A high-speed mid-wave infrared light detection system and method based on stirling refrigeration

Abstract

The application discloses a high-speed middle-wave infrared light detection system and method based on Stirling mechanism refrigeration, which comprises a middle-wave infrared detector, a Stirling mechanism refrigeration module, an FPGA control module, a signal conditioning circuit and a high-speed ADC analog-digital converter. The Stirling mechanism refrigeration module provides a low-temperature working environment for the middle-wave infrared detector; the FPGA control module generates a driving time sequence of the detector, controls the high-speed ADC analog-digital converter to read analog electric signals of the detector and completes data buffer management; the signal conditioning circuit system pre-processes the analog electric signals output by the sensor; the system can also be connected with an external computer through a USB interface to realize control triggering, reading range, integral time, spectrum signal collection, data processing and visualization. The application has the advantages of low noise, high dynamic range, fast reading speed, high output frame frequency, high spectrum resolution, no need of liquid nitrogen refrigeration, convenient use and greatly reduced maintenance cost.

Description

Technical Field

[0001] This invention relates to the field of infrared detection technology, specifically to a high-speed mid-wave infrared light detection system and method based on Stirling cooling. Background Technology

[0002] Mid-wave infrared detectors possess advantages such as high sensitivity, fast response speed, and long detection range, and are widely used in infrared imaging, target recognition, space remote sensing, and laser detection. Mid-wave infrared light detection is closely related to scientific research, education, and national defense security. Currently, all commercially available mid-wave infrared light detection systems are imported from the United States. Therefore, my country urgently needs a fully domestically developed mid-wave infrared light detection system. Mid-wave infrared focal plane detectors are divided into room-temperature detectors and cryogenic detectors. High-sensitivity mercury cadmium telluride (MCH) detectors generally operate at a low temperature of around 77 K to reduce dark current and improve detectivity. Currently, most mid-wave infrared detection systems based on MCH detectors on the market rely on additional liquid nitrogen cooling, resulting in high maintenance costs and inconvenience. Furthermore, advancements in infrared spectroscopy and imaging technology have placed higher demands on detector resolution, readout rate, and signal-to-noise ratio. Therefore, the market urgently needs a high-speed, high-resolution, high-signal-to-noise-ratio, and easy-to-use mid-wave infrared light detection system.

[0003] Several existing patent documents involve the design of cooled mid-wave infrared detection systems, but all have varying degrees of technical limitations and cannot simultaneously meet the requirements of high-speed, high-resolution, easy-to-use, and fully domestically produced mid-wave infrared spectroscopy detection. The following analysis examines several representative existing patent documents.

[0004] Chinese patent document CN110186865B (application date June 14, 2019, authorization announcement date September 19, 2023) discloses an intelligent network-type infrared gas identification device, which includes an infrared lens, an infrared detector, a detector interface module, an imaging circuit module, an ARM control and transmission module, and a remote central workstation. The device uses a narrow-band mercury cadmium telluride mid-wave Stirling cooled infrared detector. The imaging circuit module includes an AD acquisition submodule, a FLASH storage submodule, an FPGA submodule, and a communication interface submodule. The AD acquisition submodule receives four analog outputs from the detector and converts them into 16-bit digital data, which is then transmitted to the FPGA for processing. After correction by the FPGA, the data is transmitted to the remote central workstation via the ARM control and transmission module and the communication interface. However, the aforementioned CN110186865B patent solution has the following technical problems: First, it uses FLASH memory to store correction data. The read and write speed of FLASH is limited, making it difficult to meet the real-time caching requirements of large data volumes in high-speed signal acquisition scenarios, thus restricting the system's output frame rate. Second, it lacks a signal conditioning stage before analog-to-digital conversion, resulting in poor transmission quality of the analog electrical signal output by the detector and affecting detection accuracy. Third, this solution is geared towards narrow-band (3.2-3.4μm) applications for gas leak identification and is not suitable for wide-band mid-wave infrared spectral detection. Furthermore, it does not involve spectral resolution optimization and cannot meet the requirements for fine structure analysis. Fourth, this solution uses an ARM module and network for remote data transmission, resulting in a complex transmission link and significant latency, making it unsuitable for real-time acquisition and processing of high-speed infrared spectral data.

[0005] Chinese patent document CN118067248A (application date March 12, 2024, publication date May 24, 2024) discloses a driving circuit based on an indium antimonide infrared detector, including a detector timing control module, an analog preamplifier circuit, a detector bias module, a detector cooling status readout module, and an FPGA main control module. The FPGA generates an LVDS differential signal, sorts and merges four digital image signals into one original grayscale digital image; the analog preamplifier circuit performs impedance transformation, differential conversion, and analog-to-digital conversion on the analog video signal; the detector is cooled to 77K-150K by a Stirling cooler, and the temperature signal is fed back by a temperature-sensing diode and input to the FPGA via an ADC to achieve power-up control. However, the aforementioned patent solution CN118067248A has the following technical problems: First, its detector material is indium antimonide (InSb), and the cutoff wavelength of the indium antimonide detector is relatively short (about 5.5μm), which limits its application in other mid-wave infrared bands (such as 5-6μm) and is not conducive to spectral fingerprint analysis. In contrast, the mercury cadmium telluride detector can achieve wider band coverage through component adjustment. Second, this solution only involves the driving circuit itself and cannot be directly used with external computer systems, host computer software, etc. to form a complete detection system. It does not have software functions such as spectral signal acquisition, visualization processing, and background subtraction, and cannot be directly used for spectral detection. Third, its signal conditioning circuit includes impedance transformation and differential conversion, and it also inputs an additional bias voltage to the detector, but it lacks a "de-biasing voltage" stage. The baseline drift problem of the detector output signal is not effectively solved, affecting the accuracy and dynamic range of subsequent analog-to-digital conversion. Fourth, this solution does not use a high-speed cache (such as DDR2) for data caching, which limits the data transmission rate and makes it difficult to meet the large data transmission requirements of high-speed infrared spectral detection.

[0006] Chinese patent document CN118945445A (application date August 5, 2024, publication date November 12, 2024) discloses a cooled mid-wave infrared thermal imaging system, which includes an infrared objective lens module, an infrared detector, a Stirling integrated refrigerator, a signal processing module, and a power supply module. The infrared detector is cooled to a preset temperature by the Stirling refrigerator, converting the infrared radiation signal into an analog electrical signal. The signal processing module drives the refrigerator and objective lens module motors, amplifying and sampling the analog electrical signal before converting it into a digital image signal. After correction, it is converted into a standard digital video signal for output. However, the aforementioned CN118945445A patent solution has the following technical problems: First, it is geared towards thermal imaging applications and includes a continuous zoom optical system. The system architecture and application scenario are different from the spectral detection addressed by this invention. Thermal imaging systems pursue image frame rate and temperature resolution, while spectral detection systems pursue spectral resolution and signal fidelity. The two technical approaches are fundamentally different. Second, its signal processing module only amplifies and samples analog signals and does not disclose specific electronic designs such as FPGA control architecture, multi-channel ADC parallel acquisition, and signal conditioning circuits (impedance matching, DC bias removal, analog amplification), making it difficult to guarantee signal quality. Third, this solution outputs standard digital video signals and does not involve data communication with external computer systems or upper-computer spectral analysis functions, which cannot meet the data processing requirements of scientific instrument-level spectral detection, such as background subtraction, noise removal, and spectral visualization. Fourth, this solution does not disclose the specific value of the cooling temperature and the temperature control accuracy, making it impossible to assess whether it can meet the stability requirements of the 77K low-temperature operation of the mercury cadmium telluride detector.

[0007] In summary, the existing technologies have the following shortcomings: (1) Mid-wave infrared detection systems using mercury cadmium telluride detectors generally use liquid nitrogen cooling, which requires frequent replenishment of liquid nitrogen, resulting in high maintenance costs and inconvenience, making it difficult to meet the requirements for portability and long-term continuous operation; (2) Existing patented solutions either lack complete signal conditioning circuit design (impedance matching, DC bias removal, analog amplification) or lack high-speed data cache (DDR2) and high-speed transmission interface (USB3.0), making it difficult to meet the requirements of high-speed, high-resolution spectral detection for signal quality and data throughput; (3) Existing solutions have not formed a complete system solution integrating Stirling cooling, FPGA unified control, multi-channel ADC parallel acquisition, signal conditioning optimization, high-speed data transmission and host computer spectral analysis, making it difficult for various technologies to work together effectively; (4) The spectral resolution of existing solutions is limited (for example, the spectral resolution of the imported American system at a 50-line grating and a center detection wavelength of 1600 wavenumbers is only 4 wavenumbers), which cannot clearly distinguish fine spectral structures, restricting its application in scientific instruments and research fields; (5) my country urgently needs to achieve full domestic production.

[0008] Therefore, there is an urgent need in this field for a mid-wave infrared light detection system that is based on Stirling cooling, does not require liquid nitrogen, has high-speed and high-resolution detection capabilities, integrates signal conditioning, high-speed data transmission and host computer spectral analysis, and has all components domestically produced, in order to solve the above-mentioned technical problems existing in the prior art. Summary of the Invention

[0009] To address the shortcomings of existing technologies, the present invention aims to provide a high-speed mid-wave infrared light detection system and method based on Stirling refrigerator. This system and method can provide a low-temperature working environment for the detector through Stirling refrigerator to replace the traditional liquid nitrogen cooling method. It can also be combined with a high-speed FPGA control module, and has the characteristics of low readout noise, high dynamic range, fast readout speed and easy use.

[0010] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0011] A high-speed mid-wave infrared light detection system based on Stirling condenser cooling includes: a mid-wave infrared detector, a Stirling condenser cooling module, an FPGA control module, a signal conditioning circuit, and a high-speed ADC analog-to-digital converter.

[0012] The mid-wave infrared detector is used to convert the detected incident mid-wave infrared light into an analog electrical signal.

[0013] The Stirling refrigeration module is used to provide a low-temperature operating environment for the mid-wave infrared detector;

[0014] The FPGA control module is used to generate the driving timing of the mid-wave infrared detector, control the high-speed ADC analog-to-digital converter to perform synchronous acquisition, drive the Stirling machine cooling module to work and read the temperature feedback signal, and complete the acquisition data buffering and transmission control.

[0015] The signal conditioning circuit is used to perform impedance matching, DC bias removal and amplification on the analog electrical signal so that it conforms to the input range of the high-speed ADC analog-to-digital converter.

[0016] The high-speed ADC analog-to-digital converter is used to convert the analog electrical signal processed by the signal conditioning circuit into a digital signal and return it to the FPGA control module.

[0017] The FPGA control module serves as the control center and is connected to the mid-wave infrared detector, the Stirling cooling module, and the high-speed ADC analog-to-digital converter. The mid-wave infrared detector is closely connected to the Stirling cooling module and is sequentially connected to the signal conditioning circuit and the high-speed ADC analog-to-digital converter, thereby realizing the control of the detector's low-temperature working environment and the high-speed acquisition, storage, and transmission of detection data.

[0018] Furthermore, as described above, a high-speed mid-wave infrared light detection system based on Stirling cooling includes a mid-wave infrared detector comprising a mercury cadmium telluride detector chip, a readout circuit, and an infrared window.

[0019] The mercury cadmium telluride detector chip is used to convert mid-wave infrared light into electrical signals.

[0020] The readout circuit is used to read the electrical signals generated by the mercury cadmium telluride detector chip;

[0021] The infrared window is used to adjust the range of mid-wave infrared light transmission wavelengths.

[0022] Furthermore, in the high-speed mid-wave infrared light detection system based on Stirling refrigeration as described above, the Stirling refrigeration module includes a Stirling refrigerator, a metal micro Dewar, and a temperature-sensing diode.

[0023] The Stirling refrigerator is used to provide the low-temperature operating environment required by the mid-wave infrared detector;

[0024] The metal micro Dewars are used to maintain the vacuum insulation environment required for the low-temperature operation of the Stirling refrigerator.

[0025] The temperature-sensing diode is used to read the temperature of the mercury cadmium telluride detector chip.

[0026] Furthermore, in the high-speed mid-wave infrared light detection system based on Stirling cooling as described above, the FPGA control module includes an FPGA chip and a memory.

[0027] The FPGA chip is used to provide drive signals for the mid-wave infrared detector, control the high-speed ADC analog-to-digital converter to perform data acquisition, and read the temperature feedback signal of the temperature sensing diode as the safe start condition for the high-speed mid-wave infrared light detection system.

[0028] The memory is used to cache the data acquired by the high-speed ADC analog-to-digital converter.

[0029] Furthermore, in the high-speed mid-wave infrared light detection system based on Stirling cooling as described above, the signal conditioning circuit includes an impedance matching circuit, a DC bias removal circuit, and an analog amplifier circuit.

[0030] The impedance matching circuit is used to match the output analog electrical signal of the mid-wave infrared detector with the impedance of the high-speed ADC analog-to-digital converter.

[0031] The DC bias removal circuit is used to remove the DC bias voltage of the analog electrical signal;

[0032] The analog amplifier circuit is used to amplify the voltage of an analog electrical signal without DC bias, so that it can be adapted to the voltage input range of a high-speed ADC analog-to-digital converter.

[0033] Furthermore, in the high-speed mid-wave infrared light detection system based on Stirling cooling as described above, the high-speed ADC includes multiple independent analog-to-digital conversion channels that match the number of detector output channels, for synchronous and parallel acquisition of signals from each channel, and for returning the acquired data to the FPGA control module.

[0034] Furthermore, the infrared window is coated with an infrared anti-reflection film to limit the transmission wavelength range and adjust the transmission uniformity.

[0035] Furthermore, the impedance matching circuit is implemented using an emitter follower circuit, the DC bias removal circuit is implemented using a differential subtractor, and the analog amplifier circuit uses a differential amplifier to convert the single-ended signal into a differential signal and amplify it.

[0036] Furthermore, the high-speed mid-wave infrared light detection system based on Stirling cooling, as described above, can also be used in conjunction with an external computer via USB communication protocol.

[0037] The computer, through control software, configures the parameters of the high-speed mid-wave infrared light detection system, receives the digital signals for data processing, image display, and data acquisition and printing; furthermore, the computer also controls the triggering mode, integration time, reading area, and acquisition parameters of the high-speed mid-wave infrared light detection system through the control software, acquires the digital signals output by the high-speed mid-wave infrared light detection system, and performs visualization processing.

[0038] Furthermore, the control software is written in LabVIEW and runs on the Windows operating system.

[0039] This invention also discloses a high-speed mid-wave infrared light detection method based on Stirling mechanism cooling, implemented through the system described above, including the following steps:

[0040] (1) The mid-wave infrared detector is cooled to a low-temperature working environment by using a Stirling cooling module;

[0041] (2) The FPGA control module generates the driving timing sequence to drive the mid-wave infrared detector to collect mid-wave infrared light signals and convert them into analog electrical signals;

[0042] (3) The signal conditioning circuit performs impedance matching, DC bias removal and amplification on the analog electrical signal in sequence;

[0043] (4) The high-speed ADC analog-to-digital converter converts the processed analog electrical signal into a digital signal;

[0044] (5) The FPGA control module buffers and outputs the digital signal.

[0045] The beneficial effects of this invention are as follows: This invention provides a high-speed mid-wave infrared light detection system and method based on Stirling mechanism cooling, characterized by low readout noise, high dynamic range, fast readout speed, high window output frame rate, and ease of use. It features advanced technology, stability and reliability, strong performance, low cost, and high cost-effectiveness. It can be widely used in high-speed readout, data acquisition, and temperature control systems for cooled mid-wave infrared focal plane detectors, and can be applied extensively in fields such as infrared imaging, target detection, spectral analysis, scientific instruments, and national defense equipment. Attached Figure Description

[0046] Figure 1 This is a schematic diagram illustrating the principle of a control system and method for a high-speed mid-wave infrared light detection system based on Stirling mechanism refrigeration provided in an embodiment of the present invention.

[0047] Figure 2 This invention provides measured transient infrared pump-infrared detection spectral data of a high-speed mid-wave infrared light detection system based on Stirling mechanism cooling, and compares it with existing US detection systems.

[0048] Figure 3 This is measured two-dimensional infrared spectral data of a high-speed mid-wave infrared light detection system based on Stirling mechanism cooling provided in this embodiment of the invention;

[0049] Figure 4 This is a flowchart of a high-speed mid-wave infrared light detection method using a Stirling mechanism refrigeration system provided in an embodiment of the present invention.

[0050] Figure 5 This is a schematic diagram of a high-speed mid-wave infrared light detection system based on Stirling cooling, as described in a specific example of the present invention. In the diagram, black arrows represent electrical signals and control relationships, while white arrows represent the process of converting optical signals into digital signals. Detailed Implementation

[0051] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0052] like Figure 1 , Figure 5 As shown, a high-speed mid-wave infrared light detection system based on Stirling condenser cooling is disclosed. The mid-wave infrared light detection system includes: a mid-wave infrared detector 1, a Stirling condenser cooling module 2, an FPGA control module 3, a signal conditioning circuit 4, and a high-speed ADC analog-to-digital converter 5.

[0053] The mid-wave infrared detector 1 is used to convert the detected mid-wave infrared light into an electrical signal;

[0054] The mid-wave infrared detector 1 includes: a mercury cadmium telluride detector chip 11, a readout circuit 12, and an infrared window 13;

[0055] The mercury cadmium telluride detector chip 11 includes a mercury cadmium telluride thin film material and a detector chip;

[0056] The mercury cadmium telluride detector chip uses the photoelectric effect to convert mid-wave infrared light signals into analog electrical signals;

[0057] Readout circuit 12 is used for high-performance readout of analog electrical signals in the mercury cadmium telluride detector chip;

[0058] Infrared window 13 is coated with an infrared anti-reflection film, which can limit the transmission wavelength range and adjust the transmission uniformity.

[0059] The Stirling refrigeration module is used to provide the low-temperature operating environment required by the mid-wave infrared detector;

[0060] The Stirling refrigeration module 2 includes: a Stirling refrigerator 21, a metal micro Dewar 22, and a temperature sensing diode 23;

[0061] The Stirling refrigeration unit 21 consists of a motor, compressor, piston, accumulator, cold finger, and drive circuit.

[0062] The motor drives the compressor piston; the accumulator is a heat exchanger in the refrigeration system that transports and recovers the refrigerant; the cold finger is the heat exchange interface of the refrigeration system, and the working surface of the cold finger is the interface that achieves thermal coupling with the detector chip.

[0063] The detector chip is mounted on the front end of the cold finger working face of the refrigerator to obtain the required cooling temperature;

[0064] Metal micro-Dewar 22 is used to maintain the vacuum insulation required for the operation of the refrigerator, ensuring that the detector operates stably in a low-temperature environment;

[0065] Temperature-sensing diode 23 is used to read the temperature of the mercury cadmium telluride detector chip;

[0066] In this embodiment, the FPGA control module is used to generate the driving timing of the mid-wave infrared detector, control the high-speed ADC analog-to-digital converter to perform synchronous acquisition, drive the Stirling refrigeration module to work and read the temperature feedback signal, and complete the acquisition data buffering and transmission control.

[0067] The FPGA control module 3 includes: an FPGA chip 31 and a memory 32;

[0068] The FPGA chip 31, as the core control component, is used to receive triggers, provide drive signals to the mid-wave infrared detector, control the high-speed ADC analog-to-digital converter to perform data acquisition, obtain the temperature feedback signal of the temperature sensing diode, and use it as the safe start condition of the high-speed mid-wave infrared light detection system.

[0069] The memory 32 is DDR2, which is used to cache the data acquired by the high-speed ADC analog-to-digital converter to meet the requirements of high-speed signal acquisition.

[0070] The signal conditioning circuit 4 is used to perform impedance matching, DC bias removal and amplification on the analog electrical signal so that it conforms to the input range of the high-speed ADC analog-to-digital converter.

[0071] The signal conditioning circuit 4 includes an impedance matching circuit 41, a DC bias removal circuit 42, and an analog amplifier circuit 43.

[0072] In this embodiment, the impedance matching circuit 41 is implemented using an emitter follower circuit to achieve impedance matching between the detector output and the subsequent circuit, ensuring effective signal transmission.

[0073] The DC bias removal circuit 42 is implemented using a differential subtractor to remove the DC component in the analog signal and eliminate baseline drift.

[0074] The analog amplifier circuit 43 uses a differential operational amplifier to convert the single-ended signal after DC bias removal into a differential signal and amplify it to a preset voltage amplitude range, so as to maximize the utilization of the range of the high-speed ADC analog-to-digital conversion system.

[0075] Impedance matching circuit 41, DC bias removal circuit 42 and analog amplifier circuit 43 are cascaded in sequence to maximize the utilization of the ADC range.

[0076] The high-speed ADC analog-to-digital converter 5 includes multiple independent analog-to-digital conversion channels matching the number of detector output channels. These channels are used for synchronous and parallel acquisition of signals from each channel, combining the acquired signals into a full-frame image to maximize the output frame rate, and returning the acquired data to the FPGA control module. In this embodiment, the high-speed mid-wave infrared light detection system based on Stirling cooling, as described above, can also be connected to an external computer via the USB 3.0 communication protocol.

[0077] The computer, through control software, configures the parameters of the high-speed mid-wave infrared light detection system, and receives the digital signals for data processing, image display, and data acquisition and printing.

[0078] The computer, through control software, sends control commands to the high-speed mid-wave infrared light detection system according to preset trigger delay time, detector reading range, and integration time. It is also used to acquire digital signals from the high-speed mid-wave infrared light detection system and perform visualization processing on these digital signals. The control software is written in LabVIEW and runs on the Windows operating system. The control software is also used to perform operations such as subtraction and noise reduction on the spectral signals.

[0079] This invention, through the FPGA control module described above, utilizes a Stirling refrigerator and a high-speed ADC analog-to-digital converter to realize a high-speed mid-wave infrared light detection system based on a mercury cadmium telluride detector. This system features low readout noise, high dynamic range, fast readout speed, high window output frame rate, and high resolution. Furthermore, the system requires no additional liquid nitrogen cooling, making it easy to use and significantly reducing maintenance costs. The system can also be connected to a computer containing control software, enabling real-time monitoring and rapid processing of spectral signals, arbitrary selection of the acquisition range and integration time, greatly facilitating the practical application of this mid-wave infrared detection system.

[0080] Example 1

[0081] like Figure 1 , Figure 5 As shown, a high-speed mid-wave infrared light detection system based on Stirling condenser cooling includes: a mid-wave infrared detector 1, a Stirling condenser cooling module 2, an FPGA control module 3, a signal conditioning circuit 4, and a high-speed ADC analog-to-digital converter 5; the high-speed mid-wave infrared light detection system can be externally connected to a computer.

[0082] The mid-wave infrared detector 1 includes a mercury cadmium telluride detector chip 11, a readout circuit 12, and an infrared window 13;

[0083] Stirling refrigeration module 2 includes a Stirling refrigerator 21, a metal micro Dewar 22, and a temperature sensing diode 23;

[0084] FPGA control module 3 includes FPGA chip 31 and memory 32;

[0085] The signal conditioning circuit 4 is located at the analog front end and includes an impedance matching circuit 41, a DC bias removal circuit 42, and an analog amplifier circuit 43.

[0086] The external computer is used to run the control software for the high-speed mid-wave infrared light detection system;

[0087] In this embodiment, the FPGA chip communicates with the computer via a USB 3.0 interface. Power is supplied to the FPGA chip through a power circuit. The FPGA chip receives a trigger signal within a window based on parameters pre-set in the computer system's control software, controlling the generation of a drive signal for the detector to begin or stop collecting mid-wave infrared light. Simultaneously, the FPGA chip continuously provides a cooler drive, powering the Stirling cooling module to maintain the detector's required 77K low-temperature operating environment, and reads a temperature feedback signal through a temperature sensor. Specifically, the temperature sensor is a thermoelectric diode mounted near the detector chip to detect the detector temperature in real time and convert the temperature signal into an electrical signal fed back to the FPGA chip. The FPGA chip reads this temperature feedback signal and only allows the mid-wave infrared detection system to operate when the detector chip temperature is below 90K, thus preventing damage to the detector chip.

[0088] Figure 5 In the diagram, black arrows represent electrical signals and control relationships, while white arrows represent the process of converting optical signals into digital signals.

[0089] The detector converts the detected mid-wave infrared light signal into an electrical signal. This signal is then processed by a signal conditioning circuit at the analog front end, impedance matching, and DC bias removal before being amplified to the input signal range of the high-speed ADC (Analog-to-Digital Converter) system. An FPGA chip controls the high-speed ADC to perform multi-channel parallel high-speed AD conversion and buffers the resulting digital signal in memory. The FPGA chip then sends the data from memory to the computer. The control software performs data visualization, noise reduction, and other operations.

[0090] In this embodiment, the computer can communicate with the mid-wave infrared detection system via a USB 3.0 interface, thereby controlling the latter, setting parameters in advance, and acquiring, processing, and visualizing the signals.

[0091] In this embodiment, as Figure 2 As shown, through actual measurement of the infrared pump-infrared detection signal of coumarin 6-tetrahydrofuran solution, under the same test conditions (detector integration time of 10 μs, ADC sampling rate of 1 MSPS, readout area of ​​full frame 320×10 pixels, ambient temperature of room temperature), compared with the imported American mid-wave infrared light detection system (dashed line), the spectral resolution of this invention (solid line) at a center detection wavelength of 1600 wavenumber and 50-line grating dispersion was improved from 4 wavenumbers to 0.5 wavenumbers, an improvement of 8 times, and can clearly distinguish each peak type. The imported American detection system is from InfraRed, with a detector model of MCT-10-128-2×64 and a high-speed acquisition system model of FPAS-0144.

[0092] In this embodiment, as Figure 3 As shown, by actually measuring the two-dimensional infrared spectral signal of potassium thiocyanate deuterated aqueous solution, the evolution of the spectral shape with time delay can be clearly and with high resolution observed.

[0093] Example 2

[0094] like Figure 4 As shown, this embodiment discloses a high-speed mid-wave infrared light detection method based on Stirling mechanism cooling, including the following steps:

[0095] (1) The mid-wave infrared detector is cooled to a low-temperature working environment by using a Stirling cooling module;

[0096] (2) The FPGA control module generates the driving timing sequence to drive the mid-wave infrared detector to collect mid-wave infrared light signals and convert them into analog electrical signals;

[0097] (3) The signal conditioning circuit performs impedance matching, DC bias removal and amplification on the analog electrical signal in sequence;

[0098] (4) The high-speed ADC analog-to-digital converter converts the processed analog electrical signal into a digital signal;

[0099] (5) The FPGA control module buffers and outputs the digital signal.

[0100] The detection method described in this invention uses an FPGA control module as the core scheduling unit, a Stirling cooling module to provide low-temperature protection, and a signal conditioning circuit and a high-speed ADC analog-to-digital converter to complete the entire data link from optical signal acquisition. The specific implementation methods of each step are as follows:

[0101]

S1

[0102] After the system powers on, the FPGA control module first drives the Stirling refrigerator module to cool the mid-wave infrared detector, ensuring its stable operation at a low temperature of 77K. The Stirling refrigerator consists of a motor, compressor, piston, accumulator, cold finger, and drive circuitry: the motor drives the compressor piston to compress the refrigerant; the accumulator acts as a heat exchanger, transporting and recovering the refrigerant; and the cold finger serves as the heat exchange interface of the refrigeration system, its working surface thermally coupled to the detector chip. The mercury cadmium telluride detector chip is mounted on the front end of the cold finger's working surface, thus achieving the required cooling temperature.

[0103] Metal micro-Dewars are used to maintain the vacuum insulation environment required for the operation of the cryostat, reducing external heat transfer and ensuring the detector operates stably at low temperatures. This invention uses a Stirling cryostat closed-loop cooling scheme to replace traditional liquid nitrogen cooling, cooling from room temperature to 77K in only about 8 minutes, without the need for additional liquid nitrogen, making it convenient to use and significantly reducing maintenance costs.

[0104] During the cooling process, the FPGA control module reads the operating temperature of the detector chip in real time through the temperature sensor, and controls the safe operation of the mid-wave infrared detection system according to the feedback signal, ensuring that the mercury cadmium telluride detector chip always operates in a low-temperature environment with high sensitivity, safety and stability.

[0105]

S2

[0106] Once the detector reaches a stable low-temperature operating environment, the FPGA control module receives external trigger signals or internal trigger commands, generates drive timing signals according to pre-configured parameters such as integration time and reading range, and outputs them to the mid-wave infrared detector.

[0107] The mid-wave infrared detector comprises a mercury cadmium telluride (HCd) detector chip, a readout circuit, and an infrared window. The HCd detector chip utilizes the photoelectric effect to convert incident mid-wave infrared light signals into electrical signals. The readout circuit is used to read out the electrical signals from the integrated circuit in a high-performance manner, outputting an analog voltage signal. The infrared window is coated with an infrared anti-reflection film, which limits the transmission wavelength range and adjusts the transmission uniformity, ensuring that only mid-wave infrared light of the target wavelength band is effectively incident on the detector chip.

[0108] Under the timing control of the FPGA driver, the detector accumulates photogenerated charge according to the set integration time, and converts the accumulated charge into an analog voltage signal output during the readout phase, completing the conversion from mid-wave infrared light signal to analog electrical signal. The driving timing parameters can also be sent to the FPGA chip by an external computer via USB 3.0 interface, enabling flexible configuration.

[0109]

S3

[0110] The analog electrical signal output by the detector is relatively weak and contains a DC bias component, which cannot directly meet the input requirements of the high-speed ADC analog-to-digital conversion system. It needs to be preprocessed in three sub-steps by the signal conditioning circuit.

[0111]

S3-1

[0112] The signal conditioning circuit first performs impedance matching between the detector output and the high-speed ADC analog-to-digital converter. The mercury cadmium telluride detector's readout circuit has a high output impedance; if directly connected to subsequent acquisition circuits, impedance mismatch will lead to signal attenuation and distortion. Impedance matching circuits (such as emitter follower circuits) can achieve impedance transformation from high-impedance input to low-impedance output, ensuring that the analog voltage signal output by the detector is transmitted effectively and with low loss to the subsequent processing stage, thus guaranteeing signal integrity.

[0113]

S3-2

[0114] The signal after impedance matching contains a large DC bias component, which does not carry useful spectral information and occupies the quantization range of the ADC. The signal conditioning circuit removes the DC component and low-frequency baseline drift from the signal by using a DC bias removal circuit (such as a differential subtraction circuit), retaining only the AC component that carries useful information, thus freeing up effective dynamic range for subsequent amplification and analog-to-digital conversion.

[0115]

S3-3

[0116] Even after removing the DC bias, the AC signal amplitude is still relatively weak and needs to be amplified by an analog amplifier circuit. The analog amplifier circuit amplifies the signal to an amplitude that matches the input range of the high-speed ADC (Analog-to-Digital Converter), maximizing the utilization of the ADC's quantization range and thus improving the signal-to-noise ratio and dynamic range. After impedance matching, DC bias removal, and analog amplification, the signal processing circuit can output an analog electrical signal that meets the ADC input requirements.

[0117]

S4

[0118] The analog electrical signal, pre-processed by the signal conditioning circuit, is sent to the high-speed ADC analog-to-digital converter for analog-to-digital conversion. The high-speed ADC system contains multiple independent analog-to-digital conversion channels, matching the number of detector output channels, enabling synchronous parallel acquisition of output signals from multiple detectors.

[0119] Under the synchronous timing control of the FPGA control module, multiple channels simultaneously sample and quantize analog electrical signals, with each channel independently completing analog-to-digital conversion and outputting a digital signal. This multi-channel parallel acquisition method significantly shortens the acquisition time for a single frame of data compared to single-channel serial acquisition, thereby maximizing the output frame rate and meeting the high frame rate and large data volume acquisition requirements of high-speed mid-wave infrared detection. The FPGA control module combines the acquired data from multiple channels to form a complete frame of image data.

[0120]

S5

[0121] The digital signal output by the high-speed ADC analog-to-digital converter is received and buffered by the FPGA control module. The FPGA control module includes a DDR2 high-speed memory for buffering the data acquired by the ADC. The high-speed read and write performance of DDR2 can meet the buffering requirements of large amounts of data generated by four-channel parallel acquisition, thus avoiding data loss.

[0122] After caching, the FPGA control system can retrieve and output digital signals from the controller at high speed, and can also transmit digital signals to an external computer via the USB 3.0 interface. The USB 3.0 interface has high bandwidth characteristics, which can support the real-time and stable transmission of large amounts of data generated by high-speed infrared detection, ensuring fast and reliable data transfer from the detection system to the computer.

[0123] Using this method, the mid-wave infrared system can output spectral digital signals at high speed. It can also be connected to an external computer via a USB 3.0 interface, where control software (written in LabVIEW and running on a Windows operating system) processes the digital signals, displays images, and acquires and prints data.

[0124] Actual test data show that, under the same test conditions (such as the infrared pump-infrared detection signal of the coumarin 6-tetrahydrofuran solution in Example 1), the infrared pump-infrared detection signal is significantly different. Figure 2 As shown in the figure, the spectral resolution of this invention is significantly improved from 4 wavenumbers to 0.5 wavenumbers compared to the imported American detection system, an improvement of approximately 8 times. This allows for clear differentiation of various peak types, providing crucial support for fine spectral structure analysis. Furthermore, the external computer can control multiple optical parametric amplifiers via software, directly outputting two-dimensional infrared spectral data, greatly facilitating the use of mid-wave infrared detection systems and meeting the needs of complex spectral research.

[0125] Synergistic effect of each step:

[0126] The above steps (1) to (5) are executed sequentially and cooperate to form a complete detection process: the Stirling refrigeration system provides 77 K low temperature protection (S1), the FPGA drives the detector to collect infrared light signals (S2), the signal conditioning circuit system completes impedance matching, debiasing and amplification preprocessing (S3), the high-speed ADC four-channel parallel acquisition realizes high frame rate analog-to-digital conversion (S4), and the FPGA caches the signal through DDR2 and outputs digital signals at high speed (S5).

[0127] This invention achieves a high-speed mid-wave infrared light detection method with low readout noise, high dynamic range, high readout speed, high window output frame rate, and high spectral resolution through the organic combination of the above methods. It does not require additional liquid nitrogen cooling, is easy to use, significantly reduces maintenance costs, and all components are domestically produced.

[0128] Compared with the prior art, the present invention has the following outstanding advantages:

[0129] (1) This invention utilizes the Stirling cooling mechanism to provide a cooling method for the mid-wave infrared detection system, which can cool from room temperature to 77 K in just 8 minutes; compared with the common liquid nitrogen cooling mode, it greatly improves the ease of use and reduces maintenance costs;

[0130] (2) The detection system is controlled by an FPGA chip and equipped with DDR2 cache. The circuit logic is simple and the acquisition speed is extremely fast, which can meet the needs of high frequency and high speed signal acquisition.

[0131] (3) By using a high-precision ADC and multiple sensor output channels, the signals are collected and combined into a full-frame image, which can maximize the output frame rate.

[0132] (4) It can communicate with a computer using a USB 3.0 interface, and the data transmission is fast and stable;

[0133] (5) This invention can significantly improve the spectral resolution of detection, providing important support for fine structure analysis;

[0134] (6) All components are domestically produced.

[0135] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention is also intended to include these modifications and variations.

Claims

1. A high-speed mid-wave infrared light detection system based on Stirling mechanism cooling, characterized in that, The system includes: a mid-wave infrared detector, a Stirling refrigeration module, an FPGA control module, a signal conditioning circuit, and a high-speed ADC analog-to-digital converter; wherein, the mid-wave infrared detector is used to convert the detected incident mid-wave infrared light into an analog electrical signal; The Stirling refrigeration module is used to provide a low-temperature operating environment for the mid-wave infrared detector; The FPGA control module is used to generate the driving timing of the mid-wave infrared detector, control the high-speed ADC analog-to-digital converter to perform synchronous acquisition, drive the Stirling machine cooling module to work and read the temperature feedback signal, and complete the acquisition data buffering and transmission control. The signal conditioning circuit is used to perform impedance matching, DC bias removal and amplification on the analog electrical signal so that it conforms to the input range of the high-speed ADC analog-to-digital converter. The high-speed ADC analog-to-digital converter is used to convert the analog signal processed by the signal conditioning circuit into a digital signal and return it to the FPGA control module. The FPGA control module serves as the control center and is connected to the mid-wave infrared detector, the Stirling cooling module, and the high-speed ADC analog-to-digital converter. The mid-wave infrared detector is closely connected to the Stirling cooling module and is sequentially connected to the signal conditioning circuit and the high-speed ADC analog-to-digital converter to realize the control of the detector's low-temperature working environment and the high-speed acquisition, storage, and transmission of detection data.

2. The high-speed mid-wave infrared light detection system based on Stirling cooling according to claim 1, characterized in that, The mid-wave infrared detector includes: a mercury cadmium telluride detector chip, a readout circuit, and an infrared window; wherein, the mercury cadmium telluride detector chip is used to convert mid-wave infrared light into an electrical signal; the readout circuit is used to read the electrical signal generated by the mercury cadmium telluride detector chip; and the infrared window is used to adjust the transmission wavelength range of mid-wave infrared light.

3. The high-speed mid-wave infrared light detection system based on Stirling cooling according to claim 1, characterized in that, The Stirling refrigeration module includes a Stirling refrigerator, a metal micro Dewar, and a temperature-sensing diode; wherein, the Stirling refrigerator is used to provide the low-temperature operating environment required by the mid-wave infrared detector; the metal micro Dewar is used to provide the vacuum insulation environment required for the low-temperature operation of the Stirling refrigerator; and the temperature-sensing diode is used to read the temperature of the mercury cadmium telluride detector chip.

4. The high-speed mid-wave infrared light detection system based on Stirling mechanism cooling according to claim 1, characterized in that, The FPGA control module includes an FPGA chip and a memory. The FPGA chip is used to provide a drive signal for the mid-wave infrared detector, control the high-speed ADC analog-to-digital converter to perform data acquisition, and read the temperature feedback signal of the temperature sensing diode as the safe start condition of the high-speed mid-wave infrared light detection system. The memory is used to cache the data acquired by the high-speed ADC analog-to-digital converter.

5. A high-speed mid-wave infrared light detection system based on Stirling mechanism cooling according to claim 4, characterized in that, The memory uses a DDR2 cache.

6. The high-speed mid-wave infrared light detection system based on Stirling mechanism cooling according to claim 1, characterized in that, The signal conditioning circuit includes an impedance matching circuit, a DC bias removal circuit, and an analog amplifier circuit. The impedance matching circuit is used to match the output analog electrical signal of the mid-wave infrared detector with the impedance of the high-speed ADC analog-to-digital converter. The DC bias removal circuit is used to remove the DC bias voltage of the analog electrical signal. The analog amplifier circuit is used to amplify the voltage of the analog electrical signal without DC bias, so that it can be adapted to the voltage input range of the high-speed ADC analog-to-digital converter.

7. A high-speed mid-wave infrared light detection system based on Stirling mechanism cooling according to claim 1, characterized in that, The high-speed ADC includes multiple independent analog-to-digital conversion channels that match the number of detector output channels, for synchronous and parallel acquisition of signals from each channel, and for returning the acquired data to the FPGA control module.

8. A high-speed mid-wave infrared light detection system based on Stirling cooling according to claim 2, characterized in that, The infrared window is coated with an infrared anti-reflection film to limit the transmission wavelength range and adjust the transmission uniformity.

9. A high-speed mid-wave infrared light detection system based on Stirling mechanism cooling according to claim 6, characterized in that, The impedance matching circuit is implemented using an emitter follower circuit, the DC bias removal circuit is implemented using a differential subtractor, and the analog amplifier circuit uses a differential amplifier to convert the single-ended signal into a differential signal and amplify it.

10. A high-speed mid-wave infrared light detection system based on Stirling cooling according to any one of claims 1-9, characterized in that, The system can also be used with an external computer via USB communication protocol.

11. A high-speed mid-wave infrared light detection system based on Stirling mechanism cooling according to claim 10, characterized in that, The computer configures the parameters of the high-speed mid-wave infrared light detection system through control software, and receives the digital signals for data processing, image display, and data acquisition and printing.

12. A high-speed mid-wave infrared light detection system based on Stirling cooling according to claim 11, characterized in that, The computer also controls the triggering method, integration time, reading area, and acquisition parameters of the high-speed mid-wave infrared light detection system through control software, and acquires the digital signal output by the high-speed mid-wave infrared light detection system and performs visualization processing.

13. A high-speed mid-wave infrared light detection system based on Stirling cooling according to claim 12, characterized in that, The control software is written in LabVIEW and runs on the Windows operating system.

14. A high-speed mid-wave infrared light detection method based on Stirling mechanism cooling, characterized in that, Implemented by the system as described in any one of claims 1-13, comprising the following steps: (1) The mid-wave infrared detector is cooled to a low-temperature working environment by using a Stirling cooling module; (2) The FPGA control module generates the driving timing sequence to drive the mid-wave infrared detector system to collect mid-wave infrared light signals and convert them into analog electrical signals; (3) The signal conditioning circuit performs impedance matching, DC bias removal and amplification on the analog electrical signal in sequence; (4) The high-speed ADC analog-to-digital converter converts the processed analog electrical signal into a digital signal; (5) The FPGA control system buffers and outputs the digital signal.

15. The high-speed mid-wave infrared light detection method based on Stirling mechanism cooling according to claim 14, characterized in that, In step (1), the Stirling cooling module is driven by the FPGA control module to cool the mid-wave infrared detector and make it work stably in a low-temperature environment of 77 K. During the cooling process, the FPGA control module reads the working temperature of the detector chip in real time through the temperature sensor and controls the safe operation of the mid-wave infrared detection system according to the feedback signal to ensure that the mercury cadmium telluride detector chip is always in a low-temperature working environment.

16. The high-speed mid-wave infrared light detection method based on Stirling mechanism cooling according to claim 14, characterized in that, In step (2), after the detector reaches a stable low-temperature working environment, the FPGA control module receives external trigger signals or internal trigger commands, generates drive timing signals according to pre-configured parameters such as integration time and reading range, and outputs them to the mid-wave infrared detector. The mid-wave infrared detector includes a mercury cadmium telluride (MCAD) detector chip, a readout circuit, and an infrared window. The MCAD detector chip uses the photoelectric effect to convert the incident mid-wave infrared light signal into an electrical signal. The readout circuit is used to read out the electrical signal in the integrated circuit with high performance and output an analog voltage signal. The infrared window is coated with an infrared anti-reflection film, which can limit the transmission wavelength range and adjust the transmission uniformity, so that only the mid-wave infrared light of the target band can be effectively incident on the detector chip. Under the timing control of the FPGA driver, the detector accumulates photogenerated charge according to the set integration time, and converts the accumulated charge into an analog voltage signal output during the reading phase, completing the conversion from mid-wave infrared light signal to analog electrical signal; the driving timing parameters can also be sent to the FPGA chip by an external computer via USB interface to achieve flexible configuration.

17. A high-speed mid-wave infrared light detection method based on Stirling mechanism cooling according to claim 14, characterized in that, In step (3), the signal conditioning circuit first performs impedance matching between the detector output and the high-speed ADC analog-to-digital converter; the impedance matching circuit realizes the impedance transformation of high-impedance input and low-impedance output, ensuring that the analog voltage signal output by the detector is effectively and with low loss transmitted to the subsequent processing stage, thus ensuring signal integrity. The signal after impedance matching contains a large DC bias component, which does not carry useful spectral information and will occupy the quantization range of the ADC. The signal conditioning circuit removes the DC component and low-frequency baseline drift in the signal by removing the DC bias circuit, and only retains the AC component that carries useful information, thus freeing up an effective dynamic range for subsequent amplification and analog-to-digital conversion. The amplitude of the AC signal after removing the DC bias is still relatively weak and needs to be amplified by an analog amplifier circuit. The analog amplifier circuit amplifies the signal to an amplitude that matches the input range of the high-speed ADC analog-to-digital converter, maximizing the use of the ADC's quantization range, thereby improving the signal-to-noise ratio and dynamic range. After three sub-steps of impedance matching, DC bias removal, and analog amplification, the signal processing circuit outputs an analog electrical signal that meets the input requirements of the ADC.

18. The high-speed mid-wave infrared light detection method based on Stirling mechanism cooling according to claim 14, characterized in that, In step (4), the analog electrical signal preprocessed by the signal conditioning circuit is sent to the high-speed ADC analog-to-digital converter for analog-to-digital conversion; the high-speed ADC analog-to-digital converter system contains multiple independent analog-to-digital conversion channels, which match the number of detector output channels, and can synchronously and parallelly acquire the output signals of multiple detectors.

19. A high-speed mid-wave infrared light detection method based on Stirling mechanism cooling according to claim 18, characterized in that, In step (4), under the synchronous timing control of the FPGA control module, multiple channels simultaneously sample and quantize the analog electrical signal. Each channel independently completes analog-to-digital conversion and outputs a digital signal. The multi-channel parallel acquisition method significantly shortens the acquisition time of a single frame of data compared to single-channel serial acquisition, thereby maximizing the output frame rate and meeting the high frame rate and large data acquisition requirements of high-speed mid-wave infrared detection. The FPGA control module combines the multi-channel acquired data to form a complete frame of image data.

20. A high-speed mid-wave infrared light detection method based on Stirling mechanism cooling according to any one of claims 14-19, characterized in that, In step (5), the digital signal output by the high-speed ADC analog-to-digital converter is received and buffered by the FPGA control module. The FPGA control module includes a DDR2 high-speed memory, which is used to buffer the data acquired by the analog-to-digital converter. The high-speed read and write performance of DDR2 can meet the large data volume buffering requirements generated by four parallel acquisitions, thus avoiding data loss. After caching is complete, the FPGA control system can retrieve and output digital signals from the controller at high speed. It can also transmit digital signals to an external computer via a USB interface. The USB interface has high bandwidth and can support the real-time and stable transmission of large amounts of data generated by high-speed infrared detection, ensuring fast and reliable data transmission from the detection system to the computer.

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