer 2 and the interference cut-off film system structure layer 3, wherein the main film system structure layer 2 and the interference cut-off film system structure layer 3 are both made of germanium and silicon monoxide, the narrow-band optical filter has the characteristics of high transmissivity, small central wavelength tolerance, great improvement of signal-to-noise ratio, good test consistency and high accuracy.

Further, the structure of the primary film structure layer 2 adopts:

G/(0.5HL0.5H)⁶1.5(0.5HL0.5H)⁶2.15(0.5LH0.5L)⁷3.88(0.5LH0.5L)⁷/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 preferably 1400 nm.

Further, the structure of the interference cut-off film system structure layer 3 adopts:

G/(0.5HL0.5H)⁷/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 preferably 8500 nm.

Thus, in the primary film structure layer 2: the geometric thickness of the 1 st layer is 180.84 nm; the geometric thickness of the 2 nd layer is 82.9 nm; the 3 rd layer has the geometric thickness of 162.76 nm; the geometric thickness of the 4 th layer is 82.15 nm; the 5 th layer has the geometric thickness of 179.84 nm; the geometric thickness of the 6 th layer is 72.55 nm; the 7 th layer has the geometric thickness of 187.82 nm; the geometric thickness of the 8 th layer is 81.77 nm; the 9 th layer has a geometric thickness of 155.64 nm; the geometric thickness of the 10 th layer is 85.58 nm; the geometric thickness of the 11 th layer is 175.74 nm; the geometric thickness of the 12 th layer is 82.63 nm; the geometric thickness of the 13 th layer is 289.66 nm; the geometric thickness of the 14 th layer is 137.37 nm; the geometric thickness of the 15 th layer is 276.26 nm; the 16 th layer has a geometric thickness of 118.45 nm; the geometric thickness of the 17 th layer is 249.6 nm; the 18 th layer has a geometric thickness of 142.25 nm; the 19 th layer has a geometric thickness of 277.44 nm; the geometric thickness of the 20 th layer is 117.17 nm; the geometric thickness of the 21 st layer is 271.29 nm; the geometric thickness of the 22 nd layer is 126.69 nm; the geometric thickness of the 23 rd layer is 299.65 nm; the 24 th layer has a geometric thickness of 134.44 nm; the geometric thickness of the 25 th layer is 369.42 nm; the geometric thickness of the 26 th layer is 176.23 nm; the geometric thickness of the 27 th layer is 399.07 nm; the geometric thickness of the 28 th layer is 184.42 nm; the geometric thickness of the 29 th layer is 405.9 nm; the geometric thickness of the 30 th layer is 183.56 nm; the geometric thickness of the 31 st layer is 406.25 nm; the geometric thickness of the 32 nd layer is 180.49 nm; the geometric thickness of the 33 th layer is 402.17 nm; the 34 th layer has the geometric thickness of 173.58 nm; the geometric thickness of the 35 th layer is 374.93 nm; the geometric thickness of the 36 th layer is 170.24 nm; the geometric thickness of the 37 th layer is 400.94 nm; the geometric thickness of the 38 th layer is 116.58 nm; the 39 th layer has a geometric thickness of 352.25 nm; the geometric thickness of the 40 th layer is 313.85 nm; the geometric thickness of the 41 st layer is 713.31 nm; the 42 th layer has a geometric thickness of 322.43 nm; the geometric thickness of the 43 th layer is 711 nm; the geometric thickness of the 44 th layer is 316.23 nm; the geometric thickness of the 45 th layer is 712.13 nm; the geometric thickness of the 46 th layer is 329.44 nm; the geometric thickness of the 47 th layer is 838.19 nm; the 48 th layer has a geometric thickness of 323.71 nm; the geometric thickness of the 49 th layer is 695.64 nm; the geometric thickness of the 50 th layer is 314.01 nm; the geometric thickness of the 51 st layer is 750.99 nm; the geometric thickness of the 52 th layer is 354.68 nm; the geometric thickness of the 53 th layer is 356.14 nm;

in the interference cut-off film system structure layer 3: the geometric thickness of the 1 st layer is 112.3 nm; the geometric thickness of the 2 nd layer is 84.12 nm; the 3 rd layer has the geometric thickness of 1227.67 nm; the geometric thickness of the 4 th layer is 512.97 nm; the 5 th layer has the geometric thickness of 1217.52 nm; the 6 th layer has the geometric thickness of 484.83 nm; the 7 th layer has the geometric thickness of 1041.4 nm; the geometric thickness of the 8 th layer is 483.37 nm; the 9 th layer has a geometric thickness of 1199.84 nm; the 10 th layer has a geometric thickness of 484.92 nm; the geometric thickness of the 11 th layer is 1039.56 nm; the geometric thickness of the 12 th layer is 483.15 nm; the geometric thickness of the 13 th layer is 1224.48 nm; the geometric thickness of the 14 th layer is 500.92 nm; the geometric thickness of the 15 th layer is 925.04 nm; the 16 th layer has a geometric thickness of 66.7 nm; the geometric thickness of the 17 th layer is 94.5 nm; the 18 th layer has a geometric thickness of 299.91 nm; the 19 th layer has a geometric thickness of 539.42 nm;

the utility model discloses the equipment that uses mainly has: 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, a 40-point light control, a 6-point crystal film thickness control, an Aifa cold pump and the like; a Fourier transform infrared spectrometer; an ultrasonic cleaning machine; microscopes, and the like.

Further, the substrate 1 is one of single crystal silicon, sapphire, germanium and calcium fluoride.

Thus, the substrate 1 is one of single crystal silicon, sapphire, germanium, and calcium fluoride, and can be used as a substrate for a narrowband filter.

The embodiment 1 of the present invention adopts the middle and far infrared narrowband filter composed of the substrate 1, the main film system structure layer 2 and the interference cut-off film system structure layer 3, and selects the film system structure of the narrowband filter to satisfy the lambda/4 periodic symmetry (0.5HL0.5H)^SAnd (0.5LH0.5L)^SAnd germanium and silicon monoxide are selected as coating materials to manufacture the main film system structure layer 2 and the interference cut-off film system structure layer 3, so that the narrow-band filter has the characteristics of high transmissivity, small central wavelength tolerance, great improvement of signal-to-noise ratio, good test consistency and high accuracy.

As shown in fig. 2 to 4, the narrowband filter provided in embodiment 1 of the present invention is obtained by the following manufacturing method, which includes the following steps:

s1, cleaning the substrate 1 by an ultrasonic cleaner;

s2, placing the substrate 1 into a clamp, placing the clamp into a vacuum cavity, vacuumizing, and keeping the constant temperature of the coating umbrella for more than 30min at the heating temperature of 150 ℃ and the heating temperature of the light control sheet in the vacuumizing process;

s3, vacuumizing to 5.0X 10^-3Pa, carrying out pre-melting treatment on the 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 1 for 10-15 min by adopting a Hall ion source to obtain a bombarded substrate; the purpose of the bombardment is to clean all the dust on the surface of the substrate 1 and heat to increase the adhesiveness between the substrate 1 and the first coating film;

s5, vacuum degree of 1.0X 10^-3Under the condition of Pa, vacuum evaporation coating technology is adopted(evaporation-resistant thermal evaporation coating technology) depositing and coating a first SiO film layer on the surface of one side of the bombarded substrate obtained in the step S4; wherein the evaporation rate in the deposition process by adopting the vacuum evaporation coating technology is 15-25A/S; in the deposition process, the thickness and the deposition rate of the film layer are controlled by adopting a light-operated monitoring method and a quartz crystal monitoring method, so that the thickness of the film layer can be monitored more accurately;

s6, vacuum degree of 1.0X 10^-3Under the condition of Pa, depositing and plating a second germanium film layer on the surface of the first SiO film layer, which is far away from the substrate 1, by adopting a vacuum evaporation coating technology (an electron gun evaporation coating technology); wherein, the evaporation rate in the deposition process by adopting the vacuum evaporation coating technology is 6A/S; in the deposition process, the thickness and the deposition rate of the film layer are controlled by adopting a light-operated monitoring method and a quartz crystal monitoring method, so that the thickness of the film layer can be monitored more accurately;

s7, repeating S5 and S6 in sequence, plating the 3 rd to 53 th film layers of the main film structure;

s8, cooling the optical filter with the 53 film layer coated with the main film structure layer in a vacuum chamber for 1-2h, then breaking the vacuum and taking out;

s9, repeating S1-S6 to complete the plating of 19 layers of films of the interference cut-off film system structure;

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

Thus, a monocrystalline silicon material with the diameter of 100mm and the thickness of 0.49 +/-0.02 mm is adopted to be used as a substrate 1 after being cleaned by an ultrasonic cleaner, a multilayer dielectric film is evaporated on the substrate 1, the material of the coating dielectric film is germanium and silicon monoxide, and the film system of the main film system structure layer 2 adopts the following steps: g/(0.5HL0.5H)⁶1.5(0.5HL0.5H)⁶2.15(0.5LH0.5L)⁷3.88(0.5LH0.5L)⁷The interference cut-off film system structure film layer 2 adopts the following film system: g/(0.5HL0.5H)⁷the/Air, in this embodiment, optimizes the thickness of each film layer in the film train to achieve the following functions: the central wavelength is 4.26um +/-20 nm, the peak transmittance Tp is more than or equal to 88 percent, the bandwidth is 180 +/-20 nm, and the Tavg is less than 0.5 percent except for a pass band in 400-11200. Wherein the coating film adopts a vacuum thermal evaporation film deposition method.

Further, the method further comprises: and adopting a Baigela film test to carry out adhesion verification on the coated narrow-band optical filter.

Further, the specific method for verifying the adhesiveness is as follows: boiling for 2h, soaking for 72h, performing a cold-hot cycle test, a salt spray test and the like, wherein if no stripping occurs on the narrow-band filter, the film layer is not damaged.

The narrow-band filter obtained by the above method has a film system structure satisfying lambda/4 periodic symmetry (0.5HL0.5H)^SAnd (0.5LH0.5L)^SThe narrow-band filter composed of the substrate 1, the main film system structure layer 2 and the interference cut-off film system structure layer 3 has the characteristics of high transmissivity, small central wavelength tolerance, great improvement of signal-to-noise ratio, good test consistency and high accuracy.

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 should be covered by the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.

Claims (6)

1. A narrow band filter for CO₂The gas sensor is characterized in that the structure of the membrane system is a membrane system (0.5HL0.5H) satisfying lambda/4 periodic symmetry^SAnd (0.5LH0.5L)^SWherein, λ is wavelength, H is optical thickness layer of λ/4 of germanium, L is optical thickness layer of λ/4 of silicon monoxide, and S is period number.

2. A narrowband filter according to claim 1, characterized in that the narrowband filter comprises a substrate (1), a main film structure layer (2) and an interference cut-off film structure layer (3), the substrate (1) is located between the main film structure layer (2) and the interference cut-off film structure layer (3), and the main film structure layer (2) and the interference cut-off film structure layer (3) both use germanium and silicon monoxide as coating materials.

3. A narrowband filter according to claim 2, wherein the film adjacent to the substrate (1) is a first layer, the first layer in the main film structure layer (2) is a silicon monoxide film, the last layer is a silicon monoxide film, even layers are germanium films, and odd layers are silicon monoxide films; in the interference cut-off film system structure layer (3), the first layer is a silicon monoxide film layer, the last layer is a silicon monoxide film layer, the even layers are germanium film layers, and the odd layers are silicon monoxide film layers.

4. A narrowband filter according to claim 3, characterised in that the primary film-structured layer (2) is structured as:

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

wherein G is monocrystalline silicon, H is a lambda/4 optical thickness film layer of germanium, L is a lambda/4 optical thickness film layer of silicon monoxide, Air is Air, and lambda is 1300-1500 nm.

5. A narrow-band filter according to claim 3, wherein the interference cut-off film structure layer (3) is formed by:

G/(0.5HL0.5H)⁷/Air；

wherein G is monocrystalline silicon, H is a lambda/4 optical thickness film layer of germanium, L is a lambda/4 optical thickness film layer of silicon monoxide, Air is Air, and lambda is 8400-8600 nm.

6. A narrowband filter according to claim 4 or 5, characterised in that the substrate (1) is one of monocrystalline silicon, sapphire, germanium and calcium fluoride.

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