Modular laser methane monitoring method and device

Abstract

The invention provides a modular laser methane monitoring method and device.The modular laser methane monitoring device comprises an installation module used for fixing the modular laser methane monitoring device to a target installation position through an installation datum plane, so that the laser emitting direction of the device is consistent with the preset detection direction; the laser emission module is used for emitting infrared laser with a specific wavelength, and the infrared laser penetrates through air in an area to be detected and then is received by the laser receiver; the signal processing module is used for collecting the detection signal output by the laser receiver, processing the detection signal and then calculating to obtain methane gas concentration data; the communication module is used for transmitting the methane gas concentration data to a monitoring device or an upper computer and executing local data storage and abnormal concentration alarm operation at the same time, and the consistency and repeatability of the detection direction are ensured through the design of the installation reference surface with the fixed geometrical relationship; and meanwhile, the device has independent operation capability and is suitable for various detection environments. According to the scheme, the field installation and maintenance cost can be remarkably reduced, and the automation and reliability of gas safety monitoring are improved.

Description

Technical Field

[0001] This application belongs to the field of air conditioning load regulation, and in particular relates to a modular laser methane monitoring method and device. Background Technology

[0002] With the widespread use of gas transmission and distribution pipelines and residential gas facilities, methane leak detection equipment is increasingly used in gas safety monitoring. Most existing laser methane detection equipment is either a single unit or a dedicated type, resulting in a large size and dispersed components. The laser optics, electronic processing circuits, power supply modules, and communication modules are often housed in different housings or separate modules. Such structures require rewiring and power supply configuration during installation or relocation, and their bulky size makes rapid deployment difficult. Furthermore, traditional devices often require realigning with the detection direction after relocation, increasing the complexity of on-site maintenance.

[0003] Therefore, there is an urgent need for a more compact and integrated modular laser methane monitoring device that can operate independently, is easy to install, and maintains consistent detection direction when installed in different locations, thereby improving the efficiency and flexibility of the equipment. Summary of the Invention

[0004] This application provides a modular laser methane monitoring method and device, which can solve the problem that traditional devices often need to be re-aligned in the detection direction after changing the installation position, which increases the complexity of on-site maintenance.

[0005] In a first aspect, a modular laser methane monitoring method includes: The modular laser methane monitoring device is fixed to the target installation position using a mounting reference surface, so that the laser emission direction of the device is consistent with the preset detection direction; A specific wavelength of infrared laser is emitted, which passes through the air in the area to be detected and is then received by a laser receiver. The detection signal output by the laser receiver is collected, and the methane gas concentration data is calculated after processing the detection signal. The methane gas concentration data is transmitted to a monitoring device or host computer, and local data storage and abnormal concentration alarm operations are performed simultaneously.

[0006] Optionally, the processing of the detection signal and the calculation of concentration include: Send drive commands to the laser emitter to control it to generate infrared laser with a wavelength of 3.3-3.5 micrometers; It receives infrared laser light after it has been absorbed by the gas, converts the optical signal into an electrical signal, and forms an initial detection signal. The initial detection signal is acquired through an analog-to-digital converter interface, low-pass filtered, and then amplified to make the signal amplitude reach the range suitable for algorithm operation. The amplified signal is then substituted into the methane concentration calculation model and combined with the laser wavelength and optical path length parameters to calculate the real-time methane gas concentration value. The calculated concentration value is judged for its reasonableness, and abnormal data that exceeds the normal concentration range is removed, while valid concentration data is retained.

[0007] Optional, methane concentration calculation includes: The initial light intensity and the actual received light intensity of the laser receiver are obtained, and the absorbance is obtained through the logarithmic relationship between the initial light intensity and the actual received light intensity. The methane gas concentration is obtained by dividing the absorbance by the product of the methane gas absorption coefficient at the corresponding laser wavelength and the laser propagation optical path length.

[0008] Optional abnormal concentration alarm operations include: If the effective concentration data is greater than the preset alarm threshold, the local audible and visual alarm module will be activated to issue a continuous audible and visual alarm signal. An alarm data frame is generated, which includes alarm type, concentration value, detection location and time information, and is transmitted to the monitoring device or host computer through the communication module.

[0009] Optionally, it also includes decoupling correction for the effects of temperature-induced shell deformation to calculate the optical axis offset angle, the decoupling correction including: Collect the current operating ambient temperature of the device and retrieve the reference temperature from the factory calibration in the local storage module; Calculate the difference between the current temperature and the reference temperature, and combine the known thermal expansion characteristics of the material used for the shell to determine the deformation of the shell along the optical axis and perpendicular to the optical axis under this temperature difference. The deformation is converted into a coordinate offset in the coordinate system of the receiving unit's CCD sensor. Subtract the coordinate offset from the actual coordinates of the current spot center acquired by the CCD sensor to obtain the coordinate deviation caused only by the offset of the optical axis itself; The optical axis offset angle is calculated by comparing the corrected coordinate deviation with the factory standard coordinates.

[0010] Optionally, it also includes decoupling correction for the effects of optical lens distortion to calculate the optical axis offset angle, the decoupling correction including: Retrieve the optical lens distortion characteristic parameters recorded during factory calibration in the local storage module; Based on the distance between the current spot center and the center of the CCD photosensitive surface collected by the CCD sensor, determine the direction and approximate range of spot shift that may be caused by lens distortion at this position; By combining the aforementioned distortion characteristic parameters with the spot position, the offset component caused by lens distortion in the current spot center coordinates is calculated; Remove the offset component from the actual coordinates of the current spot center to obtain the true coordinate deviation caused only by the optical axis offset; The optical axis offset angle is calculated based on the actual coordinate deviation.

[0011] Optionally, after adjusting the optical axis pitch angle and horizontal tilt angle, an indirect roll angle correction step is also included: The device is activated by a light intensity distribution detection function. A complete light intensity distribution image of the adjusted laser spot is acquired by a CCD sensor, and the shape of the spot is analyzed to determine whether it presents an elliptical shape. Compare the lengths of the major and minor axes of the elliptical light spot and calculate the ratio of their lengths. If the ratio exceeds the normal range specified by the factory, it is determined that there is a roll angle deviation. Based on the degree of deviation between the length ratio and the normal range, and in conjunction with the locally stored factory-calibrated roll angle correction coefficient, determine the roll angle correction angle that needs to be adjusted. Send a roll angle adjustment command to the lockable dynamic adjustment mechanism to drive the adjustment mechanism to rotate around the optical axis to the corrected angle, and then tighten the corresponding locking screw; The light intensity distribution image of the spot is acquired again to verify whether the elliptical shape has disappeared. If the ratio of the length of the major axis to the minor axis returns to the normal range, the roll angle correction is completed. If the roll angle deviation is not corrected, repeat the roll angle deviation determination, correction angle determination and adjustment steps until the result is satisfactory.

[0012] Optionally, after replacing the CCD miniature positioning sensor or the lockable dynamic adjustment mechanism, a parameter adaptation step is also included before starting the optical axis self-test: The replaced modular component is connected to the device's signal processing module via a standardized interface, and the component sends its own basic parameters to the signal processing module. Retrieve the standard parameters from the factory calibration stored locally. These standard parameters include standard spot coordinates and optical characteristic parameters. Compare the basic parameters of the new component with these standard parameters. Based on the comparison results, the parameters of the new component are fine-tuned to ensure that the testing benchmark of the new component is consistent with the factory standard benchmark, without the need to perform a complete set of factory calibrations again. Initiate a pre-self-test, drive the laser emitter to emit a test laser, collect the spot coordinates through the new component, and verify whether the fine-tuned parameters are suitable. If the deviation between the light spot coordinates acquired during the pre-self-test and the standard coordinates is within the allowable range, proceed to the normal optical axis self-test step; if the deviation exceeds the range, repeat the parameter comparison, fine-tuning, and pre-self-test steps until the deviation is acceptable.

[0013] Optionally, when the modular laser methane monitoring device is fixed to the target installation position via the mounting reference surface, the mounting reference surface is precisely calibrated with the optical axis during the manufacturing process, and its plane normal direction maintains a fixed geometric relationship with the laser emission direction; When fixing, ensure that the mounting reference surface is in contact with the bracket, pole or wall, and fasten it with bolts, clips or adhesives. The laser emission direction can be made consistent with the preset detection direction without recalibration.

[0014] Secondly, a modular laser methane monitoring device is provided, comprising: The mounting module is used to fix the modular laser methane monitoring device to the target installation position through the mounting reference surface, so that the laser emission direction of the device is consistent with the preset detection direction. A laser emitting module is used to emit infrared laser of a specific wavelength, which is received by a laser receiver after passing through the air in the area to be detected. The signal processing module is used to acquire the detection signal output by the laser receiver, process the detection signal, and calculate the methane gas concentration data. The communication module is used to transmit the methane gas concentration data to the monitoring device or host computer, and at the same time perform local data storage and abnormal concentration alarm operations.

[0015] As can be seen from the technical solution described above, the modular laser methane monitoring method and device provided in this application achieves miniaturization and high integration through its modular integrated design, simplifying the installation process; the installation reference surface design with fixed geometric relationships ensures the consistency and repeatability of the detection direction; it also has independent operation capability and is suitable for various detection environments. This solution can significantly reduce on-site installation and maintenance costs and improve the automation and reliability of gas safety monitoring. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a flowchart illustrating a modular laser methane monitoring method in an embodiment of this application.

[0018] Figure 2 This is a schematic diagram of the overall structure in an embodiment of this application. Detailed Implementation

[0019] In the following description, specific details such as particular device structures and techniques are set forth for illustrative purposes and not for limitation, in order to provide a thorough understanding of the embodiments of this application. However, those skilled in the art will understand that this application may also be implemented in other embodiments without such specific details. In other instances, detailed descriptions of well-known devices, apparatuses, circuits, and methods are omitted so as not to obscure the description of this application with unnecessary detail.

[0020] Firstly, a modular laser methane monitoring method, such as... Figure 2 As shown, it includes: 101: Fix the modular laser methane monitoring device to the target installation position using the mounting reference surface, so that the laser emission direction of the device is consistent with the preset detection direction; 102: Emits infrared laser of a specific wavelength, which is received by a laser receiver after passing through the air in the area to be detected; 103: Collect the detection signal output by the laser receiver, process the detection signal and calculate the methane gas concentration data; 104: Transmit the methane gas concentration data to the monitoring device or host computer, and simultaneously perform local data storage and abnormal concentration alarm operations.

[0021] The purpose of this application is to provide a modular laser methane monitoring method that can be quickly installed on multiple platforms. The device employs a modular, integrated structural design, consolidating laser emission and reception, signal processing, power management, and communication modules within the same sealed housing, achieving miniaturization and independent operation. By setting an installation reference surface with a fixed geometric relationship to the optical axis in the structure, the device can automatically maintain consistent detection direction when installed in different positions, eliminating the need for repeated calibration.

[0022] The device described in this application includes an integrated housing, an optical detection module, a signal processing module, a power management module, and a communication module. The optical detection module comprises a laser emitting unit and a laser receiving unit, both arranged along the same optical axis to form a methane detection optical path. The signal processing module is used to acquire, amplify, and perform algorithmic calculations on the optical signal to obtain methane concentration data. The power management module provides a stable power supply for the entire device, and can be powered by an external power source or an internal battery, depending on the application scenario. The communication module is used for data transmission with a monitoring device or host computer, and can employ RS485, Ethernet, or wireless communication methods. The entire device is encapsulated in a sealed housing, with a compact internal structure. Modules are connected via standard interfaces, facilitating maintenance and replacement.

[0023] The mounting reference surface of the device is precisely calibrated with the optical axis during manufacturing, and its plane normal maintains a fixed geometric relationship with the laser emission direction. During installation, simply aligning the mounting reference surface with the bracket or base ensures consistent detection direction without the need for readjustment or calibration. This structure guarantees consistent detection direction across different installation positions or after repeated installations, reducing human alignment errors.

[0024] The device is small and lightweight, with overall dimensions of approximately 120 mm × 80 mm × 60 mm and a weight of less than one kilogram, making it easy for a single person to carry and deploy quickly. The casing is made of metal or high-strength composite materials, providing excellent sealing and protection with a protection rating of IP65 or higher, suitable for outdoor use. The internal power management module supports 12–48 V DC input and also has a built-in battery option, allowing for independent operation without an external power source. The communication module can provide wired or wireless data transmission as needed and supports local storage and alarm functions.

[0025] like Figure 1 As shown, the modular laser methane monitoring device of this application includes a housing 1, an optical detection module 2, a signal processing module 3, a power supply management module 4, and a communication module 5. The housing 1 adopts a sealed design with a protection level of IP65 or higher to protect the internal optical and electronic components. The optical detection module is equipped with a laser emitting unit and a laser receiving unit 6, both arranged along the same optical axis to form an optical path for methane gas detection. The signal processing module 3 is connected to the optical detection module and is used to acquire and process the received signals, calculating the methane gas concentration value through an algorithm. The power supply management module 4 provides power support for the device, allowing selection of external power supply or built-in battery power depending on the usage scenario, and has voltage stabilization and charging management functions. The communication module 5 is used to output detection data and supports wired or wireless communication methods.

[0026] The device has a mounting reference surface 7 at its bottom. This reference surface is precisely calibrated with the optical axis L during manufacturing, and its plane normal direction maintains a fixed geometric relationship with the laser emission direction. When the device is fixed to a bracket, pole, or wall via the mounting reference surface, the detection direction automatically remains consistent with the factory-calibrated direction, eliminating the need for recalibration. This structure greatly simplifies the on-site installation process and ensures consistency of the detection direction and data reliability after multiple installations.

[0027] The overall dimensions of this device are 120 mm × 80 mm × 60 mm, and its weight does not exceed 1 kg. The power supply voltage range is 12 to 48 volts DC, and the communication interface can be RS485, Ethernet, or a wireless communication module. During operation, the device continuously outputs methane concentration values, and in the event of a communication interruption, it can locally store data and trigger an audible and visual alarm. Due to its integrated packaging design, the device has good shock resistance and is suitable for long-term operation outdoors and in complex environments.

[0028] In summary, the modular laser methane monitoring device of this application achieves a high degree of integration of optical, electronic, power supply and communication modules in terms of structure. It has independent operation and direction self-alignment characteristics, is easy to install, small in size and highly reliable, and is suitable for various scenarios of gas leak monitoring.

[0029] When the device of this application is in operation, the laser emitting unit emits infrared laser light of a specific wavelength, which is absorbed by methane gas in the air and received by the receiving unit. The signal processing module analyzes the detection signal and outputs concentration data. Because the optical device and the housing are a fixed integral structure, the optical axis is stable and not easily shifted, resulting in superior detection accuracy and long-term stability compared to traditional split-type devices. The independent power supply and communication design allows the device to operate independently in fixed installation, temporary detection, or unattended scenarios.

[0030] It should be noted that the installation reference plane is a rigid plane pre-set on the device housing. During the device manufacturing process, its position is calibrated with the optical axis of the laser emission. This reference plane can ensure that the laser emission direction can be unified through the same reference when the device is fixed in different installation positions. The target installation location is a key area in the gas monitoring demand scenario, such as along the gas pipeline or near residential gas facilities. Selecting this location can ensure that the laser can cover the area where methane leakage may be detected.

[0031] For example, the preset detection direction is the laser emission direction determined in advance according to the needs of the specific monitoring scenario. For instance, when monitoring for leaks at pipe interfaces, the preset detection direction will be aimed at the interface area. The determination of this direction needs to take into account factors such as the spatial location of the area to be detected and the possible path of methane leakage. This can ensure that the laser can effectively penetrate the air area where methane may be leaking, thereby improving the targeting and accuracy of the detection.

[0032] In this embodiment, the principle of emitting infrared laser of a specific wavelength is based on the selective absorption characteristics of methane gas to infrared light of a specific wavelength. That is, methane molecules will absorb the light energy of a specific infrared wavelength. By detecting the change in the absorbed light signal, the methane concentration can be inferred. Therefore, the selection of this specific wavelength is determined based on the molecular absorption spectrum characteristics of methane gas. Not all infrared laser wavelengths can be used to detect methane. The laser receiver is a component used to capture the infrared laser light after it passes through the air in the area to be detected. It can convert the received light signal into an electrical signal that can be processed later. The design of this component needs to match the wavelength of the emitted infrared laser to ensure efficient reception of the light signal of the target wavelength.

[0033] It should be noted that the detection signal output by the laser receiver is an electrical signal obtained after the laser receiver converts the optical signal. The acquisition process of this signal must be synchronized with the timing of the laser emission to ensure that the acquired signal can accurately correspond to the result after a single laser emission passes through the area to be detected. The acquired detection signal not only includes the signal changes caused by methane absorption, but may also contain irrelevant signals such as environmental electromagnetic interference and receiver noise. Therefore, after processing the detection signal to calculate the methane gas concentration data, irrelevant interference can be removed by signal processing methods, the effective signal components related to methane absorption can be extracted, and the concentration data can be calculated based on the correlation between light absorption and concentration.

[0034] The process of transmitting methane gas concentration data to a monitoring device or host computer can be done via wired or wireless transmission methods, enabling remote monitoring and centralized management of the detection data. This allows staff to monitor the methane concentration at each monitoring point in real time from the monitoring center. This application is not limited to this.

[0035] This method, on the one hand, uses a modular design that allows the device to quickly adapt to different installation scenarios, reducing the difficulty of on-site installation; on the other hand, it ensures the specificity and accuracy of methane concentration detection through infrared light absorption detection, and, together with data storage and alarm functions, improves the reliability and timeliness of gas safety monitoring, effectively preventing safety accidents caused by methane leaks.

[0036] Optionally, the processing of the detection signal and the calculation of concentration include: Send drive commands to the laser emitter to control it to generate infrared laser with a wavelength of 3.3-3.5 micrometers; It receives infrared laser light after it has been absorbed by the gas, converts the optical signal into an electrical signal, and forms an initial detection signal. The initial detection signal is acquired through an analog-to-digital converter interface, low-pass filtered, and then amplified to make the signal amplitude reach the range suitable for algorithm operation. The amplified signal is then substituted into the methane concentration calculation model and combined with the laser wavelength and optical path length parameters to calculate the real-time methane gas concentration value. The calculated concentration value is judged for its reasonableness, and abnormal data that exceeds the normal concentration range is removed, while valid concentration data is retained.

[0037] It should be noted that the infrared laser absorbed by the gas is received and converted into an electrical signal to form the initial detection signal. It should also be noted that the initial detection signal not only contains information on the change in light intensity after the methane absorbs the light energy, but also includes irrelevant signals such as ambient light interference and the receiver's own circuit noise.

[0038] For example, the initial detection signal is acquired through an analog-to-digital converter (ADC). The ADC is a component that converts analog electrical signals into digital electrical signals. It can convert the continuous analog electrical signal output by the laser receiver, i.e., the initial detection signal, into a discrete digital signal for subsequent digital signal processing.

[0039] In this embodiment, the initial detection signal is low-pass filtered to suppress signal components with frequencies higher than that frequency. Low-pass filtering can effectively eliminate high-frequency interference and improve the signal-to-noise ratio. This application is not limited to this; the specific filtering method can be selected according to the actual interference situation, such as using digital filtering algorithms or hardware filtering circuits.

[0040] In an optional embodiment, the methane concentration calculation includes: The initial light intensity and the actual received light intensity of the laser receiver are obtained, and the absorbance is obtained through the logarithmic relationship between the initial light intensity and the actual received light intensity. The methane gas concentration is obtained by dividing the absorbance by the product of the methane gas absorption coefficient at the corresponding laser wavelength and the laser propagation optical path length.

[0041] In this embodiment, the initial light intensity and the actual received light intensity of the laser receiver are obtained. The initial light intensity is the light intensity output by the laser transmitter in the absence of methane gas absorption. It is obtained by detecting the light intensity received by the laser receiver in a standard air environment without methane during the device's factory calibration, or by calculating it by combining the output power parameter of the laser transmitter with the transmission efficiency of the device's optical device. This parameter can be used as a benchmark for subsequently judging the degree of methane absorption and is a key basic data for calculating the absorption degree.

[0042] It should be noted that the actual received light intensity is the light intensity actually captured by the laser receiver after the laser passes through the air in the area to be tested. Its acquisition process is synchronized with the detection sequence of the initial light intensity to ensure that both are acquired under the same laser emission parameters, so as to reduce the error caused by laser output fluctuations. The magnitude of the actual received light intensity will change with the methane concentration in the area to be tested. That is, the higher the methane concentration, the stronger the absorption of the laser, and the smaller the actual received light intensity. Therefore, this parameter can directly reflect the absorption of methane.

[0043] For example, the absorbance is obtained by the logarithmic relationship between the initial light intensity and the actual received light intensity, which will not be elaborated in this application.

[0044] In this embodiment, the methane gas concentration is obtained by dividing the absorbance by the product of the absorption coefficient of methane gas at the corresponding laser wavelength and the optical path length of the laser propagation. The absorption coefficient is an inherent physical parameter of methane gas at a specific infrared wavelength, and its value reflects the absorption capacity of methane at that wavelength. This parameter can be data on the absorption characteristics of methane molecules obtained by laboratory measurement.

[0045] It should be noted that the optical path length of laser propagation is the actual distance that the laser travels from the emitting unit through the air in the area to be detected to the receiving unit. The determination of this parameter needs to be combined with the installation method of the device and the detection scenario. For example, when the device is installed on the side of a pipe to monitor the pipe interface, the optical path length is the distance between the emitting unit and the receiving unit along the laser direction. If the laser needs to pass through the air area above the pipe, the actual optical path length needs to be calculated based on the installation height and detection angle. The role of the optical path length is to reflect the interaction distance between the laser and the methane gas. The longer the interaction distance, the more obvious the absorption of the laser by the same concentration of methane. Therefore, the influence of this factor needs to be reflected in the concentration calculation.

[0046] This application is not limited to this. In the actual calculation process, the initial light intensity and the actual received light intensity can also be corrected according to the characteristics of the optical device, such as the transmittance and reflectance of the lens, so as to further reduce the impact of the optical device’s own loss on the calculation results.

[0047] Further optional abnormal concentration alarm operations include: If the effective concentration data is greater than the preset alarm threshold, the local audible and visual alarm module will be activated to issue a continuous audible and visual alarm signal. An alarm data frame is generated, which includes alarm type, concentration value, detection location and time information, and is transmitted to the monitoring device or host computer through the communication module.

[0048] In this embodiment, if the effective concentration data is greater than the preset alarm threshold, the local audible and visual alarm module is activated. The preset alarm threshold is a critical value of methane concentration determined according to gas safety standards and actual monitoring needs. This threshold needs to refer to the classification standards for methane leakage risk in relevant safety regulations. For example, a warning threshold is set before the methane concentration reaches the lower limit value that may cause explosion or poisoning risk, to ensure that staff have enough time to take action. The threshold setting can be adjusted according to different monitoring scenarios. For example, the threshold can be set lower in a confined space and appropriately relaxed in an open outdoor space. This application is not limited to this.

[0049] It should be noted that the local audible and visual alarm module is a functional component used to generate sound and light alarm signals locally on the device. It can ensure that even when no one is on site or remote monitoring is interrupted, nearby personnel can still be alerted to the risk of methane leakage through intuitive audible and visual signals.

[0050] It also includes decoupling correction for the effects of temperature-induced shell deformation in calculating the optical axis offset angle, which includes: Collect the current operating ambient temperature of the device and retrieve the reference temperature from the factory calibration in the local storage module; Calculate the difference between the current temperature and the reference temperature, and combine the known thermal expansion characteristics of the material used for the shell to determine the deformation of the shell along the optical axis and perpendicular to the optical axis under this temperature difference. The deformation is converted into a coordinate offset in the coordinate system of the receiving unit's CCD sensor. Subtract the coordinate offset from the actual coordinates of the current spot center acquired by the CCD sensor to obtain the coordinate deviation caused only by the offset of the optical axis itself; The optical axis offset angle is calculated by comparing the corrected coordinate deviation with the factory standard coordinates.

[0051] It should be noted that the current operating environment temperature of the device is collected through an integrated temperature sensing element. This element can sense the temperature changes of the environment in which the device is located in real time and convert the temperature information into an electrical signal, which is then transmitted to the signal processing unit. The collected temperature data must be synchronized with the device's operating sequence to ensure that it can accurately correspond to the shell deformation state within a certain detection cycle. The reference temperature from the factory calibration is retrieved from the local storage module. The reference temperature is the ambient temperature at which the optical axis and mounting reference surface of the device are calibrated before leaving the factory. This temperature data is stored in the local storage module after calibration and can be used as a reference for judging the difference between the current temperature and the calibrated temperature.

[0052] For example, the difference between the current temperature and the reference temperature is calculated, and the deformation of the shell along the optical axis and perpendicular to the optical axis is determined under the temperature difference, based on the known thermal expansion characteristics of the material used for the shell. Thermal expansion characteristics are parameters that describe the dimensional changes of a material when the temperature changes, and are expressed as the coefficient of thermal expansion. This parameter is determined by the material of the shell and is a known material property parameter that has been determined and stored during the device design stage.

[0053] Specifically, according to the thermal expansion formula, the deformation of a material is related to the temperature difference, the original size, and the coefficient of thermal expansion. Therefore, by using the difference between the current temperature and the reference temperature, combined with the original size and coefficient of thermal expansion of the shell along the optical axis and perpendicular to the optical axis, the expansion or bending deformation of the shell in the corresponding direction under the temperature difference can be calculated; this application is not limited to this.

[0054] In this embodiment, the deformation is converted into a coordinate offset in the CCD sensor coordinate system of the receiving unit. The CCD sensor coordinate system is a two-dimensional coordinate system established to describe the position of the light spot on the photosensitive surface of the CCD sensor. Its origin is set as the geometric center of the photosensitive surface, and the coordinate axes are consistent with the mechanical reference direction of the device.

[0055] Specifically, the deformation of the housing will cause the receiving unit or the laser emitting unit to shift in position, which in turn will cause the position of the light spot formed by the laser on the CCD sensor to change. By analyzing the correspondence between the housing deformation direction and the CCD sensor coordinate system, the deformation in different directions can be converted into the offset of the light spot in the X-axis and Y-axis directions in the coordinate system.

[0056] Optionally, it also includes decoupling correction for the effects of optical lens distortion to calculate the optical axis offset angle, the decoupling correction including: Retrieve the optical lens distortion characteristic parameters recorded during factory calibration in the local storage module; Based on the distance between the current spot center and the center of the CCD photosensitive surface collected by the CCD sensor, determine the direction and approximate range of spot shift that may be caused by lens distortion at this position; By combining the aforementioned distortion characteristic parameters with the spot position, the offset component caused by lens distortion in the current spot center coordinates is calculated; Remove the offset component from the actual coordinates of the current spot center to obtain the true coordinate deviation caused only by the optical axis offset; The optical axis offset angle is calculated based on the actual coordinate deviation.

[0057] It should be noted that the optical lens distortion characteristic parameters recorded during factory calibration in the local storage module are retrieved. These distortion characteristic parameters describe the degree and direction of distortion of the optical lens at different spot positions. The acquisition process involves calibrating the lens across the entire field of view using a dedicated optical calibration device before the device leaves the factory. In other words, during the calibration process, the actual offset of the standard spot at different field of view positions of the lens is detected, a correspondence between the spot position and the amount of distortion offset is established, and distortion characteristic parameters are formed and stored in the local storage module.

[0058] In this embodiment of the application, by combining the distortion characteristic parameters and the spot position, the offset component caused by lens distortion in the current spot center coordinates is calculated. The spot position is the specific coordinate (X, Y) of the current spot center in the CCD sensor coordinate system. By combining the previously retrieved distortion characteristic parameters, the X-axis offset component and Y-axis offset component caused by lens distortion at the current spot position can be determined by interpolation calculation or parameter fitting.

[0059] It should be noted that by removing the offset component from the actual coordinates of the current spot center, the true coordinate deviation caused only by the optical axis offset is obtained. The actual coordinates of the current spot center are the result of multiple factors such as optical axis offset, lens distortion, and temperature deformation. After removing some interfering factors through other steps, further removing the offset component caused by lens distortion here can separate the spot coordinate change caused only by the optical axis offset itself, i.e., the true coordinate deviation. This step can decouple lens distortion from optical axis offset, ensuring that the optical axis offset angle calculated subsequently only reflects the positional deviation of the optical axis itself.

[0060] Optionally, after adjusting the optical axis pitch angle and horizontal tilt angle, an indirect roll angle correction step is also included: The device is activated by a light intensity distribution detection function. A complete light intensity distribution image of the adjusted laser spot is acquired by a CCD sensor, and the shape of the spot is analyzed to determine whether it presents an elliptical shape. Compare the lengths of the major and minor axes of the elliptical light spot and calculate the ratio of their lengths. If the ratio exceeds the normal range specified by the factory, it is determined that there is a roll angle deviation. Based on the degree of deviation between the length ratio and the normal range, and in conjunction with the locally stored factory-calibrated roll angle correction coefficient, determine the roll angle correction angle that needs to be adjusted. Send a roll angle adjustment command to the lockable dynamic adjustment mechanism to drive the adjustment mechanism to rotate around the optical axis to the corrected angle, and then tighten the corresponding locking screw; The light intensity distribution image of the spot is acquired again to verify whether the elliptical shape has disappeared. If the ratio of the length of the major axis to the minor axis returns to the normal range, the roll angle correction is completed. If the roll angle deviation is not corrected, repeat the roll angle deviation determination, correction angle determination and adjustment steps until the result is satisfactory.

[0061] In this embodiment, after adjusting the optical axis pitch angle and horizontal deflection angle, a roll angle indirect correction step is also included. The pitch angle is the angle by which the optical axis rotates around the horizontal axis in the vertical plane, and its adjustment is used to control the laser's emission direction in the vertical direction. The horizontal deflection angle is the angle by which the optical axis rotates around the vertical axis in the horizontal plane, and its adjustment is used to control the laser's emission direction in the horizontal direction. The adjustment of these two angles mainly solves the problem of directional deviation of the optical axis in the two-dimensional plane. The roll angle is the angle by which the optical axis rotates around its own axis. This angular deviation does not directly change the emission direction of the optical axis, but it will cause a change in the polarization state of the laser, thereby causing uneven intensity distribution of the laser spot formed on the CCD sensor.

[0062] For example, the analysis of whether the light spot shape is elliptical is achieved through an image recognition algorithm. First, the boundary range of the light spot is determined, and then the major axis and minor axis of the light spot are extracted (specifically, the major axis is the maximum distance between two points on the boundary of the light spot, and the minor axis is the maximum distance in the direction perpendicular to the major axis). If the difference between the lengths of the major axis and the minor axis exceeds a certain range, the light spot is determined to be elliptical. The appearance of this elliptical shape is a direct manifestation of the change in polarization state caused by the roll angle shift, so it can be used as a basis for judging whether the roll angle shift exists. This application is not limited to this; the roundness of the light spot can also be used to determine whether the shape of the light spot is abnormal. Specifically, roundness = 4π × area / perimeter². The roundness of a circular light spot is close to 1, and the roundness of an elliptical light spot is less than 1.

[0063] In this embodiment of the application, the lengths of the major axis and minor axis of the elliptical light spot are compared, and the ratio of their lengths is calculated. If the ratio exceeds the normal range specified by the manufacturer, it is determined that there is a roll angle deviation. The normal range specified by the manufacturer is the range of the ratio of the major axis to the minor axis length obtained by the device under the standard state without roll angle deviation when it leaves the factory.

[0064] Optionally, after replacing the CCD miniature positioning sensor or the lockable dynamic adjustment mechanism, a parameter adaptation step is also included before starting the optical axis self-test: The replaced modular component is connected to the device's signal processing module via a standardized interface, and the component sends its own basic parameters to the signal processing module. Retrieve the standard parameters from the factory calibration stored locally. These standard parameters include standard spot coordinates and optical characteristic parameters. Compare the basic parameters of the new component with these standard parameters. Based on the comparison results, the parameters of the new component are fine-tuned to ensure that the testing benchmark of the new component is consistent with the factory standard benchmark, without the need to perform a complete set of factory calibrations again. Initiate a pre-self-test, drive the laser emitter to emit a test laser, collect the spot coordinates through the new component, and verify whether the fine-tuned parameters are suitable. If the deviation between the light spot coordinates acquired during the pre-self-test and the standard coordinates is within the allowable range, proceed to the normal optical axis self-test step; if the deviation exceeds the range, repeat the parameter comparison, fine-tuning, and pre-self-test steps until the deviation is acceptable.

[0065] Fine-tuning can be achieved by sending control commands to the new component through the signal processing module to adjust the component's operating parameters based on the deviations found in the comparison. For CCD sensors, the signal amplification gain and the offset of the analog-to-digital conversion can be fine-tuned to compensate for insufficient responsiveness or pixel offset. For lockable dynamic adjustment mechanisms, the zero position of the adjustment axis and the output torque of the drive motor can be fine-tuned to correct the adjustment step size deviation or insufficient locking stability.

[0066] It should be noted that the plane normal direction and the laser emission direction maintain a fixed geometric relationship. The plane normal direction is perpendicular to the mounting reference surface, and its direction is uniquely determined by the planar shape of the mounting reference surface. The fixed geometric relationship includes two forms: one is coaxial coincidence, that is, the plane normal direction and the laser emission direction are completely consistent, which is suitable for scenarios where the laser needs to be emitted perpendicular to the mounting carrier, such as when the laser is emitted horizontally when mounted on a wall; the other is a preset fixed angle, that is, the plane normal direction and the laser emission direction form a specific angle, which is suitable for scenarios where the laser needs to be detected at an angle, such as when the laser is installed at a downward angle to detect ground pipes when mounted on a pole.

[0067] In this embodiment, fastening is achieved by bolts, clips, or adhesive. The choice of different fastening methods is based on the characteristics of the installation carrier and the installation requirements. Bolt fastening is suitable for scenarios such as brackets and uprights that need to be fixed for a long time and bear a large load, while clip fastening is suitable for scenarios that require frequent disassembly or temporary installation.

[0068] It should be noted that the laser emission direction can be made consistent with the preset detection direction without recalibration. During factory calibration, the fixed geometric relationship between the mounting reference surface and the optical axis is determined. During installation, the position of the carrier is transferred to the reference surface by the contact and fixation between the reference surface and the carrier, thereby determining the direction of the optical axis. Since the relationship between the reference surface and the optical axis is fixed, there is no need to recalibrate the optical axis direction using equipment such as a laser collimator, which can ensure that the laser emission direction is consistent with the preset detection direction.

[0069] Secondly, a modular laser methane monitoring device is provided, comprising: The mounting module is used to fix the modular laser methane monitoring device to the target installation position through the mounting reference surface, so that the laser emission direction of the device is consistent with the preset detection direction. A laser emitting module is used to emit infrared laser of a specific wavelength, which is received by a laser receiver after passing through the air in the area to be detected. The signal processing module is used to acquire the detection signal output by the laser receiver, process the detection signal, and calculate the methane gas concentration data. The communication module is used to transmit the methane gas concentration data to the monitoring device or host computer, and at the same time perform local data storage and abnormal concentration alarm operations.

[0070] It should be noted that the effect of the modular laser methane monitoring device in this embodiment is the same as that of the modular laser methane monitoring method in the embodiment, and this application will not elaborate on or limit it.

[0071] This application uses specific embodiments to illustrate the principles and implementation methods of this application. The description of the above embodiments is only for the purpose of helping to understand the methods and ideas of this application. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this application. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A modular laser methane monitoring method, characterized in that, include: The modular laser methane monitoring device is fixed to the target installation position using a mounting reference surface, so that the laser emission direction of the device is consistent with the preset detection direction; A specific wavelength of infrared laser is emitted, which passes through the air in the area to be detected and is then received by a laser receiver. The detection signal output by the laser receiver is collected, and the methane gas concentration data is calculated after processing the detection signal. The methane gas concentration data is transmitted to a monitoring device or host computer, and local data storage and abnormal concentration alarm operations are performed simultaneously.

2. The modular laser methane monitoring method according to claim 1, characterized in that, The processing of the detection signal and the calculation of concentration include: Send drive commands to the laser emitter to control it to generate infrared laser with a wavelength of 3.3-3.5 micrometers; It receives infrared laser light after it has been absorbed by the gas, converts the optical signal into an electrical signal, and forms an initial detection signal. The initial detection signal is acquired through an analog-to-digital converter interface, low-pass filtered, and then amplified to make the signal amplitude reach the range suitable for algorithm operation. The amplified signal is then substituted into the methane concentration calculation model and combined with the laser wavelength and optical path length parameters to calculate the real-time methane gas concentration value. The calculated concentration value is judged for its reasonableness, and abnormal data that exceeds the normal concentration range is removed, while valid concentration data is retained.

3. The modular laser methane monitoring method according to claim 2, characterized in that, The calculation of methane concentration includes: The initial light intensity and the actual received light intensity of the laser receiver are obtained, and the absorbance is obtained through the logarithmic relationship between the initial light intensity and the actual received light intensity. The methane gas concentration is obtained by dividing the absorbance by the product of the methane gas absorption coefficient at the corresponding laser wavelength and the laser propagation optical path length.

4. The modular laser methane monitoring method according to claim 1, characterized in that, Abnormal concentration alarm operations include: If the effective concentration data is greater than the preset alarm threshold, the local audible and visual alarm module will be activated to issue a continuous audible and visual alarm signal. An alarm data frame is generated, which includes alarm type, concentration value, detection location and time information, and is transmitted to the monitoring device or host computer through the communication module.

5. The modular laser methane monitoring method according to claim 1, characterized in that, It also includes decoupling correction for the effects of temperature-induced shell deformation in calculating the optical axis offset angle, which includes: Collect the current operating ambient temperature of the device and retrieve the reference temperature from the factory calibration in the local storage module; Calculate the difference between the current temperature and the reference temperature, and combine the known thermal expansion characteristics of the material used for the shell to determine the deformation of the shell along the optical axis and perpendicular to the optical axis under this temperature difference. The deformation is converted into a coordinate offset in the coordinate system of the receiving unit's CCD sensor. Subtract the coordinate offset from the actual coordinates of the current spot center acquired by the CCD sensor to obtain the coordinate deviation caused only by the offset of the optical axis itself; The optical axis offset angle is calculated by comparing the corrected coordinate deviation with the factory standard coordinates.

6. The modular laser methane monitoring method according to claim 1, characterized in that, It also includes decoupling correction for the effects of optical lens distortion to calculate the optical axis offset angle, which includes: Retrieve the optical lens distortion characteristic parameters recorded during factory calibration in the local storage module; Based on the distance between the current spot center and the center of the CCD photosensitive surface collected by the CCD sensor, determine the direction and approximate range of spot shift that may be caused by lens distortion at this position; By combining the aforementioned distortion characteristic parameters with the spot position, the offset component caused by lens distortion in the current spot center coordinates is calculated; Remove the offset component from the actual coordinates of the current spot center to obtain the true coordinate deviation caused only by the optical axis offset; The optical axis offset angle is calculated based on the actual coordinate deviation.

7. The modular laser methane monitoring method according to claim 1, characterized in that, After adjusting the optical axis pitch and horizontal tilt angles, the process also includes an indirect roll angle correction step. The device is activated by a light intensity distribution detection function. A complete light intensity distribution image of the adjusted laser spot is acquired by a CCD sensor, and the shape of the spot is analyzed to determine whether it presents an elliptical shape. Compare the lengths of the major and minor axes of the elliptical light spot and calculate the ratio of their lengths. If the ratio exceeds the normal range specified by the factory, it is determined that there is a roll angle deviation. Based on the degree of deviation between the length ratio and the normal range, and in conjunction with the locally stored factory-calibrated roll angle correction coefficient, determine the roll angle correction angle that needs to be adjusted. Send a roll angle adjustment command to the lockable dynamic adjustment mechanism to drive the adjustment mechanism to rotate around the optical axis to the corrected angle, and then tighten the corresponding locking screw; The light intensity distribution image of the spot is acquired again to verify whether the elliptical shape has disappeared. If the ratio of the length of the major axis to the minor axis returns to the normal range, the roll angle correction is completed. If the roll angle deviation is not corrected, repeat the roll angle deviation determination, correction angle determination and adjustment steps until the result is satisfactory.

8. The modular laser methane monitoring method according to claim 1, characterized in that, After replacing the CCD miniature positioning sensor or the lockable dynamic adjustment mechanism, a parameter adaptation step is also included before starting the optical axis self-test: The replaced modular component is connected to the device's signal processing module via a standardized interface, and the component sends its own basic parameters to the signal processing module. Retrieve the standard parameters from the factory calibration stored locally. These standard parameters include standard spot coordinates and optical characteristic parameters. Compare the basic parameters of the new component with these standard parameters. Based on the comparison results, the parameters of the new component are fine-tuned to ensure that the testing benchmark of the new component is consistent with the factory standard benchmark, without the need to perform a complete set of factory calibrations again. Initiate a pre-self-test, drive the laser emitter to emit a test laser, collect the spot coordinates through the new component, and verify whether the fine-tuned parameters are suitable. If the deviation between the light spot coordinates acquired during the pre-self-test and the standard coordinates is within the allowable range, proceed to the normal optical axis self-test step; if the deviation exceeds the range, repeat the parameter comparison, fine-tuning, and pre-self-test steps until the deviation is acceptable.

9. The modular laser methane monitoring method according to claim 1, characterized in that, When the modular laser methane monitoring device is fixed to the target installation position by means of the mounting reference surface, the mounting reference surface is precisely calibrated with the optical axis during the manufacturing process, and its plane normal direction maintains a fixed geometric relationship with the laser emission direction; When fixing, ensure that the mounting reference surface is in contact with the bracket, pole or wall, and fasten it with bolts, clips or adhesives. The laser emission direction can be made consistent with the preset detection direction without recalibration.

10. A modular laser methane monitoring device, characterized in that, include: The mounting module is used to fix the modular laser methane monitoring device to the target installation position through the mounting reference surface, so that the laser emission direction of the device is consistent with the preset detection direction. A laser emitting module is used to emit infrared laser of a specific wavelength, which is received by a laser receiver after passing through the air in the area to be detected. The signal processing module is used to acquire the detection signal output by the laser receiver, process the detection signal, and calculate the methane gas concentration data. The communication module is used to transmit the methane gas concentration data to the monitoring device or host computer, and at the same time perform local data storage and abnormal concentration alarm operations.

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