阅读说明：本技术 一种单光路浓度解调与自校正激光气体检测方法 (Single-light-path concentration demodulation and self-correction laser gas detection method ) 是由 郭清华 张书林 于庆 孙世岭 樊荣 槐利 郭江涛 李军 梁光清 张远征 赵庆川 于 2021-08-24 设计创作，主要内容包括：本发明涉及一种单光路浓度解调与自校正激光气体检测方法,属于气体检测领域。该方法为：激光器产生检测光束；检测光束通过气体测量环境；检测光束进入密封定量参考气体的单一探测器或检测光束通过密封定量参考气体气室再进入单一探测器；光束进行光电转换并采集气体吸收信号和密封参考气体器件温度,并将采集信号送入核心处理器；提取激光器吸收波长中心和整体光路气体耦合吸收值；自动调节和线性校正；将测量环境气体吸收信号去耦解调；将气体浓度值进行显示和发送。本发明使用单一光路实现了对工矿环境气体浓度的精确测量和检测过程的线性自动校正,保证了测量系统的长期工作稳定性。(The invention relates to a single-light-path concentration demodulation and self-correction laser gas detection method, and belongs to the field of gas detection. The method comprises the following steps: the laser generates a detection beam; detecting the light beam passing through the gas measurement environment; the detection light beam enters a single detector of the sealed quantitative reference gas or enters the single detector through the sealed quantitative reference gas chamber; carrying out photoelectric conversion on the light beam, acquiring a gas absorption signal and the temperature of a sealed reference gas device, and sending the acquired signal to a core processor; extracting the gas coupling absorption value of the absorption wavelength center and the whole light path of the laser; automatic adjustment and linear correction; decoupling and demodulating the measurement environment gas absorption signal; and displaying and transmitting the gas concentration value. The invention uses a single light path to realize the accurate measurement of the gas concentration of the industrial and mining environment and the linear automatic correction of the detection process, thereby ensuring the long-term working stability of the measurement system.)

1. A single light path concentration demodulation and self-correction laser gas detection method is characterized in that: the method comprises the following steps:

s1: generating a detection light source by using a laser and emitting a detection light beam;

s2: detecting the light beam passing through the gas measurement environment;

s3: a single detector for detecting the light beam entering the sealed quantitative reference gas;

s3: carrying out photoelectric conversion on the detection light beam, acquiring a gas absorption signal and the temperature of a sealed reference gas device, and sending the acquired signal to a core processor;

s4: the core processor analyzes and converts the harmonic signal and extracts the absorption wavelength center lambda of the laser_cAnd an integral light pathGas coupling absorption value A_ω；

S5: the core processor will lambda_cAnd λ_θComparing, and calibrating the central value lambda_θPerforming center autoregressive adjustment and linear correction;

s6: the core processor inverts the sealing concentration to C according to the temperature_RReference gas equivalent absorption value A_εCoupling the absorption value A to the whole_ωThe difference with A epsilon is used for realizing the measurement of the absorption signal A of the environmental gas_CDe-coupled demodulation, i.e. A_C＝A_ω-Aε；

S7: core processor according to A_CAnd performing concentration inversion on the value to obtain a measured gas concentration value C in the measuring environment, and displaying and sending the gas concentration value.

2. The single light path concentration demodulation and self-calibration laser gas detection method as claimed in claim 1, wherein: in S3, the detection beam passes through the sealed quantitative reference gas cell and then enters the single detector.

3. The single light path concentration demodulation and self-calibration laser gas detection method as claimed in claim 1, wherein: the detection beam is not split.

4. The single light path concentration demodulation and self-calibration laser gas detection method as claimed in claim 1, wherein: the core processor is an MCU.

5. The single-light-path concentration demodulation and self-calibration laser gas detection method as claimed in claim 4, wherein: the MCU is respectively in data connection with the display circuit, the communication interface, the sound-light alarm module, the temperature control circuit, the laser driving circuit and the AD acquisition circuit;

the laser driving circuit is connected with the DFB laser;

the temperature control circuit is connected with the DFB laser;

and the AD acquisition circuit is also respectively connected with the temperature sensor circuit and the photoelectric conversion detection circuit.

6. The single-light-path concentration demodulation and self-calibration laser gas detection method as claimed in claim 5, wherein: after S7, the method further includes: and performing sound-light alarm after the concentration value of the detected gas reaches a set threshold value.

7. The single light path concentration demodulation and self-calibration laser gas detection method as claimed in claim 1, wherein: the laser is a wavelength tunable laser.

Technical Field

The invention belongs to the field of gas detection, and relates to a single-light-path concentration demodulation and self-correction laser gas detection method.

Background

At present, in the gas concentration detection process of the industries such as coal mines, petrifaction and the like, a tunable semiconductor laser absorption spectroscopy gas detection Technology (TDLAS) is widely applied, and has the characteristics of high measurement precision, high detection speed and good stability; the laser gas detection method adopts a wavelength modulation spectroscopy technology (WMS) to realize the detection of gas concentration, the technology analyzes the gas concentration by detecting a gas characteristic absorption spectrum signal, a tunable laser is adopted as a detection light source, and the method can realize the underground CH of a coal mine₄、CO、O₂、CO₂、C₂H₂、C₂H₄And detecting the gas with various characteristics.

The laser gas detection method and the detection device adopted at present are mainly installed in the environment with poor working conditions, and if the detection device does not perform linear self-correction by referring to a gas chamber, the detection device is easily influenced by various environmental factors to cause the performance change of the detection device, and the phenomena of inaccurate measurement and the like are caused. At present, the existing detection device adopting the light splitting technology and combining the reference gas chamber needs at least two independent light paths to respectively realize the independent measurement function of measuring the gas concentration of the light path and the automatic correction of the laser wavelength center of the light path of the reference gas chamber to realize the linear correction function; although the method realizes the linear self-correction of the detection device and ensures the long-term stability of the product, at least two detections are needed for synchronous detection, the technology is complex to realize and has higher cost, and meanwhile, the product has a complex optical path structure and is not easy to highly integrate and further miniaturize.

In order to further promote the application of the laser gas detection method and the detection device to scenes such as intelligent mine, internet of things construction and the like, a laser gas detection device with an automatic correction function, which can realize high integration and low cost of single light path coupling sealing reference gas, is urgently needed at present so as to ensure the reliability, stability and miniaturization of a gas measurement device. The single light path method solves the problem of distortion and deformation of a coupling absorption curve of the high-concentration gas in the environment by measuring the coupling sealing quantitative low-concentration reference gas in the light path, and realizes the accurate detection of the wavelength center of the laser under the condition of sealing the low-concentration reference gas by a harmonic algorithm; and then, through a large amount of temperature experiments, an equivalent absorption concentration change model of the quantitative reference gas concentration under different temperature states is established, and the high-precision concentration decoupling detection of the whole optical path is realized.

Disclosure of Invention

In view of the above, the present invention provides a method for single optical path concentration demodulation and self-calibration laser gas detection.

In order to achieve the purpose, the invention provides the following technical scheme:

a single light path concentration demodulation and self-correction laser gas detection method comprises the following steps:

s1: generating a detection light source by using a laser and emitting a detection light beam;

s2: detecting the light beam passing through the gas measurement environment;

s3: a single detector for detecting the light beam entering the sealed quantitative reference gas;

s3: carrying out photoelectric conversion on the detection light beam, acquiring a gas absorption signal and the temperature of a sealed reference gas device, and sending the acquired signal to a core processor;

s4: the core processor analyzes and converts the harmonic signal and extracts the absorption wavelength center lambda of the laser_cAnd the gas coupling absorption value A of the whole optical path_ω；

S5: the core processor will lambda_cAnd λ_θComparing, and calibrating the central value lambda_θPerforming center autoregressive adjustment and linear correction;

s6: the core processor inverts the sealing concentration to C according to the temperature_RReference gas equivalent absorption value A_εCoupling the absorption value A to the whole_ωThe difference with A epsilon is used for realizing the measurement of the absorption signal A of the environmental gas_CDe-coupled demodulation, i.e. A_C＝A_ω-Aε；

S7: core processor according to A_CAnd performing concentration inversion on the value to obtain a measured gas concentration value C in the measuring environment, and displaying and sending the gas concentration value.

Optionally, in S3, the detection beam passes through the sealed quantitative reference gas cell and then enters the single detector.

Optionally, the detection beam is not split.

Optionally, the core processor is an MCU.

Optionally, the MCU is respectively connected to the display circuit, the communication interface, the sound and light alarm module, the temperature control circuit, the laser driving circuit and the AD acquisition circuit;

the laser driving circuit is connected with the DFB laser;

the temperature control circuit is connected with the DFB laser;

and the AD acquisition circuit is also respectively connected with the temperature sensor circuit and the photoelectric conversion detection circuit.

Optionally, after S7, the method further includes: and performing sound-light alarm after the concentration value of the detected gas reaches a set threshold value.

Optionally, the laser is a wavelength tunable laser.

The invention has the beneficial effects that: the invention can realize that a single optical path can finish the accurate measurement of the gas concentration of the industrial and mining environment and the linear automatic correction of the detection process, thereby ensuring the long-term working stability of the measurement system, reducing the potential safety hazard and reducing the maintenance times of workers; meanwhile, the number of the photoelectric detectors is reduced, the cost and the space are saved, the high integration and the miniaturization of a measuring system are facilitated, and the system is suitable for popularization and use in the scene of application requirements of the Internet of things.

Additional advantages, objects, and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention. The objectives and other advantages of the invention may be realized and attained by the means of the instrumentalities and combinations particularly pointed out hereinafter.

Drawings

For the purposes of promoting a better understanding of the objects, aspects and advantages of the invention, reference will now be made to the following detailed description taken in conjunction with the accompanying drawings in which:

FIG. 1 is a flow chart of the present detection method;

FIG. 2 is a schematic diagram of a laser beam path structure;

FIG. 3 is a schematic diagram of a laser optical path structure

Fig. 4 is a detection schematic.

Detailed Description

The embodiments of the present invention are described below with reference to specific embodiments, and other advantages and effects of the present invention will be easily understood by those skilled in the art from the disclosure of the present specification. The invention is capable of other and different embodiments and of being practiced or of being carried out in various ways, and its several details are capable of modification in various respects, all without departing from the spirit and scope of the present invention. It should be noted that the drawings provided in the following embodiments are only for illustrating the basic idea of the present invention in a schematic way, and the features in the following embodiments and examples may be combined with each other without conflict.

Wherein the showings are for the purpose of illustrating the invention only and not for the purpose of limiting the same, and in which there is shown by way of illustration only and not in the drawings in which there is no intention to limit the invention thereto; to better illustrate the embodiments of the present invention, some parts of the drawings may be omitted, enlarged or reduced, and do not represent the size of an actual product; it will be understood by those skilled in the art that certain well-known structures in the drawings and descriptions thereof may be omitted.

The same or similar reference numerals in the drawings of the embodiments of the present invention correspond to the same or similar components; in the description of the present invention, it should be understood that if there is an orientation or positional relationship indicated by terms such as "upper", "lower", "left", "right", "front", "rear", etc., based on the orientation or positional relationship shown in the drawings, it is only for convenience of description and simplification of description, but it is not an indication or suggestion that the referred device or element must have a specific orientation, be constructed in a specific orientation, and be operated, and therefore, the terms describing the positional relationship in the drawings are only used for illustrative purposes, and are not to be construed as limiting the present invention, and the specific meaning of the terms may be understood by those skilled in the art according to specific situations.

FIG. 1 is a flow chart of the detection method, the method comprises the following steps:

the method comprises the following steps: generating a detection light source by using a laser, wherein a monochromatic light beam output by the laser is used as a detection light beam;

step two: passing the detection beam of step one through a gas measurement environment;

step three: the detection light beam enters a single detector of the sealed quantitative reference gas or passes through a sealed quantitative reference gas chamber and then enters the single detector (as shown in figures 2 and 3);

step four: carrying out photoelectric conversion on the light beam, acquiring a gas absorption signal and sealing the temperature of a reference gas device, and sending the acquired signal to a core processor;

step five: the core processor analyzes and converts the harmonic signal and extracts the absorption wavelength center lambda of the laser_cAnd the gas coupling absorption value A of the whole optical path_ω；

Step six: core(s)The processor will_cAnd λ_θComparing, and calibrating the central value lambda_θPerforming center autoregressive adjustment and linear correction;

step seven: the core processor inverts the sealing concentration to C according to the temperature_RReference gas equivalent absorption value A_εCoupling the absorption value A to the whole_ωThe difference with A epsilon is used for realizing the measurement of the absorption signal A of the environmental gas_C(i.e. A)_C＝A_ω-a epsilon) decoupling demodulation;

step eight: core processor according to A_CAnd performing concentration inversion on the value to obtain a measured gas concentration value C in the measurement environment, displaying and sending the gas concentration value, and judging whether to alarm or not.

Fig. 4 is a detection schematic.

Finally, the above embodiments are only intended to illustrate the technical solutions of the present invention and not to limit the present invention, and although the present invention has been described in detail with reference to the preferred embodiments, it will be understood by those skilled in the art that modifications or equivalent substitutions may be made on the technical solutions of the present invention without departing from the spirit and scope of the technical solutions, and all of them should be covered by the claims of the present invention.