Continuous zooming thermal infrared imager based on high-temperature scene spectrum gating

Abstract

The invention belongs to the technical field of infrared imaging, and discloses a high-temperature scene spectrum gating-based continuous zooming thermal infrared imager, which comprises an optical lens assembly, an optical lens control circuit board, a medium-wave refrigeration infrared detector, an infrared detector interface processing circuit board and a preprocessing circuit board, the optical lens control circuit board controls the optical lens assembly to converge infrared radiation energy of a target scene to a focal plane of the medium-wave refrigeration infrared detector, a clear and stable image is generated, and detection, recognition and tracking of a target are achieved. The medium-wave refrigeration infrared detector converts the target radiation energy into an analog electric signal; the infrared detector interface processing circuit board is used for buffering and amplifying the analog electric signal and converting the analog electric signal into a digital signal through A / D conversion; the preprocessing circuit board is used for carrying out non-uniformity correction, bad element detection and bad element replacement and gain and bias control on image signals and outputting analog and digital video signals. According to the invention, the target can be quickly identified and tracked.

Description

Technical Field

[0001] The invention belongs to the technical field of infrared imaging and relates to a high-temperature scene spectral gating continuous zoom infrared thermal imager. Background Art

[0002] The continuous zoom infrared thermal imager (hereinafter referred to as "infrared thermal imager") is an important component of the detection and identification of vehicle-mounted optoelectronic equipment. It is used in many aspects such as typical vehicle target detection and tracking, and carries out spectrally selected infrared imaging image processing in high-temperature scenes. It has the functions of observing the target area through optical lenses and medium-wave cooled detector components, real-time imaging, and receiving control timing and instructions from the control system.

[0003] Existing infrared thermal imagers have the following disadvantages: (1) The image is easily saturated in high-temperature scenes. (2) It affects target detection and the target display is not clear enough. (3) The optical system cannot continuously zoom. Summary of the Invention

[0004] (1) Purpose of the invention

[0005] The purpose of the present invention is to provide a high-temperature scene spectral gating continuous zoom infrared thermal imager, which can achieve clear imaging of the target, effectively eliminate the influence of high-temperature atmosphere on the infrared thermal imager image, shorten the image saturation time, and can continuously zoom.

[0006] (2) Technical solution

[0007] In order to solve the above technical problems, the present invention provides a high-temperature scene spectral gating continuous zoom infrared thermal imager, which includes an optical lens assembly, an infrared detector core assembly, and an optical lens control circuit board 7; the infrared detector core assembly includes a medium-wave cooled infrared detector 8, an infrared detector interface processing circuit board 9, a pre-processing circuit board 10 and a refrigerator interface circuit board 11; the optical lens control circuit board controls the optical lens assembly to converge the infrared radiation energy of the target scene onto the focal plane of the medium-wave cooled infrared detector, generating a clear and stable image, and realizing the detection, identification and tracking of the target; the medium-wave cooled infrared detector converts the target radiation energy into an analog electrical signal; the infrared detector interface processing circuit board is used to buffer, amplify, and A / D convert the analog electrical signal into a digital signal; the pre-processing circuit board is used to perform non-uniformity correction, bad pixel detection and bad pixel replacement, gain and bias control on the image signal, and output analog and digital video signals; the refrigerator interface circuit board is connected to the refrigerator.

[0008] Furthermore, the continuous zoom infrared thermal imager further comprises a power-on control power supply board 12 , which is responsible for supplying power to the infrared detector core assembly, the medium-wave cooled infrared detector, and the optical lens control circuit board.

[0009] Furthermore, the optical lens assembly includes an optical lens 1, a spectral gating filter 6, a zoom mechanism 2, a focusing mechanism 3, an imaging main frame 4, and a correction shutter 5; the optical lens 1 and the infrared detector core assembly are both installed on the imaging main frame 4; the infrared detector core assembly and the spectral gating filter 6 are integrated into a design and installed on the main frame through an adapter bracket; the zoom mechanism 2 and the focusing mechanism 3 are used to zoom and focus the optical lens 1; the spectral gating filter 6 is arranged behind the optical lens 1 to gate the imaging spectrum; the correction shutter 5 is set in front of the medium-wave cooled infrared detector.

[0010] Furthermore, the spectral gating filter is installed between the optical lens and the infrared detector core assembly, fixed to the imaging main frame through a pressing ring, and participates in the imaging of the optical system.

[0011] Furthermore, the continuous zoom infrared thermal imager also includes an infrared detector core component fixing seat 13, a circuit adapter bracket 14, a circuit reinforcement bracket 15, and an interface circuit reinforcement ring 18. The infrared detector core component fixing seat 13 supports and installs the infrared detector core component, the circuit adapter bracket 14 connects the infrared detector interface processing circuit board 9 and the preprocessing circuit board 10, and the circuit reinforcement bracket 15 and the interface circuit reinforcement ring 18 reinforce the infrared detector interface processing circuit board 9.

[0012] Furthermore, the continuous zoom infrared thermal imager also includes a preprocessing circuit heat sink 16 and a power-on control circuit heat sink 17. The preprocessing circuit heat sink 16 is arranged outside the preprocessing circuit board 10, and the power-on control circuit heat sink 17 is arranged outside the power-on control power supply board 12 to dissipate heat.

[0013] Furthermore, the power-on control power supply board 12 has an input voltage of DC +20V to +35V, and outputs a voltage of 6V in two channels and 9V in one channel, each channel driving 3A.

[0014] Furthermore, the optical lens adopts a folded imaging light path mode, and the optical lens structure adopts a U-shaped structure layout.

[0015] Furthermore, the optical lens is an optical lens with a focal length of 15mm to 300mm and 20x continuous zoom, the longest focal length is 300mm, and the medium-wave infrared band is 3.7μm to 4.8μm.

[0016] Furthermore, the optical lens is composed of 12 lenses, made of Ge and Si materials, including 5 aspherical surfaces and one diffraction surface; the optical lens system adopts three-time optical path folding.

[0017] (3) Beneficial effects

[0018] The above technical solution provides a high-temperature scene spectral gating continuous zoom infrared thermal imager with the following beneficial effects:

[0019] (1) Design a spectral gating filter, and use spectral band selection technology to extract the effective band information of the target based on the high temperature window of the tail flame and the influence of atmospheric thermal radiation.

[0020] (2) Optical lens design parameters: 15mm~300mm continuous zoom infrared lens, with continuous switching function between large field of view and small field of view.

[0021] (3) A real-time acquisition function of infrared imaging images suitable for high-temperature scenes is proposed, which is conducive to rapid identification and tracking of targets. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a main view of the structure of the infrared thermal imager based on high temperature scene spectrum gating continuous zoom of the present invention;

[0023] Figure 2 This is a cross-sectional view of the installation position AA of the spectral gating filter structure of the present invention;

[0024] Figure 3 This is a bottom view of the structure of the infrared thermal imager with continuous zoom based on spectrum gating for high-temperature scenes according to the present invention.

[0025] Figure 4 This is a block diagram of the infrared thermal imager of the present invention;

[0026] Figure 5 This is a three-dimensional model diagram of the infrared thermal imager of the present invention;

[0027] Figure 6 Schematic diagram of the optical path of the optical lens of the present invention;

[0028] Figure 7 is a two-dimensional diagram of the optical filter of the present invention;

[0029] Figure 8 A schematic diagram of an engine tail flame scene is collected for the present invention. DETAILED DESCRIPTION

[0030] In order to make the purpose, content and advantages of the present invention more clear, the specific implementation methods of the present invention are further described in detail below with reference to the accompanying drawings and examples.

[0031] As a key component in optoelectronic detection and identification, infrared thermal imagers are installed within optoelectronic equipment to convert infrared radiation from objects and scenes in the observation area into real-time thermal video, which is then output to the optoelectronic equipment. Infrared thermal imagers are primarily used to provide video data for panoramic searches, thermal imaging, early warning, and target identification.

[0032] Reference Figures 1 to 5As shown, the present embodiment of the high-temperature scene spectral gating continuous zoom infrared thermal imager includes an optical lens assembly, an infrared detector core assembly, and an optical lens control circuit board 7; the infrared detector core assembly includes a medium-wave cooled infrared detector 8, an infrared detector interface processing circuit board 9, a pre-processing circuit board 10, and a refrigerator interface circuit board 11; the optical lens control circuit board controls the optical lens assembly to converge the infrared radiation energy of the target scene onto the focal plane of the medium-wave cooled infrared detector, generating a clear and stable image, thereby realizing detection, identification, and tracking of the target; the medium-wave cooled infrared detector converts the target radiation energy into an analog electrical signal; the infrared detector interface processing circuit board is used to buffer, amplify, and A / D convert the analog electrical signal into a digital signal; the pre-processing circuit board is used to perform non-uniformity correction, bad pixel detection and bad pixel replacement, gain and offset control on the image signal, and output analog and digital video signals; the refrigerator interface circuit board is connected to the refrigerator.

[0033] The continuous zoom infrared thermal imager further comprises a power-on control power supply board 12 , which is responsible for supplying power to the infrared detector core assembly, the medium-wave cooled infrared detector, and the optical lens control circuit board.

[0034] The optical lens assembly includes an optical lens 1, a spectral gating filter 6, a zoom mechanism 2, a focusing mechanism 3, an imaging main frame 4, and a correction shutter 5; the optical lens 1 and the infrared detector core assembly are both installed on the imaging main frame 4, which is convenient for system disassembly and assembly; the infrared detector core assembly and the spectral gating filter 6 are integrated into a design and installed on the main frame through an adapter bracket, which can facilitate debugging and subsequent maintenance and save space; the zoom mechanism 2 and the focusing mechanism 3 are used to zoom and focus the optical lens 1; the spectral gating filter 6 is arranged behind the optical lens 1 to gate the imaging spectrum; the correction shutter 5 is set in front of the medium-wave cooled infrared detector.

[0035] The spectral gating filter is installed between the optical lens and the infrared detector core assembly, fixed to the imaging main frame through a pressure ring, and participates in the imaging of the optical system.

[0036] The continuous zoom infrared thermal imager also includes an infrared detector core component fixing seat 13, a circuit adapter bracket 14, a circuit reinforcement bracket 15, and an interface circuit reinforcement ring 18. The infrared detector core component fixing seat 13 supports and installs the infrared detector core component. The circuit adapter bracket 14 connects the infrared detector interface processing circuit board 9 and the pre-processing circuit board 10. The circuit reinforcement bracket 15 and the interface circuit reinforcement ring 18 reinforce the infrared detector interface processing circuit board 9.

[0037] The continuous zoom infrared thermal imager also includes a preprocessing circuit heat sink 16 and a power-on control circuit heat sink 17. The preprocessing circuit heat sink 16 is arranged outside the preprocessing circuit board 10, and the power-on control circuit heat sink 17 is arranged outside the power-on control power supply board 12 to dissipate heat.

[0038] The power-on control power supply board 12 has an input voltage of DC +20V~+35V, an output voltage of 6V in two ways and 9V in one way, with a driving capacity of 3A per way and a power-on control function.

[0039] The optical lens assembly adopts the folded imaging light path method, and the optical lens structure adopts a U-shaped structure layout, which is miniaturized, modularized and weight-reduced to reduce the system volume and weight.

[0040] The optical lens focal length parameters are 15mm to 300mm, 20x continuous zoom optical lens, the maximum focal length is 300mm, the medium-wave infrared band is 3.7μm to 4.8μm; the infrared thermal imager volume envelope is ≤207mm×169mm×97mm;

[0041] The horizontal field of view angle range is at least 1.83° to 18.18° (±5%). Combining the parameters of the medium-wave infrared detector and the geometric relationship, the system focal length range can be obtained. With a certain margin, the lens focal length range is determined to be 15mm to 300mm.

[0042] Figure 6 In the optical lens, 12 lenses are made of conventional Ge and Si materials, including five aspherical surfaces and one diffraction surface, which effectively corrects the system aberrations. To meet the miniaturization requirements of the system, the optical system adopts three-way optical path folding to effectively reduce the system length and meet the envelope requirements. In order to compress the size of the first lens as much as possible, a secondary imaging structure is required. At the telephoto end, the entrance pupil of the lens is located near the first lens. The zoom function is mainly undertaken by the primary imaging part, and the secondary imaging part is mainly responsible for the connection of the pupil and the correction of some residual aberrations.

[0043] The system is designed using optical design software. The typical focal length optical path diagram in the design results is as follows: Figure 6 shown.

[0044] Figure 7Hot air saturates the medium-wave infrared detector. The high temperature environment saturates the medium-wave infrared detector and simultaneously "heats" the surrounding air. The hot air cannot dissipate quickly enough, resulting in the presence of high-temperature thermal radiation. Although not visually visible, hot air may have absorption peaks in the medium-wave infrared. Carbon dioxide and water vapor are the primary contributors to infrared radiation in the air. Carbon dioxide has an absorption peak around 4.2 μm, well within the medium-wave band. A spectral gating filter was designed to address the high-temperature window of the tail plume and the influence of atmospheric thermal radiation, using spectral band selection technology to extract effective target band information. The front protective window and surrounding air are heated to 350°C, causing the medium-wave thermal imager to saturate and affect image contrast. This suppresses the impact of carbon dioxide on image quality. Using band selection technology, imaging performance is significantly improved. The average transmittance from 3.5 μm to 4.1 μm exceeds 90%, with a cutoff wavelength of less than 2% and an average reflectance exceeding 98% starting at 4.1 μm.

[0045] Figure 3 The infrared detector core component uses a single FPGA to build an integrated information processing platform with a miniaturized, modular and universal design. The medium-wave infrared detector uses a 640×512 array and a 15μ pixel size.

[0046] Figure 1 The imaging main frame structure connects the optical lens and infrared detector core assembly functions.

[0047] The image processing method for infrared imaging of high-temperature scenes realizes high-temperature scenes, continuous zoom, and infrared imaging, and can clearly image the target environment in a temperature range above 500°C, thereby achieving clear display of targets in a high-temperature range. Figure 8 An example of a high-temperature acquisition image collected.

[0048] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A high temperature scene spectral gating continuous zoom infrared thermal imager, characterized in that: The invention comprises an optical lens assembly, an infrared detector core assembly, and an optical lens control circuit board (7); the infrared detector core assembly comprises a medium-wave refrigerated infrared detector (8), an infrared detector interface processing circuit board (9), a pre-processing circuit board (10), and a refrigerator interface circuit board (11); the optical lens control circuit board controls the optical lens assembly to converge the infrared radiation energy of the target scene onto the focal plane of the medium-wave refrigerated infrared detector, thereby generating a clear and stable image and realizing the detection, identification, and tracking of the target; the medium-wave refrigerated infrared detector converts the target radiation energy into an analog electrical signal; the infrared detector interface processing circuit board is used for buffering, amplifying, and A / D converting the analog electrical signal into a digital signal; the pre-processing circuit board is used for performing non-uniformity correction, bad pixel detection and bad pixel replacement, gain and bias control on the image signal, and outputting analog and digital video signals; the refrigerator interface circuit board is connected to the refrigerator.

2. The high temperature scene spectral gating continuous zoom infrared thermal imager according to claim 1, characterized in that: The continuous zoom infrared thermal imager also includes a power-on control power supply board (12), which is responsible for supplying power to the infrared detector core assembly, the medium-wave cooling infrared detector, and the optical lens control circuit board.

3. The high temperature scene spectral gating continuous zoom infrared thermal imager according to claim 2, characterized in that: The optical lens assembly comprises an optical lens (1), a spectral gating filter (6), a zoom mechanism (2), a focusing mechanism (3), an imaging main frame (4), and a correction shutter (5); the optical lens (1) and the infrared detector core assembly are both mounted on the imaging main frame (4); the infrared detector core assembly and the spectral gating filter (6) are designed as an integrated whole and are mounted on the main frame via an adapter bracket; the zoom mechanism (2) and the focusing mechanism (3) are used to zoom and focus the optical lens (1); the spectral gating filter (6) is arranged behind the optical lens (1) to gating the imaging spectrum; and the correction shutter (5) is arranged in front of the medium-wave refrigerated infrared detector.

4. The high temperature scene spectral gating continuous zoom infrared thermal imager according to claim 3, characterized in that: The spectral gating filter is installed between the optical lens and the infrared detector core component, fixed on the imaging main frame through a pressing ring, and participates in the imaging of the optical system.

5. The high temperature scene spectral gating continuous zoom infrared thermal imager according to claim 4, characterized in that: The continuous zoom infrared thermal imager further comprises an infrared detector core component fixing seat (13), a circuit adapter bracket (14), a circuit reinforcement bracket (15), and an interface circuit reinforcement ring (18). The infrared detector core component fixing seat (13) supports and mounts the infrared detector core component, the circuit adapter bracket (14) performs adapter connection on the infrared detector interface processing circuit board (9) and the pre-processing circuit board 10, and the circuit reinforcement bracket (15) and the interface circuit reinforcement ring (18) reinforce the infrared detector interface processing circuit board (9).

6. The high temperature scene spectral gating continuous zoom infrared thermal imager according to claim 5, characterized in that: The continuous zoom infrared thermal imager further comprises a pre-processing circuit heat sink (16) and a power-on control circuit heat sink (17). The pre-processing circuit heat sink (16) is arranged outside the pre-processing circuit board (10), and the power-on control circuit heat sink (17) is arranged outside the power-on control power supply board (12), for heat dissipation.

7. The high temperature scene spectral gating continuous zoom infrared thermal imager according to claim 6, characterized in that: The power-on control power supply board (12) has an input voltage of DC +20V to +35V, and an output voltage of 6V divided into two paths and 9V divided into one path, with each path driving 3A.

8. The high temperature scene spectral gating continuous zoom infrared thermal imager according to claim 7, characterized in that: The optical lens adopts a folded imaging light path mode, and the optical lens structure adopts a U-shaped structure layout.

9. The high temperature scene spectral gating continuous zoom infrared thermal imager according to claim 8, characterized in that: The optical lens has a focal length of 15 mm to 300 mm and 20 times continuous zoom, the longest focal length is 300 mm, and the medium-wave infrared band is 3.7 μm to 4.8 μm.

10. The high temperature scene spectral gating continuous zoom infrared thermal imager according to claim 9, characterized in that: The optical lens is composed of 12 lenses made of Ge and Si materials, including 5 aspherical surfaces and one diffraction surface; the optical lens system adopts three-times optical path folding.

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