Gas concentration detection method and system for lensless laser gas sensor

Abstract

The invention belongs to the field of gas concentration detection, and provides a gas concentration detection method and system for a lensless laser gas sensor, and the method comprises the following steps: carrying out first period scanning on detected gas in the range of a basic wavelength scanning period, and obtaining an initial detection signal; reducing the basic wavelength scanning period according to a sampling point corresponding to the central wavelength of the absorption peak of the detected gas to obtain a short wavelength scanning period, and scanning the detected gas for multiple times within the range of the short wavelength scanning period to obtain multiple reduced period detection signals; in the same range as the basic wavelength scanning period, scanning the detected gas in the last period to obtain a last detection signal; and comparing the initial detection signal with the last detection signal, and if the change of the detection signals is within a preset range, linearly superposing multiple times of shortened period detection signals as an effective measurement value of the gas concentration. According to the invention, the signal-to-noise ratio of the detection signal is improved, and the purpose of rapid and high-sensitivity detection is achieved.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of gas concentration detection, and particularly relates to a gas concentration detection method and system for a lensless laser gas sensor. BACKGROUND

[0002] The statements in this section merely provide background information related to the present application and do not necessarily constitute the prior art.

[0003] The tunable diode laser absorption spectroscopy (TDLAS) is used to analyze the selective absorption of laser energy by the absorption peak of the measured gas, and the corresponding gas concentration is calculated. In the process of miniaturization, practicality and intelligence of laser spectroscopy gas sensors, various miniaturized laser spectroscopy gas sensor probes have appeared. In order to improve the measurement accuracy of the detected gas and reduce the size of the sensor probe, the method of using a mirror to change the propagation path of the light beam in the measurement cell is widely used in these miniaturized gas sensors. The space between the laser source and the detector is usually used as the measurement cell in the gas cell or gas absorption cell of a general gas sensor. In the case where the volume of the sensor is limited, in order to increase the measurement optical path length, the gas cell usually uses multiple mirrors to make the light beam pass through the gas cell multiple times, thereby achieving the effect of obtaining a longer measurement optical path in a smaller space. The White reflection cavity and Herriott reflection cavity schemes, etc. Due to the use of multiple optical elements to form the absorption cell in the above reflection cavities, the optical structure of the absorption cell becomes complex; if the position of any element changes relative to the position of other elements, the optical path will change accordingly, thereby affecting the measurement accuracy. Especially since these sensing light paths are distributed in a three-dimensional space, the volume of the entire gas absorption cell is large, the mechanical structure is poor, especially in some application sites, such as in the energy storage battery box or in the battery pack of a new energy vehicle, the stability of the gas sensor based on these three-dimensional gas cells is poor, and the service life is limited, which is not conducive to large-scale popularization and use.

[0004] And at present most of the laser methane gas sensor is using TO-can laser and detector, the collimating lens of TO-can laser changes the divergent light beam emitted by the laser light source into parallel light beam, and the converging lens of TO-can detector converges the laser parallel light beam to the light sensitive surface of the detector. Due to the lens collimation and convergence in the optical path, the surface of the two lenses will always produce a certain amount of reflected light, when the reflected light reenters the resonant cavity of the laser, it will cause interference phenomenon. When using tunable laser absorption spectroscopy (TDLAS) to measure the concentration of gas, the wavelength of the laser is tuned by the driving current of the laser, which causes interference in the laser resonator and interference ripple in the output signal of the detector of the detection system. This interference ripple forms a background noise signal that changes with the ambient temperature. This noise not only reduces the detection sensitivity of the gas concentration, but also seriously affects the long-term stability of the instrument, and further affects the measurement accuracy of the gas concentration.

[0005] Based on the above defects, in the Chinese patent application with application number 202510590670.1 and invention name "lensless laser gas sensing module based on COB, packaging method and application", a lensless laser gas sensor is proposed. Since there is no lens in the detection optical path, the influence of lens interference in the conventional laser gas sensor can be effectively avoided, so that the detected signal is only randomly generated, and the noise signal strength is centered on zero and normally distributed white noise; However, when a gas sensor with a small gas cell volume and a short absorption optical path length is used, the sensitivity of the gas concentration detection is often reduced, which cannot meet the actual needs of micro gas leak detection. SUMMARY

[0006] In order to solve the above problems, the present application provides a gas concentration detection method and system for a lensless laser gas sensor. Without significantly increasing the detection time, the present application uses a sensor with a small measurement optical path length, and utilizes the feature that the detection signal of the lensless laser gas sensor only produces random white noise. By using a large number of small wavelength scanning periods to scan at the absorption peak and superimposing each small period detection signal, the white noise in the detection signal is cancelled out, while the absorption signal is continuously added, thereby improving the signal-to-noise ratio of the detection signal and increasing the detection sensitivity.

[0007] According to some embodiments, the first aspect of the present application provides a gas concentration detection method for a lensless laser gas sensor, which adopts the following technical solution: The gas concentration detection method for a lensless laser gas sensor includes: The lensless laser gas sensor driven by the sawtooth wave driving current drives the laser to scan the measured gas for a first period in a range of a basic wavelength scanning period, and obtain an initial detection signal; According to the sampling point corresponding to the absorption peak center wavelength of the measured gas, the basic wavelength scanning period is reduced to obtain a short wavelength scanning period, and the measured gas is scanned for multiple times in the range of the short wavelength scanning period to obtain multiple reduced period detection signals; The lensless laser gas sensor driven by the sawtooth wave driving current drives the laser to scan the measured gas for a last period in the same range as the basic wavelength scanning period, and obtain a last detection signal; The initial detection signal and the last detection signal are compared, and if the change of the detection signal is within a preset range, the multiple reduced period detection signals are linearly superimposed as the effective measurement value of the gas concentration.

[0008] Further, the initial detection signal includes a starting measurement value at a starting sampling point, a starting measurement value at a terminal sampling point, and an initial measurement value at the absorption peak center wavelength of the measured gas in the range of the basic wavelength scanning period.

[0009] Further, the starting measurement value at the starting sampling point is an average of initial measurement values corresponding to the first m sampling points; The initial measurement value of the terminal sampling point is an average of initial measurement values corresponding to the last m sampling points; The initial measurement value at the absorption peak center wavelength of the measured gas is an average of initial measurement values corresponding to the first and last (m-1) / 2 sampling points around the absorption peak wavelength of the measured gas.

[0010] Further, the last detection signal includes a last measurement value at a starting sampling point, a last measurement value at a terminal sampling point, and a last measurement value at the absorption peak center wavelength of the measured gas in the range of the basic wavelength scanning period.

[0011] Further, the last measurement value at the starting sampling point is an average of last measurement values corresponding to the first m sampling points; The last measurement value at the terminal sampling point is an average of last measurement values corresponding to the last m sampling points; The last measurement value at the absorption peak center wavelength of the measured gas is an average of last measurement values corresponding to the first and last (m-1) / 2 sampling points around the absorption peak center wavelength of the measured gas.

[0012] Further, the sampling point corresponding to the absorption peak center wavelength of the measured gas is used to reduce the basic wavelength scanning period to obtain a short wavelength scanning period, and the measured gas is scanned multiple times within the short wavelength scanning period to obtain multiple reduced period detection signals, including: The sampling point corresponding to the absorption peak center wavelength of the measured gas is N; Then, the k sampling points before and after the sampling point corresponding to the absorption peak center wavelength of the measured gas are used as the short wavelength scanning period. The measured gas is scanned multiple times within the short wavelength scanning period to obtain multiple reduced period detection signals.

[0013] According to some embodiments, the second aspect of the present application provides a gas concentration detection system for a lensless laser gas sensor, which adopts the following technical solution: The gas concentration detection system for the lensless laser gas sensor includes: The initial scanning sequence is used to drive the lensless laser gas sensor of the laser based on the set sawtooth wave driving current, to scan the measured gas for the first cycle within the basic wavelength scanning period, and to obtain an initial detection signal. The short period measurement scanning sequence is used to reduce the basic wavelength scanning period according to the sampling point corresponding to the absorption peak center wavelength of the measured gas to obtain a short wavelength scanning period, and to scan the measured gas multiple times within the short wavelength scanning period to obtain multiple reduced period detection signals. The last scanning sequence is used to drive the lensless laser gas sensor of the laser based on the set sawtooth wave driving current, to scan the measured gas for the last cycle within the same range as the basic wavelength scanning period, and to obtain a last detection signal. The gas concentration effective value determination sequence is used to compare the initial detection signal and the last detection signal, and if the change of the detection signal is within the preset range, the multiple reduced period detection signals are linearly superimposed as the effective gas concentration measurement value.

[0014] According to some embodiments, the third aspect of the present application provides an MCU readable storage medium.

[0015] An MCU readable storage medium has an embedded program stored thereon, which, when executed by a processor, implements the steps in the gas concentration detection method for the lensless laser gas sensor according to the first aspect described above.

[0016] According to some embodiments, the fourth aspect of the present application provides an MCU computer device.

[0017] An MCU device comprises a memory, a processor, and an embedded program stored on the memory and executable on the processor, and the processor implements the steps in the gas concentration detection method for a lensless laser gas sensor according to the first aspect.

[0018] According to some embodiments, the fifth aspect of the present application provides a computer program product or computer program.

[0019] A computer program product or computer program comprises computer instructions stored in a computer readable storage medium, and a processor of a computer device reads the computer instructions from the computer readable storage medium, and the processor executes the computer instructions to enable the computer device to perform the steps in the gas concentration detection method for a lensless laser gas sensor according to the first aspect.

[0020] Compared with the prior art, the present application has the following beneficial effects: When the lensless laser gas sensor based on COB is used, there is no lens in the detection light path, so the lens interference in the conventional laser module can be effectively avoided, so that the detected signal is only random white noise, and the noise signal strength is centered on zero and normally distributed, therefore, through low-pass filtering and multiple detection signal superposition, the measured signal strength can be effectively increased, that is, the random white noise signal is superimposed multiple times, and the positive and negative noise signals are partially suppressed, and the measured gas absorption peak signal is continuously enhanced in continuous linear superposition, and as a result, the signal-to-noise ratio of the detection signal is greatly improved, and this signal processing method is equivalent to "increasing" the optical path length of the sensor module by several times through superposition several times, so that the actual physical optical path can be kept small, and the measurement sensitivity and precision of the equivalent long optical path can be obtained.

[0021] The gas sensor with a relatively small gas absorption cell volume and a relatively short absorption optical path length is used to achieve relatively high measurement sensitivity, so as to meet the actual demand of detecting the micro-leakage of individual battery cells. A specially designed detection process is adopted, and through real-time peak searching, multiple sampling measurements, data calibration, and linear superposition, under the condition of a relatively small measurement optical path length, the interference ripple caused by the lens in the detection signal and the noise of the detection signal which is only normally distributed white noise are used, and the measurement result of multiple superimposed fast small period scanning is used to greatly improve the signal-to-noise ratio of the detection signal, so that the detection precision of the entire sensor module is improved, and the methane gas detection precision of nearly 100ppm is obtained in the measurement optical path length of 65mm, which provides effective technical support for meeting the demand of detecting methane micro-leakage. BRIEF DESCRIPTION OF DRAWINGS

[0022] The accompanying drawings, which form a part of this specification, are included to provide a further understanding of the application, and are incorporated by reference in their entirety.

[0023] Figure 1 A schematic diagram of a COB-based lensless laser gas sensing module employed in an embodiment of the present application; Figure 2 A flow chart of a detection method specially designed for an embodiment of the present application; Figure 3 A schematic diagram of an absorption peak spectrum generated by a conventional sawtooth wave driving current; Figure 4 A schematic diagram of an absorption peak spectrum generated by a driving current of an embodiment of the present application; Figure 5 An absorption peak value signal when the methane concentration is 500 ppm in an embodiment of the present application, employing sawtooth wave current wavelength scanning; Figure 6 An absorption peak value signal when the methane concentration is 500 ppm in an embodiment of the present application, employing 15 sawtooth wave current wavelength scanning and then superimposing. DETAILED DESCRIPTION

[0024] The present application will be further described with reference to the drawings and embodiments.

[0025] It should be noted that the following detailed description is merely exemplary and is intended to provide further description of the application. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs.

[0026] It is to be understood that the singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise. It should be noted that, as used in this specification and the appended claims, the singular form "a," "an," and "the" include plural referents unless the context clearly dictates otherwise. It should also be noted that, as used in this specification and the appended claims, the term "or" is generally employed in its sense of "and / or" unless the context clearly dictates otherwise.

[0027] The embodiments in the present application and the features in the embodiments can be combined with each other without conflict.

[0028] Embodiment One The embodiment provides a gas concentration detection method for a lens-free laser gas sensor. The embodiment takes the method applied to a server as an example. It can be understood that the method can also be applied to a terminal, that is, embedded software of an internal MCU of the sensor. Within the permission range of information transmission delay, the method can also be applied to a terminal, a server and a system, and is realized through interaction of the terminal and the server. The server can be a physical server, a server cluster composed of multiple physical servers or a distributed system, or a cloud server providing basic cloud computing services such as cloud service, cloud database, cloud computing, cloud function, cloud storage, network server, cloud communication, middleware service, domain name service, security service CDN, and big data and artificial intelligence platform. The terminal can be a smart phone, a tablet computer, a notebook computer, a desktop computer, a smart speaker, a smart watch and the like, but is not limited thereto. The terminal and the server can be directly or indirectly connected through wired or wireless communication, which is not limited in the application. In the embodiment, the method comprises the following steps: The lens-free laser gas sensor driven by the set sawtooth wave driving current drives the laser, and the measured gas is scanned for the first cycle within the range of the basic wavelength scanning period to obtain an initial detection signal. The basic wavelength scanning period is reduced according to the sampling point corresponding to the absorption peak center wavelength of the measured gas to obtain a short wavelength scanning period, and the measured gas is scanned for multiple times within the range of the short wavelength scanning period to obtain multiple reduced cycle detection signals. The lens-free laser gas sensor driven by the set sawtooth wave driving current drives the laser, and the measured gas is scanned for the first cycle within the range of the basic wavelength scanning period to obtain an initial detection signal. The initial detection signal and the last detection signal are compared, and if the change of the detection signal is within a preset range, the multiple reduced cycle detection signals are linearly superimposed as the effective measurement value of the gas concentration.

[0029] As shown in Figure 2 The method described in the embodiment has the following process: Step 1: Connect the COB-based lens-free laser gas sensing module to the detection system, power on the module and make it enter the working state. As shown in Figure 1As shown, the COB-based lensless laser gas sensing module has a management control circuit integrated on a COB board; a laser chip and a detector chip are respectively bonded on the COB board; the laser chip is used for emitting a tunable laser beam; the detector chip is used for detecting and receiving the tunable laser beam absorbed by the measured gas and transmitting a signal to the management control circuit; the light emitting point of the laser chip and the photosensitive surface of the detector chip are respectively arranged in correspondence with the focal points of the first parabolic mirror and the second parabolic mirror; when the module works, the laser beam emitted by the laser chip is approximately collimated light after being reflected by the first parabolic mirror, passes through a beam channel, and is focused on the photosensitive surface of the detector by the second parabolic mirror; in this way, the COB board, the two parabolic mirrors and the beam channel form a detection gas chamber of the measured gas.

[0030] The laser gas sensing module further includes a temperature and pressure sensor for measuring the ambient temperature and pressure, a photodetector for converting the laser light intensity tuned by the measured gas into an electrical signal, and a microprocessor for calculating the concentration of the measured gas based on the absorption peak coefficient.

[0031] Since there is no lens in the optical path of the detection gas chamber, the lens interference in the conventional laser module is avoided, so that the detected signal is only white noise randomly generated and normally distributed, therefore, by low-pass filtering and superposition of multiple detection results, the measured signal strength can be effectively increased, and as a result, the signal-to-noise ratio of the detection signal is improved.

[0032] Step 2: Use the set sawtooth wave driving current to drive the laser, scan the measured gas in the range of a basic wavelength scanning period for the first period, obtain the initial detection signal, make the laser wavelength scanning contain the wavelength interval of the gas absorption peak wavelength, and obtain the corresponding detection signal of the detector at the same time; Taking 1100 sampling points in a basic wavelength scanning period as an example, in the first period, the initial measurement value I 起始初 at the starting sampling point of the basic wavelength scanning period interval (the average value of the initial measurement values corresponding to the first m sampling points, for example, the first eleven sampling points), the initial measurement value I 终止初 at the terminal sampling point (the average value of the initial measurement values corresponding to the last m sampling points, for example, the last eleven sampling points), and the initial measurement value I 吸收峰初 at the absorption peak center wavelength of the measured gas (the average value of the initial measurement values corresponding to (m-1) / 2 sampling points before and after the absorption peak center wavelength of the measured gas, for example, five sampling points before and after the absorption peak center wavelength of the measured gas) are obtained.

[0033] Step 3: Reduce the basic wavelength scanning period according to the sampling point corresponding to the absorption peak center wavelength of the measured gas, to obtain a short wavelength scanning period, and perform multiple scans on the measured gas within the short wavelength scanning period to obtain multiple reduced period detection signals, the process being as follows: The sampling point corresponding to the absorption peak center wavelength of the measured gas is N; Then, the k = (m-1) / 2 sampling points before and after the sampling point corresponding to the absorption peak center wavelength of the measured gas are taken as the short wavelength scanning period. Perform multiple periodic scans on the measured gas within the short wavelength scanning period to obtain multiple reduced period detection signals.

[0034] That is, if the sampling point value corresponding to the absorption peak center wavelength of the measured gas is N; reduce the range of the basic wavelength scanning period to a smaller range, that is, take the k sampling points before and after the sampling point corresponding to the absorption peak center wavelength of the measured gas as the short wavelength scanning period, that is, (N-k, N+k) is the short wavelength scanning period.

[0035] Perform multiple scans on the measured gas within the short wavelength scanning period to obtain multiple reduced period detection signals; each reduced period detection signal contains the measurement values of all sampling points within the short wavelength scanning period; For convenience of calculation, take the measurement values of the 5 sampling points before and after the absorption peak center wavelength as an example, that is, within the range of (N-5, N+5), perform multiple fast scans on the detector intensity at this position, the starting point and the ending point of the short wavelength scanning period are N-5 and N+5 respectively, and each short wavelength scanning period is 11 sampling points, so in each short wavelength scanning period, the measurement values corresponding to the 11 sampling points around the absorption peak can be obtained.

[0036] Since the basic wavelength scanning period is reduced from 1100 sampling points to a smaller short wavelength scanning period of 11 sampling points around the absorption peak center wavelength corresponding to the measured gas, that is, the laser drive current scanning range is adjusted to correspond to the 5 sampling points before and after the absorption peak wavelength of the measured gas by using the known correspondence between the laser drive current and the wavelength, and multiple fast scans are performed on this wavelength interval, the measurement values of multiple groups of 11 absorption peak peak intensities including the absorption peak are obtained, and then these multiple groups of measurement values are linearly superimposed, and the intensity of the absorption peak of the measured gas is thus linearly amplified. Step 4: Use the sawtooth wave drive current set in the first period to drive the last period of the laser again, and perform a scan on the measured gas within the same range as the basic wavelength scanning period to obtain the last detection signal.

[0037] That is, for example, a long scanning period covers 1100 sampling points, the last detection signal can be obtained, which includes the last measurement value I 起始末 at the starting sampling point of the basic wavelength scanning period, the last measurement value I 终止末 at the ending sampling point, the average of the last measurement values of the first m sampling points, for example, the first eleven sampling points, the last measurement value I 吸收峰末 at the ending sampling point, the average of the last measurement values of the last m sampling points, for example, the last eleven sampling points, and the last measurement value I 起始初 at the absorption peak wavelength of the measured gas. Step 5: comparing the initial detection signal and the last detection signal, if the change of the detection signal is within the preset range, the linear superposition of the multiple reduced period detection signals is taken as the effective measurement value of the gas concentration, and the process is as follows: comparing the measurement values at the starting sampling point and the ending sampling point of the basic wavelength scanning period corresponding to the first period and the last period, and the measurement value at the absorption peak wavelength of the measured gas; If the changes of the three measurement values are within the preset error range, it means that the detection system does not change in the fast multiple scanning process, so all the reduced period detection signals are valid values, and the linear superposition result is also a valid measurement value. That is, in the fast scanning superposition process of the short wavelength scanning period, the working state of the module is basically unchanged, so within the range of (N-5, N+5), the linear superposition of the multiple reduced period detection signals is the effective measurement value of the gas concentration. That is, comparing the measurement values at the starting sampling point and the ending sampling point of the basic wavelength scanning period corresponding to the first period and the last period, and the measurement value at the absorption peak wavelength of the measured gas, if the changes of the three groups of measurement values are within the preset error range, i.e. not greater than the white noise intensity, it means that the linear superposition of the measurement values of the fast multiple scanning is a valid measurement value. Step 6: using the wavelength scanning data of the first sawtooth wave and the last sawtooth wave, the baseline of the detection signal can be obtained through processing, and the measurement value of this gas concentration is calculated by subtracting the corresponding baseline value from the multiple superimposed detector measurement values at the absorption peak wavelength. That is, using the wavelength scanning data of the first sawtooth wave and the last sawtooth wave, i.e. the starting point (1, I 起始初 / I 起始末 ) and the ending point (1100, I 终止初 / I 终止末), the baseline of the detection signal can be obtained by linear fitting of the 11 sampling points and the corresponding measurement values of the starting point and the 11 sampling points and the corresponding measurement values of the ending point, and the baseline value and the measurement value I of the detector at the wavelength of the absorption peak of the multiple superimposed absorption peaks are used to calculate the signal value of this measurement. 吸收峰 , the signal value of this measurement is calculated.

[0038] Step 7: The measurement system is calibrated by using the method of steps 1-6 and the conventional methane standard gas, and the calibration coefficient between the measurement value and the concentration value is obtained.

[0039] Step 8: When measuring again based on the lensless laser gas sensing of COB, the concentration value of the measured gas is obtained by inverting all the measured signal values using the expression coefficient between the measurement value and the concentration value. When the sensor measures, all the measured signals are inverted into the concentration value of the measured gas using these calibration coefficients. In practical applications, all the measured signal values can be inverted into the concentration value of the measured gas using these calibration coefficients.

[0040] Figure 3 and Figure 4 are schematic diagrams of the absorption peak spectrum generated by the conventional sawtooth wave driving current and the absorption peak spectrum generated by the driving current of the present application, respectively. The main difference between the two is that in the scanning waveform of Figure 3 , the middle current scanning of the first and last scanning is normal sawtooth wave scanning, while in Figure 4 , the middle scanning is high-frequency fast scanning around the gas absorption peak, and then the detection signals obtained by scanning are directly superimposed to form the final measurement value, as shown in step 3; Figure 5 is the measurement value of 500 ppm methane gas detected by using the conventional detection method in the detection system, while Figure 6 is the measurement value of 500 ppm methane gas obtained by superimposing the detection signal 15 times by using the fast detection method of the present application. The method of the present application can be applied to the detection of different gases (such as methane, acetylene, carbon monoxide, etc.).

[0041] The embodiment changes the conventional wavelength scanning method of repeated sawtooth waves into only full basic wavelength scanning cycles in the first and last scans, and short wavelength scanning cycles between the two cycles; for example, a basic wavelength scanning cycle has 1100 sampling points, and between two full wavelength scans, a short wavelength scanning cycle is used, that is, at the sampling point value N corresponding to the center wavelength of the absorption peak, the scanning current only scans 5 points on both sides of N sampling points to form a small scanning cycle with only 11 scanning points. Thus, each short wavelength scanning cycle takes only one percent of the time of a full basic wavelength scanning cycle, thus greatly improving the detection speed, that is, 100 short wavelength scanning cycle measurements can be achieved in the time of a full basic wavelength scanning cycle. At the same time, the linear superposition of the one hundred measurements is equivalent to the result obtained by expanding the relatively small measurement optical path length by 100 times, that is, the method uses the principle of "time for space" to improve the detection accuracy. Using the same principle, the equivalent expanded measurement optical path length can be set and increased according to actual needs.

[0042] It should be noted that this detection method is only applicable to lensless laser gas sensors, because there is no interference caused by the lens, and thus there is no change in the background white noise caused by changes in the ambient temperature. In this case, the white noise will be cancelled out or suppressed when superimposed, and the absorption peak signal will increase with the number of superpositions. Due to the absence of interference ripples caused by the lens, the measurement accuracy of the test system is also relatively stable when the ambient temperature changes. Embodiment Two The embodiment provides a gas concentration detection system for a lensless laser gas sensor, comprising: A first scan sequence is used to drive the lensless laser gas sensor of the laser based on the set sawtooth wave driving current to scan the measured gas in a first cycle within a basic wavelength scanning cycle range, and obtain an initial detection signal; A short cycle measurement scan sequence is used to reduce the basic wavelength scanning cycle according to the sampling point corresponding to the center wavelength of the absorption peak of the measured gas, to obtain a short wavelength scanning cycle, and to scan the measured gas in the short wavelength scanning cycle range multiple times to obtain multiple reduced cycle detection signals; A last scan sequence is used to drive the lensless laser gas sensor of the laser based on the set sawtooth wave driving current to scan the measured gas in the last cycle within the same range as the basic wavelength scanning cycle, and obtain a last detection signal; The sequence for determining the effective value of the gas concentration compares the initial detection signal and the last detection signal, and if the change of the detection signal is within a preset range, the linear superposition of the multiple reduced period detection signals is taken as the effective measurement value of the gas concentration.

[0043] The above sequence and the examples and application scenarios realized by the corresponding steps are the same as those disclosed in Embodiment One, but are not limited to the disclosure in Embodiment One. It should be noted that the above execution sequence can be executed in the MCU as part of the system.

[0044] The descriptions of the various embodiments in the above embodiments are each focused on, and the parts not described in detail in a certain embodiment can be referred to the relevant description of other embodiments.

[0045] Embodiment Three The embodiment provides an MCU or a computer readable storage medium, and the MCU or the computer readable storage medium stores an embedded program which is executed by a processor to realize the steps in the gas concentration detection method for the lensless laser gas sensor as described in Embodiment One.

[0046] Embodiment Four The embodiment provides an MCU device, which comprises a memory, a processor and an embedded program stored in the memory and executable on the processor, and the processor realizes the steps in the gas concentration detection method for the lensless laser gas sensor as described in Embodiment One when executing the program.

[0047] Embodiment Five The embodiment provides a computer program product or a computer program, which comprises computer instructions stored in a computer readable storage medium, and a processor of a computer device reads the computer instructions from the computer readable storage medium, and the processor executes the computer instructions to enable the computer device to execute the steps in the gas concentration detection method for the lensless laser gas sensor as described in Embodiment One.

[0048] Those skilled in the art should understand that the embodiments of the present application can provide a method, a system or a computer program product. Therefore, the present application can adopt a hardware embodiment, a software embodiment or an embodiment combining software and hardware aspects. Moreover, the present application can adopt the form of a computer program product implemented on one or more computer usable storage media (including but not limited to magnetic disk storage and optical storage, etc.) containing computer usable program codes.

[0049] The embodiments of methods, apparatuses (systems) and computer program products according to the present application can be described in flowcharts and / or block diagrams in reference to the methods, apparatuses (systems) and computer program products according to the embodiments of the present application. It should be understood that each flow and / or block in the flowcharts and / or block diagrams and combinations of flows and / or blocks in the flowcharts and / or block diagrams can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing apparatus to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing apparatus generate a means for implementing the functions specified in the flowcharts and / or block diagrams. Figure 1 The flowcharts and / or block diagrams can include one or more flows and / or blocks that each represent a computer program instructions. Figure 1 The flowcharts and / or block diagrams can include one or more flows and / or blocks that each represent a computer program instructions.

[0050] The computer program instructions can also be stored in a computer-readable storage that can direct the computer or other programmable data processing apparatus to work in a specific manner, so that the instructions stored in the computer-readable storage produce a manufactured product including instruction apparatus, which implements the functions specified in the flowcharts and / or block diagrams. Figure 1 The flowcharts and / or block diagrams can include one or more flows and / or blocks that each represent a computer program instructions. Figure 1 The flowcharts and / or block diagrams can include one or more flows and / or blocks that each represent a computer program instructions.

[0051] The computer program instructions can also be loaded into a computer or other programmable data processing apparatus, so that a series of operation steps are performed on the computer or other programmable data processing apparatus to produce a computer-implemented process, so that the instructions executed on the computer or other programmable data processing apparatus provide a means for implementing the functions specified in the flowcharts and / or block diagrams. Figure 1 The flowcharts and / or block diagrams can include one or more flows and / or blocks that each represent a computer program instructions. Figure 1 The flowcharts and / or block diagrams can include one or more flows and / or blocks that each represent a computer program instructions.

[0052] A person of ordinary skill in the art can understand that all or part of the above-mentioned flow of the embodiment method can be implemented by a computer program to instruct the related hardware, and the program can be stored in a computer-readable storage medium, and the program can include the flow of the above-mentioned embodiment method when executed. The storage medium can be a magnetic disc, an optical disc, a read-only memory (ROM) or a random access memory (RAM), etc.

[0053] The above describes the specific embodiments of the present application in conjunction with the accompanying drawings, but is not a limitation on the protection scope of the present application. A person of ordinary skill in the art should understand that various modifications or variations made by the person of ordinary skill in the art on the basis of the technical solutions of the present application without creative labor are still within the protection scope of the present application.

Claims

1. A gas concentration detection method for a lensless laser gas sensor, characterized by, The lensless laser gas sensor driven by the sawtooth wave driving current is used to scan the measured gas for the last cycle in the same range as the basic wavelength scanning period, and an end detection signal is obtained. The initial detection signal and the end detection signal are compared, and if the change of the detection signal is within a preset range, the linear superposition of the multiple reduced period detection signals is taken as the effective measurement value of the gas concentration. The initial detection signal includes a starting measurement value at a starting sampling point, an initial measurement value at a terminal sampling point, and an initial measurement value at an absorption peak wavelength of the measured gas within the range of the basic wavelength scanning period. The initial measurement value at the starting sampling point is an average of initial measurement values corresponding to the first m sampling points. The initial measurement value at the terminal sampling point is an average of initial measurement values corresponding to the last m sampling points.

2. The gas concentration detection method for a lensless laser gas sensor according to claim 1, wherein The initial measurement value at the absorption peak wavelength of the measured gas is an average of initial measurement values corresponding to (m-1) / 2 sampling points before and after the absorption peak center wavelength of the measured gas.

3. The gas concentration detection method for a lensless laser gas sensor according to claim 2, wherein The end detection signal includes an end measurement value at a starting sampling point, an end measurement value at a terminal sampling point, and an end measurement value at an absorption peak wavelength of the measured gas within the range of the basic wavelength scanning period. The end measurement value at the starting sampling point is an average of end measurement values corresponding to the first m sampling points. The end measurement value at the terminal sampling point is an average of end measurement values corresponding to the last m sampling points.

4. The gas concentration detection method for a lensless laser gas sensor according to claim 1, wherein The end measurement value at the absorption peak wavelength of the measured gas is an average of end measurement values corresponding to (m-1) / 2 sampling points before and after the absorption peak center wavelength of the measured gas.

5. The gas concentration detection method for a lensless laser gas sensor according to claim 4, wherein The absorption peak center wavelength of the measured gas corresponds to N sampling points. The k sampling points before and after the sampling point corresponding to the absorption peak center wavelength of the measured gas are taken as the short wavelength scanning period. The lensless laser gas sensor driven by the sawtooth wave driving current is used to scan the measured gas for the last cycle in the same range as the basic wavelength scanning period, and an end detection signal is obtained.

6. The gas concentration detection method for a lensless laser gas sensor according to claim 1, wherein The initial detection signal and the end detection signal are compared, and if the change of the detection signal is within a preset range, the linear superposition of the multiple reduced period detection signals is taken as the effective measurement value of the gas concentration. The initial detection signal includes a starting measurement value at a starting sampling point, an initial measurement value at a terminal sampling point, and an initial measurement value at an absorption peak wavelength of the measured gas within the range of the basic wavelength scanning period. The initial detection signal includes a starting measurement value at a starting sampling point, an initial measurement value at a terminal sampling point, and an initial measurement value at an absorption peak wavelength of the measured gas within the range of the basic wavelength scanning period. ​ 7. A gas concentration detection system for a lensless laser gas sensor, characterized by ​ ​ The short-period measurement scanning sequence is used to reduce the basic wavelength scanning period according to the sampling point corresponding to the absorption peak center wavelength of the measured gas, to obtain a short wavelength scanning period, and to perform multiple scans on the measured gas within the short wavelength scanning period to obtain multiple reduced-period detection signals. The last scanning sequence is used to drive the lensless laser gas sensor of the laser based on the set sawtooth wave driving current, to perform a last-period scan on the measured gas within the same range as the basic wavelength scanning period, and to obtain a last detection signal. The gas concentration effective value determination sequence is used to compare the initial detection signal and the last detection signal, and if the change in the detection signal is within a preset range, to linearly superimpose the multiple reduced-period detection signals as the effective measurement value of the gas concentration.

8. An MCU readable storage medium having stored thereon an embedded program, the program comprising: The program is executed by the processor to implement the steps in the gas concentration detection method for the lensless laser gas sensor according to any one of claims 1-6.

9. An MCU device comprising a memory, a processor, and an embedded program stored on the memory and executable on the processor, wherein, The processor executes the program to implement the steps in the gas concentration detection method for the lensless laser gas sensor according to any one of claims 1-6.

10. A computer program product, characterised in that, The computer program product includes a computer program that, when executed by a processor, implements the steps in the gas concentration detection method for the lensless laser gas sensor according to any one of claims 1-6.

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