Gas detection optical module and its temperature control self-setting, wavelength, and light intensity self-calibration method

Abstract

The invention discloses a gas detection optical module and a temperature control self-setting, wavelength, and light intensity self-calibration method thereof. The gas detection optical module comprises a power supply circuit, a laser driving circuit, a laser temperature control circuit, a measurement signal acquisition circuit, a reference signal acquisition circuit, and a data processing circuit. The laser driving circuit, the laser temperature control circuit, the measurement signal acquisition circuit, and the reference signal acquisition circuit are connected with the data processing circuit. The output end of the laser driving circuit is connected with the laser. The laser temperature control circuit is connected with a TEC and a thermistor of the laser. The measurement signal acquisition circuit is connected with a measurement detector. The reference signal acquisition circuit is connected with a reference detector. The data processing circuit is used for realizing temperature control self-setting, wavelength self-calibration, light intensity self-calibration, and gas concentration detection.

Description

Technical Field

[0001] The invention belongs to the technical field of gas detection, and in particular relates to a gas detection optical module and a temperature control self-setting, wavelength, and light intensity self-calibration method thereof. Background Art

[0002] TDLAS (Tunable Diode Laser Absorption Spectroscopy) and Photoacoustic Spectroscopy (PAS) are both based on tunable diode lasers, and use the "frequency-selective" characteristics of the gas molecules to measure the characteristics of the gas being measured. The "frequency-selective" characteristics of gas molecules on light waves avoid cross-interference from other irrelevant gas components, making it the preferred solution for current accurate real-time online gas detection systems. It has the characteristics of fast response speed, low measurement limit, and self-calibration, and is particularly suitable for the measurement of hazardous gases, including methane, carbon monoxide, carbon dioxide, oxygen, ammonia, hydrogen sulfide, acetylene, ethylene and other gases.

[0003] A large number of gas detection solutions and equipment based on spectral detection technology have emerged, and various measurement methods have appeared in the field of industrial applications, including fixed test systems, distributed test systems, and telemetry test systems.

[0004] The existing devices for online gas detection using TDLAS technology and photoacoustic spectroscopy (PAS) technology have the following main technical problems:

[0005] (1) The optical modules currently used in real-time online detectors on the market do not have the function of self-detection and self-setting of laser temperature control. That is, when each laser is matched with an optical module, it is necessary to manually debug to find the temperature control point corresponding to the wavelength absorbed by the measured gas, which greatly reduces the production efficiency of the sensor and increases the production cost.

[0006] (2) The optical modules used in real-time online detectors on the market do not have the self-calibration function of laser light intensity and wavelength. According to the Beer-Lambert Law, wavelength changes and intrinsic light intensity changes will lead to changes in the absorbed light intensity, which will cause changes in the gas concentration after inversion. However, due to changes in the operating temperature and aging of the laser, the wavelength will drift and the output light intensity slope efficiency will change. Therefore, the optical modules used in current gas sensors need to be returned to the factory for calibration regularly, and cannot achieve long-term stable and reliable operation.

[0007] (3) The optical modules used in the real-time online detectors on the market do not have the algorithm filtering function for small changes in laser light intensity. This results in poor stability of sensor indications or slow response speed after using multiple averaging algorithms. Summary of the invention

[0008] The present invention aims to solve at least one of the technical problems existing in the prior art, and proposes a gas detection optical module and a method for self-setting temperature control, wavelength and light intensity self-calibration thereof.

[0009] The technical solution of the present invention is implemented as follows: The present invention discloses a temperature control self-setting method for a gas detection optical module, comprising the following steps: controlling a laser driving circuit to output a corresponding periodic continuous modulation signal to tune a laser, wherein a single periodic signal of the modulation signal comprises a first part signal for wavelength calibration and real-time measurement and a second part signal for light intensity calibration;

[0010] Controlling the laser temperature control circuit to perform a set temperature scan on the laser according to a set scanning range;

[0011] Receive the electrical signal output by the reference detector and solve it. When the signal has an absorption peak or zero crossing point λ that meets the set requirements c When the temperature T corresponding to the signal is obtained c ;

[0012] Control the laser temperature control circuit to set the temperature of the laser. The laser temperature setting point is T c .

[0013] Furthermore, the first part of the signal is a first superimposed signal formed by superimposing a low-frequency half-sawtooth wave with a high-frequency sine wave;

[0014] The second partial signal is one of the following: a second superimposed signal formed by superimposing a high-frequency sine wave on a high-level constant voltage signal, a third superimposed signal formed by superimposing a high-frequency sine wave on a low-level constant voltage signal, a front section non-absorbed portion of the first superimposed signal, and a rear section non-absorbed portion of the first superimposed signal; or, the second partial signal is any combination of the following six signals: a low-level constant voltage signal, a high-level constant voltage signal, a second superimposed signal, a third superimposed signal, a front section non-absorbed portion of the first superimposed signal, and a rear section non-absorbed portion of the first superimposed signal, and each combination includes at least one of the second superimposed signal, the third superimposed signal, a front section non-absorbed portion of the first superimposed signal, and a rear section non-absorbed portion of the first superimposed signal;

[0015] The amplitude and frequency of the sine wave of the first superimposed signal are consistent with the amplitude and frequency of the sine wave of the second superimposed signal and / or the third superimposed signal;

[0016] The level of the low-level constant voltage signal of the second part of the signal or / and the low-level constant voltage signal of the third superimposed signal is the same as the starting low level of the first superimposed signal of the first part of the signal;

[0017] The level of the high-level constant voltage signal of the second partial signal and / or the high-level constant voltage signal of the second superimposed signal is the same as the end point high level of the first superimposed signal of the first partial signal.

[0018] Further, the laser temperature control circuit is controlled to perform a set temperature scan on the laser according to the set scanning range, specifically including: changing the laser temperature setting point according to the set scanning range so that the electrical signal output by the received reference detector appears after being resolved to meet the requirements of the absorption peak point or zero crossing point λ c .

[0019] Further, the laser temperature control circuit is controlled to perform a set temperature scan on the laser according to the set scanning range, specifically including: changing the laser temperature setting point according to the set scanning range so that the electrical signal output by the received reference detector appears after being resolved to meet the requirements of the absorption peak point or zero crossing point λ c , and make λ c The position is located at the center of a single-period signal of a direct absorption signal or a harmonic signal;

[0020] The electrical signal output by the reference detector is the original absorption signal. The original absorption signal is filtered, fitted, and solved to obtain a direct absorption signal. The original absorption signal is solved by phase-locked filtering to obtain a harmonic signal.

[0021] The present invention also discloses a wavelength self-calibration method for a gas detection optical module, comprising the following steps:

[0022] Controlling the laser driving circuit to output a corresponding periodic continuous modulation signal to tune the laser, wherein a single periodic signal of the modulation signal includes a first part signal for wavelength calibration and real-time measurement and a second part signal for light intensity calibration;

[0023] Receive the electrical signal output by the reference detector and solve it to get the direct absorption signal. When the peak value A of the direct absorption signal θ The corresponding horizontal coordinate position λ θ1 Deviation from the set requirement λ c When the laser temperature set point is adjusted, the position λ of the direct absorption signal is corrected. θ1 , so that the position λ θ1 Back to Lambda c Location;

[0024] or

[0025] Receive the electrical signal output by the reference detector and solve it to get the first harmonic signal. When the first harmonic passes through the zero point position λ θ Deviation from λ c When the laser temperature set point is adjusted, it is used to correct the zero crossing position of the first harmonic θ, so that the harmonic zero crossing position λ θ Back to Lambda c Location;

[0026] or

[0027] Receive the electrical signal output by the reference detector and solve it to obtain the second harmonic signal. When the horizontal coordinate position λ corresponding to the second harmonic peak θ2 Deviation from λ c When the laser temperature set point is adjusted, the position λ of the second harmonic signal is corrected. θ2 , so that the position λ θ2 Back to Lambda c Location.

[0028] The present invention also discloses a light intensity self-calibration method for a gas detection optical module, comprising the following steps:

[0029] Controlling the laser driving circuit to output a corresponding periodic continuous modulation signal to tune the laser, wherein a single periodic signal of the modulation signal includes a first part signal for wavelength calibration and real-time measurement and a second part signal for light intensity calibration;

[0030] receiving an electrical signal outputted by a reference detector or a measuring detector, namely, an original absorption signal, and when detecting that the sine wave level in the second part of the original absorption signal changes compared with the first set value, controlling the laser driving circuit to adjust the amplitude of the sine wave level of the modulation signal so that the sine wave level in the modulation signal returns to the first set value;

[0031] An electrical signal output by a reference detector or a measuring detector, i.e., an original absorption signal, is received. When it is detected that a high-level constant voltage signal or a low-level constant voltage signal in a second part of the original absorption signal changes compared to a second set value, the laser driving circuit is controlled to adjust the starting or ending level of the low-frequency sawtooth wave of the modulation signal, and the amplitude of the low-frequency sawtooth wave level is not adjusted.

[0032] The present invention also discloses a gas detection optical module, comprising:

[0033] A power supply circuit, which is used to supply power to the entire device;

[0034] A laser driving circuit, wherein an output end of the laser driving circuit is connected to the laser, and an input end of the laser driving circuit is connected to a first output end of the data processing circuit;

[0035] A laser temperature control circuit, wherein the output end of the laser temperature control circuit is connected to the TEC of the laser, and the input end of the laser temperature control circuit is connected to the second output end of the data processing circuit;

[0036] A measurement signal acquisition circuit, wherein the measurement signal acquisition circuit comprises a measurement end transimpedance amplifier circuit, wherein an input end of the measurement end transimpedance amplifier circuit is connected to the measurement detector, and an output end of the measurement end transimpedance amplifier circuit is connected to a first input end of the data processing circuit;

[0037] A reference signal acquisition circuit, wherein the reference signal acquisition circuit comprises a reference end transimpedance amplifier circuit, wherein an input end of the reference end transimpedance amplifier circuit is connected to a reference detector, and an output end of the reference end transimpedance amplifier circuit is connected to a second input end of the data processing circuit;

[0038] A data processing circuit, wherein the first input end of the data processing circuit is used to receive the electrical signal output by the transimpedance amplifier circuit at the measuring end, the second input end of the data processing circuit is used to receive the electrical signal output by the transimpedance amplifier circuit at the reference end, the data processing circuit is used to use the electrical signal output by the transimpedance amplifier circuit at the reference end to perform temperature self-setting and wavelength real-time self-calibration, the data processing circuit is used to use the electrical signal output by the transimpedance amplifier circuit at the measuring end to measure the concentration of the measured gas, and the data processing circuit is used to use the electrical signal output by the transimpedance amplifier circuit at the reference end or the electrical signal output by the transimpedance amplifier circuit at the measuring end to perform light intensity real-time self-calibration.

[0039] Furthermore, the measurement signal acquisition circuit also includes a measurement end analog phase-locked filtering circuit, which is located between the output end of the measurement end transimpedance amplifier circuit and the first input end of the data processing circuit, and the measurement end transimpedance amplifier circuit is used to convert the current signal of the measurement detector into a voltage signal and amplify the signal, and the measurement end analog phase-locked filtering circuit is used to perform phase-locked filtering on the electrical signal output by the measurement end transimpedance amplifier circuit, and output it to the first input end of the data processing circuit for ADC conversion;

[0040] The reference signal acquisition circuit also includes a reference end analog phase-locked filter circuit, which is located between the output end of the reference end transimpedance amplifier circuit and the second input end of the data processing circuit. The reference end trans-group amplifier circuit is used to convert the current signal of the reference detector into a voltage signal and amplify the signal. The reference end analog phase-locked filter circuit is used to perform phase-locked filtering on the electrical signal output by the reference end trans-group amplifier circuit and output it to the second input end of the data processing circuit for ADC conversion.

[0041] The first input end of the data processing circuit is used to receive the electrical signal output by the analog phase-locked filter circuit at the measuring end to obtain the harmonic signal at the measuring end, and the data processing circuit is used to measure the concentration of the measured gas using the harmonic signal at the measuring end;

[0042] The second input end of the data processing circuit is used to receive the electrical signal output by the reference end analog phase-locked filter circuit to obtain the reference end harmonic signal, and the data processing circuit is used to use the reference end harmonic signal to perform temperature self-setting and wavelength real-time self-calibration;

[0043] The third input terminal of the data processing circuit is used to receive the electrical signal output by the transimpedance amplifier circuit at the measuring end or the electrical signal output by the transimpedance amplifier circuit at the reference end, and obtain the original absorption signal at the measuring end or the original absorption signal at the reference end. The data processing circuit is used to perform real-time self-calibration of light intensity using the original absorption signal at the measuring end or the original absorption signal at the reference end.

[0044] Furthermore, the first input terminal of the data processing circuit is used to receive the electrical signal output by the transimpedance amplifier circuit at the measuring end for ADC conversion to obtain the original absorption signal at the measuring end;

[0045] The data processing circuit is provided with a measuring end digital phase-locked filtering module and / or a measuring end digital filtering module, wherein the measuring end digital phase-locked filtering module is used to perform digital phase-locked filtering on the original absorption signal of the measuring end to obtain the measuring end harmonic signal, and the measuring end digital filtering module is used to filter, fit and solve the original absorption signal of the measuring end to obtain the measuring end direct absorption signal;

[0046] The data processing circuit is used to measure the concentration of the measured gas using the harmonic signal of the measuring end and / or the direct absorption signal of the measuring end;

[0047] The second input terminal of the data processing circuit is used to receive the electrical signal output by the reference end cross-group amplification circuit for ADC conversion to obtain the reference end original absorption signal;

[0048] The data processing circuit is provided with a reference end digital phase-locked filtering module and / or a reference end digital filtering module, wherein the reference end digital phase-locked filtering module is used to perform digital phase-locked filtering on the original absorption signal of the reference end to obtain a reference end harmonic signal, and the reference end digital filtering module is used to filter, fit and solve the original absorption signal of the reference end to obtain a reference end direct absorption signal;

[0049] The data processing circuit is used to use the reference end harmonic signal or the reference end direct absorption signal to perform temperature self-setting and wavelength real-time self-calibration;

[0050] The data processing circuit is used for performing real-time self-calibration of light intensity using the original absorption signal of the measuring end or the original absorption signal of the reference end.

[0051] The present invention also discloses a gas detection optical module, comprising:

[0052] A power supply circuit, which is used to supply power to the entire device;

[0053] A laser driving circuit, wherein an output end of the laser driving circuit is connected to the laser, and an input end of the laser driving circuit is connected to a first output end of the data processing circuit;

[0054] A laser temperature control circuit, wherein the output end of the laser temperature control circuit is connected to the TEC of the laser, and the input end of the laser temperature control circuit is connected to the second output end of the data processing circuit;

[0055] A reference measurement signal acquisition circuit, wherein the reference measurement signal acquisition circuit comprises a reference measurement transimpedance amplifier circuit, wherein an input end of the reference measurement transimpedance amplifier circuit is connected to a reference measurement detector, and an output end of the reference measurement transimpedance amplifier circuit is connected to a first input end of a data processing circuit;

[0056] A data processing circuit, wherein a first input terminal of the data processing circuit is used to receive the electrical signal output by the reference measurement transimpedance amplifier circuit for ADC conversion to obtain a reference measurement original absorption signal;

[0057] A reference measurement analog phase-locked filter circuit is provided between the output end of the reference measurement transimpedance amplifier circuit and the second input end of the data processing circuit, or a reference measurement digital phase-locked filter module and / or a reference measurement digital filter module is provided in the data processing circuit;

[0058] The reference measurement analog phase-locked filter circuit is used to perform phase-locked filtering on the electrical signal output by the reference measurement transimpedance amplifier circuit, and output it to the second input end of the data processing circuit for ADC conversion, so that the second input end of the data processing circuit receives the electrical signal output by the reference measurement analog phase-locked filter circuit to obtain a reference measurement harmonic signal;

[0059] The reference measurement digital phase-locked filtering module is used to perform digital phase-locked filtering on the reference measurement original absorption signal to obtain a reference measurement harmonic signal, and the reference measurement digital filtering module is used to filter, fit, and solve the reference measurement original absorption signal to obtain a reference measurement direct absorption signal;

[0060] The data processing circuit is used to measure the concentration of the measured gas using the reference measurement harmonic signal and / or the reference measurement direct absorption signal;

[0061] The data processing circuit is used to perform temperature self-setting and wavelength real-time self-calibration using a reference measurement harmonic signal or a reference measurement direct absorption signal;

[0062] The data processing circuit is used to perform real-time self-calibration of light intensity using a reference measurement original absorption signal.

[0063] Furthermore, the data processing circuit is used to measure the concentration of the measured gas using harmonic signals and / or direct absorption signals, and is used to use the concentration of the measured gas measured by the harmonic signal as the concentration of the measured gas when the volume concentration of the measured gas is less than a preset value; and to use the concentration of the measured gas measured by the direct absorption signal as the concentration of the measured gas when the volume concentration of the measured gas is greater than the preset value.

[0064] Compared with the prior art, the present invention has the following beneficial effects:

[0065] By adopting the temperature control self-setting method of the present invention, the gas detection optical module of the present invention can realize the temperature control self-detection and self-setting function of any laser. That is, when each laser is matched with the optical module, there is no need for manual debugging to find the temperature control point corresponding to the wavelength absorbed by the measured gas, which greatly improves the production efficiency of the sensor and reduces the production cost.

[0066] By adopting the light intensity wavelength self-calibration method of the present invention, the gas detection optical module of the present invention can realize the real-time self-calibration of laser light intensity and wavelength, overcome the wavelength drift, laser threshold and light intensity slope efficiency changes caused by the temperature change and laser life aging of the laser, and truly realize the life-long maintenance-free and calibration-free use of the optical module sensor. The reliability and environmental adaptability of the product are greatly improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0067] Figure 1 This is a principle block diagram of a gas detection optical module provided in Embodiment 1 of the present invention;

[0068] Figure 2 A schematic diagram of modulation and demodulation waveforms of a gas detection optical module provided in Embodiment 1 of the present invention;

[0069] Figure 3 A schematic diagram of the first harmonic waveform of the electrical signal output by the transimpedance amplifier circuit provided by the present invention after analog phase-locked filtering;

[0070] Figure 4 A principle block diagram of a gas detection optical module provided in Embodiment 2 of the present invention;

[0071] Figure 5 A schematic diagram of modulation and demodulation waveforms of a gas detection optical module provided in the second embodiment of the present invention;

[0072] Figure 6 This is a waveform diagram of the electrical signal output by the transimpedance amplifier circuit provided by the present invention after filtering, fitting and solving, wherein Figure 6 In the figure, (a) is a schematic diagram of the waveform after filtering and fitting, and (b) is a schematic diagram of the waveform of the direct absorption signal after solution;

[0073] Figure 7 A principle block diagram of another gas detection optical module provided in Embodiment 2 of the present invention;

[0074] Figure 8 A schematic diagram of modulation and demodulation waveforms of a gas detection optical module provided in the second embodiment of the present invention;

[0075] Fig. 9 A schematic diagram of the second harmonic waveform of the electrical signal output by the transimpedance amplifier circuit provided by the present invention after being digitally phase-locked filtered;

[0076] Fig.10 This is a principle block diagram of a gas detection optical module provided in Embodiment 3 of the present invention;

[0077] Fig.11 A schematic diagram of modulation and demodulation waveforms of a gas detection optical module provided in Embodiment 3 of the present invention;

[0078] Fig.12 This is a schematic diagram of a demodulated waveform of an electrical signal output by a transimpedance amplifier circuit according to Embodiment 3 of the present invention after being digitized, filtered, and digitally phase-locked filtered, wherein Fig.12 In the figure, (a) is a schematic diagram of the waveform after filtering and fitting, (b) is a schematic diagram of the waveform of the direct absorption signal after solution, and (c) is a schematic diagram of the second harmonic waveform after digital phase-locked filtering;

[0079] Fig.13 A circuit diagram of a laser driving circuit provided in Embodiment 1 of the present invention;

[0080] Fig.14 A circuit diagram of a laser temperature control circuit provided in Embodiment 1 of the present invention;

[0081] Fig.15 A circuit diagram of a transimpedance amplifier circuit provided in Embodiment 1 of the present invention;

[0082] Fig.16 A circuit diagram of an analog phase-locked filter circuit provided in Embodiment 1 of the present invention;

[0083] Fig.17 A circuit diagram of a power supply circuit provided in Embodiment 1 of the present invention;

[0084] Fig.18 A circuit diagram of an MCU data processing circuit provided in Embodiment 1 of the present invention. DETAILED DESCRIPTION

[0085] In order to enable those skilled in the art to better understand the technical solution of the present invention, the technical solution in the embodiment of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiment of the present invention. Obviously, the described embodiment is a part of the embodiment of the present invention, not all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0086] Example 1: See Figures 1 to 3 , an embodiment of the present invention discloses a gas detection optical module, comprising:

[0087] A power supply circuit, which is used to supply power to the entire device;

[0088] A laser driving circuit, wherein an output end of the laser driving circuit is connected to a laser, and an input end of the laser driving circuit is connected to a first DAC output end of a data processing circuit;

[0089] A laser temperature control circuit, wherein the output end of the laser temperature control circuit is connected to the TEC and the thermistor of the laser, and the input end of the laser temperature control circuit is connected to the second DAC output end of the data processing circuit;

[0090] A measurement signal acquisition circuit, wherein the measurement signal acquisition circuit comprises a measurement end transimpedance amplifier circuit and a measurement end analog phase-locked filter circuit, wherein the input end of the measurement end transimpedance amplifier circuit is connected to the measurement detector, and the measurement end analog phase-locked filter circuit is located between the output end of the measurement end transimpedance amplifier circuit and the first ADC input end of the data processing circuit, wherein the measurement end transimpedance amplifier circuit is used to convert the current signal of the measurement detector into a voltage signal and amplify the signal, and the measurement end analog phase-locked filter circuit is used to perform phase-locked filtering on the electrical signal output by the measurement end transimpedance amplifier circuit, and output the signal to the first ADC input end of the data processing circuit for ADC conversion;

[0091] A reference signal acquisition circuit, the reference signal acquisition circuit comprising a reference end transimpedance amplifier circuit and a reference end analog phase-locked filter circuit, the input end of the reference end transimpedance amplifier circuit is connected to the reference detector, the reference end analog phase-locked filter circuit is located between the output end of the reference end transimpedance amplifier circuit and the second ADC input end of the data processing circuit, the reference end cross-group amplifier circuit is used to convert the current signal of the reference detector into a voltage signal and amplify the signal, the reference end analog phase-locked filter circuit is used to perform phase-locked filtering on the electrical signal output by the reference end cross-group amplifier circuit, and output it to the second ADC input end of the data processing circuit for ADC conversion;

[0092] A data processing circuit, wherein a first ADC input terminal of the data processing circuit is used to receive an electrical signal output by an analog phase-locked filter circuit at a measuring end to obtain a harmonic signal at a measuring end, and the data processing circuit is used to measure the concentration of a measured gas using the harmonic signal at the measuring end;

[0093] The second ADC input end of the data processing circuit is used to receive the electrical signal output by the reference end analog phase-locked filter circuit to obtain the reference end harmonic signal, and the data processing circuit is used to use the reference end harmonic signal to perform temperature self-setting and wavelength real-time self-calibration;

[0094] The third ADC input terminal of the data processing circuit is used to receive the electrical signal output by the transimpedance amplifier circuit at the measuring end or the electrical signal output by the transimpedance amplifier circuit at the reference end, and obtain the original absorption signal at the measuring end or the original absorption signal at the reference end. The data processing circuit is used to perform real-time self-calibration of light intensity using the original absorption signal at the measuring end or the original absorption signal at the reference end.

[0095] The data processing circuit is used to measure the concentration of the measured gas using the harmonic signal at the measuring end, specifically including: when the harmonic signal at the measuring end is the first harmonic, obtaining the peak-to-peak value A of the first harmonic signal c , zero-crossing value A (zero-crossing value A is the zero-crossing point position λ c The corresponding vertical coordinate is the baseline), and A c / A is used as the original value for inversion of the detected gas concentration, and the gas concentration is inverted based on the original value for inversion of the detected gas concentration. Figure 3 A schematic diagram of a first harmonic waveform of an electrical signal output by a transimpedance amplifier circuit provided in an embodiment of the present invention after analog phase-locked filtering.

[0096] When the harmonic signal at the measuring end is the second harmonic, the peak-to-peak value A of the second harmonic signal is obtained. c2 , A c2 or A c2 / A is used as the original value for inversion of detected gas concentration.

[0097] Specifically, the zero crossing position λ c =(peak position λ L +Trough position λ H ) / 2.

[0098] The gas detection optical module of this embodiment includes a laser, and the laser is used to generate a laser beam.

[0099] The gas detection optical module of this embodiment includes a spectrometer, which is used to split the laser beam output by the laser into a measurement light and a reference light, and guide the measurement light to the measurement gas chamber and guide the reference light to the reference gas chamber.

[0100] The gas detection optical module of this embodiment includes a measurement detector, which is used to receive the measurement light emitted after passing through the measurement gas chamber and convert it into a measurement electrical signal.

[0101] The gas detection optical module of this embodiment includes a reference detector, which is used to receive the reference light emitted after passing through the reference gas chamber and convert it into a reference electrical signal.

[0102] The data processing circuit includes a data processing module, an ADC module and a DAC module, and the data processing module is connected to the ADC module and the DAC module respectively. The first DAC module of the data processing circuit is connected to the laser driving circuit to modulate the laser. The second DAC module of the data processing circuit is also connected to the laser temperature control circuit to control the temperature of the laser. The ADC module of the data processing circuit is connected to the reference signal acquisition circuit (the reference signal acquisition circuit of this embodiment includes a reference analog phase-locked filter circuit and a reference end transimpedance amplifier circuit) for demodulating the reference detector signal to self-calibrate the wavelength and light intensity of the laser. The ADC module of the data processing circuit is also connected to the measurement signal acquisition circuit (the measurement signal acquisition circuit of this embodiment includes a measurement analog phase-locked filter circuit and a measurement end transimpedance amplifier circuit) for demodulating the measurement photoelectric detector signal to measure the concentration of the measured gas, and can also perform real-time self-calibration of the light intensity.

[0103] In some embodiments, see Fig.18 The data processing module adopts an MCU module, and the ADC module and the DAC module are integrated in the MCU module. Of course, the ADC module and the DAC module can also be located outside the MCU module. The model of the MCU in this embodiment is STM32H743VIT6.

[0104] In some embodiments, the laser driving circuit may be a voltage-controlled current source laser driving circuit. Fig.13The laser driving circuit includes an operational amplifier U6 and an operational amplifier U4. The in-phase input terminal of the operational amplifier U6 is connected to the first DAC output terminal of the data processing circuit via a resistor R12. The in-phase input terminal of the operational amplifier U6 is respectively connected to one end of a resistor R9 and one end of a resistor R5. The other end of the resistor R9 is grounded. The other end of the resistor R5 is connected to the output terminal of the operational amplifier U6. The output terminal of the operational amplifier U6 is connected to the in-phase input terminal of the operational amplifier U4 via a resistor R11. The in-phase input terminal of the operational amplifier U4 is connected to one end of a resistor R14. The other end of the resistor R14 is respectively connected to one end of a capacitor C22 and a positive electrode of the laser. The other end of the capacitor C22 is grounded. The in-phase input terminal of the operational amplifier U4 is respectively connected to one end of a resistor R2 and one end of a resistor R4. The other end of the resistor R2 is grounded. The other end of the resistor R4 is connected to the output terminal of the operational amplifier U4. The output terminal of the operational amplifier U4 is connected to one end of a resistor R10. The other end of the resistor R10 is connected to the positive electrode of the laser.

[0105] In some embodiments, see Fig.14 The laser temperature control circuit uses ADN8834 as the temperature control chip to build the circuit.

[0106] In some embodiments, see Fig.15 The measuring end transimpedance amplifier circuit and the reference end transimpedance amplifier circuit both adopt a transimpedance amplifier, which includes an operational amplifier U2. The in-phase input terminal of the operational amplifier U2 is respectively connected to one end of the resistor R7 and one end of the capacitor C11, and the other end of the resistor R7 and the other end of the capacitor C11 are grounded. The inverting input terminal of the operational amplifier U2 is the input terminal of the transimpedance amplifier circuit, which is used to receive the electrical signal output by the detector. The inverting input terminal of the operational amplifier U2 is respectively connected to one end of the resistor R1 and one end of the capacitor C1, and the other end of the resistor R1 and the other end of the capacitor C1 are connected to the output terminal of the operational amplifier U2. The output terminal of the operational amplifier U2 is the output terminal of the transimpedance amplifier circuit, which is used to output the amplified electrical signal.

[0107] In some embodiments, see Fig.16The reference analog phase-locked filter circuit and the measurement analog phase-locked filter circuit are both constructed using a phase-locked chip. The analog phase-locked filtering circuit includes a phase-locked chip, an input pin INP of the phase-locked chip is connected to the output end of the measuring end transimpedance amplifier circuit or the output end of the reference end transimpedance amplifier circuit, an input pin INN of the phase-locked chip is respectively connected to one end of a capacitor C64 and a common mode voltage output pin VOCM of the phase-locked chip, the other end of the capacitor C64 is grounded, an XOUT pin of the phase-locked chip is respectively connected to one end of a resistor R27 and one end of a resistor R28, the other end of the resistor R28 is respectively connected to one end of a capacitor C45 and one end of a crystal oscillator X1, the other end of the capacitor C45 is grounded, the other end of the resistor R27 is connected to a clock input pin CLKIN of the phase-locked chip, the other end of the crystal oscillator X1 and one end of a capacitor C41, the other end of the capacitor C41 is grounded, an output pin OUTP of the phase-locked chip is connected to a first ADC input end or a second ADC input end of a data processing circuit, and a serial clock pin SCLK, a serial data input and output pin SDA, a synchronous output pin SYNCO, a chip selection pin or an address selection pin CS of the phase-locked chip are connected to the data processing circuit. The boot mode selection pin BOOT of the phase-locked chip is grounded.

[0108] In some embodiments, the model of the phase-locked chip is ADA2200.

[0109] In some embodiments, see Fig.17 The power circuit includes a power management chip and a level conversion chip, wherein the input end of the power management chip is connected to the input voltage (such as 5V), the output end of the power management chip is connected to the input end of the level conversion chip, and the output end of the level conversion chip is used to output a first voltage, such as 3.3V in this embodiment. The model of the power management chip is MP5087GG. The model of the level conversion chip is SY98003D. The power circuit also includes a power module for converting the first voltage into the voltage required by the present invention.

[0110] Furthermore, the reference gas chamber is provided with a gas to be tested.

[0111] Preferably, the current set temperature of the laser can be inverted according to the resistance value of the thermistor in the laser detected by the laser temperature control circuit, and the laser set temperature range T0 to T1 can be scanned by the temperature control circuit. n .

[0112] Preferably, the data processing circuit is used to receive the electrical signal of the reference detector through the reference signal acquisition circuit, and n When the range is reached, the data processing circuit compares the zero crossing point λ of the signal after harmonic solution. c , thereby determining the zero-crossing position λ that meets the set requirements cThe corresponding laser temperature control temperature is the laser temperature setting point T c , so that the wavelength of the laser is self-aligned with the absorption wavelength of the gas being measured.

[0113] In some embodiments, the data processing circuit is used to track in real time the electrical signal of the reference detector received by the reference signal acquisition circuit, when its first harmonic passes through the zero point position λ θ Deviation from λ c When adjusting the laser temperature set point (such as changing the laser temperature set point T c to T c1 ), used to correct the zero crossing position of the first harmonic λ θ , so that the harmonic zero crossing position λ θ Back to Lambda c position, thereby calibrating the laser wavelength in real time to the absorption wavelength of the gas being measured.

[0114] In other embodiments, the data processing circuit is used to track the electrical signal of the reference detector received by the reference signal acquisition circuit in real time to obtain a second harmonic signal. θ2 Deviation from λ c When the laser temperature set point is adjusted, the position λ of the second harmonic signal is corrected. θ2 , so that the position λ θ2 Back to Lambda c Location.

[0115] Preferably, the data processing circuit is used to receive the electrical signal output by the reference detector or the measurement detector, that is, the original absorption signal, and when it is detected that the sine wave level in the second part of the original absorption signal changes compared with the first set value, the laser driving circuit is controlled to adjust the sine wave level amplitude of the modulation signal so that the sine wave levels of the first part of the modulation signal and the second part return to the set value, thereby maintaining the stability of the laser output light intensity;

[0116] The data processing circuit receives the electrical signal output by the reference detector or the measuring detector, i.e., the original absorption signal. When it is detected that the high-level constant voltage signal or the low-level constant voltage signal in the second part of the original absorption signal changes compared with the second set value, the laser driving circuit is controlled to adjust the starting or ending level of the low-frequency sawtooth wave of the modulation signal, and the amplitude of the low-frequency sawtooth wave level is not adjusted.

[0117] Furthermore, a temperature sensor and a pressure sensor are provided in the measuring gas chamber, wherein the temperature sensor is used to detect the temperature of the measuring gas chamber and transmit the temperature to the data processing circuit, and the pressure sensor is used to detect the pressure of the measuring gas chamber and transmit the pressure to the data processing circuit. The data processing circuit corrects the obtained gas concentration according to the detected temperature and pressure.

[0118] The embodiment of the present invention also discloses a temperature control self-setting method for a gas detection optical module, comprising the following steps:

[0119] Controlling the laser driving circuit to output a corresponding periodic continuous modulation signal to tune the laser, wherein a single periodic signal of the modulation signal includes a first part signal for wavelength calibration and real-time measurement and a second part signal for light intensity calibration;

[0120] Controlling the laser temperature control circuit to perform a set temperature scan on the laser according to a set scanning range;

[0121] Receive the electrical signal output by the reference detector and solve it. When the signal has a zero crossing point λ that meets the set requirements c When the temperature T corresponding to the signal is obtained c ;

[0122] Control the laser temperature control circuit to set the temperature of the laser. The laser temperature setting point is T c , so that the laser wavelength is self-aligned with the absorption wavelength of the gas being measured.

[0123] Further, see Figure 2 , Figure 5 , Figure 8 , Fig.11 , the first part of the signal is a first superimposed signal formed by superimposing a low-frequency half-sawtooth wave with a high-frequency sine wave;

[0124] The second partial signal is one of the following: a second superimposed signal formed by superimposing a high-frequency sine wave on a high-level constant voltage signal, a third superimposed signal formed by superimposing a high-frequency sine wave on a low-level constant voltage signal, a front section non-absorbed portion of the first superimposed signal, and a rear section non-absorbed portion of the first superimposed signal; or, the second partial signal is any combination of the following six signals: a low-level constant voltage signal, a high-level constant voltage signal, a second superimposed signal, a third superimposed signal, a front section non-absorbed portion of the first superimposed signal, and a rear section non-absorbed portion of the first superimposed signal, and each combination includes at least one of the second superimposed signal, the third superimposed signal, a front section non-absorbed portion of the first superimposed signal, and a rear section non-absorbed portion of the first superimposed signal;

[0125] The amplitude and frequency of the sine wave of the first superimposed signal are consistent with the amplitude and frequency of the sine wave of the second superimposed signal and / or the third superimposed signal;

[0126] The level of the low-level constant voltage signal of the second part of the signal or / and the low-level constant voltage signal of the third superimposed signal is the same as the starting low level of the first superimposed signal of the first part of the signal;

[0127] The level of the high-level constant voltage signal of the second partial signal and / or the high-level constant voltage signal of the second superimposed signal is the same as the end point high level of the first superimposed signal of the first partial signal.

[0128] Preferably, the second partial signal is one of a second superimposed signal formed by superimposing a high-level constant voltage signal with a high-frequency sine wave, and a third superimposed signal formed by superimposing a low-level constant voltage signal with a high-frequency sine wave, or the second partial signal is any combination of a low-level constant voltage signal, a high-level constant voltage signal, a second superimposed signal, and a third superimposed signal, and each combination includes at least one of the second superimposed signal and the third superimposed signal.

[0129] Further, the time period corresponding to the high-level constant voltage signal and the second superimposed signal is located after the time period corresponding to the first superimposed signal, and the time period corresponding to the low-level constant voltage signal and the third superimposed signal is located before the time period corresponding to the first superimposed signal.

[0130] As a specific embodiment, the voltage-controlled current source laser driving circuit uses a low-level constant current signal superimposed on a high-frequency sine wave and a low-frequency half-sawtooth wave superimposed on a high-frequency sine wave to periodically and continuously tune the laser. The low-level constant voltage signal is 40mA, the half-sawtooth wave is 40mA to 70mA with a frequency of 5HZ, the peak-to-peak amplitude of the high-frequency sine wave is 2mA, and the frequency is 2KHZ to modulate the laser output.

[0131] Further, the laser temperature control circuit is controlled to perform a set temperature scan on the laser according to the set scanning range, specifically including: changing the laser temperature setting point according to the set scanning range so that the electrical signal output by the received reference detector appears at a zero crossing point λ that meets the requirements after being resolved. c .

[0132] Control the laser temperature control circuit to scan the laser temperature according to the set scanning range, specifically including: changing the laser temperature setting point according to the set scanning range so that the electrical signal output by the received reference detector appears at the required zero crossing point λ after being resolved c , and make λ c The position is located at the center of a single period of the first harmonic signal.

[0133] The electrical signal output by the reference detector is the original absorption signal. The original absorption signal is filtered, fitted, and solved to obtain a direct absorption signal. The original absorption signal is solved by phase-locked filtering to obtain a harmonic signal.

[0134] The embodiment of the present invention also discloses a method for real-time wavelength self-calibration of a gas detection optical module, comprising the following steps:

[0135] Controlling the laser driving circuit to output a corresponding periodic continuous modulation signal to tune the laser, wherein a single periodic signal of the modulation signal includes a first part signal for wavelength calibration and real-time measurement and a second part signal for light intensity calibration;

[0136] Receive the electrical signal output by the reference detector and solve it to get the first harmonic signal. When the first harmonic passes through the zero point position λ θ Deviation from λ c When the laser temperature set point is adjusted, it is used to correct the zero crossing position of the first harmonic θ , so that the harmonic zero crossing position λ θ Back to Lambda c Location;

[0137] or

[0138] Receive the electrical signal output by the reference detector and solve it to obtain the second harmonic signal. When the horizontal coordinate position λ corresponding to the second harmonic peak θ2 Deviation from λ c When the laser temperature set point is adjusted, the position λ of the second harmonic signal is corrected. θ2 , so that the position λ θ2 Back to Lambda c Location.

[0139] Optionally, adjust the laser temperature set point to correct the first harmonic zero crossing position λ θ , so that the harmonic zero crossing position λ θ Back to Lambda c Position, specifically including: get λ θ Deviation from λ c The temperature adjustment amount is obtained according to the deviation value, and the laser temperature setting point is changed from T c Adjust to T c1， Thus correcting the harmonic zero crossing position λ θ Return to λ c Location.

[0140] The present invention also discloses a method for real-time self-calibration of light intensity of a gas detection optical module, comprising the following steps:

[0141] Controlling the laser driving circuit to output a corresponding periodic continuous modulation signal to tune the laser, wherein a single periodic signal of the modulation signal includes a first part signal for wavelength calibration and real-time measurement and a second part signal for light intensity calibration;

[0142] receiving an electrical signal outputted by a reference detector or a measuring detector, namely, an original absorption signal, and when detecting that the sine wave level in the second part of the original absorption signal changes compared with the first set value, controlling the laser driving circuit to adjust the sine wave level amplitude of the modulation signal so that the sine wave level of the modulation signal returns to the set value;

[0143] An electrical signal output by a reference detector or a measuring detector, i.e., an original absorption signal, is received. When it is detected that a high-level constant voltage signal or a low-level constant voltage signal in a second part of the original absorption signal changes compared to a second set value, the laser driving circuit is controlled to adjust the starting or ending level of the low-frequency sawtooth wave of the modulation signal, and the amplitude of the low-frequency sawtooth wave level is not adjusted.

[0144] The embodiment of the present invention also discloses a gas concentration measurement control method of a gas detection optical module, comprising the following steps:

[0145] Step S1: Complete the self-setting of the laser temperature so that its wavelength is self-aligned with the absorption wavelength of the gas being measured;

[0146] Step S2: completing the wavelength and light intensity self-calibration of the laser;

[0147] Step S3: Receive the electrical signal from the measurement signal acquisition circuit and obtain the peak-to-peak value A of the first harmonic of the signal after harmonic resolution. c , zero crossing value A, A c / A is used as the original value of the detected gas concentration inversion;

[0148] Step S4: Invert the gas concentration using the Beer-Lambert law based on the original value of the gas concentration.

[0149] The laser gas detection device of the present invention can realize the self-detection and self-setting function of the temperature control of any laser. That is, when each laser is matched with an optical module, there is no need for manual debugging to find the temperature control point corresponding to the wavelength absorbed by the measured gas, which greatly improves the production efficiency of the sensor and reduces the production cost.

[0150] The laser gas detection device of the present invention can realize the real-time self-correction of laser light intensity and the real-time self-calibration of wavelength, which overcomes the wavelength drift, laser threshold and light intensity slope efficiency changes caused by the temperature change and laser life aging of the laser, and truly realizes the life cycle of the optical module sensor without maintenance and calibration, greatly improving the reliability and environmental adaptability of the product. The laser gas detection device of the present invention has the algorithm filtering function of small changes in laser light intensity. It increases the stability of sensor indication and improves the response speed of gas detection.

[0151] Example 2: See Figures 4 to 9, an embodiment of the present invention discloses a gas detection optical module, comprising:

[0152] A power supply circuit, which is used to supply power to the entire device;

[0153] A laser driving circuit, wherein an output end of the laser driving circuit is connected to a laser, and an input end of the laser driving circuit is connected to a first DAC output end of a data processing circuit;

[0154] A laser temperature control circuit, wherein the output end of the laser temperature control circuit is connected to the TEC and the thermistor of the laser, and the input end of the laser temperature control circuit is connected to the second DAC output end of the data processing circuit;

[0155] A measurement signal acquisition circuit, wherein the measurement signal acquisition circuit comprises a measurement end transimpedance amplifier circuit, wherein an input end of the measurement end transimpedance amplifier circuit is connected to the measurement detector, and an output end of the measurement end transimpedance amplifier circuit is connected to a first ADC input end of a data processing circuit;

[0156] A reference signal acquisition circuit, wherein the reference signal acquisition circuit comprises a reference end transimpedance amplifier circuit, wherein an input end of the reference end transimpedance amplifier circuit is connected to a reference detector, and an output end of the reference end transimpedance amplifier circuit is connected to a second ADC input end of a data processing circuit;

[0157] A data processing circuit, wherein the first ADC input terminal of the data processing circuit is used to receive the electrical signal output by the transimpedance amplifier circuit at the measuring end for ADC conversion to obtain the original absorption signal at the measuring end; the second ADC input terminal of the data processing circuit is used to receive the electrical signal output by the transimpedance amplifier circuit at the reference end for ADC conversion to obtain the original absorption signal at the reference end;

[0158] The data processing circuit is provided with a measuring end digital phase-locked filtering module and / or a measuring end digital filtering module, wherein the measuring end digital phase-locked filtering module is used to perform digital phase-locked filtering on the original absorption signal of the measuring end to obtain the measuring end harmonic signal, and the measuring end digital filtering module is used to filter, fit and solve the original absorption signal of the measuring end to obtain the measuring end direct absorption signal;

[0159] The data processing circuit is used to measure the concentration of the measured gas using the harmonic signal of the measuring end and / or the direct absorption signal of the measuring end;

[0160] The data processing circuit is provided with a reference end digital phase-locked filtering module and / or a reference end digital filtering module, wherein the reference end digital phase-locked filtering module is used to perform digital phase-locked filtering on the original absorption signal of the reference end to obtain a reference end harmonic signal, and the reference end digital filtering module is used to filter, fit and solve the original absorption signal of the reference end to obtain a reference end direct absorption signal;

[0161] The data processing circuit is used to use the reference end harmonic signal or the reference end direct absorption signal to perform temperature self-setting and wavelength real-time self-calibration;

[0162] The data processing circuit is used for performing real-time self-calibration of light intensity using the original absorption signal of the measuring end or the original absorption signal of the reference end.

[0163] Furthermore, the data processing circuit is used to measure the concentration of the gas to be measured using the harmonic signal at the measuring end and / or the direct absorption signal at the measuring end, and is used to use the concentration of the gas to be measured measured by the harmonic signal at the measuring end as the concentration of the gas to be measured when the volume concentration of the gas to be measured is less than a preset value; and to use the concentration of the gas to be measured measured by the direct absorption signal at the measuring end as the concentration of the gas to be measured when the volume concentration of the gas to be measured is greater than the preset value.

[0164] This embodiment can use a digital phase-locked filter algorithm (i.e., a digital phase-locked filter module) or a digital filter algorithm (i.e., a digital filter module) provided in the data processing circuit to replace the analog phase-locked filter circuit in the first embodiment to simplify the circuit. The other technical features of this embodiment are the same as those of the first embodiment.

[0165] The embodiment of the present invention also discloses a method for self-setting temperature control of a gas detection optical module, comprising the following steps:

[0166] Controlling the laser driving circuit to output a corresponding periodic continuous modulation signal to tune the laser, wherein a single periodic signal of the modulation signal includes a first part signal for wavelength calibration and real-time measurement and a second part signal for light intensity calibration;

[0167] Controlling the laser temperature control circuit to perform a set temperature scan on the laser according to a set scanning range;

[0168] Receive the electrical signal output by the reference detector and solve it. When the signal has an absorption peak or zero crossing point λ that meets the set requirements c When the temperature T corresponding to the signal is obtained c ;

[0169] Control the laser temperature control circuit to set the temperature of the laser. The laser temperature setting point is T c , so that the laser wavelength is self-aligned with the absorption wavelength of the gas being measured.

[0170] Further, see Figure 2 , Figure 5 , Figure 8 , Fig.11 , the first part of the signal is a first superimposed signal formed by superimposing a low-frequency half-sawtooth wave with a high-frequency sine wave;

[0171] The second partial signal is one of the following: a second superimposed signal formed by superimposing a high-frequency sine wave on a high-level constant voltage signal, a third superimposed signal formed by superimposing a high-frequency sine wave on a low-level constant voltage signal, a front section non-absorbed portion of the first superimposed signal, and a rear section non-absorbed portion of the first superimposed signal; or, the second partial signal is any combination of the following six signals: a low-level constant voltage signal, a high-level constant voltage signal, a second superimposed signal, a third superimposed signal, a front section non-absorbed portion of the first superimposed signal, and a rear section non-absorbed portion of the first superimposed signal, and each combination includes at least one of the second superimposed signal, the third superimposed signal, a front section non-absorbed portion of the first superimposed signal, and a rear section non-absorbed portion of the first superimposed signal;

[0172] The amplitude and frequency of the sine wave of the first superimposed signal are consistent with the amplitude and frequency of the sine wave of the second superimposed signal and / or the third superimposed signal;

[0173] The level of the low-level constant voltage signal of the second part of the signal or / and the low-level constant voltage signal of the third superimposed signal is the same as the starting low level of the first superimposed signal of the first part of the signal;

[0174] The level of the high-level constant voltage signal of the second partial signal and / or the high-level constant voltage signal of the second superimposed signal is the same as the end point high level of the first superimposed signal of the first partial signal.

[0175] Preferably, the second partial signal is one of a second superimposed signal formed by superimposing a high-level constant voltage signal with a high-frequency sine wave, and a third superimposed signal formed by superimposing a low-level constant voltage signal with a high-frequency sine wave, or the second partial signal is any combination of a low-level constant voltage signal, a high-level constant voltage signal, a second superimposed signal, and a third superimposed signal, and each combination includes at least one of the second superimposed signal and the third superimposed signal.

[0176] Further, the time period corresponding to the high-level constant voltage signal and the second superimposed signal is located after the time period corresponding to the first superimposed signal, and the time period corresponding to the low-level constant voltage signal and the third superimposed signal is located before the time period corresponding to the first superimposed signal.

[0177] Further, the laser temperature control circuit is controlled to perform a set temperature scan on the laser according to the set scanning range, specifically including: changing the laser temperature setting point according to the set scanning range so that the electrical signal output by the received reference detector appears after being resolved to meet the requirements of the absorption peak point or zero crossing point λ c .

[0178] Control the laser temperature control circuit to scan the laser at the set temperature according to the set scanning range, specifically including: changing the laser temperature setting point according to the set scanning range so that the electrical signal output by the received reference detector appears after the calculation to meet the requirements of the absorption peak point or zero crossing point λ c , and make λ c The position is located at the center of the single-period signal of the direct absorption signal or the harmonic signal, and the absorption peak point is located at the center of the single-period signal of the original absorption signal;

[0179] The electrical signal output by the reference detector is the original absorption signal. The original absorption signal is filtered, fitted, and solved to obtain a direct absorption signal. The original absorption signal is solved by phase-locked filtering to obtain a harmonic signal. Figure 6 This is a waveform diagram of the electrical signal output by the transimpedance amplifier circuit provided by the present invention after filtering, fitting and solving, wherein Figure 6 In the figure, (a) is a schematic diagram of the waveform after filtering and fitting, and (b) is a schematic diagram of the waveform of the directly absorbed signal after solution.

[0180] The embodiment of the present invention also discloses a method for real-time wavelength self-calibration of a gas detection optical module, comprising the following steps:

[0181] Controlling the laser driving circuit to output a corresponding periodic continuous modulation signal to tune the laser, wherein a single periodic signal of the modulation signal includes a first part signal for wavelength calibration and real-time measurement and a second part signal for light intensity calibration;

[0182] Receive the electrical signal output by the reference detector and solve it to get the direct absorption signal. When the peak value A of the direct absorption signal θ The corresponding horizontal coordinate position λ θ1 Deviation from the set requirement λ c When the laser temperature set point is adjusted, the position λ of the direct absorption signal is corrected. θ1 , so that the position λ θ1 Back to Lambda c Location;

[0183] or

[0184] Receive the electrical signal output by the reference detector and solve it to get the first harmonic signal. When the first harmonic passes through the zero point position λ θ Deviation from λ c When the laser temperature set point is adjusted, it is used to correct the zero crossing position of the first harmonic θ , so that the harmonic zero crossing position λ θ Back to Lambda c Location;

[0185] or

[0186] Receive the electrical signal output by the reference detector and solve it to obtain the second harmonic signal. When the horizontal coordinate position λ corresponding to the second harmonic peak θ2 Deviation from λ c When the laser temperature set point is adjusted, the position λ of the second harmonic signal is corrected. θ2 , so that the position λ θ2 Back to Lambda c Location.

[0187] The present invention also discloses a method for real-time self-calibration of light intensity of a gas detection optical module, comprising the following steps:

[0188] Controlling the laser driving circuit to output a corresponding periodic continuous modulation signal to tune the laser, wherein a single periodic signal of the modulation signal includes a first part signal for wavelength calibration and real-time measurement and a second part signal for light intensity calibration;

[0189] receiving an electrical signal outputted by a reference detector or a measuring detector, namely, an original absorption signal, and when detecting that the sine wave level in the second part of the original absorption signal changes compared with a first set value, controlling the laser driving circuit to adjust the sine wave level amplitude of the modulation signal so that the sine wave levels of the first part of the modulation signal and the second part of the modulation signal return to the set value;

[0190] An electrical signal output by a reference detector or a measuring detector, i.e., an original absorption signal, is received. When it is detected that a high-level constant voltage signal or a low-level constant voltage signal in a second part of the original absorption signal changes compared to a second set value, the laser driving circuit is controlled to adjust the starting or ending level of the low-frequency sawtooth wave of the modulation signal, and the amplitude of the low-frequency sawtooth wave level is not adjusted.

[0191] The embodiment of the present invention also discloses a gas concentration measurement control method of a gas detection optical module, comprising the following steps:

[0192] Step S1: Complete the self-setting of the laser temperature so that its wavelength is self-aligned with the absorption wavelength of the gas being measured;

[0193] Step S2: completing the wavelength and light intensity self-calibration of the laser;

[0194] Step S3: Receive the electrical signal from the transimpedance amplifier circuit at the measuring end and obtain the peak-to-peak value A of the first harmonic of the signal after harmonic resolution. c , zero crossing value A, A c / A is used as the original value of the detected gas concentration inversion, or the peak-to-peak value A of the second harmonic signal is obtained c2 , A c2 or A c2 / A is used as the original value of the detected gas concentration inversion, or the peak value A of the direct absorption signal is obtained c1， A c1The original value of the detected gas concentration is used as the gas concentration inversion value based on the original value of the detected gas concentration.

[0195] Step S4: Invert the gas concentration using the Beer-Lambert law based on the original value of the gas concentration.

[0196] Example 3: See Figures 10 to 12 , an embodiment of the present invention discloses a gas detection optical module, comprising:

[0197] A power supply circuit, which is used to supply power to the entire device;

[0198] A laser driving circuit, wherein an output end of the laser driving circuit is connected to a laser, and an input end of the laser driving circuit is connected to a first DAC output end of a data processing circuit;

[0199] A laser temperature control circuit, wherein the output end of the laser temperature control circuit is connected to the TEC and the thermistor of the laser, and the input end of the laser temperature control circuit is connected to the second DAC output end of the data processing circuit;

[0200] A reference measurement signal acquisition circuit, wherein the reference measurement signal acquisition circuit comprises a reference measurement transimpedance amplifier circuit, wherein an input end of the reference measurement transimpedance amplifier circuit is connected to a reference measurement detector, and an output end of the reference measurement transimpedance amplifier circuit is connected to a first ADC input end of a data processing circuit;

[0201] A data processing circuit, wherein a first ADC input terminal of the data processing circuit is used to receive the electrical signal output by the reference measurement transimpedance amplifier circuit for ADC conversion to obtain a reference measurement original absorption signal;

[0202] A reference measurement analog phase-locked filter circuit is provided between the output end of the reference measurement transimpedance amplifier circuit and the second ADC input end of the data processing circuit, or a reference measurement digital phase-locked filter module and / or a reference measurement digital filter module is provided in the data processing circuit;

[0203] The reference measurement analog phase-locked filter circuit is used to perform phase-locked filtering on the electrical signal output by the reference measurement transimpedance amplifier circuit, and output it to the second ADC input end of the data processing circuit for ADC conversion, so that the second ADC input end of the data processing circuit receives the electrical signal output by the reference measurement analog phase-locked filter circuit to obtain a reference measurement harmonic signal;

[0204] The reference measurement digital phase-locked filtering module is used to perform digital phase-locked filtering on the reference measurement original absorption signal to obtain a reference measurement harmonic signal, and the reference measurement digital filtering module is used to filter, fit, and solve the reference measurement original absorption signal to obtain a reference measurement direct absorption signal;

[0205] The data processing circuit is used to measure the concentration of the measured gas using the reference measurement harmonic signal and / or the reference measurement direct absorption signal;

[0206] The data processing circuit is used to perform temperature self-setting and wavelength real-time self-calibration using a reference measurement harmonic signal or a reference measurement direct absorption signal;

[0207] The data processing circuit is used to perform real-time self-calibration of light intensity using a reference measurement original absorption signal.

[0208] In some embodiments, the data processing circuit is used to measure the concentration of the measured gas using a reference measurement harmonic signal and / or a reference measurement direct absorption signal, and is used to use the concentration of the measured gas measured by the reference measurement harmonic signal as the concentration of the measured gas when the volume concentration of the measured gas is less than a preset value; and to use the concentration of the measured gas measured by the reference measurement direct absorption signal as the concentration of the measured gas when the volume concentration of the measured gas is greater than a preset value.

[0209] That is, the present invention uses the peak-to-peak value A of the harmonic signal at a small volume concentration. c The data processing circuit is used to measure the concentration of the measured gas using the harmonic signal at the measuring end, specifically including: when the harmonic signal at the measuring end is the first harmonic, obtaining the peak-to-peak value A of the first harmonic signal c , zero-crossing value A (zero-crossing value A is the zero-crossing point position λ c The corresponding vertical coordinate is the baseline), and A c / A is used as the original value for inversion of the detected gas concentration, and the gas concentration is inverted based on the original value for inversion of the detected gas concentration.

[0210] See also Fig.12 When the harmonic signal at the measuring end is the second harmonic, the peak-to-peak value A of the second harmonic signal is obtained. c2 , A c2 or A c2 / A is used as the original value for inversion of detected gas concentration.

[0211] Use the peak A of the direct absorption signal at high volume concentrations c1 The gas concentration is inverted as the original value of the detected gas concentration. The inverted value Cr+t is deducted from the reference gas chamber concentration value Cr to obtain the original measured gas concentration value Ct.

[0212] In some embodiments, the data processing circuit is further used to invert the gas concentration according to the original value of the detected gas concentration inversion, and convert the harmonic solution gas concentration inversion value C r+t Subtract the reference gas chamber concentration value C r Then get the original measured gas concentration value C t .

[0213] The gas detection optical module of this embodiment includes a laser, which is used to generate a laser beam and make the laser beam pass through a measurement gas chamber and a reference gas chamber in sequence.

[0214] The gas detection optical module of this embodiment includes a reference measurement detector, which is used to receive the optical signal emitted after passing through the measurement gas chamber and the reference gas chamber in sequence, and convert the optical signal into a reference measurement electrical signal.

[0215] Furthermore, the reference gas chamber is provided with a gas to be tested.

[0216] Furthermore, a temperature sensor and a pressure sensor are provided in the measuring gas chamber, wherein the temperature sensor is used to detect the temperature of the measuring gas chamber and transmit the temperature to the data processing circuit, and the pressure sensor is used to detect the pressure of the measuring gas chamber and transmit the pressure to the data processing circuit. The data processing circuit corrects the obtained gas concentration according to the detected temperature and pressure.

[0217] The optical paths of the first and second embodiments are: the laser output light beam is output to the measurement path and the reference path after being split, and then passes through the measurement gas chamber and the reference gas chamber respectively to reach the measurement detector and the reference detector, forming a parallel optical path. However, the optical path of this embodiment is different from that of the first and second embodiments in that the laser output light beam passes through the measurement gas chamber and the reference gas chamber in sequence to reach the reference measurement detector, forming a series optical path.

[0218] The data processing circuit of this embodiment is the same as the data processing circuits disclosed in the first and second embodiments.

[0219] The data processing circuit includes a data processing module, an ADC module and a DAC module, and the data processing module is connected to the ADC module and the DAC module respectively. The DAC module of the data processing circuit is connected to the laser driving circuit to modulate the laser. The DAC module of the data processing circuit is also connected to the laser temperature control circuit to perform temperature control on the laser. Different from the first and second embodiments, the present embodiment combines the measuring end transimpedance amplifier circuit and the reference end transimpedance amplifier circuit into one, becoming a reference measurement transimpedance amplifier circuit. The data processing circuit is connected to the reference measurement acquisition circuit, and is used to demodulate the signal of the reference measurement detector, so as to self-calibrate the wavelength and light intensity of the laser and measure the concentration of the measured gas.

[0220] In some embodiments, the reference measurement acquisition circuit includes a reference measurement transimpedance amplifier circuit (the reference measurement transimpedance amplifier circuit of this embodiment does not have an analog phase-locked filter circuit), the input end of the reference measurement transimpedance amplifier circuit is connected to the reference measurement detector, and the output end of the reference measurement transimpedance amplifier circuit is connected to the ADC input end of the data processing circuit. A reference measurement digital phase-locked filter module is provided in the data processing circuit, and the ADC module of the data processing circuit is used to receive the electrical signal output by the reference measurement transimpedance amplifier circuit for ADC conversion to obtain a digital signal, and the reference measurement digital phase-locked filter module is used to perform digital phase-locked filtering on the digital signal to obtain a reference measurement harmonic signal, and the data processing circuit is used to use the reference measurement harmonic signal to implement the steps of the light intensity wavelength self-calibration method described below. This embodiment uses the digital phase-locked filter algorithm in the data processing circuit to replace the analog phase-locked filter circuit of the first embodiment to simplify the circuit. Of course, the reference measurement acquisition circuit of some embodiments can also set an analog phase-locked filter circuit between the reference measurement transimpedance amplifier circuit and the data processing circuit to replace the digital phase-locked filter algorithm in the data processing circuit.

[0221] The power supply circuit of this embodiment is the same as the power supply circuit disclosed in Embodiment 1 and Embodiment 2. The laser driving circuit of this embodiment is the same as the laser driving circuit disclosed in Embodiment 1 and Embodiment 2. The laser temperature control circuit of this embodiment is the same as the laser temperature control circuit disclosed in Embodiment 1 and Embodiment 2. The reference measurement transimpedance amplifier circuit of this embodiment adopts a transimpedance amplifier, which is the same as the transimpedance amplifier circuit disclosed in Embodiment 1 and Embodiment 2.

[0222] The embodiment of the present invention also discloses a temperature control self-setting method for a gas detection optical module, comprising the following steps:

[0223] Controlling the laser driving circuit to output a corresponding periodic continuous modulation signal to tune the laser, wherein a single periodic signal of the modulation signal includes a first part signal for wavelength calibration and real-time measurement and a second part signal for light intensity calibration;

[0224] Controlling the laser temperature control circuit to perform a set temperature scan on the laser according to a set scanning range;

[0225] Receive the electrical signal output by the reference detector and solve it. When the signal has an absorption peak or zero crossing point λ that meets the set requirements c When the temperature T corresponding to the signal is obtained c ;

[0226] Control the laser temperature control circuit to set the temperature of the laser. The laser temperature setting point is T c , so that the laser wavelength is self-aligned with the absorption wavelength of the gas being measured.

[0227] Further, see Figure 2 , Figure 5 , Figure 8 , Fig.11 , the first part of the signal is a first superimposed signal formed by superimposing a low-frequency half-sawtooth wave with a high-frequency sine wave;

[0228] The second partial signal is one of the following: a second superimposed signal formed by superimposing a high-frequency sine wave on a high-level constant voltage signal, a third superimposed signal formed by superimposing a high-frequency sine wave on a low-level constant voltage signal, a front section non-absorbed portion of the first superimposed signal, and a rear section non-absorbed portion of the first superimposed signal; or, the second partial signal is any combination of the following six signals: a low-level constant voltage signal, a high-level constant voltage signal, a second superimposed signal, a third superimposed signal, a front section non-absorbed portion of the first superimposed signal, and a rear section non-absorbed portion of the first superimposed signal, and each combination includes at least one of the second superimposed signal, the third superimposed signal, a front section non-absorbed portion of the first superimposed signal, and a rear section non-absorbed portion of the first superimposed signal;

[0229] The amplitude and frequency of the sine wave of the first superimposed signal are consistent with the amplitude and frequency of the sine wave of the second superimposed signal and / or the third superimposed signal;

[0230] The level of the low-level constant voltage signal of the second part of the signal or / and the low-level constant voltage signal of the third superimposed signal is the same as the starting low level of the first superimposed signal of the first part of the signal;

[0231] The level of the high-level constant voltage signal of the second partial signal and / or the high-level constant voltage signal of the second superimposed signal is the same as the end point high level of the first superimposed signal of the first partial signal.

[0232] Preferably, the second partial signal is one of a second superimposed signal formed by superimposing a high-level constant voltage signal with a high-frequency sine wave, and a third superimposed signal formed by superimposing a low-level constant voltage signal with a high-frequency sine wave, or the second partial signal is any combination of a low-level constant voltage signal, a high-level constant voltage signal, a second superimposed signal, and a third superimposed signal, and each combination includes at least one of the second superimposed signal and the third superimposed signal.

[0233] Further, the time period corresponding to the high-level constant voltage signal and the second superimposed signal is located after the time period corresponding to the first superimposed signal, and the time period corresponding to the low-level constant voltage signal and the third superimposed signal is located before the time period corresponding to the first superimposed signal.

[0234] Further, the laser temperature control circuit is controlled to perform a set temperature scan on the laser according to the set scanning range, specifically including: changing the laser temperature setting point according to the set scanning range so that the electrical signal output by the received reference detector appears after being resolved to meet the requirements of the absorption peak point or zero crossing point λc .

[0235] Control the laser temperature control circuit to scan the laser at the set temperature according to the set scanning range, specifically including: changing the laser temperature setting point according to the set scanning range so that the electrical signal output by the received reference detector appears after the calculation to meet the requirements of the absorption peak point or zero crossing point λ c , and make λ c The position is located at the center of the single-period signal of the direct absorption signal or the harmonic signal, and the absorption peak point is located at the center of the single-period signal of the original absorption signal;

[0236] The electrical signal output by the reference detector is the original absorption signal. The original absorption signal is filtered, fitted, and solved to obtain a direct absorption signal. The original absorption signal is solved by phase-locked filtering to obtain a harmonic signal.

[0237] The embodiment of the present invention also discloses a method for real-time wavelength self-calibration of a gas detection optical module, comprising the following steps:

[0238] Controlling the laser driving circuit to output a corresponding periodic continuous modulation signal to tune the laser, wherein a single periodic signal of the modulation signal includes a first part signal for wavelength calibration and real-time measurement and a second part signal for light intensity calibration;

[0239] Receive the electrical signal output by the reference detector and solve it to get the direct absorption signal. When the peak value A of the direct absorption signal θ The corresponding horizontal coordinate position λ θ1 Deviation from the set requirement λ c When the laser temperature set point is adjusted, the position λ of the direct absorption signal is corrected. θ1 , so that the position λ θ1 Back to Lambda c Location;

[0240] or

[0241] Receive the electrical signal output by the reference detector and solve it to get the first harmonic signal. When the first harmonic passes through the zero point position λ θ Deviation from λ c When the laser temperature set point is adjusted, it is used to correct the zero crossing position of the first harmonic θ , so that the harmonic zero crossing position λ θ Back to Lambda c Location;

[0242] or

[0243] Receive the electrical signal output by the reference detector and solve it to obtain the second harmonic signal. When the horizontal coordinate position λ corresponding to the second harmonic peak θ2 Deviation from λ cWhen the laser temperature set point is adjusted, the position λ of the second harmonic signal is corrected. θ2 , so that the position λ θ2 Back to Lambda c Location.

[0244] The present invention also discloses a method for real-time self-calibration of light intensity of a gas detection optical module, comprising the following steps:

[0245] Controlling the laser driving circuit to output a corresponding periodic continuous modulation signal to tune the laser, wherein a single periodic signal of the modulation signal includes a first part signal for wavelength calibration and real-time measurement and a second part signal for light intensity calibration;

[0246] receiving an electrical signal outputted by a reference detector or a measuring detector, namely, an original absorption signal, and when detecting that the sine wave level in the second part of the original absorption signal changes compared with a first set value, controlling the laser driving circuit to adjust the sine wave level amplitude of the modulation signal so that the sine wave levels of the first part of the modulation signal and the second part of the modulation signal return to the set value;

[0247] An electrical signal output by a reference detector or a measuring detector, i.e., an original absorption signal, is received. When it is detected that a high-level constant voltage signal or a low-level constant voltage signal in a second part of the original absorption signal changes compared to a second set value, the laser driving circuit is controlled to adjust the starting or ending level of the low-frequency sawtooth wave of the modulation signal, and the amplitude of the low-frequency sawtooth wave level is not adjusted.

[0248] The embodiment of the present invention also discloses a gas concentration measurement control method of a gas detection optical module, comprising the following steps:

[0249] Step S1: Complete the self-setting of the laser temperature so that its wavelength is self-aligned with the absorption wavelength of the gas being measured;

[0250] Step S2: completing the wavelength and light intensity self-calibration of the laser;

[0251] Step S3: Receive the electrical signal of the reference measurement detector through the reference measurement acquisition circuit, and calculate the peak value A of the first harmonic of the signal after harmonic resolution. c , zero crossing value A, A c / A is used as the original value of the detected gas concentration inversion;

[0252] Step S4: Invert the gas concentration using the Beer-Lambert law according to the original value of the gas concentration;

[0253] Step S5: The value C obtained by inverting the gas concentration by harmonic solution r+t Subtract the reference gas chamber concentration value C r Then get the original measured gas concentration value C t .

[0254] The present invention uses the total absorption signal after the measurement path signal is superimposed on the reference path signal as the signal input method. On the one hand, it greatly simplifies the complexity of the external optical path structure. The external optical path structure is a parallel optical path of the laser output light beam after splitting to the measurement path and the reference path, and then passes through the measurement air chamber and the reference air chamber respectively to the measurement path detector and the reference path detector. Simplified, the laser output light beam passes through the measurement air chamber and the reference air chamber and reaches the series optical path of the measurement reference detector. On the other hand, since the measurement detector transimpedance amplifier circuit and the reference detector transimpedance amplifier circuit are combined into one, the circuit structure of the optical module is also simplified after it becomes the reference measurement detector transimpedance amplifier circuit. Without reducing the product performance, the use and production cost of the product are reduced, and the performance of the product is improved.

[0255] The present invention solves the problems that the optical module used in the existing real-time online detector does not have the self-detection and self-setting functions of the laser temperature control. The drift of the laser wavelength, the laser threshold, and the change of the light intensity slope efficiency require regular factory calibration, which makes it impossible to achieve long-term stable and reliable operation. The lack of the algorithm filtering function when the light intensity changes slightly causes a series of problems such as poor stability of the sensor indication or slow response speed after using multiple averaging algorithms.

[0256] In summary, the self-stabilizing fully integrated optical-mechanical assembly for gas detection provided by the present invention can select components with different light beam output forms for the light emitting assembly while other structural components and assembly methods remain unchanged; the reference detector assembly and the detection detector optical assembly can also select components with different light receiving forms. After combining the innovative active optical interference link coupling adjustment process and laser welding process, the temperature adaptability and reliability of the product are improved, the manufacturing cost and the use cost are reduced, and the product is truly free of calibration and calibration after leaving the factory.

[0257] It is to be understood that the above embodiments are merely exemplary embodiments used to illustrate the principles of the present invention, but the present invention is not limited thereto. For those of ordinary skill in the art, various modifications and improvements can be made without departing from the spirit and essence of the present invention, and these modifications and improvements are also considered to be within the scope of protection of the present invention.

Claims

1. A light intensity self-calibration method for a gas detection optical module, characterized in that: The steps include: Controlling the laser driving circuit to output a corresponding periodic continuous modulation signal to tune the laser, wherein a single periodic signal of the modulation signal includes a first part signal for wavelength calibration and real-time measurement and a second part signal for light intensity calibration; The first part of the signal is a first superimposed signal formed by superimposing a low-frequency half-sawtooth wave with a high-frequency sine wave; The second partial signal is one of the following: a second superimposed signal formed by superimposing a high-frequency sine wave on a high-level constant voltage signal, a third superimposed signal formed by superimposing a high-frequency sine wave on a low-level constant voltage signal, a front section non-absorbed portion of the first superimposed signal, and a rear section non-absorbed portion of the first superimposed signal; or, the second partial signal is any combination of the following six signals: a low-level constant voltage signal, a high-level constant voltage signal, a second superimposed signal, a third superimposed signal, a front section non-absorbed portion of the first superimposed signal, and a rear section non-absorbed portion of the first superimposed signal, and each combination includes at least one of the second superimposed signal, the third superimposed signal, a front section non-absorbed portion of the first superimposed signal, and a rear section non-absorbed portion of the first superimposed signal; receiving an electrical signal outputted by a reference detector or a measuring detector, namely, an original absorption signal, and when detecting that the sine wave level in the second part of the original absorption signal changes compared with the first set value, controlling the laser driving circuit to adjust the amplitude of the sine wave level of the modulation signal so that the sine wave level in the modulation signal returns to the first set value; An electrical signal output by a reference detector or a measuring detector, i.e., an original absorption signal, is received. When it is detected that a high-level constant voltage signal or a low-level constant voltage signal in a second part of the original absorption signal changes compared to a second set value, the laser driving circuit is controlled to adjust the starting or ending level of the low-frequency sawtooth wave of the modulation signal, and the amplitude of the low-frequency sawtooth wave level is not adjusted.

2. The light intensity self-calibration method of the gas detection optical module according to claim 1 is characterized in that: The amplitude and frequency of the sine wave of the first superimposed signal are consistent with the amplitude and frequency of the sine wave of the second superimposed signal and / or the third superimposed signal; The level of the low-level constant voltage signal of the second part of the signal or / and the low-level constant voltage signal of the third superimposed signal is the same as the starting low level of the first superimposed signal of the first part of the signal; The level of the high-level constant voltage signal of the second partial signal and / or the high-level constant voltage signal of the second superimposed signal is the same as the end point high level of the first superimposed signal of the first partial signal.

3. A gas detection optical module, characterized in that: include: A power supply circuit, which is used to supply power to the entire device; A laser driving circuit, wherein an output end of the laser driving circuit is connected to the laser, and an input end of the laser driving circuit is connected to a first output end of the data processing circuit; A laser temperature control circuit, wherein the output end of the laser temperature control circuit is connected to the TEC of the laser, and the input end of the laser temperature control circuit is connected to the second output end of the data processing circuit; A measurement signal acquisition circuit, wherein the measurement signal acquisition circuit comprises a measurement end transimpedance amplifier circuit, wherein an input end of the measurement end transimpedance amplifier circuit is connected to the measurement detector, and an output end of the measurement end transimpedance amplifier circuit is connected to a first input end of the data processing circuit; A reference signal acquisition circuit, wherein the reference signal acquisition circuit comprises a reference end transimpedance amplifier circuit, wherein an input end of the reference end transimpedance amplifier circuit is connected to a reference detector, and an output end of the reference end transimpedance amplifier circuit is connected to a second input end of the data processing circuit; A data processing circuit, wherein the first input end of the data processing circuit is used to receive the electrical signal output by the transimpedance amplifier circuit at the measuring end, the second input end of the data processing circuit is used to receive the electrical signal output by the transimpedance amplifier circuit at the reference end, the data processing circuit is used to use the electrical signal output by the transimpedance amplifier circuit at the reference end to perform temperature control self-setting and wavelength self-calibration, the data processing circuit is used to use the electrical signal output by the transimpedance amplifier circuit at the reference end or the electrical signal output by the transimpedance amplifier circuit at the measuring end to perform the steps of the light intensity self-calibration method as described in claim 1 or 2, and the data processing circuit is used to measure the concentration of the gas being measured using the electrical signal output by the transimpedance amplifier circuit at the measuring end.

4. The gas detection optical module according to claim 3, characterized in that: The measurement signal acquisition circuit also includes a measurement end analog phase-locked filter circuit, which is located between the output end of the measurement end transimpedance amplifier circuit and the first input end of the data processing circuit. The measurement end transimpedance amplifier circuit is used to convert the current signal of the measurement detector into a voltage signal and amplify the signal. The measurement end analog phase-locked filter circuit is used to perform phase-locked filtering on the electrical signal output by the measurement end transimpedance amplifier circuit, and output it to the first input end of the data processing circuit for ADC conversion. The reference signal acquisition circuit also includes a reference end analog phase-locked filter circuit, which is located between the output end of the reference end transimpedance amplifier circuit and the second input end of the data processing circuit. The reference end transimpedance amplifier circuit is used to convert the current signal of the reference detector into a voltage signal and amplify the signal. The reference end analog phase-locked filter circuit is used to perform phase-locked filtering on the electrical signal output by the reference end transimpedance amplifier circuit and output it to the second input end of the data processing circuit for ADC conversion. The first input end of the data processing circuit is used to receive the electrical signal output by the analog phase-locked filter circuit at the measuring end to obtain the harmonic signal at the measuring end, and the data processing circuit is used to measure the concentration of the measured gas using the harmonic signal at the measuring end; The second input end of the data processing circuit is used to receive the electrical signal output by the reference end analog phase-locked filter circuit to obtain the reference end harmonic signal, and the data processing circuit is used to use the reference end harmonic signal to perform temperature control self-setting and wavelength self-calibration; The third input terminal of the data processing circuit is used to receive the electrical signal output by the transimpedance amplifier circuit at the measuring end or the electrical signal output by the transimpedance amplifier circuit at the reference end to obtain the original absorption signal at the measuring end or the original absorption signal at the reference end. The data processing circuit is used to perform the steps of the light intensity self-calibration method as described in claim 1 or 2 using the original absorption signal at the measuring end or the original absorption signal at the reference end.

5. The gas detection optical module according to claim 3, characterized in that: The first input end of the data processing circuit is used to receive the electrical signal output by the transimpedance amplifier circuit at the measuring end for ADC conversion to obtain the original absorption signal at the measuring end; The data processing circuit is provided with a measuring end digital phase-locked filtering module and / or a measuring end digital filtering module, wherein the measuring end digital phase-locked filtering module is used to perform digital phase-locked filtering on the original absorption signal of the measuring end to obtain the measuring end harmonic signal, and the measuring end digital filtering module is used to filter, fit and solve the original absorption signal of the measuring end to obtain the measuring end direct absorption signal; The data processing circuit is used to measure the concentration of the measured gas using the harmonic signal of the measuring end and / or the direct absorption signal of the measuring end; The second input end of the data processing circuit is used to receive the electrical signal output by the reference end transimpedance amplifier circuit for ADC conversion to obtain the reference end original absorption signal; The data processing circuit is provided with a reference end digital phase-locked filtering module and / or a reference end digital filtering module, wherein the reference end digital phase-locked filtering module is used to perform digital phase-locked filtering on the original absorption signal of the reference end to obtain a reference end harmonic signal, and the reference end digital filtering module is used to filter, fit and solve the original absorption signal of the reference end to obtain a reference end direct absorption signal; The data processing circuit is used to perform temperature control self-setting and wavelength self-calibration using the reference end harmonic signal or the reference end direct absorption signal; The data processing circuit is used to perform the steps of the light intensity self-calibration method as claimed in claim 1 or 2 using the original absorption signal of the measuring end or the original absorption signal of the reference end.

6. A gas detection optical module, characterized in that: include: A power supply circuit, which is used to supply power to the entire device; A laser driving circuit, wherein an output end of the laser driving circuit is connected to the laser, and an input end of the laser driving circuit is connected to a first output end of the data processing circuit; A laser temperature control circuit, wherein the output end of the laser temperature control circuit is connected to the TEC of the laser, and the input end of the laser temperature control circuit is connected to the second output end of the data processing circuit; A reference measurement signal acquisition circuit, wherein the reference measurement signal acquisition circuit comprises a reference measurement transimpedance amplifier circuit, wherein an input end of the reference measurement transimpedance amplifier circuit is connected to a reference measurement detector, and an output end of the reference measurement transimpedance amplifier circuit is connected to a first input end of a data processing circuit; A data processing circuit, wherein a first input terminal of the data processing circuit is used to receive the electrical signal output by the reference measurement transimpedance amplifier circuit for ADC conversion to obtain a reference measurement original absorption signal; A reference measurement analog phase-locked filter circuit is provided between the output end of the reference measurement transimpedance amplifier circuit and the second input end of the data processing circuit, or a reference measurement digital phase-locked filter module and / or a reference measurement digital filter module is provided in the data processing circuit; The reference measurement analog phase-locked filter circuit is used to perform phase-locked filtering on the electrical signal output by the reference measurement transimpedance amplifier circuit, and output it to the second input end of the data processing circuit for ADC conversion, so that the second input end of the data processing circuit receives the electrical signal output by the reference measurement analog phase-locked filter circuit to obtain a reference measurement harmonic signal; The reference measurement digital phase-locked filtering module is used to perform digital phase-locked filtering on the reference measurement original absorption signal to obtain a reference measurement harmonic signal, and the reference measurement digital filtering module is used to filter, fit, and solve the reference measurement original absorption signal to obtain a reference measurement direct absorption signal; The data processing circuit is used to perform temperature control self-setting and wavelength self-calibration using a reference measurement harmonic signal or a reference measurement direct absorption signal; The data processing circuit is used to perform the steps of the light intensity self-calibration method as claimed in claim 1 or 2 using the reference measurement original absorption signal; The data processing circuit is used to measure the concentration of the measured gas using the reference measurement harmonic signal and / or the reference measurement direct absorption signal.

7. The gas detection optical module according to claim 5 or 6, characterized in that: The data processing circuit is used to measure the concentration of the measured gas using the harmonic signal and / or the direct absorption signal, and is used to use the measured gas concentration measured by the harmonic signal as the measured gas concentration when the volume concentration of the measured gas is less than a preset value; and to use the measured gas concentration measured by the direct absorption signal as the measured gas concentration when the volume concentration of the measured gas is greater than the preset value.

8. The gas detection optical module according to any one of claims 3 to 6, characterized in that: The temperature control is set automatically, including the following steps: Controlling the laser driving circuit to output a corresponding periodic continuous modulation signal to tune the laser, wherein a single periodic signal of the modulation signal includes a first part signal for wavelength calibration and real-time measurement and a second part signal for light intensity calibration; Controlling the laser temperature control circuit to perform a set temperature scan on the laser according to a set scanning range; Receive the electrical signal output by the reference detector and solve it. When the signal has an absorption peak or zero crossing point λ that meets the set requirements c When the temperature T corresponding to the signal is obtained c ; Control the laser temperature control circuit to set the temperature of the laser. The laser temperature setting point is T c .

9. The gas detection optical module according to claim 8, characterized in that: Control the laser temperature control circuit to scan the laser at the set temperature according to the set scanning range, specifically including: changing the laser temperature setting point according to the set scanning range so that the electrical signal output by the received reference detector appears after the calculation to meet the requirements of the absorption peak point or zero crossing point λ c .

10. The gas detection optical module according to any one of claims 3 to 6, characterized in that: Wavelength self-calibration includes the following steps: Controlling the laser driving circuit to output a corresponding periodic continuous modulation signal to tune the laser, wherein a single periodic signal of the modulation signal includes a first part signal for wavelength calibration and real-time measurement and a second part signal for light intensity calibration; Receive the electrical signal output by the reference detector and solve it to get the direct absorption signal. When the peak value A of the direct absorption signal θ The corresponding horizontal coordinate position λ θ1 Deviation from the set requirement λ c When the laser temperature set point is adjusted, the position λ of the direct absorption signal is corrected. θ1 , so that the position λ θ1 Back to Lambda c Location; or Receive the electrical signal output by the reference detector and solve it to get the first harmonic signal. When the first harmonic passes through the zero point position λ θ Deviation from λ c When the laser temperature set point is adjusted, it is used to correct the zero crossing position of the first harmonic θ , so that the harmonic zero crossing position λ θ Back to Lambda c Location; or Receive the electrical signal output by the reference detector and solve it to obtain the second harmonic signal. When the horizontal coordinate position λ corresponding to the second harmonic peak θ2 Deviation from λ c When the laser temperature set point is adjusted, the position λ of the second harmonic signal is corrected. θ2 , so that the position λ θ2 Back to Lambda c Location.

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