High-sensitivity infrared multispectral imaging intelligent sensor

Abstract

The application discloses a high-sensitivity infrared multispectral imaging intelligent sensor, a refrigeration type middle-short wave infrared imaging detector comprising a metal Dewar, an MCT infrared focal plane array, a CMOS readout circuit and a Stirling refrigerating machine, wherein the MCT infrared focal plane array and the CMOS readout circuit are arranged in the metal Dewar, and the Stirling refrigerating machine is arranged below the metal Dewar; the uncooled type long-wave infrared imaging detector is a thermal radiation type detector, comprising an absorbing layer, a thermal sensitive layer, a supporting leg, an interconnection wire and a substrate; after the absorbing layer absorbs infrared radiation, the absorbing layer converts the infrared radiation into heat energy; the temperature of the sensitive layer changes; the change of the temperature causes the change of resistance; the change of the resistance is converted into a current or voltage signal and is extracted. In the application, the middle-short wave and long-wave infrared combined imaging detection is adopted, the infrared spectrum is subdivided by using a multispectral filter rotating wheel, the gas spectrum has high distinguishability, and the imaging signal-to-noise ratio is high.

Description

Technical Field

[0001] This invention belongs to the field of infrared sensors and relates to a high-sensitivity infrared multispectral imaging intelligent sensor. Background Technology

[0002] Infrared imaging gas detection technology can be categorized based on whether its operating wavelength is classified into traditional thermal radiation imaging technology and spectral thermal imaging technology; and based on its imaging principle, it can be divided into cooled infrared imaging technology and uncooled infrared imaging technology. Cooled infrared imaging technology uses the absorption of infrared radiation to generate an electrical signal. Its detection element is a special semiconductor material, such as mercury oxide or indium antimonide. When infrared radiation shines on the detection element, it excites charge carriers within the element, thereby generating an electrical signal. However, because the lifetime of charge carriers is very short, the detection element needs to be cooled to a low temperature to ensure the detector's sensitivity and response speed. Uncooled infrared detectors use semiconductor materials, such as silicon and germanium. When infrared radiation shines on the detection element, it is converted into heat energy, causing a temperature change in the detection element, which in turn causes a change in the element's resistance. This change in resistance is converted into a current or voltage signal, which is then extracted, completing the infrared detection. However, existing rapid detection systems typically can only detect a single gas or a few types of gases within a narrow frequency band. Summary of the Invention

[0003] To solve the above problems, the technical solution of the present invention is: a high-sensitivity infrared multispectral imaging intelligent sensor, comprising a cooled mid-to-short-wave infrared imaging detector, an uncooled long-wave infrared imaging detector, and a multispectral filter wheel, wherein, The cooled mid-to-short-wave infrared imaging detector includes a metal Dewar, an MCT infrared focal plane array, a CMOS readout circuit, and a Stirling cooler. The MCT infrared focal plane array and the CMOS readout circuit are housed in the metal Dewar, while the Stirling cooler is located below the metal Dewar. The uncooled long-wave infrared imaging detector is a thermal radiation detector, which includes an absorption layer, a heat-sensitive layer, support legs, interconnecting wires and a substrate. After the absorption layer absorbs infrared radiation, it converts it into heat energy. The temperature of the heat-sensitive layer changes, and the temperature change causes a change in resistance. The change in resistance is converted into a current or voltage signal and extracted. The multispectral filter wheel includes filters with various parameters, one of which is placed in front of the cooled short-wave infrared imaging detector and one in front of the uncooled long-wave infrared imaging detector.

[0004] Preferably, the MCT infrared focal plane array is a 640×512 MCT infrared focal plane array with a center distance of 15μm.

[0005] Preferably, the cooled mid-shortwave infrared imaging detector has an infrared response of 1.5–6 μm in the ultra-wideband mid-shortwave range.

[0006] Preferably, the thermally sensitive layer of the uncooled long-wave infrared imaging detector is a VOx material.

[0007] Preferably, the infrared response of the uncooled long-wave infrared imaging detector is an ultra-wideband long-wavelength of 8~14µm.

[0008] Preferably, the multispectral filter wheel is disc-shaped, with several filters of different parameters evenly arranged on the disc.

[0009] Compared with the prior art, the beneficial effects of the present invention are as follows: joint imaging is achieved by using a highly sensitive cooled mid-to-short-wave infrared imaging detector and an uncooled long-wave infrared imaging detector; a multispectral filter wheel is designed to subdivide the infrared spectrum; the finer the resolution band of the imaging, the higher the gas spectrum resolution and the higher the imaging signal-to-noise ratio. Attached Figure Description

[0010] Figure 1 This is a structural block diagram of a high-sensitivity infrared multispectral imaging smart sensor according to a specific embodiment of the present invention; Figure 2 This is a schematic diagram of the structure of a cooled mid-to-short-wave infrared imaging detector for a high-sensitivity infrared multispectral imaging smart sensor according to a specific embodiment of the present invention. Figure 3 This is a schematic diagram of the pixel composition of an uncooled long-wave infrared imaging detector of a high-sensitivity infrared multispectral imaging smart sensor according to a specific embodiment of the present invention. Figure 4 This is a schematic diagram illustrating the principle of infrared spectral imaging for hazardous gas leaks using a high-sensitivity infrared multispectral imaging smart sensor, according to a specific embodiment of the present invention. Figure 5 This is a schematic diagram of the multispectral filter wheel structure of a high-sensitivity infrared multispectral imaging smart sensor according to a specific embodiment of the present invention. Detailed Implementation

[0011] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0012] Conversely, this invention encompasses any substitutions, modifications, equivalent methods, and solutions made within the spirit and scope of the invention as defined in the claims. Furthermore, to provide a better understanding of the invention, certain specific details are described in detail below. However, those skilled in the art will fully understand the invention even without these detailed descriptions.

[0013] See Figure 1 It includes a cooled mid-to-short-wave infrared imaging detector 10, an uncooled long-wave infrared imaging detector 20, and a multispectral filter wheel 30, wherein... See Figure 2 The cooled mid-to-shortwave infrared imaging detector 10 includes a metal Dewar, an MCT infrared focal plane array 11, a CMOS readout circuit 12, and a Stirling cooler. The MCT infrared focal plane array 11 and the CMOS readout circuit 12 are disposed in the metal Dewar, and the Stirling cooler is disposed below the metal Dewar.

[0014] Cooled infrared detectors operate on the principle of interacting with electrons in the detector material through an incident photon flux, resulting in an internal photon effect. The infrared focal plane array (FLAS) chip is the core component of a cooled infrared detector, and based on its operating principle, it can be divided into PV detectors and PC detectors. PC detectors rely on incident light radiation causing intrinsic or impurity absorption in the photosensitive material, thereby altering its conductivity. Considering the design requirements, the project intends to select a PC detector.

[0015] PC detectors have selective response wavelengths; they only respond when the energy of the incident photon is greater than the electron activation energy in the photosensitive material. The project plans to select mercury cadmium telluride (MCT) as the photosensitive material due to its low noise, fast response time, and wide coverage, to achieve highly sensitive, wide-band infrared imaging.

[0016] In a specific embodiment, the wideband MCT detector is selected as a mid-to-shortwave cooled infrared focal plane detector, including a 640×512 MCT infrared focal plane array 11 with a center distance of 15μm, a 640×512 CMOS readout circuit 12, a metal Dewar and a rotating integral Stirling refrigerator, which has an ultra-wideband mid-to-shortwave infrared response of 1.5 to 6μm.

[0017] The uncooled long-wave infrared imaging detector 20 is a thermal radiation detector, including an absorption layer 21, a thermally sensitive layer 22, a support leg 23, an interconnecting wire 24, and a substrate 25. The substrate 25 includes a reflector and a readout circuit. After the absorption layer 21 absorbs infrared radiation, it converts it into heat energy. The temperature of the sensitive layer changes, and the temperature change causes a change in resistance. The change in resistance is converted into a current or voltage signal and extracted.

[0018] See Figure 3 The long-wave infrared imaging detector 20 is a thermal radiation detector (Bolometer) with a suspended, heat-insulated microbridge structure, consisting of an absorption layer 21, a heat-sensitive layer 22, support legs 23, interconnecting wires 24, and a substrate 25. After the absorption layer 21 absorbs infrared radiation, it converts it into heat energy. Then, the temperature of the heat-sensitive layer 22 changes, causing a change in resistance. This change in resistance is converted into a current or voltage signal and extracted.

[0019] The resistance-temperature coefficient of the sensitive layer material is a key factor affecting the performance of the Bolometer. To meet the high requirements for performance and image quality, VOx is selected as the thermosensitive layer material. It has high NETD and sensitivity, and VOx material has low 1 / f noise and high image quality, which can meet the project requirements.

[0020] In a specific embodiment, an uncooled infrared thermal imaging detector based on vanadium oxide is selected, which has a resolution of 640×512, a pixel size of 12μm, a built-in 14-bit ADC, a thermal response time of less than 12ms, an operating temperature of -40℃ to +85℃, and an ultra-wideband long-wave infrared response of 8~14um.

[0021] The multispectral filter wheel 30 includes filters with various parameters, one of which is placed in front of the cooled mid-to-short-wave infrared imaging detector 10 and the uncooled long-wave infrared imaging detector 20.

[0022] See Figure 4 This describes the principle of infrared imaging detection for gas leaks. Industrial hazardous gases exhibit characteristic absorption spectra in specific wavelengths. When dynamic leaking gas is present in the field of view of an infrared imaging detector, dynamic radiation differences will form in the corresponding absorption bands, thus creating infrared radiation grayscale difference image information. The higher the gas concentration, the stronger the absorption, and the more obvious the grayscale difference. Therefore, gas leaks can be detected by detecting dynamic gas infrared radiation grayscale images, and the gas concentration can be determined based on the magnitude of the grayscale difference.

[0023] Industrial hazardous gases exhibit characteristic absorption spectra in the 3–7 μm wavelength range. When dynamic leakage gas is present in the field of view of an infrared imaging detector, dynamic radiation differences will form in the corresponding absorption band, thus creating infrared radiation grayscale difference image information of the target scene. The higher the gas concentration, the stronger the absorption and the more obvious the grayscale difference. Therefore, gas leaks can be detected by detecting dynamic gas trace images, and the gas concentration can be determined based on the concentration difference.

[0024] The finer the resolution band of infrared spectral imaging, the higher the gas spectral resolution. With a given detection sensitivity, the operating band width (i.e., spectral resolution) and the imaging signal-to-noise ratio (SNR) are mutually constrained. Therefore, limiting the infrared radiation entering the detector in a single sampling moment can significantly improve the imaging SNR, ensuring high sensitivity and high detection accuracy. For this purpose, a filter wheel 30 with multiple parameter filters is designed (see [reference]). Figure 5 The filters Filter0 to Filter7 are set on the disc-shaped rotating wheel 30 on the left side. See the diagram for the projection effect. Figure 5 On the right, each filter is used for narrowband detection at its respective center wavelength. Installed at the front of the infrared detector, when the filter wheel 30 rotates, it can achieve infrared imaging of a single predetermined narrowband wavelength of the scene under test, and the type of gas can be determined from the infrared image.

[0025] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A high-sensitivity infrared multispectral imaging smart sensor, characterized in that, This includes cooled mid- and short-wave infrared imaging detectors, uncooled long-wave infrared imaging detectors, and multispectral filter rotors, among which... The cooled mid-to-short-wave infrared imaging detector includes a metal Dewar, an MCT infrared focal plane array, a CMOS readout circuit, and a Stirling cooler. The MCT infrared focal plane array and the CMOS readout circuit are housed in the metal Dewar, while the Stirling cooler is located below the metal Dewar. The uncooled long-wave infrared imaging detector is a thermal radiation detector, which includes an absorption layer, a heat-sensitive layer, support legs, interconnecting wires and a substrate. After the absorption layer absorbs infrared radiation, it converts it into heat energy. The temperature of the heat-sensitive layer changes, and the temperature change causes a change in resistance. The change in resistance is converted into a current or voltage signal and extracted. The multispectral filter wheel includes filters with various parameters, one of which is placed in front of the cooled short-wave infrared imaging detector and one in front of the uncooled long-wave infrared imaging detector.

2. The sensor according to claim 1, characterized in that, The MCT infrared focal plane array is specifically a 640×512 MCT infrared focal plane array with a center distance of 15μm.

3. The sensor according to claim 1, characterized in that, The cooled mid-shortwave infrared imaging detector has an infrared response of 1.5–6 μm in the ultra-wideband mid-shortwave range.

4. The sensor according to claim 1, characterized in that, The thermally sensitive layer of the uncooled long-wave infrared imaging detector is made of VOx material.

5. The sensor according to claim 1, characterized in that, The uncooled long-wave infrared imaging detector has an infrared response of 8~14µm, which is an ultra-wideband long-wavelength.

6. The sensor according to claim 5, characterized in that, The multispectral filter wheel is disc-shaped, with several filters of different parameters evenly arranged on the disc.

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