Domestic circuit design method of infrared sweep imaging system

Abstract

The invention relates to a domestic circuit design method of an infrared sweep imaging system, and belongs to the technical field of infrared thermal imaging. According to the invention, the 100% localized infrared sweep imaging system is realized, each sub-module can perform high-speed communication, each sub-module can quickly respond to an overall instruction for an object flying at a high speed, and the matching precision error of each sub-module is reduced with lower communication delay. The sampling rate and the output video frame frequency of the infrared detector are improved through circuit design.

Description

Technical Field

[0001] The present invention belongs to the field of infrared thermal imaging technology, and in particular relates to a localized circuit design method for an infrared swing scanning imaging system. Background Art

[0002] The advantages of a swing-scan imaging spectrometer include a wide field of view, excellent inter-band pixel alignment, robust data stability, and a wide spectral range. These advantages enable a swing-scan imaging spectrometer to provide a large total field of view when acquiring images, ensuring that different bands always focus on the same pixel, thereby enhancing data stability. Furthermore, because the target light is split after entering the objective lens, a single instrument can cover an extremely wide spectral range, spanning the visible to the infrared. Currently, there is an urgent need to design a domestically produced swing-scan imaging system for infrared applications. Summary of the Invention

[0003] (1) Technical issues to be resolved

[0004] The technical problems to be solved by the present invention are: first, to design a circuit of a 100% domestically produced infrared swing scanning imaging system; second, to improve the sampling rate of the infrared detector and the output video frame rate of the infrared swing scanning imaging system.

[0005] (2) Technical solution

[0006] In order to solve the above technical problems, the present invention provides a method for designing a localized circuit for an infrared swing-scanning imaging system, wherein the localized circuit for the infrared swing-scanning imaging system is designed to include an infrared lens assembly, a medium-wave cooled infrared detector assembly, an infrared imaging circuit, a swing machine assembly, and a motor;

[0007] The infrared lens assembly includes a continuous zoom lens and a motor drive circuit. The infrared lens assembly is used to receive infrared radiation from a scene and focus it on the focal plane of the infrared detector in the medium-wave cooled infrared detector assembly. The optical zoom and focus operations are completed by controlling the motor. The motor drive circuit is used to provide power and control signals to the motor to control the optical zoom and focus of the continuous zoom lens.

[0008] The medium-wave refrigerated infrared detector assembly includes an infrared detector and a refrigerator, wherein the refrigerator is used to provide a suitable working environment for the infrared detector; the infrared detector is used to complete the photoelectric conversion of infrared radiation and generate a voltage signal;

[0009] The infrared imaging circuit is used to process the voltage signal output by the infrared detector and transmit the image data in the form of SDI digital video to the receiving and display device at the back end. The infrared imaging circuit also communicates with the RS422 format serial port of the motor drive circuit to control the motor drive circuit to adjust the lens focal length;

[0010] The swing machine assembly includes a swing machine and a driving circuit. The driving circuit is used to control the periodic scanning motion of the swing mirror. The swing machine is used to participate in the continuous zoom lens imaging.

[0011] Preferably, the localized circuit of the infrared swing scanning imaging system further includes a power supply circuit for providing power to the infrared lens assembly, the medium wave cooled infrared detector assembly, the infrared imaging circuit, and the swing machine assembly respectively.

[0012] Preferably, the infrared imaging circuit is used to perform conditioning, noise reduction filtering, non-uniformity correction, blind pixel replacement, digital detail enhancement and stretch display processing on the voltage signal output by the infrared detector.

[0013] Preferably, the infrared imaging circuit adopts a parallel communication architecture design of FPGA module + 6 RS422 serial ports, wherein the FPGA module adopts Fudan Microelectronics JFM7K325T8-N series FPGA, and the peripheral circuit of the FPGA module includes a 30MHz crystal oscillator, a 256M capacity SDRAM, a 64M serial FLASH and related power supply; the 30MHz crystal oscillator is used to provide a clock source for the FPGA module, the 256M capacity SDRAM is used to cache image data, the FPGA module can execute the image correction algorithm, and the 64M serial FLASH is used to store programs and image correction parameters.

[0014] Preferably, the 30MHz crystal oscillator uses the active crystal oscillator ZPB-26-30MHz produced by 707 Factory, the 256M capacity SDRAM uses the SDRAM chip SM48LC16M32M of Guowei Electronics, and the 64M serial FLASH uses the FLASH chip SM25P54.

[0015] Preferably, the FPGA module generates an MC clock as a clock signal, and the infrared detector performs signal sampling according to the MC clock, and the frequency of the MC clock is 10 MHZ.

[0016] Preferably, the infrared imaging circuit adopts the Camera Link digital video output format. After the FPGA module receives the signal from the infrared detector, it designs the row synchronization signal, field synchronization signal, and data valid signal based on the data encoding requirements of the Camera Link digital video circuit and the pixel clock, and synchronizes them with the pixel data.

[0017] The present invention also provides a localized circuit of an infrared swing scanning imaging system designed by adopting the method.

[0018] (3) Beneficial effects

[0019] 1. The present invention provides a 100% domestically produced infrared swing-scan imaging system, whose submodules are capable of high-speed communication. For high-speed flying objects, each submodule can quickly respond to overall instructions, reducing the coordination accuracy error of each submodule with lower communication delay.

[0020] 2. The present invention provides an infrared scanning imaging system that improves the infrared detector sampling rate and output video frame rate through the following designs:

[0021] 1) When acquiring real-time data such as information on high-speed moving objects and disaster monitoring, the MC clock is designed to capture image signals with a wider frequency range at a higher sampling rate, which can more completely preserve the original image information and reduce distortion, thereby improving the signal-to-noise ratio and making the image quality purer.

[0022] 2) Through the design of the infrared imaging circuit, a higher image output frame rate achieves smoother and clearer motion effects (especially in fast-moving and instantly changing scenes). At the same time, the high frame rate image data can significantly reduce the input delay of the next stage, thereby improving the response speed of the subsequent stage. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 The block diagram of the infrared scanning imaging system designed for the present invention;

[0024] Figure 2 Design a framework diagram for the infrared imaging circuit;

[0025] Figure 3 This is the RS422 serial port circuit diagram;

[0026] Figure 4 This is the sampling clock timing diagram required for the detector to work normally;

[0027] Figure 5 This is the Camera Link digital video circuit diagram. DETAILED DESCRIPTION

[0028] 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.

[0029] The present invention provides a method for designing a localized circuit for an infrared swing scanning imaging system. In this method, the localized circuit for the infrared swing scanning imaging system is designed to be composed of an infrared lens assembly, a medium-wave refrigerated infrared detector assembly, an infrared imaging circuit, a power supply circuit, a swing machine assembly, and a motor. The block diagram is shown in FIG. Figure 1 As shown, the functions of each part are as follows:

[0030] 1. Infrared lens assembly: This includes a variable-zoom lens and a motor drive circuit. The infrared lens assembly receives infrared radiation from the scene and focuses it on the focal plane of the infrared detector in the medium-wave cooled infrared detector assembly. Optical zoom and focus operations can be achieved by controlling the motor. The motor drive circuit provides power and control signals to the motor, controlling the optical zoom and focus of the variable-zoom lens.

[0031] 2. Medium-wave cooled infrared detector assembly: includes an infrared detector and a refrigerator. The refrigerator is responsible for providing a suitable working environment for the infrared detector; the infrared detector is responsible for completing the photoelectric conversion of infrared radiation and generating a voltage signal.

[0032] 3. Infrared imaging circuit: This circuit is responsible for conditioning, noise reduction filtering, non-uniformity correction, blind pixel replacement, digital detail enhancement (DDE), and stretching the voltage signal output by the infrared detector, and then transmits the image data in the form of SDI digital video to the back-end receiving and display device. The infrared imaging circuit is also responsible for communicating with the RS422 serial port of the motor drive circuit to control the motor drive circuit to adjust the lens focal length.

[0033] 4. Power supply circuit: provides stable and reliable power supply for infrared lens assembly, medium wave cooling infrared detector assembly, infrared imaging circuit and pendulum assembly.

[0034] 5. Swing machine assembly: includes a swing machine and a drive circuit. The drive circuit is used to control the periodic scanning motion of the swing mirror. The swing machine is used to participate in continuous zoom lens imaging.

[0035] The application provides a high-speed communication circuit design of each sub-module of an infrared scanning imaging system. The specific design scheme of the infrared imaging circuit is as follows: an FPGA module+6 RS422 serial ports parallel communication architecture is adopted, wherein a core processor of the FPGA module adopts a high-performance FPGA of a JFM7K325T8-N series of Fudan Microelectronics; a 30MHz crystal oscillator, a 256M capacity SDRAM, a 64M serial FLASH and related power supplies are included in the peripheral circuit; the 30MHz crystal oscillator provides a clock source for the FPGA module; the 256M capacity SDRAM is used to buffer image data; the FPGA module executes an image correction algorithm; and the 64M serial FLASH is used to store programs and image correction parameters. The 30MHz crystal oscillator selects an active crystal oscillator ZPB-26-30MHz produced by 707 Factory; the 256M capacity SDRAM selects an SDRAM chip SM48LC16M32M of Guo Microelectronics; and the 64M serial FLASH selects a FLASH chip SM25P54. The RS422 serial port communication circuit chip adopts an SIT3490 of a domestic Na Core Micro Company. The chip adopts 3V-3.6V voltage power supply, the common mode input voltage range is -7V~+12V, the output voltage is 3V, the dissipation power is 471mW, the data rate is 10.0Mbps, full duplex and half duplex modes are provided, and up to 32 transceivers are supported in the bus connection. The infrared imaging circuit framework is as shown in Figure 2 The RS422 serial port circuit is as shown in Figure 3 .

[0036] Advantages: the FPGA module is composed of a plurality of programmable logic modules. This parallel processing mechanism is particularly suitable for completing repetitive digital signal processing tasks, and the FPGA far exceeds the serial execution architecture of a general-purpose DSP processor in performance. In addition, the FPGA also has the characteristics of low delay because the data processing does not need to pass through an operating system and is directly completed at the hardware level, so that extremely low data processing delay is achieved. This low delay characteristic is aimed at high-speed flying objects, and each sub-module can quickly respond to the overall instruction, so that the cooperation precision error of each sub-module is reduced with lower communication delay.

[0037] The application provides a design scheme for improving the sampling rate of an infrared detector and improving the output video frame frequency of an infrared scanning imaging system.

[0038] 1) Increase the sampling frequency of the infrared detector. The MC clock is the clock signal generated by the FPGA module, and the infrared detector samples the signal according to the MC clock. The sampling clock frequency range of the MC clock is 5-10MHZ. This embodiment uses the highest sampling clock frequency of 10MHZ. When acquiring real-time data such as high-speed moving object information and disaster monitoring, a higher sampling rate can more completely retain the information of the original image, reduce distortion, thereby improving the signal-to-noise ratio of the signal and making the image quality purer. The detector sampling clock timing is as follows: Figure 4 shown.

[0039] 2) Improve the image output frame rate. The infrared imaging circuit of the present invention adopts the Camera Link digital video output format, which is an open high-speed serial communication protocol, mainly used in digital camera interfaces. Camera Link image output has no frame delay. The present invention uses a basic configuration (Base) transmission rate of 2.04Gb / s, supports ports ABC, and has 1 chip. Achieve smoother and clearer motion effects, especially in fast-moving and instantly changing scenes. At the same time, high frame rate image data can significantly reduce the input delay of the next level, thereby improving the response speed of the subsequent level. Camera Link digital video circuit such as Figure 5 As shown. Working principle: After the FPGA module receives the signal from the infrared detector, it designs the row synchronization signal, field synchronization signal, and data valid signal based on the data encoding requirements of the Cameralink digital video circuit and the pixel clock, and synchronizes them with the pixel data. Innovation: Convert the above parallel signals into serial differential signals. 1. Strong anti-interference ability. Since the differential signal uses two opposite signals at the same time, it can eliminate common mode noise and improve the quality of the signal. 2. Improve signal integrity. The differential signal can better maintain the stability of the signal and reduce the impact of signal attenuation and distortion. 3. Reduce external electromagnetic radiation. In high-frequency signals, the differential signal can significantly reduce the amount of radiation by using two opposite signal lines at the same time, which not only helps to reduce interference with surrounding equipment, but also improves the overall performance of the system.

[0040] 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 localized circuit design method for an infrared scanning imaging system, characterized in that: The domestic circuit design of the infrared swing scanning imaging system includes an infrared lens assembly, a medium-wave refrigerated infrared detector assembly, an infrared imaging circuit, a swing machine assembly and a motor; The infrared lens assembly includes a continuous zoom lens and a motor drive circuit. The infrared lens assembly is used to receive infrared radiation from a scene and focus it on the focal plane of the infrared detector in the medium-wave cooled infrared detector assembly. The optical zoom and focus operations are completed by controlling the motor. The motor drive circuit is used to provide power and control signals to the motor to control the optical zoom and focus of the continuous zoom lens. The medium-wave refrigerated infrared detector assembly includes an infrared detector and a refrigerator, wherein the refrigerator is used to provide a suitable working environment for the infrared detector; the infrared detector is used to complete the photoelectric conversion of infrared radiation and generate a voltage signal; The infrared imaging circuit is used to process the voltage signal output by the infrared detector and transmit the image data in the form of SDI digital video to the receiving and display device at the back end. The infrared imaging circuit also communicates with the RS422 format serial port of the motor drive circuit to control the motor drive circuit to adjust the lens focal length; The swing machine assembly includes a swing machine and a driving circuit. The driving circuit is used to control the periodic scanning motion of the swing mirror. The swing machine is used to participate in the continuous zoom lens imaging.

2. The method according to claim 1, wherein The localized circuit of the infrared swing scanning imaging system also includes a power supply circuit, which is used to provide power to the infrared lens assembly, the medium-wave cooled infrared detector assembly, the infrared imaging circuit, and the swing machine assembly respectively.

3. The method according to claim 1, wherein The infrared imaging circuit is used to perform conditioning, noise reduction filtering, non-uniformity correction, blind pixel replacement, digital detail enhancement and stretch display processing on the voltage signal output by the infrared detector.

4. The method according to claim 1, wherein The infrared imaging circuit adopts a parallel communication architecture design of FPGA module + 6 RS422 serial ports, wherein the FPGA module adopts Fudan Microelectronics JFM7K325T8-N series FPGA. The peripheral circuit of the FPGA module includes a 30MHz crystal oscillator, 256M capacity SDRAM, 64M serial FLASH and related power supply; the 30MHz crystal oscillator is used to provide a clock source for the FPGA module, the 256M capacity SDRAM is used to cache image data, the FPGA module can execute the image correction algorithm, and the 64M serial FLASH is used to store programs and image correction parameters.

5. The method according to claim 1, wherein The 30MHz crystal oscillator uses the active crystal oscillator ZPB-26-30MHz produced by 707 Factory, the 256M capacity SDRAM uses the SDRAM chip SM48LC16M32M of Guowei Electronics, and the 64M serial FLASH uses the FLASH chip SM25P54.

6. The method according to claim 1, wherein The FPGA module generates the MC clock as the clock signal. The infrared detector samples the signal according to the MC clock. The frequency of the MC clock is 10 MHz.

7. The method according to claim 1, wherein The infrared imaging circuit adopts the Camera Link digital video output format. After the FPGA module receives the signal from the infrared detector, it designs the row synchronization signal, field synchronization signal, and data valid signal based on the data encoding requirements of the Camera Link digital video circuit and the pixel clock, and synchronizes them with the pixel data.

8. A domestically produced circuit for an infrared sweep imaging system designed using the method according to any one of claims 1 to 7.

Images