Multi-path optical switch switching type gas detection system and multi-component gas detection method

Abstract

The application provides a multi-path optical switch switching type gas detection system and a multi-component gas detection method, which comprise a laser light source module, an optical path selection unit, a gas absorption cell, an environmental parameter acquisition unit, a gain adjustment unit, a signal distribution unit and a controller; the controller executes a time division multiplexing control program, in each time slot, synchronously selects a laser for a target gas, sets an amplification gain as a preset gain value corresponding to the target gas, and routes an amplified signal to an associated processing channel, and finally corrects the concentration by using real-time air pressure and temperature collected in the gas absorption cell. Through synchronous time division multiplexing of the optical path, the gain and the signal channel and real-time environmental compensation, the application realizes high-precision and wide-dynamic-range detection of multi-component gases with significantly different absorption strengths under a compact structure.

Description

Technical Field

[0001] This invention relates to the field of laser gas detection technology, specifically to a multi-channel optical switch-type gas detection system and a multi-component gas detection method, particularly a multi-channel optical switch-type gas detection system with programmable gain adjustment and a multi-component gas time-division detection method, especially a detection system based on tunable semiconductor laser absorption spectroscopy (TDLAS) for simultaneously or time-divisionally detecting multiple gas components such as acetylene, methane, ethane, ethylene, and carbon monoxide. Background Technology

[0002] Tunable semiconductor laser absorption spectroscopy (TDLAS) is a gas detection technology based on the narrow linewidth characteristics of tunable semiconductor lasers. It achieves concentration measurement by scanning the absorption lines of gas molecules. The core components include tunable semiconductor lasers, photodetectors, and data acquisition cards. This technology is based on the Lambert-Beer law and uses wavelength modulation to analyze changes in transmitted light intensity to invert gas concentration.

[0003] Tunable semiconductor laser absorption spectroscopy is widely used in gas detection due to its high selectivity and sensitivity. However, existing technologies have the following drawbacks when detecting multi-component gases: a) multiple independent detection systems connected in parallel result in high cost and large size; b) a single laser scans multiple absorption peaks in a time-division manner, leading to slow response and limited wavelength tuning range; c) fixed-gain photoelectric detection methods struggle to simultaneously address the detection needs of both strong and weak absorbing gases; and d) a lack of real-time compensation for environmental parameters (pressure, temperature) within the gas absorption cell affects accuracy. Summary of the Invention

[0004] To address the shortcomings of existing technologies, the purpose of this invention is to provide a multi-channel optical switch-type gas detection system and a method for detecting multi-component gases.

[0005] A multi-channel optical switch-type gas detection system according to the present invention includes: a gas absorption cell, a photodetector, a controller, a laser source module, an optical path selection unit, a gain adjustment unit, and a signal distribution unit; The photodetector and the controller are disposed at the emission end of the gas absorption cell; The laser source module includes multiple lasers, and the output wavelengths of the multiple lasers are respectively configured to cover the characteristic absorption lines of different target gases. The optical path selection unit has multiple input terminals and a common output terminal; the multiple input terminals of the optical path selection unit are respectively coupled to multiple lasers, and the common output terminal of the optical path selection unit is coupled to the entrance of the gas absorption cell. The environmental parameter acquisition unit is installed inside the gas absorption pool and is used to detect the gas pressure and temperature inside the gas absorption pool in real time. The gain adjustment unit is connected to the photodetector and is configured to respond to the controller's command to set the amplification gain to a preset gain value corresponding to the target gas, based on the target gas corresponding to the currently selected laser. The signal distribution unit has a common signal input terminal and multiple output terminals, and the common signal input terminal of the signal distribution unit is connected to the output terminal of the gain adjustment unit.

[0006] Preferably, the controller is configured to execute a time-division multiplexing control program to synchronously: control the optical path selection unit to select the laser corresponding to the current target gas in each time slot; control the gain adjustment unit to set a preset gain value corresponding to the target gas; and control the signal distribution unit to route the amplified signal to the signal processing channel associated with the target gas. The controller is also configured to: store a preset correspondence table including the correspondence between gas types and preset gain values; and when setting the gain value of the gain adjustment unit, query the preset correspondence table according to the current target gas to obtain the corresponding preset gain value.

[0007] Preferably, the laser in the laser source module is a distributed feedback laser or a vertical cavity surface emitter laser; And / or, the optical path selection unit is a microelectromechanical system optical switch, and the switching time of the microelectromechanical system optical switch is no more than 5 milliseconds; And / or, the signal distribution unit is a single-pole multi-throw analog switch.

[0008] Preferably, the environmental parameter acquisition unit includes a pressure sensor and a temperature sensor, both of which are located inside the gas absorption pool; And / or, the gain adjustment unit includes a programmable gain amplifier, and the controller includes a digital-to-analog converter for generating a control voltage to set the gain of the programmable gain amplifier.

[0009] Preferably, the system also includes: a signal processing board; The multiple output terminals of the signal distribution unit are connected in parallel to a single input terminal of the signal processing board.

[0010] Preferably, the system also includes: a communication interface module and a display screen; The communication interface module includes a universal serial bus interface, an RS485 communication interface, and a universal asynchronous transceiver interface. The display screen is connected to the universal asynchronous transceiver interface and is used to display the gas concentration after pressure and temperature compensation collected by the environmental parameter acquisition unit.

[0011] Preferably, the controller is any one of the following: a microcontroller, a field-programmable gate array, or a digital signal processor.

[0012] This invention also provides a method for time-division detection of multi-component gases, employing the aforementioned multi-channel optical switch-type gas detection system, comprising the following steps: Step S1: Within a time slot, a target gas is selected, and an optical path selection unit is controlled to select the laser corresponding to the target gas, so that the beam emitted by the laser passes through a gas absorption cell. Step S2: Based on the target gas, control a gain adjustment unit to set the gain used to amplify the photoelectric detection signal to a preset gain value corresponding to the target gas; Step S3: Control a signal distribution unit to route the signal amplified by the gain adjustment unit to the signal processing channel associated with the target gas for processing; Step S4: Collect the real-time gas pressure and temperature in the gas absorption cell, and correct the gas concentration obtained by the signal processing channel based on the real-time gas pressure and temperature; Step S5: For other target gases, repeat steps S1 to S4.

[0013] Preferably, the method further includes: before starting the detection, performing an initialization step to acquire and store initial air pressure and initial temperature as reference values; wherein, the correction in step S4 is based on the change in the real-time air pressure and temperature relative to the reference values.

[0014] Preferably, step S2 includes: obtaining the preset gain value corresponding to the target gas by querying a preset correspondence table containing the correspondence between gas types and preset gain values; And / or, step S3 includes: outputting the amplified signal to a common signal processing channel through the signal distribution unit, and triggering the processing of the signal on the common signal processing channel in a time-division manner.

[0015] Compared with the prior art, the present invention has the following beneficial effects: 1. This invention achieves cyclic detection of multi-component gases under the same compact hardware architecture through synchronous time-division multiplexing control of the optical path selection unit, gain adjustment unit and signal distribution unit, which significantly reduces system size and hardware cost.

[0016] 2. For target gases with different absorption intensities, the present invention allows the controller to independently set the programmable gain for each gas according to a preset correspondence table. This avoids saturation of strong absorption signals while ensuring that weak absorption signals have sufficient signal-to-noise ratio, greatly expanding the dynamic range of concentration detection of the system.

[0017] 3. This invention effectively eliminates measurement errors caused by environmental fluctuations by integrating pressure and temperature sensors inside the gas absorption cell and introducing real-time environmental parameter correction during concentration calculation, significantly improving the accuracy and stability of on-site detection. Furthermore, the multi-interface compatible design enhances the system's adaptability to different application scenarios. Attached Figure Description

[0018] Other features, objects, and advantages of the present invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings: Figure 1 This is a structural framework diagram of a multi-channel optical switch-type gas detection system; Figure 2 This is a timing diagram for the time-sharing control of multi-gas detection in an MCU controller.

[0019] The diagram shows: 10. Laser array; 11. First laser; 12. Second laser; 13. Third laser; 20. 1×3 optical switch; 30. Gas absorption cell; 31. Pressure sensor; 32. Temperature sensor; 40. Infrared photodetector; 50. Programmable amplifier module; 60. Single-pole eight-throw analog switch; 70. Signal processing board; 80. MCU controller; 81. USB communication interface; 82. RS485 communication interface; 83. UART communication interface; 84. Serial port screen. Detailed Implementation

[0020] The present invention will now be described in detail with reference to specific embodiments. These embodiments will help those skilled in the art to further understand the present invention, but do not limit the invention in any way. It should be noted that those skilled in the art can make several changes and improvements without departing from the concept of the present invention. These all fall within the protection scope of the present invention.

[0021] Example 1 This embodiment provides a multi-channel optical switch-type gas detection system, including: a gas absorption cell 30, a photodetector, a controller, a laser source module, an optical path selection unit, a gain adjustment unit, and a signal distribution unit; the photodetector and controller are disposed at the emission end of the gas absorption cell 30; the laser source module includes multiple lasers, the output wavelengths of which are respectively configured to cover the characteristic absorption spectra of different target gases; the optical path selection unit has multiple input terminals and a common output terminal; the multiple input terminals of the optical path selection unit are respectively coupled to the multiple lasers, and the common output terminal of the optical path selection unit is coupled to the inlet of the gas absorption cell 30; an environmental parameter acquisition unit is disposed within the gas absorption cell 30 for real-time detection of the gas pressure and temperature within the gas absorption cell 30; the gain adjustment unit is connected to the photodetector and is configured to respond to the controller's command, setting the amplification gain to a preset gain value corresponding to the target gas corresponding to the currently selected laser; the signal distribution unit has a common signal input terminal and multiple output terminals, the common signal input terminal of the signal distribution unit being connected to the output terminal of the gain adjustment unit.

[0022] like Figure 1 As shown, in this embodiment, the laser source module is a laser array 10, which includes three lasers: a first laser 11, a second laser 12, and a third laser 13. The output wavelength of the first laser 11 covers the characteristic absorption lines of acetylene gas, the output wavelength of the second laser 12 covers the characteristic absorption lines of methane and / or ethane and / or ethylene, and the output wavelength of the third laser 13 covers the characteristic absorption lines of carbon monoxide.

[0023] Furthermore, the system also includes: a signal processing board 70; multiple output terminals of the signal distribution unit are connected in parallel to a single input terminal of the signal processing board 70.

[0024] Furthermore, the system also includes a communication interface module and a display screen; the communication interface module includes a universal serial bus interface, an RS485 communication interface 82, and a universal asynchronous transceiver interface; the display screen is connected to the universal asynchronous transceiver interface and is used to display the gas concentration after pressure and temperature compensation collected by the environmental parameter acquisition unit. In this embodiment, the display screen is a serial port screen 84, the universal serial bus interface is a USB communication interface 81, and the universal asynchronous transceiver interface is a UART communication interface 83.

[0025] Furthermore, the controller is configured to execute a time-division multiplexing control program to synchronously: control the optical path selection unit to select the laser corresponding to the current target gas; control the gain adjustment unit to set a preset gain value corresponding to the target gas; and control the signal distribution unit to route the amplified signal to the signal processing channel associated with the target gas within each time slot; the controller is also configured to: store a preset correspondence table including the correspondence between gas types and preset gain values; and when setting the gain value of the gain adjustment unit, query the preset correspondence table according to the current target gas to obtain the corresponding preset gain value.

[0026] Furthermore, the laser in the laser source module is a distributed feedback laser or a vertical-cavity surface-emitting laser. The optical path selection unit is a microelectromechanical system (MEMS) optical switch, and the switching time of the MEMS optical switch is no more than 5 milliseconds. The signal distribution unit is a single-pole multi-throw (SPMD) analog switch. In this embodiment, the SPMD analog switch is a single-pole eight-throw (SP8) analog switch 60.

[0027] Furthermore, the environmental parameter acquisition unit includes a pressure sensor 31 and a temperature sensor 32, both of which are located inside the gas absorption pool 30.

[0028] Furthermore, the gain adjustment unit includes a programmable gain amplifier, and the controller includes a digital-to-analog converter (DAC) for generating a control voltage to set the gain of the programmable gain amplifier.

[0029] Furthermore, the controller can be any of the following: a microcontroller, a field-programmable gate array, or a digital signal processor.

[0030] This embodiment also provides a method for detecting multi-component gases, employing the aforementioned multi-channel optical switch-type gas detection system, including the following steps: Step S1: Within a time slot, select a target gas and control an optical path selection unit to select the laser corresponding to the target gas, so that the beam emitted by the laser passes through a gas absorption cell 30. Step S2: Based on the target gas, control a gain adjustment unit to set the gain used to amplify the photoelectric detection signal to a preset gain value corresponding to the target gas; Step S3: Control a signal distribution unit to route the signal amplified by the gain adjustment unit to the signal processing channel associated with the target gas for processing; Step S4: Collect the real-time gas pressure and temperature in the gas absorption cell 30, and correct the gas concentration obtained by the signal processing channel based on the real-time gas pressure and temperature. Step S5: For other target gases, repeat steps S1 to S4.

[0031] Furthermore, the method also includes: before starting the detection, performing an initialization step to acquire and store the initial air pressure and initial temperature as reference values; wherein, the correction in step S4 is based on the change in real-time air pressure and temperature relative to the reference values.

[0032] Further, step S2 includes: obtaining the preset gain value corresponding to the target gas by querying a preset correspondence table containing the correspondence between gas types and preset gain values.

[0033] Further, step S3 includes: outputting the amplified signal to a common signal processing channel through the signal distribution unit, and triggering the processing of the signal on the common signal processing channel in a time-division manner.

[0034] Example 2 Those skilled in the art can understand this embodiment as a more specific description of Embodiment 1.

[0035] like Figure 1 As shown, this embodiment provides a multi-channel optical switch-type gas detection system with programmable gain adjustment, including: a laser array 10, a 1×3 optical switch 20, a gas absorption cell 30, an infrared photodetector 40, a programmable amplifier module 50, a single-pole eight-throw analog switch 60, a signal processing board 70, an MCU controller 80, a pressure sensor 31, a temperature sensor 32, and a communication interface module.

[0036] The laser array 10 includes three lasers with different output wavelengths: a first laser 11, a second laser 12, and a third laser 13. The input terminals of a 1×3 optical switch 20 are connected to the three lasers respectively, and the incident terminal of the gas absorption cell 30 is connected to the common output terminal of the 1×3 optical switch 20. An infrared photodetector 40 is positioned at the exit terminal of the gas absorption cell 30. The input terminal of a programmable amplifier module 50 is connected to the output terminal of the infrared photodetector 40, and the control terminal of the programmable amplifier module 50 is connected to an MCU controller 80.

[0037] The common input terminal of the single-pole eight-throw analog switch 60 is connected to the output terminal of the programmable amplifier module 50. The control ports of the MCU controller 80 are connected to the control terminals of the 1×3 optical switch 20, the programmable amplifier module 50, and the single-pole eight-throw analog switch 60, respectively. The signal processing board 70 is connected to the output terminal of the single-pole eight-throw analog switch 60.

[0038] Pressure sensor 31 and temperature sensor 32 are disposed in gas absorption tank 30 and connected to MCU controller 80. The communication interface module includes USB communication interface 81, RS485 communication interface 82 and UART communication interface 83, wherein UART communication interface 83 is connected to a serial port panel 84.

[0039] Furthermore, the second laser 12 is a wavelength scanning laser, whose scanning range covers the absorption spectra of at least two of the gases, including methane, ethane, and ethylene.

[0040] Furthermore, the programmable amplifier module 50 is a voltage-controlled gain amplifier.

[0041] Furthermore, the MCU controller 80 internally stores a table corresponding to gas types and gain values, which is used to synchronously adjust the gain of the programmable amplifier module 50 when switching lasers.

[0042] Furthermore, the 1×3 optical switch 20 is a MEMS-type fiber optic switch or a mechanical optical switch.

[0043] Furthermore, the MCU controller 80 uses a time-sharing control method to synchronize the switching actions of the 1×3 optical switch 20, the programmable amplifier module 50, and the single-pole eight-throw analog switch 60, thereby achieving a one-to-one correspondence between the laser, gain level, and signal channel.

[0044] Example 3 Those skilled in the art can understand this embodiment as a more specific description of Embodiment 1.

[0045] like Figure 1 As shown, this embodiment provides a multi-component gas detection system based on laser array and optical switch switching, including laser array 10, optical path switching module, gas absorption cell 30, photoelectric detection and programmable amplification module, signal routing and processing module, and communication and display module.

[0046] The laser array 10 includes three lasers: a first laser 11, whose output wavelength corresponds to the absorption peak of acetylene (C2H2); a second laser 12, whose output wavelength covers at least one of methane (CH4), ethane (C2H6), and ethylene (C2H4), or multiple lasers in a time-division scanning manner; and a third laser 13, whose output wavelength corresponds to the absorption peak of carbon monoxide (CO). The output of each laser is connected to the input of a 1×3 optical switch 20 via optical fiber or a spatial optical path.

[0047] The optical path switching module includes an MCU controller 80 and a 1×3 optical switch 20. The output of the MCU controller 80 is connected to the optical switch control terminal, which is used to select any laser to be connected to the common output terminal.

[0048] The incident light port of the gas absorption cell 30 is connected to the common output terminal of the 1×3 optical switch 20. The absorption cell is filled with the gas to be measured and is equipped with a pressure sensor 31 and a temperature sensor 32. The signal output terminals of both sensors are connected to the ADC input port of the MCU controller 80.

[0049] The photoelectric detection and programmable amplification module includes an infrared photodetector 40, whose photosensitive surface receives emitted light transmitted through the absorption cell. The detector output is connected to the input of a programmable amplification module 50. The control terminal of the programmable amplification module 50 is connected to an MCU controller 80 to dynamically adjust the amplification gain based on the currently detected gas type and expected absorption intensity. The output of the programmable amplification module 50 is connected to the common input of a single-pole eight-throw analog switch 60.

[0050] The signal routing and processing module includes a single-pole eight-throw analog switch 60 and at least one signal processing board 70 (containing phase-locked amplifier, ADC conversion, etc.). The control terminal of the MCU controller 80 is connected to the address selection terminal of the analog switch to route the amplified signal to the specified processing channel. The multiple output terminals of the analog switch are respectively connected to different input channels of the signal processing board.

[0051] The communication and display module includes a USB communication interface 81, an RS485 communication interface 82, and a UART communication interface 83. The UART communication interface is connected to a serial port screen 84 for real-time display of data such as gas concentration, pressure, and temperature.

[0052] like Figure 2 As shown, the working principle is as follows: a. Initialization: The system is powered on, and the MCU reads the values ​​from the air pressure and temperature sensors.

[0053] b. Gain pre-configuration: The MCU presets the gain value of the programmable amplifier module according to the type of gas to be measured (e.g., strong absorption of acetylene and weak absorption of carbon monoxide) and stores it in the memory.

[0054] c. Detection cycle: The MCU controls the 1×3 optical switch to switch to the first laser (such as acetylene).

[0055] The MCU sets the gain of the programmable amplifier module to the corresponding acetylene level.

[0056] The MCU controls the single-pole eight-throw analog switch to connect the corresponding signal processing channel.

[0057] The laser passes through the absorption cell, the detector receives the signal, and the signal is sent to the processing board for concentration demodulation after being amplified by a programmable control and switched by an analog switch.

[0058] The MCU compensates and corrects the concentration results based on the current air pressure and temperature.

[0059] Switch to the second and third lasers in sequence, and repeat the above steps.

[0060] Display and Upload: All gas concentration results are displayed in real time on the serial port screen and can be uploaded to the host computer via USB or RS485.

[0061] The system in this embodiment can achieve a wide dynamic range. Through the programmable gain amplification module, the optimal gain can be independently configured for gases with different absorption intensities, avoiding weak signals being overwhelmed by noise or strong signals being saturated.

[0062] The system optical path in this embodiment is simplified. A 1×3 optical switch enables multiple lasers to share the same absorption cell and optical path in a time-division manner, reducing system complexity and cost.

[0063] The system signal channels in this embodiment are flexible, and the single-pole eight-throw analog switch enables flexible matching of detector signals with multiple processing channels, facilitating expansion.

[0064] The system in this embodiment can achieve environmental compensation, collect air pressure and temperature in real time and participate in concentration calculation, significantly improving the accuracy of on-site detection.

[0065] The system in this embodiment is compatible with multiple interfaces, including USB, RS485, UART, and serial port screen, which meet the needs of laboratory debugging and industrial field deployment.

[0066] This embodiment provides a multi-channel optical switch-type gas detection system with programmable gain adjustment, belonging to the field of laser gas detection technology. The system includes: at least three lasers of different wavelengths, corresponding to the detection of acetylene, methane / ethane / ethylene, and carbon monoxide, respectively; the laser outputs are connected to a gas absorption cell 30 via a 1×3 optical switch 20, the absorption cell containing a pressure sensor 31 and a temperature sensor 32; the absorption cell outputs are sequentially connected to an infrared photodetector 40, a programmable amplifier module 50, and a single-pole eight-throw analog switch 60, with each output of the analog switch connected to a signal processing board 70; an MCU controller 80 is connected to the control terminals of the 1×3 optical switch, the programmable amplifier module, and the single-pole eight-throw analog switch, enabling synchronous switching of the optical path, gain, and signal channel; the MCU is also connected to a USB communication interface 81, an RS485 communication interface 82, and a UART communication interface 83, with the UART communication interface connected to a serial port screen 84.

[0067] This embodiment achieves high-precision, wide dynamic range detection of multi-component gases by using a time-division multiplexing structure of optical and analog switches, combined with programmable gain adjustment and gas pressure and temperature compensation. It has the advantages of compact structure, low cost and strong adaptability.

[0068] This embodiment proposes a multi-component gas detection system that integrates a 1×3 optical switch, a single-pole eight-throw analog switch, and a programmable gain amplifier module. By using an MCU to coordinate optical path switching, signal routing, and detector gain adjustment, and in conjunction with a pressure / temperature compensation algorithm, it achieves high-precision, wide dynamic range detection of multiple gases.

[0069] Example 4 Those skilled in the art can understand this embodiment as a more specific description of Embodiment 2 and Embodiment 3.

[0070] In this embodiment, the MCU controller 80 uses an STM32F103 series microcontroller. The three lasers are as follows: First laser 11: Acetylene detection laser, center wavelength 1532nm; Second laser 12: Methane / ethane / ethylene multiplexed laser, 1650nm tunable laser, wavelength scanning is achieved through current tuning; Third laser 13: Carbon monoxide laser, 1565nm.

[0071] The 1×3 optical switch 20 is a MEMS type optical switch with a switching time ≤5ms. The programmable amplifier module 50 uses an AD8330 variable gain amplifier with a gain range of 0dB to 50dB, and its voltage is adjusted by the DAC output of the MCU. The single-pole eight-throw analog switch 60 uses an ADG708.

[0072] The system workflow is as follows: a. After power-on, the MCU controller 80 reads the values ​​of the barometric pressure sensor 31 (20.1 kPa) and the temperature sensor 32 (298 K).

[0073] b. Start the loop detection: Channel 1 (Acetylene): The MCU controller 80 controls the 1×3 optical switch 20 to connect the first laser 11, sets the gain of the programmable amplifier module 50 to 20dB, and controls the single-pole eight-throw analog switch 60 to connect Channel 1. After acquiring the second harmonic signal, the concentration is calculated by combining it with the pressure and temperature correction coefficient, and displayed as 0.5ppm.

[0074] Channel 2 (Methane / Ethane / Ethylene): The MCU controller 80 controls the 1×3 optical switch 20 to connect the second laser 12, sets the gain of the programmable amplifier module 50 to 35dB, and controls the single-pole eight-throw analog switch 60 to connect channel 2. The scan yields a methane concentration of 1.2ppm, and the concentrations of ethane and ethylene are calculated simultaneously.

[0075] Channel 3 (Carbon Monoxide): The MCU controller 80 controls the 1×3 optical switch 20 to turn on the third laser 13, sets the gain of the programmable amplifier module 50 to 45dB, controls the single-pole eight-throw analog switch 60 to turn on channel 3, and the measured CO concentration is 8.0ppm.

[0076] c. All results are displayed in list form on the serial port screen 84 and uploaded to the industrial control PLC via the RS485 communication interface 82.

[0077] Example 5 The difference from Embodiment 4 is that in this embodiment, the system is configured with only one signal processing board 70, which includes a lock-in amplifier and an analog-to-digital converter (ADC). The MCU connects all the outputs of the single-pole eight-throw analog switch 60 to the input of this single signal processing board in parallel. Through time-division control, the MCU sequentially routes the signals of each channel to the same processing board for lock-in amplification and analog-to-digital conversion, realizing sequential processing of multiple gases. This solution can further reduce hardware costs and board area, and is suitable for applications with a large number of channels but low processing speed requirements.

[0078] This invention achieves high-precision, wide dynamic range detection of multi-component gases with significant differences in absorption strength within a compact architecture by synchronous time-division multiplexing of optical paths, gain, and signal channels, along with real-time environmental compensation.

[0079] In the description of this application, it should be understood that the terms "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0080] Specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art can make various changes or modifications within the scope of the claims, which do not affect the essence of the present invention. Unless otherwise specified, the embodiments and features described in this application can be arbitrarily combined with each other.

Claims

1. A multi-channel optical switch-type gas detection system, characterized in that, include: Gas absorption cell, photodetector, controller, laser source module, optical path selection unit, gain adjustment unit, and signal distribution unit; The photodetector and the controller are disposed at the emission end of the gas absorption cell; The laser source module includes multiple lasers, and the output wavelengths of the multiple lasers are respectively configured to cover the characteristic absorption lines of different target gases. The optical path selection unit has multiple input terminals and a common output terminal; the multiple input terminals of the optical path selection unit are respectively coupled to multiple lasers, and the common output terminal of the optical path selection unit is coupled to the entrance of the gas absorption cell. The environmental parameter acquisition unit is installed inside the gas absorption pool and is used to detect the gas pressure and temperature inside the gas absorption pool in real time. The gain adjustment unit is connected to the photodetector and is configured to respond to the controller's command to set the amplification gain to a preset gain value corresponding to the target gas, based on the target gas corresponding to the currently selected laser. The signal distribution unit has a common signal input terminal and multiple output terminals, and the common signal input terminal of the signal distribution unit is connected to the output terminal of the gain adjustment unit.

2. The multi-channel optical switch switching gas detection system according to claim 1, characterized in that, The controller is configured to execute a time-division multiplexing control program to synchronously: control the optical path selection unit to select the laser corresponding to the current target gas in each time slot; control the gain adjustment unit to set a preset gain value corresponding to the target gas; and control the signal distribution unit to route the amplified signal to the signal processing channel associated with the target gas. The controller is also configured to store a preset correspondence table that includes the correspondence between gas types and preset gain values; And when setting the gain value of the gain adjustment unit, the corresponding preset gain value is obtained by querying the preset correspondence table according to the current target gas.

3. The multi-channel optical switch switching gas detection system according to claim 1, characterized in that, The laser in the laser source module is a distributed feedback laser or a vertical cavity surface emitter laser. And / or, the optical path selection unit is a microelectromechanical system optical switch, and the switching time of the microelectromechanical system optical switch is no more than 5 milliseconds; And / or, the signal distribution unit is a single-pole multi-throw analog switch.

4. The multi-channel optical switch switching gas detection system according to claim 1, characterized in that, The environmental parameter acquisition unit includes a pressure sensor and a temperature sensor, both of which are located inside the gas absorption pool. And / or, the gain adjustment unit includes a programmable gain amplifier, and the controller includes a digital-to-analog converter for generating a control voltage to set the gain of the programmable gain amplifier.

5. The multi-channel optical switch switching gas detection system according to claim 1, characterized in that, The system also includes: a signal processing board; The multiple output terminals of the signal distribution unit are connected in parallel to a single input terminal of the signal processing board.

6. The multi-channel optical switch switching gas detection system according to claim 1, characterized in that, The system also includes: a communication interface module and a display screen; The communication interface module includes a universal serial bus interface, an RS485 communication interface, and a universal asynchronous transceiver interface. The display screen is connected to the universal asynchronous transceiver interface and is used to display the gas concentration after pressure and temperature compensation collected by the environmental parameter acquisition unit.

7. The multi-channel optical switch switching gas detection system according to claim 1, characterized in that, The controller can be any of the following: microcontroller, field-programmable gate array, or digital signal processor.

8. A method for detecting multi-component gases, characterized in that, The multi-channel optical switch switching gas detection system according to any one of claims 1 to 7 includes the following steps: Step S1: Within a time slot, a target gas is selected, and an optical path selection unit is controlled to select the laser corresponding to the target gas, so that the beam emitted by the laser passes through a gas absorption cell. Step S2: Based on the target gas, control a gain adjustment unit to set the gain used to amplify the photoelectric detection signal to a preset gain value corresponding to the target gas; Step S3: Control a signal distribution unit to route the signal amplified by the gain adjustment unit to the signal processing channel associated with the target gas for processing; Step S4: Collect the real-time gas pressure and temperature in the gas absorption cell, and correct the gas concentration obtained by the signal processing channel based on the real-time gas pressure and temperature; Step S5: For other target gases, repeat steps S1 to S4.

9. The multi-component gas detection method according to claim 8, characterized in that, The method further includes: before starting the detection, performing an initialization step to acquire and store the initial air pressure and initial temperature as reference values; wherein, the correction in step S4 is based on the change in the real-time air pressure and temperature relative to the reference values.

10. The method for detecting multi-component gases according to claim 8, characterized in that, Step S2 includes: obtaining the preset gain value corresponding to the target gas by querying a preset correspondence table containing the correspondence between gas types and preset gain values; And / or, step S3 includes: outputting the amplified signal to a common signal processing channel through the signal distribution unit, and triggering the processing of the signal on the common signal processing channel in a time-division manner.

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