A medium-wave infrared bandpass filter and infrared detection system

Abstract

The present invention discloses a medium-wave infrared bandpass filter and an infrared detection system, wherein the medium-wave infrared bandpass filter comprises a substrate, a main film system and a secondary film system, wherein the main film system is located on a first side of the substrate, the secondary film system is located on a second side of the substrate, the second side is opposite to the first side, the main film system comprises 22 layers of high refractive index film layers and low refractive index film layers alternately stacked from the substrate to the outside according to the main film system structure, and the secondary film system comprises 40 layers of high refractive index film layers and low refractive index film layers alternately stacked from the substrate to the outside according to the secondary film system structure. The medium-wave infrared bandpass filter can have a good light transmission effect in the wavelength range of 4.5-5.0 μm, with an average transmittance of more than 92%, and is highly cut off in the 1-4.2 μm and 5.3-7.5 μm bands, with an average transmittance of less than 1%, which can effectively reduce stray light interference and improve the sensitivity and detection efficiency of the infrared detector.

Description

Technical Field

[0001] The invention relates to an infrared filter, in particular to a medium-wave infrared bandpass filter and an infrared detection system. Background Art

[0002] Optical bandpass filters are very important optical equipment components. Their main function is to divide the spectrum within a certain range into two parts. One part that does not allow light to pass is called the cutoff area, and the other part that requires light to pass fully is called the bandpass area. Bandpass filters play a very important role in various optical systems. Infrared bandpass filters are mainly used in infrared spectrum detection systems. They have the function of filtering out background clutter and are of great significance for improving the signal-to-noise ratio and improving the performance of optical systems. For example, medium-wave infrared bandpass filters have very important applications in aerospace and military fields. However, in the existing technology, infrared detection products in the 4.5~5.0μm band cannot meet the requirements of high anti-interference ability. Summary of the invention

[0003] The present invention provides a medium-wave infrared bandpass filter and an infrared detection system, which can achieve good light transmission effect in the 4.5-5.0 μm wavelength range, with an average transmittance greater than 92%, and highly cut off in the 1-4.2 μm and 5.3-7.5 μm bands, with an average transmittance less than 1%, and can effectively reduce stray light interference and improve the sensitivity and detection efficiency of the infrared detector.

[0004] To achieve the above object, the embodiments of the present invention adopt the following technical solutions:

[0005] A medium-wave infrared bandpass filter comprises a substrate, a main film system and a secondary film system, wherein the main film system is located on a first side of the substrate, the secondary film system is located on a second side of the substrate, the second side is opposite to the first side, the main film system comprises 22 layers of high refractive index film layers and low refractive index film layers alternately stacked from the substrate to the outside according to the main film system structure, and the main film system structure is:

[0006] Base / 100nmH, 168.16nmL, 289.58nmH, 289.28nmL, 94.57nmH, 207.05nmL, 119.59nmH, 207.52nmL, 110.11nmH, 142.63nmL, 141.76nmH, 193.42nmL, 102.84nmH, 200.24nmL, 117.89nmH, 215.78nmL, 120.3nmH, 227.84nmL, 133.46nmH, 295.93nmL, 1 75.74nmH, 93.36nmL, 100.25nmH, 267.95nmL, 147.34nmH, 378.79nmL, 118.88nmH, 218.73nmL, 161.95nmH, 265.16nmL, 17 0.91nmH, 292.49nmL, 190.64nmH, 252.43nmL, 121.57nmH, 369.07nmL, 189.81nmH, 239.76nmL, 177.43nmH, 308.71nmL, 20 3.62nmH, 392.15nmL, 240.24nmH, 477.95nmL, 188.33nmH, 313.4nmL, 174.28nmH, 425.13nmL, 215.07nmH, 395.61nmL, 21 2.94nmH, 554.72nmL, 287.21nmH, 445.7nmL, 228.52nmH, 459.98nmL, 270.58nmH, 531.94nmL, 389.87nmH, 483.45nmL, 296 .24nmH, 331.56nmL, 267.24nmH, 585.94nmL, 325.66nmH, 662.1nmL, 349.42nmH, 741.38nmL, 411.56nmH, 649.64nmL, 344.25nmH, 670.92nmL, 407.07nmH, 678.32nmL, 446.68nmH, 553.64nmL, 302.63nmH, 688.27nmL, 556.68nmH, 1038.85nmL / air;

[0007] The secondary film system includes 40 layers of high refractive index film layers and low refractive index film layers alternately stacked from the base to the outside according to the secondary film system structure. The secondary film system structure is:

[0008] substrate / 100 nmH, 136.77 nmL, 1181.43 nmH, 1431.38 nmL, 870.15 nmH, 1070.45 nmL, 825.44 nmH, 1364.95 nmL, 637.07 nmH, 1455.45 nmL, 762.61 nmH, 1121.56 nmL, 840.25 nmH, 1433.45 nmL, 522.8 nmH, 894.92 nmL / air;

[0009] Among them, H represents a high refractive index film layer, L represents a low refractive index film layer, and the thickness of H and L is the thickness of the film layer.

[0010] According to one aspect of the present invention, the primary film system and the secondary film system are formed by a physical vapor deposition method.

[0011] According to one aspect of the present invention, the substrate is a germanium substrate.

[0012] According to one aspect of the present invention, the high refractive index film layer is a germanium film layer, and the low refractive index film layer is a zinc sulfide film layer.

[0013] According to one aspect of the present invention, the germanium film layer is coated by physical vapor deposition using electron gun evaporation.

[0014] According to one aspect of the present invention, the zinc sulfide film layer is deposited by physical vapor deposition using a resistance boat thermal evaporation method.

[0015] According to one aspect of the present invention, the refractive index of the high refractive index film layer is greater than 3.

[0016] According to one aspect of the present invention, the medium-wave infrared bandpass filter has an average transmittance greater than 92% in the wavelength range of 4.5-5.0 μm.

[0017] According to one aspect of the present invention, the medium-wave infrared bandpass filter has an average transmittance of less than 1% in the wavelength ranges of 1-4.2 μm and 5.3-7.5 μm.

[0018] An infrared detection system includes: an infrared detector for converting received infrared radiation into an electrical signal; a signal processing module for processing the electrical signal output by the infrared detector to extract information; and also includes the medium-wave infrared bandpass filter as described above, wherein the medium-wave infrared bandpass filter is arranged on the photosensitive side of the infrared detector.

[0019] Advantages of the implementation of the present invention: The medium-wave infrared bandpass filter provided by the present invention has a bandpass spectral range of 4.5~5.0μm and an average transmittance of >92%; the cut-off spectral range is 1~4.2μm and 5.3~7.5μm, and the average transmittance is <1%, which can well improve the signal-to-noise ratio, enhance the signal strength, and improve the detector response rate; it can be used in various infrared optical detection systems to reduce the influence of background clutter, enhance the signal strength, and improve the detector response and resolution. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0021] Figure 1 This is a schematic diagram of the structure of the medium-wave infrared bandpass filter of the present invention;

[0022] Figure 2 This is the spectral transmittance curve of the germanium substrate.

[0023] Figure 3 This is the spectral transmittance curve of the main film system of the medium-wave infrared bandpass filter.

[0024] Figure 4 This is the spectral transmittance curve of the mid-wave infrared bandpass filter sub-film system.

[0025] Figure 5 It is the spectral transmittance curve of the medium-wave infrared bandpass filter. DETAILED DESCRIPTION

[0026] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0027] Embodiment 1

[0028] like Figure 1 , Figure 2 , Figure 3 , Figure 4 and Figure 5As shown, a medium-wave infrared bandpass filter, the working band range is 4.5~5.0μm, including a substrate 2, a main film system 1 and a secondary film system 3, the main film system is located on the first side of the substrate, the secondary film system is located on the second side of the substrate, the second side is opposite to the first side, the main film system and the secondary film system described in this embodiment are multi-layer film irregular film system structures, the main film system includes high refractive index film layers and low refractive index film layers alternately stacked from the substrate to the outside according to the main film system structure, a total of 22 layers, the main film system structure is:

[0029] substrate / 100 nmH, 981.15 nmL, 260.54 nmH, 818.82 nmL, 423.4 nmH, 538.62 nmL, 400.43 nmH, 781.62 nmL, 298.85 nmH, 694.75 nmL, 403.62 nmH, 667.75 nmL, 347.66 nmH, 731.58 nmL, 382.17 nmH, 625.62 nmL, 452.13 nmH, 674.99 nmL, 595.49 nmH, 1098.45 nmL, 286.06 nmH, 496.05 nmL / air;

[0030] The secondary film system includes high refractive index film layers and low refractive index film layers alternately stacked from the base to the outside according to the secondary film system structure, totaling 40 layers. The secondary film system structure is:

[0031] Base / 100nmH, 169.81nmL, 154.76nmH, 259.89nmL, 95.34nmH, 206.72nmL, 134.06nmH, 206.41nmL, 135.87nmH, 254.68nmL, 127.89nmH, 75.57nmL, 87.07nmH, 252.36nmL, 155.39nmH, 257.11nmL, 136.54nmH, 267.54nmL, 182.39nmH, 311.22nmL, 13 6.12 nmH, 252.39 nmL, 173.42 nmH, 344.56 nmL, 187.76 nmH, 483.27 nmL, 165.85 nmH, 380.84 nmL, 307.22 nmH, 404.6 nmL, 143.22 nmH, 511.18 nmL, 197.25 nmH, 389.52 nmL, 350.9 nmH, 211.97 nmL, 209.51 nmH, 361.78 nmL, 347.58 nmH, 595.17 nmL / air;

[0032] Among them, H represents a high refractive index film layer, L represents a low refractive index film layer, and the thickness of the film layer is H and L. In practical applications, the substrate can be a transparent film, including but not limited to glass, silicon substrate, germanium substrate, etc.

[0033] In this embodiment, the main film system and the secondary film system can be formed by a physical vapor deposition method.

[0034] In practical applications, the refractive index of the high refractive index film layer is greater than 3.

[0035] In this embodiment, the provided medium-wave infrared bandpass filter uses an infrared Fourier spectrometer to measure the optical properties of the film. The spectral curve corresponding to the main film system on the front side is shown in Figure 3 , the spectral curve corresponding to the back secondary film system can be found in Figure 4 , the spectral curve of the filter after double-sided coating can be found in Figure 5 , achieving an average transmittance of more than 92% in the wavelength range of 4.5~5.0μm; and an average transmittance of less than 1% in the wavelength ranges of 1~4.2μm and 5.3~7.5μm.

[0036] The medium-wave infrared bandpass filter described in this embodiment has an average transmittance greater than 92% in the wavelength range of 4.5-5.0 μm, and an average transmittance less than 1% in the wavelength range of 1-4.2 μm and 5.3-7.5 μm. It can well improve the signal-to-noise ratio, enhance the signal strength, and improve the detector response rate; it can be used in various infrared optical detection systems to reduce the impact of background clutter, enhance signal strength, and improve detector response and resolution.

[0037] Embodiment 2

[0038] like Figures 1 to 5 As shown, a medium-wave infrared bandpass filter, with an operating band range of 4.5~5.0μm, includes a germanium substrate 2, a main film system 1 and a secondary film system 3, the main film system and the secondary film system are generated by a physical vapor deposition method, the main film system is located on the first side of the substrate, the secondary film system is located on the second side of the germanium substrate, the second side is opposite to the first side, the main film system includes germanium film layers and zinc sulfide film layers alternately stacked from the germanium substrate to the outside according to the main film system structure, a total of 22 layers, the main film system structure is:

[0039] Germanium substrate / 100nmH, 981.15nmL, 260.54nmH, 818.82nmL, 423.4nmH, 538.62nmL, 400.43nmH, 781.62nmL, 298.85nmH, 694.75nmL, 403.62nmH, 667.75nmL, 347.66nmH, 731.58nmL, 382.17nmH, 625.62nmL, 452.13nmH, 674.99nmL, 595.49nmH, 1098.45nmL, 286.06nmH, 496.05nmL / air;

[0040] The sub-film system includes germanium film layers and zinc sulfide film layers alternately stacked from the base to the outside according to the sub-film system structure, totaling 40 layers. The sub-film system structure is:

[0041] Germanium substrate / 100nmH, 169.81nmL, 154.76nmH, 259.89nmL, 95.34nmH, 206.72nmL, 134.06nmH, 206.41nmL, 135.87nmH, 254.68nmL, 127.89nmH, 75.57nmL, 87.07nmH, 252.36nmL, 155.39nmH, 257.11nmL, 136.54nmH, 267.54nmL, 182.39nmH, 311.22nmL, 1 36.12 nmH, 252.39 nmL, 173.42 nmH, 344.56 nmL, 187.76 nmH, 483.27 nmL, 165.85 nmH, 380.84 nmL, 307.22 nmH, 404.6 nmL, 143.22 nmH, 511.18 nmL, 197.25 nmH, 389.52 nmL, 350.9 nmH, 211.97 nmL, 209.51 nmH, 361.78 nmL, 347.58 nmH, 595.17 nmL / air;

[0042] Wherein, H represents the germanium film layer, L represents the zinc sulfide film layer, and the value before H and L is the thickness of the film layer.

[0043] In this embodiment, the germanium film layer is physically vapor deposited by electron gun evaporation, and the zinc sulfide film layer is physically vapor deposited by resistance boat thermal evaporation. Specifically, the coating is carried out by physical vapor deposition (PVD), wherein the germanium (GE) material is evaporated by electron gun, and the zinc sulfide (ZNS) material is evaporated by resistance boat thermal evaporation. In order to increase the firmness and reliability of the film layer, an ion source is used to assist in cleaning the substrate surface before coating, and the initial coating temperature is maintained at about 160°C. During the coating process, the vacuum degree is maintained below 2×10E-3Pa, the material evaporation rate is controlled within 10A / s, and a quartz crystal oscillator is used to monitor the film thickness.

[0044] The refractive index of the germanium film layer is greater than 3.

[0045] In this embodiment, the provided medium-wave infrared bandpass filter uses an infrared Fourier spectrometer to measure the optical properties of the film. The spectral curve corresponding to the main film system on the front side is shown in Figure 3 , the spectral curve corresponding to the back secondary film system can be found in Figure 4 , the spectral curve of the filter after double-sided coating can be found in Figure 5 , achieving an average transmittance of more than 92% in the wavelength range of 4.5~5.0μm; and an average transmittance of less than 1% in the wavelength ranges of 1~4.2μm and 5.3~7.5μm.

[0046] The medium-wave infrared bandpass filter described in this embodiment has an average transmittance greater than 92% in the wavelength range of 4.5-5.0 μm, and an average transmittance less than 1% in the wavelength range of 1-4.2 μm and 5.3-7.5 μm. It can well improve the signal-to-noise ratio, enhance the signal strength, and improve the detector response rate; it can be used in various infrared optical detection systems to reduce the impact of background clutter, enhance signal strength, and improve detector response and resolution.

[0047] Embodiment 3

[0048] An infrared detection system includes: an infrared detector for converting received infrared radiation into an electrical signal; a signal processing module for processing the electrical signal output by the infrared detector to extract information; and a medium-wave infrared bandpass filter as described in Example 1 or Example 2, wherein the medium-wave infrared bandpass filter is arranged on the photosensitive side of the infrared detector. Through the medium-wave infrared bandpass filter, an average transmittance greater than 92% is achieved in the wavelength range of 4.5 to 5.0 μm; and an average transmittance less than 1% in the wavelength range of 1 to 4.2 μm and 5.3 to 7.5 μm. Infrared light with a wavelength of 4.5 to 5.0 μm is selectively transmitted to ensure that the detector only receives infrared radiation with a wavelength of 4.5 to 5.0 μm related to the target. The signal-to-noise ratio can be well improved, the signal strength can be enhanced, the detector response rate can be improved, the influence of background clutter can be reduced, the signal strength can be enhanced, and the detector response and resolution can be improved.

[0049] The above is only a 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 any technician familiar with the art within the technical scope disclosed in the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention shall be based on the protection scope of the claims.

Claims

1. A mid-wave infrared bandpass filter, comprising a substrate, a main film system and a secondary film system, wherein the main film system is located on a first side of the substrate, and the secondary film system is located on a second side of the substrate, the second side being opposite to the first side, characterized in that: The main film system includes 22 layers of high refractive index film layers and low refractive index film layers alternately stacked from the base to the outside according to the main film system structure. The main film system structure is: substrate / 100 nmH, 981.15 nmL, 260.54 nmH, 818.82 nmL, 423.4 nmH, 538.62 nmL, 400.43 nmH, 781.62 nmL, 298.85 nmH, 694.75 nmL, 403.62 nmH, 667.75 nmL, 347.66 nmH, 731.58 nmL, 382.17 nmH, 625.62 nmL, 452.13 nmH, 674.99 nmL, 595.49 nmH, 1098.45 nmL, 286.06 nmH, 496.05 nmL / air; The secondary film system includes 40 layers of high refractive index film layers and low refractive index film layers alternately stacked from the base to the outside according to the secondary film system structure. The secondary film system structure is: Base / 100nmH, 169.81nmL, 154.76nmH, 259.89nmL, 95.34nmH, 206.72nmL, 134.06nmH, 206.41nmL, 135.87nmH, 254.68nmL, 127.89nmH, 75.57nmL, 87.07nmH, 252.36nmL, 155.39nmH, 257.11nmL, 136.54nmH, 267.54nmL, 182.39nmH, 311.22nmL, 13 6.12 nmH, 252.39 nmL, 173.42 nmH, 344.56 nmL, 187.76 nmH, 483.27 nmL, 165.85 nmH, 380.84 nmL, 307.22 nmH, 404.6 nmL, 143.22 nmH, 511.18 nmL, 197.25 nmH, 389.52 nmL, 350.9 nmH, 211.97 nmL, 209.51 nmH, 361.78 nmL, 347.58 nmH, 595.17 nmL / air; Among them, H represents a high refractive index film layer, L represents a low refractive index film layer, H and L are the thicknesses of the film layers, the high refractive index film layer is a germanium film layer, and the low refractive index film layer is a zinc sulfide film layer.

2. The medium-wave infrared bandpass filter according to claim 1, characterized in that: The main film system and the secondary film system are generated by a physical vapor deposition method.

3. The medium-wave infrared bandpass filter according to claim 1, characterized in that: The substrate is a germanium substrate.

4. The medium-wave infrared bandpass filter according to claim 1, characterized in that: The germanium film layer is coated by physical vapor deposition using an electron gun evaporation method.

5. The medium-wave infrared bandpass filter according to claim 1, characterized in that: The zinc sulfide film layer is physically vapor deposited by thermal evaporation in a resistance boat.

6. The medium-wave infrared bandpass filter according to claim 1, characterized in that: The refractive index of the high refractive index film layer is greater than 3.

7. The medium-wave infrared bandpass filter according to any one of claims 1 to 6, characterized in that: The medium-wave infrared bandpass filter has an average transmittance greater than 92% within the wavelength range of 4.5-5.0 μm.

8. The medium-wave infrared bandpass filter according to any one of claims 1 to 6, characterized in that: The medium-wave infrared bandpass filter has an average transmittance of less than 1% within the wavelength ranges of 1-4.2 μm and 5.3-7.5 μm.

9. An infrared detection system comprising: An infrared detector for converting received infrared radiation into electrical signals; a signal processing module for processing the electrical signals output by the infrared detector to extract information; characterized in that it also includes a medium-wave infrared bandpass filter as described in any one of claims 1 to 8, wherein the medium-wave infrared bandpass filter is arranged on the photosensitive side of the infrared detector.

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