Infrared long-wave-pass optical filter with working wave band of 5500-14000 nm

Abstract

The utility model discloses an infrared long-wave-pass optical filter with a working wave band of 5500-14000 nm, the infrared long-wave-pass optical filter with the working wave band of 5500-14000 nm 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, the secondary film system is located on a 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 28 high-refractive-index film layers and low-refractive-index film layers which are alternately overlaid outwards from the substrate according to the structure of the main film system, and the secondary film system comprises 48 high-refractive-index film layers and low-refractive-index film layers which are alternately overlaid outwards from the substrate according to the structure of the secondary film system. According to the infrared long-wave-pass optical filter, a good light transmission effect can be achieved within the wavelength interval of 5500-14000 nm, high cut-off is achieved within the wave band of 400-5000 nm, stray light interference can be effectively reduced, and the sensitivity and sensing efficiency of an infrared sensor are improved.

Description

Technical Field

[0001] The utility model relates to an infrared filter, in particular to an infrared long-wave pass filter with a working band of 5500-14000nm. Background Art

[0002] Optical filters are optical devices used to select the required radiation band. Long-wave pass filters allow light with a wavelength greater than the selected wavelength to pass through, and cut off light with a wavelength less than the selected wavelength. In optical components, light energy is lost due to reflection from the surface of the component. In order to reduce the reflection loss on the surface of the component, a transparent dielectric film is often deposited on the surface of the optical component, so that the component can achieve the effect of reducing reflection and increasing transmission within a specific wavelength range. In other unnecessary wavelength ranges, it increases reflection and reduces transmission, that is, cuts off. Due to the continuous development of coating technology, long-wave pass filters, as a very practical optical film product, have been widely used in a variety of infrared sensing and imaging temperature measurement devices in the fields of industry, agriculture, scientific research, and military.

[0003] The band with high transmittance of electromagnetic radiation in atmospheric transmission is called the atmospheric window. The infrared atmospheric window mainly includes near infrared (780~1000nm), short-wave infrared (1000~2500nm), medium-wave infrared (3000~5000nm), and long-wave infrared (8000~14000nm). The development of infrared imaging technology started with long-wave infrared, and then gradually expanded to medium-wave infrared and short-wave infrared. When selecting the working band of infrared thermal imager, the principle to be followed is to make the most of infrared radiation energy and use the atmospheric infrared transmission window. Experiments show that it is beneficial to choose long-wave infrared to detect objects in the temperature range of -73℃~+349℃. This temperature range includes the temperature of most objects, so it is widely used in our production and life.

[0004] Silicon has excellent infrared optical and physical properties. Since silicon crystals have good transparency to infrared light in the 1500~14000nm band in the atmosphere, they are ideal window materials for infrared sensors. In addition, silicon substrates are low-cost and easy to realize wafer-level materials, which are suitable for mass production. Therefore, the application prospects of silicon-based filters are very broad, and they have an irreplaceable position in the field of infrared optics. However, in the existing technology, infrared sensing products in the 5500~14000nm band cannot meet the requirements of high anti-interference ability. Utility Model Content

[0005] The utility model provides an infrared long-wave pass filter with a working band of 5500-14000nm, which can have a good light transmission effect in the wavelength range of 5500~14000nm, with an average transmittance of more than 85%, and a high cutoff in the band of 400~5000nm, with an average transmittance of less than 1%, which can effectively reduce stray light interference and improve the sensitivity and sensing efficiency of infrared sensors.

[0006] In order to achieve the above object, the embodiment of the utility model adopts the following technical solution:

[0007] An infrared long-wave pass filter with a working band of 5500-14000nm, 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, and the main film system comprises 28 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:

[0008] Substrate / 155 nmH, 250 nmL, 233 nmH, 340 nmL, 162 nmH, 340 nmL, 166 nmH, 396 nmL, 211 nmH, 352 nmL, 191 nmH, 283 nmL, 181 nmH, 403 nmL, 223 nmH, 469 nmL, 273 nmH, 426nmL, 281 nmH, 488 nmL, 221 nmH, 627 nmL, 224 nmH, 429 nmL, 372 nmH, 280 nmL, 296nmH, 1048nmL / air;

[0009] The secondary film system includes 48 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:

[0010] Substrate / 69 nmH, 157 nmL, 138 nmH, 191 nmL, 120 nmH, 191 nmL, 105 nmH, 186 nmL, 85 nmH, 169 nmL, 107 nmH, 181 nmL, 109 nmH, 176 nmL, 101 nmH, 189 nmL, 98 nmH, 204nmL, 131 nmH, 351 nmL, 105 nmH, 217 nmL, 116 nmH, 325 nmL, 139 nmH, 232 nmL, 167 nmH, 256 nmL, 144 nmH, 283 nmL, 155 nmH, 415 nmL, 130 nmH, 388 nmL, 160 nmH, 386 nmL, 240nmH, 301 nmL, 184 nmH, 305 nmL, 177 nmH, 494 nmL, 223 nmH, 301 nmL, 754 nmH, 35 nmL, 314 nmH, 889 nmL / air;

[0011] 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.

[0012] According to one aspect of the present invention, the main film system and the secondary film system are generated by a physical vapor deposition method.

[0013] According to one aspect of the present invention, the substrate is a silicon substrate.

[0014] According to one aspect of the utility model, the high refractive index film layer is a germanium film layer, and the low refractive index film layer is a zinc sulfide film layer.

[0015] According to one aspect of the utility model, the germanium film layer is coated by physical vapor deposition using electron gun evaporation.

[0016] According to one aspect of the utility model, the zinc sulfide film layer is physically vapor deposited by thermal evaporation using a resistance boat.

[0017] According to one aspect of the present invention, the refractive index of the high refractive index film layer is greater than 3.

[0018] According to one aspect of the utility model, the infrared long-wave pass filter with an operating band of 5500-14000nm has an average transmittance greater than 85% within the wavelength range of 5500~14000nm.

[0019] According to one aspect of the utility model, the infrared long-wave pass filter with an operating band of 5500-14000nm has an average transmittance of less than 1% within the wavelength range of 400~5000nm.

[0020] Advantages of the implementation of the utility model: The utility model provides an infrared long-wave pass filter with a working band of 5500-14000nm, a spectral range of the bandpass zone of 5500~14000nm, and an average transmittance of >85%; a spectral range of the cut-off zone of 400~5000nm, and an average transmittance of <1%, which can well improve the signal-to-noise ratio, enhance the signal strength, and improve the sensor response rate; it can be used in various infrared optical sensing systems to reduce the influence of background clutter, enhance the signal strength, and improve the sensor response and resolution. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] 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 creative work.

[0022] Figure 1 This is a schematic diagram of the structure of the infrared long-wave pass filter with a working band of 5500-14000nm described in the utility model;

[0023] Figure 2 This is the spectral transmittance curve of silicon substrate.

[0024] Figure 3 This is the spectral transmittance curve of the main film system of the infrared longwave pass filter with a working band of 5500-14000nm.

[0025] Figure 4 This is the spectral transmittance curve of the infrared longwave pass filter sub-film system with a working band of 5500-14000nm.

[0026] Figure 5 This is the spectral transmittance curve of the infrared longwave pass filter with a working band of 5500-14000nm. DETAILED DESCRIPTION

[0027] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0028] Embodiment 1

[0029] like Figure 1 , Figure 2 , Figure 3 and Figure 4 As shown, an infrared long-wave pass filter with a working band of 5500-14000nm, the working band range is 5500~14000nm, 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 28 layers, the main film system structure is:

[0030] Substrate / 155 nmH, 250 nmL, 233 nmH, 340 nmL, 162 nmH, 340 nmL, 166 nmH, 396 nmL, 211 nmH, 352 nmL, 191 nmH, 283 nmL, 181 nmH, 403 nmL, 223 nmH, 469 nmL, 273 nmH, 426nmL, 281 nmH, 488 nmL, 221 nmH, 627 nmL, 224 nmH, 429 nmL, 372 nmH, 280 nmL, 296nmH, 1048nmL / air;

[0031] 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 48 layers. The secondary film system structure is:

[0032] Substrate / 69 nmH, 157 nmL, 138 nmH, 191 nmL, 120 nmH, 191 nmL, 105 nmH, 186 nmL, 85 nmH, 169 nmL, 107 nmH, 181 nmL, 109 nmH, 176 nmL, 101 nmH, 189 nmL, 98 nmH, 204nmL, 131 nmH, 351 nmL, 105 nmH, 217 nmL, 116 nmH, 325 nmL, 139 nmH, 232 nmL, 167 nmH, 256 nmL, 144 nmH, 283 nmL, 155 nmH, 415 nmL, 130 nmH, 388 nmL, 160 nmH, 386 nmL, 240nmH, 301 nmL, 184 nmH, 305 nmL, 177 nmH, 494 nmL, 223 nmH, 301 nmL, 754 nmH, 35 nmL, 314 nmH, 889 nmL / air;

[0033] 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 H and L. In practical applications, the substrate may be a transparent film, including but not limited to glass, silicon substrate, germanium substrate, etc.

[0034] In this embodiment, the main film system and the secondary film system can be formed by a physical vapor deposition method.

[0035] In practical applications, the refractive index of the high refractive index film layer is greater than 3.

[0036] In this embodiment, the infrared long-wave pass filter provided 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 FIG. 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 greater than 85% in the wavelength range of 5500~14000nm; and an average transmittance less than 1% in the wavelength range of 400~5000nm.

[0037] The infrared long-wave pass filter with a working band of 5500-14000nm described in this embodiment has an average transmittance greater than 85% in the wavelength range of 5500~14000nm; and an average transmittance less than 1% in the wavelength range of 400~5000nm. It can well improve the signal-to-noise ratio, enhance the signal strength, and improve the sensor response rate; it can be used in various infrared optical sensing systems to reduce the influence of background clutter, enhance the signal strength, and improve the sensor response and resolution.

[0038] Embodiment 2

[0039] like Figures 1 to 4 As shown, an infrared long-wave pass filter with a working band of 5500-14000nm, the working band range is 5500~14000nm, including a silicon substrate, 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 silicon substrate, the secondary film system is located on the second side of the silicon 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 silicon substrate to the outside according to the main film system structure, a total of 28 layers, the main film system structure is:

[0040] Silicon substrate / 155 nmH, 250 nmL, 233 nmH, 340 nmL, 162 nmH, 340 nmL, 166 nmH, 396nmL, 211 nmH, 352 nmL, 191 nmH, 283 nmL, 181 nmH, 403 nmL, 223 nmH, 469 nmL, 273 nmH, 426 nmL, 281 nmH, 488 nmL, 221 nmH, 627 nmL, 224 nmH, 429 nmL, 372 nmH, 280 nmL, 296nmH, 1048nmL / air;

[0041] The sub-film system includes germanium film layers and zinc sulfide film layers alternately stacked from the silicon substrate outward according to the sub-film system structure, totaling 48 layers. The sub-film system structure is:

[0042] Silicon substrate / 69 nmH, 157 nmL, 138 nmH, 191 nmL, 120 nmH, 191 nmL, 105 nmH, 186nmL, 85 nmH, 169 nmL, 107 nmH, 181 nmL, 109 nmH, 176 nmL, 101 nmH, 189 nmL, 98 nmH, 204nmL, 131 nmH, 351 nmL, 105 nmH, 217 nmL, 116 nmH, 325 nmL, 139 nmH, 232 nmL, 167 nmH, 256 nmL, 144 nmH, 283 nmL, 155 nmH, 415 nmL, 130 nmH, 388 nmL, 160 nmH, 386 nmL, 240nmH, 301 nmL, 184 nmH, 305 nmL, 177 nmH, 494 nmL, 223 nmH, 301 nmL, 754 nmH, 35 nmL, 314 nmH, 889 nmL / air;

[0043] 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.

[0044] 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.

[0045] The refractive index of the germanium film layer is greater than 3.

[0046] In this embodiment, the infrared long-wave pass filter provided 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 FIG. 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 greater than 85% in the wavelength range of 5500~14000nm; and an average transmittance less than 1% in the wavelength range of 400~5000nm.

[0047] The infrared long-wave pass filter with a working band of 5500-14000nm described in this embodiment has an average transmittance greater than 85% in the wavelength range of 5500~14000nm; and an average transmittance less than 1% in the wavelength range of 400~5000nm. It can well improve the signal-to-noise ratio, enhance the signal strength, and improve the sensor response rate; it can be used in various infrared optical sensing systems to reduce the influence of background clutter, enhance the signal strength, and improve the sensor response and resolution.

[0048] The above is only a specific implementation of the utility model, but the protection scope of the utility model is not limited thereto. Any changes or substitutions that can be easily thought of by any technician familiar with the technical field within the technical scope disclosed in the utility model should be included in the protection scope of the utility model. Therefore, the protection scope of the utility model shall be based on the protection scope of the claims.

Claims

1. An infrared long-wave pass filter with a working band of 5500-14000nm, 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 is opposite to the first side, and characterized in that: The main film system includes 28 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 / 155 nmH, 250 nmL, 233 nmL, 340 nmL, 162 nmH, 340 nmL, 166 nmH, 396 nmL, 211nmH, 352 nmL, 191 nmH, 283 nmL, 181 nmH, 403 nmL, 223 nmH, 469 nmL, 273 nmH, 426 nmL, 281 nmH, 488 nmL, 221 nmH, 627 nmL, 224 nmH, 429 nmL, 372 nmH, 280 nmL, 296nmH, 1048nmL / air; The secondary film system includes 48 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: Substrate / 69 nmH, 157 nmL, 138 nmH, 191 nmL, 120 nmH, 191 nmL, 105 nmH, 186 nmL, 85nmH, 169 nmL, 107 nmH, 181 nmL, 109 nmH, 176 nmL, 101 nmH, 189 nmL, 98 nmH, 204 nmL, 131 nmH, 351 nmL, 105 nmH, 217 nmL, 116 nmH, 325 nmL, 139 nmH, 232 nmL, 167 nmH, 256nmL, 144 nmH, 283 nmL, 155 nmH, 415 nmL, 130 nmH, 388 nmL, 160 nmH, 386 nmL, 240 nmH, 301 nmL, 184 nmH, 305 nmL, 177 nmH, 494 nmL, 223 nmH, 301 nmL, 754 nmH, 35 nmL, 314nmH, 889 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 infrared long-wave pass filter with a working band of 5500-14000nm 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 infrared long-wave pass filter with a working band of 5500-14000nm according to claim 1, characterized in that: The substrate is a silicon substrate.

4. The infrared long-wave pass filter with a working band of 5500-14000nm 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 infrared long-wave pass filter with a working band of 5500-14000 nm 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 infrared long-wave pass filter with a working band of 5500-14000 nm 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 infrared long-wave pass filter with a working band of 5500-14000 nm according to claim 1, characterized in that: The refractive index of the high refractive index film layer is greater than 3.

8. The infrared long-wave pass filter with an operating band of 5500-14000 nm according to any one of claims 1 to 7, characterized in that: The infrared long-wave pass filter with a working band of 5500-14000nm has an average transmittance greater than 85% within the wavelength range of 5500~14000nm.

9. The infrared long-wave pass filter with an operating band of 5500-14000 nm according to any one of claims 1 to 7, characterized in that: The infrared long-wave pass filter with a working band of 5500-14000nm has an average transmittance of less than 1% within the wavelength range of 400-5000nm.

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