Infrared detector and infrared imager

Abstract

An infrared detector includes: an infrared light absorber for absorbing infrared light and converting the infrared light into heat; a thermoelectric element, the infrared light absorber being disposed on the thermoelectric element; an electrical signal detector for detecting a change in electrical properties of the thermoelectric element; the infrared light absorber including a plurality of carbon nanotubes forming a network structure and a plurality of carbon particles located in the network structure. The invention further relates to an infrared imager.

Description

TECHNICAL FIELD

[0001] The present application relates to an infrared detector and an infrared imager, in particular to an infrared detector and an infrared imager based on carbon nanotubes. BACKGROUND

[0002] Infrared radiation is electromagnetic wave with wavelength between visible light and microwave, which cannot be perceived by human eyes. In order to perceive the existence of such radiation and measure its intensity, it must be converted into other physical quantities that can be perceived and measured. Infrared detector is a device that converts infrared signal into electrical signal output, which can be used to detect the existence of infrared or the size of infrared energy, and is widely used in medical, prospecting, military and life fields. Because of its low price and stable technical performance, it has become a research hotspot for more and more people.

[0003] Infrared detector can be divided into active infrared detector and passive infrared detector. Active infrared detector is composed of infrared transmitter, infrared receiver and alarm system. When a person or object contacts the infrared emitted by the infrared transmitter, the infrared receiver produces signal change, so that the alarm is alarmed. Passive infrared detector does not include infrared emitter. When external infrared signal is generated and received, a certain signal will be generated, so as to detect the existence and energy of infrared. An infrared detector, whether active infrared detector or passive infrared detector, should include at least one object sensitive to infrared radiation, which can be called detection element or infrared absorber. However, the absorption rate of the existing infrared absorber is low. SUMMARY

[0004] Therefore, it is necessary to provide an infrared detector and an infrared imager, which has high absorption rate.

[0005] An infrared detector includes: an infrared light absorber for absorbing infrared light and converting the infrared light into heat; a thermoelectric element, wherein the infrared light absorber is arranged on the thermoelectric element; an electrical signal detector for detecting the change of electrical property of the thermoelectric element; the infrared light absorber includes a plurality of carbon nanotubes and a plurality of carbon particles, the plurality of carbon nanotubes form a network structure, and the plurality of carbon particles are located in the network structure.

[0006] An infrared imager includes: an infrared detector assembly for converting infrared light into electrical signal; a signal processor for processing and calculating the electrical signal to obtain thermal field distribution data; an infrared image display for displaying an infrared thermal image according to the thermal field distribution data; the infrared detector assembly includes a plurality of infrared detectors arranged in array.

[0007] Compared with the prior art, the present application sets carbon nanotubes and carbon particles in a solvent to form a light absorber pre-liquid, and after spraying the light absorber pre-liquid, a light absorber capable of absorbing infrared light can be formed, which not only has a high absorption rate of up to 99.9%, but also has an omnidirectional absorption performance. BRIEF DESCRIPTION OF DRAWINGS

[0008] Figure 1 A transmission electron microscope (TEM) photo of the carbon nanotubes dispersed in the ethanol solution in the first embodiment of the present application.

[0009] Figure 2 A scanning electron microscope (SEM) photo of the carbon black powder with a diameter of 20 microns in the first embodiment of the present application.

[0010] Figure 3 An optical photo of the carbon nanotubes suspension with 1 gram of carbon black powder added in the first embodiment of the present application.

[0011] Figure 4 An optical photo of the carbon nanotubes suspension with 5 grams of carbon black powder added in the first embodiment of the present application.

[0012] Figure 5 An optical photo of the carbon nanotubes suspension with 7 grams of carbon black powder added in the first embodiment of the present application.

[0013] Figure 6 An optical photo of a toy before spraying the light absorber pre-liquid in the second embodiment of the present application.

[0014] Figure 7 An optical photo of a toy after spraying the light absorber pre-liquid in the second embodiment of the present application.

[0015] Figure 8 A SEM photo of the pure carbon nanotube dispersion spraying layer in the second embodiment of the present application.

[0016] Figure 9 A SEM photo of a quartz substrate after spraying the light absorber pre-liquid in the second embodiment of the present application.

[0017] Figure 10 A SEM photo of the pure carbon nanotube dispersion spraying layer in the second embodiment of the present application.

[0018] Figure 11 A SEM photo of the light absorber in the second embodiment of the present application.

[0019] Figure 12 Another SEM photo of the pure carbon nanotube dispersion spraying layer in the second embodiment of the present application.

[0020] Figure 13 Another SEM photograph of the light absorber described in the second embodiment of the present application.

[0021] Figure 14 Reflectance spectrum of the light absorber described in the second embodiment of the present application in the visible wavelength range.

[0022] Figure 15 Reflectance spectrum of the light absorber described in the second embodiment of the present application in the near-infrared wavelength range.

[0023] Figure 16 Reflectance spectrum of the light absorber described in the second embodiment of the present application in the mid-infrared wavelength range.

[0024] Figure 17 Reflectance spectrum of the light absorber described in the second embodiment of the present application at an incident angle of 15°.

[0025] Figure 18 Reflectance spectrum of the light absorber described in the second embodiment of the present application at an incident angle of 30°.

[0026] Figure 19 Reflectance spectrum of the light absorber described in the second embodiment of the present application at an incident angle of 45°.

[0027] Figure 20 Reflectance spectrum of the light absorber described in the second embodiment of the present application at an incident angle of 60°.

[0028] Figure 21 Thermographic photograph of the light absorber containing 5 g of carbon particles (the light absorber pre-liquid is sprayed on a silicon substrate) described in the second embodiment of the present application.

[0029] Figure 22 Time-temperature curve of the light absorber containing 5 g of carbon particles (the light absorber pre-liquid is sprayed on a silicon substrate) described in the second embodiment of the present application exposed to sunlight.

[0030] Figure 23 Optical photograph after the light absorber pre-liquid is sprayed on a quartz substrate in the second embodiment of the present application.

[0031] Figure 24 Thermal image captured by the infrared thermal imager in the second embodiment of the present application.

[0032] Figure 25 Optical photograph of a water droplet falling on the surface of the light absorber in the second embodiment of the present application.

[0033] Figure 26 Structural schematic diagram of an infrared detector provided in the third embodiment of the present application.

[0034] Figure 27 Structure diagram of infrared imager provided by the third embodiment of the present application.

[0035] Figure 28 Structure diagram of infrared camouflage fabric provided by the fourth embodiment of the present application.

[0036] Figure 29 Optical photo of infrared camouflage fabric provided by the fourth embodiment of the present application.

[0037] Figure 30 Optical photo of hand covered by infrared camouflage fabric provided by the fourth embodiment of the present application.

[0038] Figure 31 Thermal image photo of hand covered by infrared camouflage fabric provided by the fourth embodiment of the present application.

[0039] Figure 32 Structure diagram of infrared camouflage clothes provided by the fourth embodiment of the present application.

[0040] Figure 33 Structure diagram of solar energy collector provided by the fifth embodiment of the present application.

[0041] Figure 34 Structure diagram of solar energy water heater provided by the fifth embodiment of the present application.

[0042] Explanation of main element symbols

[0043] Infrared detector 100

[0044] Infrared light absorber 110

[0045] Thermoelectric element 112

[0046] Electric signal detector 114

[0047] Infrared imager 200

[0048] Infrared receiver 210

[0049] Infrared detector assembly 220

[0050] Signal processor 230

[0051] Infrared image display 240

[0052] Infrared camouflage fabric 300

[0053] Fabric substrate 310

[0054] Infrared camouflage clothes 400

[0055] Solar energy collector 500

[0056] box 502

[0057] transparent cover plate 504

[0058] thermal insulation material 506

[0059] heat absorbing plate 508

[0060] base 5080

[0061] coating 5082

[0062] fluid channel 5084

[0063] solar water heater 600

[0064] water inlet pipe 602

[0065] water outlet pipe 604

[0066] water storage tank 606

[0067] The following detailed description will further illustrate the present application in conjunction with the above-mentioned drawings. DETAILED DESCRIPTION

[0068] The infrared detector and the infrared imager provided by the present application will be further described in detail below in conjunction with the drawings and specific embodiments.

[0069] The first embodiment of the present application provides a light absorber pre-liquid, which includes a solvent, a plurality of carbon nanotubes and a plurality of carbon particles. The plurality of carbon nanotubes and the plurality of carbon particles are located in the solvent. The light absorber pre-liquid is a suspension solution.

[0070] The plurality of carbon nanotubes form a flocculent structure in the solvent. The flocculent structure refers to that the plurality of carbon nanotubes are attracted to and entangled with each other by Van der Waals force to form a network structure. That is, the carbon nanotubes are not completely dispersed in the solvent, but form a network structure in the solvent. The carbon nanotubes can be single-walled carbon nanotubes, double-walled carbon nanotubes or multi-walled carbon nanotubes. In this embodiment, the carbon nanotubes are multi-walled carbon nanotubes with an average diameter of 20 nm.

[0071] The plurality of carbon particles are located in the network structure, and each carbon particle is inserted into the network structure and surrounded or coated by the plurality of carbon nanotubes. Specifically, part of the surface of some carbon particles is in direct contact with the carbon nanotubes, and part of the surface is exposed outside. The type of the carbon particles is not limited, such as carbon black.

[0072] The type of the solvent is not limited, such as an organic solvent. Preferably, the solvent is a volatile organic solvent.

[0073] The light absorber pre-liquid in the embodiment is composed of the solvent, the plurality of carbon nanotubes and the plurality of carbon particles, the carbon particles are carbon black powder, and the solvent is ethanol.

[0074] When the mass of the carbon particles is too small, the light absorber prepared by using the light absorber pre-liquid has poor absorption performance. When the mass of the carbon particles is too large, it is difficult to spray the light absorber pre-liquid. The mass ratio of the carbon nanotubes to the carbon particles is: carbon nanotubes: carbon particles = 4:5 to 4:70. The content of the solvent can be adjusted according to actual conditions to ensure that the light absorber pre-liquid can be subjected to a spraying process. In the light absorber pre-liquid, when the solvent is 200 mL (milliliter) and the carbon nanotubes are 0.4 g (gram), the mass of the carbon particles is 0.5 g to 7 g. In the embodiment, the ethanol solvent is 200 mL, the carbon nanotubes are 0.4 g, and the carbon particles are 5 g.

[0075] The first embodiment of the application further provides a preparation method of the light absorber pre-liquid, which comprises the following steps:

[0076] S11, providing a plurality of carbon nanotubes;

[0077] S12, putting the plurality of carbon nanotubes into the solvent to perform flocculation treatment, so as to obtain a carbon nanotube suspension; and

[0078] S13, putting a plurality of carbon particles into the carbon nanotube suspension and mixing.

[0079] In step S11, the preparation method of the carbon nanotubes is not limited, for example, arc discharge method, laser evaporation method or chemical vapor deposition method. In the embodiment, the carbon nanotubes are prepared by using the chemical vapor deposition method, which comprises the following steps:

[0080] S111, growing a carbon nanotube array on a growth substrate; and

[0081] S112, scraping the carbon nanotube array from the growth substrate by using a blade or other tools to obtain a plurality of carbon nanotubes.

[0082] In step S111, the length of the plurality of carbon nanotubes in the carbon nanotube array is not limited. Preferably, the length of the carbon nanotubes is greater than 100 μm (micrometer). The plurality of carbon nanotubes are substantially parallel to each other and substantially perpendicular to the surface of the growth substrate. The carbon nanotube array provided in the embodiment is one of a single-walled carbon nanotube array, a double-walled carbon nanotube array and a multi-walled carbon nanotube array.

[0083] In this embodiment, the carbon nanotube array is prepared by chemical vapor deposition. The steps include: (a) providing a flat growth substrate, which can be a P-type or N-type silicon substrate, or a silicon substrate with an oxide layer, and preferably an 8-inch silicon substrate; (b) forming a catalyst layer on the surface of the growth substrate, which can be made of iron (Fe), cobalt (Co), nickel (Ni), or an alloy of any combination thereof; (c) annealing the growth substrate with the catalyst layer in air at 700-900°C for about 30-90 minutes; (d) placing the treated growth substrate in a reaction furnace, heating to 500-740°C in a protective gas environment, and then introducing a carbon source gas to react for about 5-30 minutes to grow the carbon nanotube array with a height greater than 100 microns. The carbon nanotube array is a pure carbon nanotube array formed by a plurality of carbon nanotubes parallel to each other and perpendicular to the growth substrate. Due to the long length of the generated carbon nanotubes, some of the carbon nanotubes can be intertwined. By controlling the growth conditions as described above, the carbon nanotube array is substantially free of impurities such as amorphous carbon or residual catalyst metal particles. In this embodiment, the carbon source gas can be acetylene or other chemically active hydrocarbons, and the protective gas can be nitrogen, ammonia, or inert gas.

[0084] In step S12, the flocculation treatment can be performed by ultrasonic dispersion or high-intensity stirring. Preferably, the flocculation treatment is performed by ultrasonic dispersion for 10-30 minutes. Due to the large specific surface area of the carbon nanotubes and the strong van der Waals force between the intertwined carbon nanotubes, the flocculation treatment does not completely disperse the carbon nanotubes in the solvent, and the carbon nanotubes are attracted and intertwined by van der Waals force to form a network structure, which can also be referred to as a flocculent structure. Figure 1 The transmission electron microscope (TEM) image of the carbon nanotubes dispersed in the ethanol solution in this embodiment is shown in Figure 2. Figure 1 As can be seen, the carbon nanotubes are connected to form a network structure.

[0085] In step S12, a dispersant can be added, which in this embodiment is polyvinylpyrrolidone (PVP).

[0086] In step S13, the mixing method is not limited, and in this embodiment, ultrasonic oscillation is used for mixing. Figure 2 The optical image of the carbon black powder in this embodiment is shown in Figure 3.

[0087] The mass ratio of carbon nanotubes and carbon particles in steps S12 and S13 is: carbon nanotubes: carbon particles = 4:5 to 4:70. The content of the solvent can be adjusted according to actual conditions to ensure that the light absorber pre-liquid can be subjected to a spraying process. Preferably, the solvent is 200 mL, the carbon nanotubes are 0.4 g, and the carbon particles are 0.5 g to 7 g.

[0088] The light absorber pre-liquid can also be prepared by mixing carbon nanotubes and carbon particles first and then dispersing them in the solvent.

[0089] Example 1

[0090] A carbon nanotube array with a height of 285 microns was grown on an 8-inch silicon wafer and scraped off the silicon wafer and placed in an ethanol solvent. Then, PVP was added (0.1 g of PVP was added per 200 mL of ethanol solvent), and ultrasonic flocculation treatment was performed using an ultrasonic cell disruptor. Finally, carbon black powder with a diameter of 10 μm was added, and ultrasonic treatment was performed for 0.5 h (hour). A stable light absorber pre-liquid was obtained. In Example 1, when 1 g of carbon black powder was added to the carbon nanotube suspension, the aggregation of the carbon nanotubes and the carbon black powder was not obvious, as shown in FIG. 1. When 5 g of carbon black powder was added to the carbon nanotube suspension, the carbon nanotubes and the carbon black powder aggregated together, as shown in FIG. 2, but the light absorber pre-liquid could still be sprayed using a spray gun, and the sprayed layer remained uniform. However, when 7 g of carbon black powder was added to the carbon nanotube suspension, the aggregation of the carbon nanotubes and the carbon black powder was very serious, and a precipitate was deposited at the bottom of the bottle, which was clearly separated from the upper liquid, as shown in FIG. 3. Figure 3 Figure 4 Figure 5 Figure 5 In Example 1, the upper liquid was transparent, which indicated that the content of carbon nanotubes in the upper liquid was very low. The precipitate was a gel-like substance and could not be used for spraying. Therefore, the addition of 5 g of carbon black powder to the carbon nanotube suspension formed by 200 mL of ethanol solvent and 0.4 g of carbon nanotubes was the optimal ratio for spraying.

[0091] The light absorber pre-liquid and the preparation method thereof have the following advantages: first, the light absorber pre-liquid can be sprayed on other objects to form a light absorber that can absorb infrared light and sunlight; second, the preparation method is simple and can be mass-produced.

[0092] A second embodiment of the present application provides a light absorber, which includes a plurality of carbon nanotubes and a plurality of carbon particles. The plurality of carbon nanotubes forms a network structure, and the plurality of carbon particles is located in the network structure. Each carbon particle is inserted into the network structure and surrounded or coated by the plurality of carbon nanotubes, and the carbon particle is in direct contact with the carbon nanotube. The network structure of the carbon nanotubes connects the plurality of carbon particles together.

[0093] ​​​Further, the light absorber can also include a substrate for supporting the light absorber. The kind, shape, thickness, etc. of the substrate are not limited. The substrate can be quartz, polymer, metal, ceramic, cloth, etc. The surface of the substrate can be planar, curved, or irregular. In this embodiment, the substrate is quartz.

[0094] The second embodiment of the present application further provides a method for preparing the light absorber, including the following steps:

[0095] S21, providing the light absorber pre-liquid; and

[0096] S22, spraying the light absorber pre-liquid on the substrate.

[0097] In step S21, the light absorber pre-liquid has been described in detail in the first embodiment, which will not be repeated here.

[0098] In step S22, the spraying method is not limited. In this embodiment, a spray gun is used for spraying, the diameter of the spray gun is 1 mm, the carrier gas is nitrogen with a pressure of 0.3 Mpa, the effective spraying range is about 150 mm, and the solution consumption is 100 ml / min.

[0099] Further, after step S22, drying can be performed by heating or the like to remove the solvent. In this embodiment, the solvent is ethanol, which is completely dried within a few minutes after spraying, and does not need any heat treatment.

[0100] Figure 6 An optical photo of the toy before spraying the light absorber pre-liquid, Figure 7 An optical photo of the toy after spraying the light absorber pre-liquid. By Figure 7 It can be seen that the light absorber pre-liquid can be uniformly sprayed on the irregular surface.

[0101] In this embodiment, the light absorber pre-liquid is sprayed on a quartz substrate to form a light absorber, Figures 8 to 23 which is a performance characterization of the light absorber.

[0102] Figure 8 A scanning electron microscope (SEM) photo of the pure carbon nanotube dispersion layer, which refers to only dispersing carbon nanotubes in a solvent, and the solute is only carbon nanotubes. Figure 9 A SEM photo of the quartz substrate after spraying the light absorber pre-liquid (light absorber). By Figure 8 and Figure 9It was found that multiple carbon nanotubes are effectively and uniformly attached to multiple carbon particles, forming a spray coating. Through the connecting effect of the carbon nanotubes, multiple carbon particles are stacked with gaps, thereby giving the light absorber multiple pores, forming a porous structure that improves light absorption.

[0103] Figure 10 SEM image of the coating layer of the pure carbon nanotube dispersion. Figure 10 In the process, the surface of the pure carbon nanotube dispersion spray coating is relatively flat, with an average surface roughness of tens of micrometers. Figure 11 This is a SEM image of the light absorber. Figure 11 In the process, the surface of the light absorber maintains the undulating morphology of the pure carbon nanotube dispersion spray coating, with carbon particles evenly distributed on the top surface.

[0104] Figure 12 Another SEM image of the pure carbon nanotube dispersion coating. Figure 13 Another SEM image of the light absorber. Figure 12 and Figure 13 It can be seen that the surface roughness of the light absorber is greater than that of the pure carbon nanotube dispersion spray coating.

[0105] Depend on Figures 10 to 13 It can be seen that the introduction of carbon particles increases the surface roughness of the light absorber, thereby improving the scattering and absorption of light on the surface of the light absorber.

[0106] Figures 14 to 16 The light absorber exhibits a reflectance spectrum under perpendicular incident and unpolarized conditions, wherein... Figure 14 The reflectance spectrum of the light absorber in the visible light wavelength range (400nm-800nm) is shown below. Figure 15 The reflectance spectrum of the light absorber in the near-infrared wavelength range (800nm-2μm) is shown below. Figure 16 The reflectance spectrum of the light absorber in the mid-infrared wavelength range (2μm-20μm).

[0107] Depend on Figures 14 to 16 It is known that, within a broad spectral range from visible light (400 nm) to mid-infrared (20 μm), the reflectivity of the light absorber decreases with increasing carbon particle content. A light absorber containing 5 g of carbon particles exhibits a reflectivity of 0.075% in the visible light wavelength range, 0.05% in the near-infrared wavelength range, and 0.02% in the mid-infrared wavelength range. Figures 14 to 16In the present application, CNT spray refers to a pure carbon nanotube dispersion liquid spray layer, CNT array refers to a carbon nanotube array, the reflectivity of the light absorber is lower than that of the pure carbon nanotube dispersion liquid spray layer, and close to that of the carbon nanotube array. The low reflectivity of the light absorber indicates that the light absorber has good light absorption performance.

[0108] Figures 17 to 20 The reflectance spectrum of the light absorber in the visible wavelength range is measured at an incident angle of 0° to 60°, wherein the incident angle refers to the angle between the light and the normal line, and the normal line is perpendicular to the surface of the light absorber. Among them, Figure 17 The reflectance spectrum of the light absorber is measured at an incident angle of 15°, Figure 18 The reflectance spectrum of the light absorber is measured at an incident angle of 30°, Figure 19 The reflectance spectrum of the light absorber is measured at an incident angle of 45°, Figure 20 The reflectance spectrum of the light absorber is measured at an incident angle of 60°. By Figures 17 to 20 It can be seen that the light absorber still has approximately the same reflectivity at different incident angles, indicating that the reflectivity of the light absorber is independent of the incident angle. This indicates that the light absorber has excellent omnidirectional absorption performance in the visible wavelength range. The "omnidirectional absorption" refers to the fact that the light absorber has a high absorption rate at each incident angle.

[0109] Figure 20 In the present application, the light absorber containing 5g of carbon particles has an absorption rate of more than 99.9% at an incident angle of 60°, which is almost the same as that of the CNT array. Therefore, the light absorber achieves an omnidirectional high absorption efficiency of 99.9% in a wide wavelength range of 400nm to 20μm, and is independent of the incident angle.

[0110] Figure 21 The thermal imager photo of the light absorber containing 5g of carbon particles (spraying the light absorber pre-liquid on the silicon substrate), Figure 22 The time-temperature curve of the light absorber containing 5g of carbon particles (spraying the light absorber pre-liquid on the silicon substrate) exposed to sunlight, and the temperature rise behavior of the light absorber under solar radiation is studied. A solar simulator is used as the radiation source, and the standard power density is 1000W / m 2 The temperature of the light absorber is monitored by a mid-infrared thermal imager. Figure 21 In the present application, at first, the sample cannot be distinguished from the surrounding environment, after 0.5s (seconds), the sample will absorb sunlight and the temperature will begin to rise, at this time the sample can be clearly distinguished from the surrounding environment, and as time increases, the temperature of the sample will rise until the temperature remains stable. Figure 22The temperature of the sample recorded by the thermal imager is shown as a function of time, wherein the spray layer of pure carbon nanotube dispersion and the silicon substrate are used as a contrast, and the light absorber containing 5g carbon particles is optimal in terms of the heating rate and the equilibrium temperature.

[0111] Figure 23 The optical photograph after spraying the light absorber pre-preparation liquid on the quartz substrate, Figure 24 The thermal image captured by the infrared thermal imager under the irradiation of the solar simulation system. Figure 23 and Figure 24 It can be seen that the light absorber can absorb sunlight and collect the heat of the sunlight. Figures 21 to 24 It shows that the light absorber has good solar heat collection performance.

[0112] Figure 25 The optical photograph of the water droplets falling on the surface of the light absorber. Figure 25 It can be seen that the contact angle of the light absorber containing 5g carbon particles with the water droplets reaches 165°, and the water droplets easily roll off, indicating that the light absorber has excellent super-hydrophobic properties and the wetting performance can remain stable without damaging the surface of the light absorber. When the water droplets slide off the surface of the light absorber, dust and dirt can be removed with the water droplets, indicating that the light absorber has good self-cleaning performance.

[0113] The light absorber and the preparation method thereof have the following advantages: first, the spraying process can be implemented on a curved, irregularly shaped or uneven surface; second, the light absorber is composed of carbon nanotubes and carbon particles, that is, only carbon materials are formed, which can avoid the influence of other materials on the absorption of sunlight and infrared light; third, the introduction of carbon particles improves the surface roughness of the light absorber and improves the light absorption rate; fourth, the light absorber is formed only by carbon materials, thereby having good absorption performance in a wide wavelength range (400nm-20μm) with an absorption rate of 99.9%; fifth, the light can be omnidirectionally absorbed in a wide wavelength range (400nm-20μm) and is independent of the incident angle; sixth, the light absorber has excellent super-hydrophobic properties and good self-cleaning performance.

[0114] Please refer to Figure 26The third embodiment of the present application provides an infrared detector 100, which comprises an infrared light absorber 110, a thermoelectric element 112 and an electric signal detector 114. The infrared light absorber 110 is arranged on the thermoelectric element 112 and directly contacts the thermoelectric element 112. When the thermoelectric element 112 and the infrared light absorber 110 are arranged in a stack, the length extension direction of the carbon nanotubes in the infrared light absorber 110 is parallel to the contact surface of the thermoelectric element 112 and the infrared light absorber 110. The electric signal detector 114 is electrically connected to the thermoelectric element 112 through a wire, and the electric signal detector 114 and the thermoelectric element 112 form a loop in series, which is used to detect the electrical signal change of the thermoelectric element 112.

[0115] The infrared light absorber 110 is formed by spraying the light absorber pre-preparation liquid onto the thermoelectric element 112, that is, the infrared light absorber 110 has the same structure and performance as the light absorber, which will not be described here.

[0116] The infrared light absorber 110 has a high thermal conductivity coefficient, so that the infrared light absorber 110 can transfer heat to the thermoelectric element 112 after absorbing infrared light. When the thermoelectric element 112 absorbs heat, the temperature of the thermoelectric element 112 rises, so that the electrical properties of the thermoelectric element 112 change.

[0117] The thermoelectric element 112 can be a pyroelectric element, a thermistor or a thermocouple element, etc. Specifically, the pyroelectric element is a material with a high thermoelectric coefficient, such as lead zirconate titanate ceramic, lithium tantalate, lithium niobate, titanium trisulfate, etc. The thermistor can be a semiconductor thermistor, a metal thermistor, an alloy thermistor, etc. In this embodiment, the thermoelectric element 112 is a lead zirconate titanate ceramic.

[0118] Since the electric signal detector 114 is used to detect the change of the electric signal of the thermoelectric element 112, the type of the electric signal detector 114 is different according to the different thermoelectric elements 112. In an embodiment, the thermoelectric element 112 is a pyroelectric element, the temperature rise of which causes the voltage or current to appear at both ends of the pyroelectric element, at this time, the electric signal detector 114 can be a current-voltage converter, which is connected in series with the pyroelectric element to form a loop, so that the change of the voltage or current of the pyroelectric element can be detected. In another embodiment, the thermoelectric element 112 is a thermistor, the temperature rise of which causes the resistance to change, at this time, the electric signal detector 114 includes a power supply and a current detector, which are connected in series with the thermistor to form a loop, and the change of the current is measured by the current detector to detect the resistance change of the thermistor. In another embodiment, the thermoelectric element 112 is a thermocouple, the infrared light absorber 110 is arranged at one end of the thermocouple, and the temperature difference between both ends of the thermocouple causes the potential difference to appear between both ends of the thermocouple, at this time, the electric signal detector 114 can be a voltage detector, which is connected in series with the thermocouple to form a loop, so that the potential change of the thermocouple can be detected.

[0119] The working process of the infrared detector 100 is as follows: the infrared light is radiated to the infrared light absorber 110 (i.e. the light absorber), the light absorber absorbs the infrared light and converts the absorbed infrared light into heat; the heat is transmitted to the thermoelectric element 112; the temperature of the thermoelectric element 112 rises after absorbing the heat, which causes the electric properties such as resistance, current or voltage of the thermoelectric element 112 to change, when the electric signal detector 114 is electrically connected with both ends of the thermoelectric element 112 to form a loop, the electric signal detector 114 can detect the change of the electric signal of the thermoelectric element 112, so that the existence of the infrared light in the detection area can be detected.

[0120] The infrared detector 100 provided by the third embodiment of the present application has the following advantages: first, the infrared light absorber 110 has good absorption effect on the near-infrared to mid-infrared light with a wavelength of 2 μm-20 μm, which improves the responsivity and sensitivity of the thermoelectric element 112, so that the infrared detector 100 has higher sensitivity; second, the infrared light absorber 110 not only has omnidirectional absorption performance, but also is independent of polarization, which expands the use range of the infrared detector 100.

[0121] Please refer to Figure 27The third embodiment of the present application further provides an infrared imager 200, which comprises an infrared receiver 210, an infrared detector assembly 220, a signal processor 230 and an infrared image display 240. The infrared receiver 210 is used for receiving infrared radiation spectrum and transferring infrared light to the infrared detector assembly 220; the infrared detector assembly 220 is used for converting infrared radiation spectrum into electrical signal and transferring the electrical signal to the signal processor 230; the signal processor 230 is used for processing the electrical signal to obtain thermal field distribution data; and the infrared image display 240 displays infrared thermal image according to the thermal field distribution data.

[0122] The infrared receiver 210 is used for receiving infrared radiation spectrum emitted by an object, i.e. infrared light emitted by the object. Further, the infrared receiver 210 can also converge the infrared radiation spectrum. In the embodiment, the infrared receiver 210 is an infrared lens. Specifically, infrared radiation spectrum emitted by the object is received and converged by the infrared lens and then directly transferred to the infrared detector assembly 220. It can be understood that the infrared receiver 210 can also be omitted.

[0123] The infrared detector assembly 220 comprises a plurality of infrared detectors 100 in the third embodiment, which are uniformly distributed in a two-dimensional array, and each infrared detector 100 can convert infrared radiation spectrum into electrical signal change. It can be understood that each infrared detector 100 corresponds to a pixel point, and each infrared detector 100 converts infrared radiation spectrum at the location into electrical signal, thereby realizing detection of infrared radiation spectrum emitted by the object by the infrared detector assembly 220. The distance between any two adjacent infrared detectors 100 can be selected according to the resolution requirement of thermal imaging.

[0124] The signal processor 230 is used for processing and calculating electrical signal of each infrared detector 100, thereby obtaining thermal field distribution of the object. Specifically, the signal processor 230 calculates temperature data of the object surface position corresponding to each infrared detector 100 according to electrical signal change of the infrared detector 100. That is, the signal processor 230 can calculate thermal field distribution data of the object according to electrical signal.

[0125] The infrared image display 240 is used to display the infrared thermal image of the measured object. The infrared thermal image of the infrared image display 240 is displayed according to the thermal field distribution data of the object, and different temperatures are displayed by different colors. Therefore, the infrared thermal image displayed by the infrared image display 240 corresponds to the temperature distribution of the object, and is used to reflect the temperature condition of each position of the object. For example, when the infrared imager 200 is used in the medical field, the whole body thermal imaging of the human body can be performed, and the professional doctor can judge the disease nature and the lesion degree of different parts of the human body according to the thermal image, thereby providing the basis for clinical diagnosis.

[0126] When the infrared imager 200 works, the infrared light emitted by the object is received by the infrared receiver 210; the infrared receiver 210 receives and converges the infrared light, and then transmits the infrared light to the infrared detector assembly 220; the infrared detector assembly 220 converts the infrared light into an electrical signal, and then transmits the electrical signal to the signal processor 230; the signal processor 230 processes and calculates the electrical signal, so as to obtain the temperature data of each position of the object, that is, the thermal field distribution data of the object; and the infrared image display 240 displays the infrared thermal image of the object according to the calculated thermal field distribution data.

[0127] The infrared imager 200 provided by the third embodiment of the present application has the following advantages: first, the infrared light absorber 110 has good absorption effect on near-infrared to mid-infrared light with a wavelength of 2 μm-20 μm, thereby improving the responsivity and sensitivity of the thermoelectric element 112, so that the infrared imager 200 has high sensitivity; second, the infrared light absorber 110 not only has omnidirectional absorption performance, but also is independent of polarization, thereby expanding the use range of the infrared imager 200.

[0128] Please refer to Figure 28 The fourth embodiment of the present application provides an infrared stealth cloth 300, which comprises a cloth substrate 310 and the infrared light absorber 110 arranged on the cloth substrate 310. The infrared stealth cloth 300 is formed by spraying the light absorber pre-preparation liquid on the cloth substrate 310, so that the infrared light absorber 110 has the same material, structure and performance as the light absorber, which will not be described herein again. The infrared light absorber 110 can also be arranged between two cloth substrates 310 to form a sandwich structure. The plurality of carbon nanotubes are parallel to the surface of the infrared light absorber 110 close to the cloth substrate 310.

[0129] The cloth substrate 310 has a through hole, so that the infrared light absorber 110 is suspended on the cloth substrate 310. The material of the cloth substrate 310 is not limited, which can be an insulating material or a conductor, a flexible material or a non-flexible material. In the embodiment, the material of the cloth substrate 310 is not limited, such as cotton, polyester, silk, wool, hemp, leather, etc. In another embodiment, the infrared light absorber 110 is sewn between two layers of cloth.

[0130] Figure 29 As shown in the optical photo of the infrared stealth cloth 300, the infrared stealth cloth 300 has good softness. The infrared stealth cloth 300 has a low density of 3×10 -6 g / mm 2 , and is ultra-light, which can be applied in space or military fields.

[0131] Figure 30 As shown in the optical photo of the stealth effect test of the infrared stealth cloth 300, Figure 31 As shown in the thermal image photo captured by the infrared thermal imager when the hand covered with the infrared stealth cloth 300, Figure 30 and Figure 31 it can be seen that when the infrared stealth cloth 300 covers the hand, the infrared emitted by the hand is absorbed by the infrared stealth cloth 300 and cannot be detected by other infrared detection systems through the infrared stealth cloth 300. Therefore, the infrared stealth cloth 300 has good stealth effect.

[0132] Please refer to Figure 32 , the fourth embodiment of the present application further provides an infrared stealth clothes 400, which is at least partially made of the infrared stealth cloth 300. That is, the infrared stealth clothes 400 can be entirely made of the infrared stealth cloth 300, or partially made of the infrared stealth cloth 300. The infrared stealth clothes 400 is not limited to clothes, but can be gloves, masks, etc., which can be collectively referred to as infrared stealth clothing. The infrared stealth clothing includes a clothes body, at least part of the cloth of the clothes body is the infrared stealth cloth 300.

[0133] The infrared stealth cloth 300 and the infrared stealth clothes 400 provided by the fourth embodiment of the present application have the following advantages: first, the infrared light absorber 110 has good absorption effect on near-infrared to mid-infrared light with a wavelength of 2 μm-20 μm, which improves the stealth effect of the infrared stealth cloth 300 and the infrared stealth clothes 400; second, the infrared light absorber 110 not only has omnidirectional absorption performance, but also is independent of polarization, which expands the use range of the infrared stealth cloth 300 and the infrared stealth clothes 400, and further improves their stealth effect.

[0134] Due to the good absorption performance of the infrared light absorber 110 (i.e. the light absorber) in the infrared camouflage fabric 300 to sunlight, the infrared camouflage fabric 300 can also be prepared into a sun umbrella and other sun-shading tools.

[0135] Please refer to Figure 33 The fifth embodiment of the present application provides a solar collector 500, which comprises a box 502, a transparent cover plate 504, a thermal insulation material 506 and a heat absorbing plate 508. The box 502 has an opening, which is preferably arranged at the top of the box 502. The transparent cover plate 504 is arranged at or covers the opening of the box 502, so that sunlight can pass through the transparent cover plate 504 and enter the box 502. The thermal insulation material 506 is arranged inside the box 502 and forms a thermal insulation space. Preferably, the thermal insulation material 506 is arranged on the inner side of the box 502, so that the thermal insulation space is located inside the box 502. The heat absorbing plate 508 is located in the thermal insulation space, and the heat absorbing plate 508 comprises a plurality of fluid channels 5084 for facilitating the flow of water or other fluids.

[0136] The heat absorbing plate 508 comprises a base 5080 and a coating 5082, and the coating 5082 is arranged on the surface of the base 5080. The coating 5082 is the light absorber in the second embodiment, and has the same structure and performance. That is, the coating 5082 comprises a plurality of carbon nanotubes and a plurality of carbon particles, the plurality of carbon nanotubes form a network structure, and the plurality of carbon particles are located in the network structure, each carbon particle is inserted into the network structure and surrounded or coated by the plurality of carbon nanotubes, and the carbon particle is in direct contact with the carbon nanotube. The network structure of the carbon nanotubes connects the plurality of carbon particles together. The coating 5082 can be arranged on the entire surface of the base 5080, or arranged on the surface of the base 5080 close to the transparent cover plate and in direct contact with the base 5080. The coating 5082 can be formed by spraying the light absorber pre-prepared liquid on the base 5080. The base 5080 comprises the plurality of fluid channels 5084.

[0137] The material of the box 502 is not limited, and is preferably metal. The transparent cover plate 504 can be made of a material with high light transmittance, and in this embodiment, the transparent cover plate 504 is a glass cover plate. The thermal insulation material 506 can be asbestos, foam, etc. The material of the base 5080 is not limited, such as metal, carbon nanotube film, quartz, silicon dioxide, etc., and in this embodiment, the material of the base 5080 is metal.

[0138] It can be understood that the solar collector 500 further comprises some components for fastening the above-mentioned elements together, which include screws, nuts and the like.

[0139] The sunlight transmits through the transparent cover plate 504 and irradiates on the heat-absorbing plate 508, the solar radiation energy is absorbed by the heat-absorbing plate 508, converted into heat energy, and transmitted to the fluid in the fluid channel 5084, and the fluid is heated.

[0140] Please refer to Figure 34 The fifth embodiment of the present application further provides a solar water heater 600, which comprises the solar collector 500, an inlet pipe 602, an outlet pipe 604 and a water storage tank 606. The inlet pipe 602 is connected with one end of the fluid channel 5084, and the outlet pipe 604 is connected with the other end of the fluid channel 5084. One end of the outlet pipe 604 is connected with the fluid channel 5084, and the other end is connected with the water storage tank 606. The fluid such as water flows into the fluid channel 5084 from the inlet pipe 602, and then flows out from the outlet pipe 604 and into the water storage tank 606. In this embodiment, the base body 5080 comprises a plurality of fluid channels 5084, one end of each fluid channel 5084 is connected with the inlet pipe 602, and the other end of each fluid channel 5084 is connected with the outlet pipe 604.

[0141] The water storage tank 606 further comprises an outlet (not shown in the figure), so that the water in the water storage tank 606 can flow out from the outlet.

[0142] Further, the outlet pipe 604 and the water storage tank 606 can each be provided with a thermal insulation layer, so as to insulate the warm water or hot water flowing through the outlet pipe 604 and the water storage tank 606. The material of the thermal insulation layer is the same as that of the thermal insulation material 506.

[0143] The working process of the solar water heater 600 is as follows: the sunlight transmits through the transparent cover plate 504 and irradiates on the heat-absorbing plate 508, the solar radiation energy is absorbed by the heat-absorbing plate 508, converted into heat energy, and transmitted to the fluid channel 5084. In this way, the cold water entering from the inlet pipe 602 is heated by the solar energy in the fluid channel 5084, and the temperature gradually rises to become warm water or hot water, which flows into the water storage tank 606 from the outlet pipe 604 for use.

[0144] The solar collector 500 and the solar water heater 600 have the following advantages: first, the omnidirectional light absorption of the coating 5082 can improve the heat collection performance, that is, improve the heat absorption rate and reduce the heat loss of sunlight; second, the coating 5082 has excellent super-hydrophobic properties and good self-cleaning performance, which prolongs the service life of the solar collector 500 and the solar water heater 600.

[0145] In addition, those skilled in the art will also make other changes within the spirit of the present application, and of course, these changes made according to the spirit of the present application should be included in the scope of protection required by the present application.

Claims

1. An infrared detector comprising: an infrared light absorber for absorbing infrared light and converting the infrared light into heat; a thermoelectric element, the infrared light absorber being disposed on the thermoelectric element; an electrical signal detector for detecting a change in electrical property of the thermoelectric element; characterized in that the infrared light absorber is composed of carbon nanotubes and carbon particles, a plurality of the carbon nanotubes forming a network structure, a plurality of the carbon particles being located in the network structure, each of the carbon particles being inserted into the network structure and surrounded by a plurality of the carbon nanotubes, the thermoelectric element being disposed in a laminated and contacting manner with the infrared light absorber, an extending direction of the carbon nanotubes being parallel to a contact surface of the thermoelectric element and the infrared light absorber; wherein the infrared light absorber is formed by spraying a light absorber pre-liquid onto the thermoelectric element, the light absorber pre-liquid comprising a solvent, a plurality of carbon nanotubes and a plurality of carbon particles, the plurality of carbon nanotubes and the plurality of carbon particles being located in the solvent, the plurality of carbon nanotubes forming a flocculent structure in the solvent, 0.4 g of the carbon nanotubes and 5 g of the carbon particles being added per 200 mL of the solvent.

2. The infrared detector of claim 1, wherein, The thermoelectric element is one or more of a pyroelectric element, a thermistor and a thermocouple.

3. The infrared detector of claim 1, wherein, The thermoelectric element is a pyroelectric element, and the electrical signal detector is a current-voltage changer.

4. The infrared detector of claim 1, wherein, The thermoelectric element is a thermistor, and the electrical signal detector comprises a power supply and a current detector, the electrical signal detector being configured to detect a change in resistance of the thermoelectric element.

5. The infrared detector of claim 1, wherein, The thermoelectric element is a thermocouple, and the electrical signal detector is a voltage detector, the voltage detector being configured to detect a change in potential of the thermoelectric element.

6. An infrared imager comprising: an infrared detector assembly for converting infrared light into electrical signals; a signal processor for processing the electrical signals to obtain thermal field distribution data; an infrared image display for displaying an infrared thermal image according to the thermal field distribution data; characterized in that the infrared detector assembly comprises a plurality of infrared detectors arranged in an array, each of the infrared detectors being the infrared detector as claimed in any one of claims 1-5.

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