Medium-wave infrared band-pass filter and infrared detection system

Abstract

The invention discloses a medium-wave infrared band-pass filter and an infrared detection system.The medium-wave infrared band-pass filter comprises a substrate, a main film system and a secondary film system, 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, and the main film system is located on the first side of the substrate. The main film system comprises 22 high-refractive-index film layers and low-refractive-index film layers which are alternately overlapped outwards from the substrate according to the structure of the main film system, and the secondary film system comprises 40 high-refractive-index film layers and low-refractive-index film layers which are alternately overlapped outwards from the substrate according to the structure of the secondary film system. According to the medium-wave infrared band-pass optical filter, a good light transmission effect can be achieved within the wavelength interval of 4.5-5.0 microns, the average transmittance is larger than 92%, high cut-off is achieved within the wave bands of 1-4.2 microns and 5.3-7.5 microns, the average transmittance is smaller than 1%, stray light interference can be effectively reduced, and the sensitivity and detection efficiency of an infrared detector are improved.

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 crucial components in optical equipment. Their primary function is to divide the spectrum within a specific range into two parts: the cutoff region, which blocks light from passing, and the passband region, which allows light to pass freely. Bandpass filters play a crucial role in various optical systems. Infrared bandpass filters are primarily used in infrared spectroscopy systems, filtering out background noise and playing a crucial role in improving the signal-to-noise ratio and the performance of optical systems. For example, mid-wave infrared bandpass filters have crucial applications in aerospace and military applications. However, existing infrared detection products in the 4.5-5.0 μm band do not meet the requirements for high anti-interference capabilities. 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 4.5-5.0μm wavelength range, with an average transmittance of more than 92%, and highly cut off in the 1-4.2μm and 5.3-7.5μm bands, with an average transmittance of less than 1%. It can effectively reduce stray light interference and improve the sensitivity and detection efficiency of the infrared detector.

[0004] To achieve the above objectives, the embodiments of the present invention adopt the following technical solutions: A medium-wave infrared bandpass filter comprises a substrate, a main film system, and a secondary film system. 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. The main film system comprises 22 layers of high-refractive-index film layers and low-refractive-index film layers alternately stacked from the substrate outward according to the main film system structure. The main film system structure is as follows: Substrate / 100 nmH, 168.16 nmH, 289.58 nmH, 289.28 nmH, 94.57 nmH, 207.05 nmH, 119.59 nmH, 207.52 nmH, 110.11 nmH, 142.63 nmH, 141.76 nmH, 193.42 nmH, 102.84 nmH, 200.24 nmH, 117.89 nmH, 215.78 nmH, 120.3 nmH, 227.84 nmH, 133.46 nmH, 295.93 nmH, 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 .24 nmH, 331.56 nmH, 267.24 nmH, 585.94 nmH, 325.66 nmH, 662.1 nmH, 349.42 nmH, 741.38 nmH, 411.56 nmH, 649.64 nmH, 344.25 nmH, 670.92 nmH, 407.07 nmH, 678.32 nmH, 446.68 nmH, 553.64 nmH, 302.63 nmH, 688.27 nmH, 556.68 nmH, 1038.85 nmH / 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 outward according to the secondary film system structure. The secondary film system structure is: 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; Wherein, H represents the high refractive index film layer, L represents the low refractive index film layer, and the number between H and L is the thickness of the film layer.

[0005] 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.

[0006] According to one aspect of the present invention, the substrate is a germanium substrate.

[0007] 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.

[0008] According to one aspect of the present invention, the germanium film layer is deposited by physical vapor deposition using an electron gun evaporation method.

[0009] 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.

[0010] According to one aspect of the present invention, the refractive index of the high refractive index film layer is greater than 3.

[0011] 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 to 5.0 μm.

[0012] 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.

[0013] 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.

[0014] 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 cutoff spectral range is 1~4.2μm and 5.3~7.5μm, and the average transmittance is less than 1%, which can greatly improve the signal-to-noise ratio, enhance the signal intensity, and improve the detector response rate; and can be used in various infrared optical detection systems to reduce the influence of background clutter, enhance the signal intensity, and improve the detector response and resolution. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. 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 any creative work.

[0016] Figure 1 This is a schematic structural diagram of the medium-wave infrared bandpass filter according to the present invention; Figure 2 This is the spectral transmittance curve of the germanium substrate.

[0017] Figure 3 This is the spectral transmittance curve of the main film system of the medium-wave infrared bandpass filter.

[0018] Figure 4 This is the spectral transmittance curve of the mid-wave infrared bandpass filter secondary film system.

[0019] Figure 5 is the spectral transmittance curve of the medium-wave infrared bandpass filter. DETAILED DESCRIPTION

[0020] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. 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 making creative efforts are within the scope of protection of the present invention.

[0021] Example 1

[0022] like Figure 1 、 Figure 2 、 Figure 3 、 Figure 4 and Figure 5As shown, a medium-wave infrared bandpass filter with an operating band range of 4.5-5.0 μm includes a substrate 2, a main film system 1, and a secondary film system 3. 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. The main film system and the secondary film system described in this embodiment are multi-layer irregular film structures. The main film system includes high-refractive index film layers and low-refractive index film layers alternately stacked from the substrate outward according to the main film system structure, totaling 22 layers. The main film system structure is as follows: 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 outward according to the secondary film system structure. The secondary film system structure is as follows: Substrate / 100 nmH, 169.81 nmH, 154.76 nmH, 259.89 nmH, 95.34 nmH, 206.72 nmH, 134.06 nmH, 206.41 nmH, 135.87 nmH, 254.68 nmH, 127.89 nmH, 75.57 nmH, 87.07 nmH, 252.36 nmH, 155.39 nmH, 257.11 nmH, 136.54 nmH, 267.54 nmH, 182.39 nmH, 311.22 nmH, 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; Wherein, H represents a high refractive index film layer, L represents a low refractive index film layer, and the thickness of the film layer is represented by H and L. In practical applications, the substrate may be a transparent film, including but not limited to glass, silicon substrate, germanium substrate, etc.

[0023] In this embodiment, the primary film system and the secondary film system can be formed by a physical vapor deposition method.

[0024] In practical applications, the refractive index of the high refractive index film layer is greater than 3.

[0025] In this embodiment, the optical properties of the provided medium-wave infrared bandpass filter are measured using an infrared Fourier spectrometer. The spectral curve corresponding to the main film system on the front side is shown in FIG. Figure 3 , the spectral curve corresponding to the back secondary film system can be found in Figure 4 , the spectral curve of the double-sided coated filter can be found in Figure 5 , achieving an average transmittance greater than 92% in the wavelength range of 4.5~5.0μm; and an average transmittance less than 1% in the wavelength range of 1~4.2μm and 5.3~7.5μm.

[0026] The medium-wave infrared bandpass filter described in this embodiment has an average transmittance greater than 92% in the 4.5-5.0μm wavelength range and less than 1% in the 1-4.2μm and 5.3-7.5μm wavelength ranges. This significantly improves the signal-to-noise ratio, enhances signal strength, and increases detector responsivity. 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.

[0027] Example 2

[0028] like Figures 1 to 5 As shown, a medium-wave infrared bandpass filter with an operating band range of 4.5-5.0 μm 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 formed by physical vapor deposition. 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 germanium substrate, the second side being opposite to the first side. The main film system includes germanium film layers and zinc sulfide film layers alternately stacked from the germanium substrate outward according to the main film system structure, totaling 22 layers. The main film system structure is as follows: Germanium 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 germanium film layers and zinc sulfide film layers alternately stacked from the base outward according to the secondary film system structure, totaling 40 layers. The secondary film system structure is: 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; Wherein, H represents the germanium film layer, L represents the zinc sulfide film layer, and the number between H and L is the thickness of the film layer.

[0029] In this embodiment, the germanium film layer is deposited using electron gun evaporation via physical vapor deposition (PVD), while the zinc sulfide film layer is deposited using resistance boat thermal evaporation. Specifically, the films are deposited using physical vapor deposition (PVD), with the germanium (GE) material evaporated using an electron gun and the zinc sulfide (ZNS) material evaporated using resistance boat thermal evaporation. To enhance the film's durability and reliability, an ion source is used to assist in cleaning the substrate surface before coating, maintaining an initial coating temperature of approximately 160°C. During the coating process, the vacuum level is maintained below 2×10E-3 Pa, the evaporation rate of each material is controlled within 10A / s, and a quartz crystal oscillator is used to monitor film thickness.

[0030] The refractive index of the germanium film layer is greater than 3.

[0031] In this embodiment, the optical properties of the provided medium-wave infrared bandpass filter are measured using an infrared Fourier spectrometer. The spectral curve corresponding to the main film system on the front side is shown in FIG. Figure 3 , the spectral curve corresponding to the back secondary film system can be found in Figure 4 , the spectral curve of the double-sided coated filter can be found in Figure 5, achieving an average transmittance greater than 92% in the wavelength range of 4.5~5.0μm; and an average transmittance less than 1% in the wavelength range of 1~4.2μm and 5.3~7.5μm.

[0032] The medium-wave infrared bandpass filter described in this embodiment has an average transmittance greater than 92% in the 4.5-5.0μm wavelength range and less than 1% in the 1-4.2μm and 5.3-7.5μm wavelength ranges. This significantly improves the signal-to-noise ratio, enhances signal strength, and increases detector responsivity. 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.

[0033] Example 3

[0034] An infrared detection system includes: 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; and a medium-wave infrared bandpass filter as described in Example 1 or Example 2, disposed on the photosensitive side of the infrared detector. The medium-wave infrared bandpass filter achieves an average transmittance greater than 92% within the 4.5-5.0μm wavelength range and an average transmittance less than 1% within the 1-4.2μm and 5.3-7.5μm wavelength ranges. This selectively transmits infrared light with a wavelength of 4.5-5.0μm, ensuring that the detector only receives infrared radiation with a wavelength of 4.5-5.0μm that is relevant to the target. This can significantly improve the signal-to-noise ratio, enhance signal strength, increase detector response rate, reduce the impact of background clutter, enhance signal strength, and improve detector response and resolution.

[0035] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in the present invention should be included in the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be based on the scope of protection 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, and the thickness of H and L is the thickness of the 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 high refractive index film layer is a germanium film layer, and the low refractive index film layer is a zinc sulfide film layer.

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

6. The medium-wave infrared bandpass filter according to claim 4, characterized in that: The zinc sulfide film layer is physically vapor deposited by thermal evaporation in a resistance boat.

7. 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.

8. The medium-wave infrared bandpass filter according to any one of claims 1 to 7, 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.

9. The medium-wave infrared bandpass filter according to any one of claims 1 to 7, 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.

10. 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 9, wherein the medium-wave infrared bandpass filter is arranged on the photosensitive side of the infrared detector.

Images