Gas sensing monitoring system

Abstract

This gas detection system combines gas sensing and gas imaging functions in a compact, reliable, and cost-effective manner, and can also provide distance information to the target volume being sensed, as well as the presence of elevated smoke or particle levels within the target volume. [Solution] The gas sensing monitoring system implements a tunable diode laser absorption spectroscopy (TDLAS) sensor system equipped with a camera to detect and visualize gas leaks, smoke, and particulate matter. The system is housed in a specially designed housing that protects the TDLAS sensor system from environmental factors and physical damage. The housing includes a power and control system that links the functions of both components. An optical window with mechanical actuators and optical filters is used to reduce optical interference and improve performance. The housing configuration, which can accommodate both the camera and the TDLAS sensor system, allows visualization of the presence of gas leaks or particulate matter and smoke, or the distance to an area of ​​interest in space. The system can accurately measure gas concentrations and improve the sensitivity and specificity of gas leak detection.

Description

Technical Field

[0001] This technology relates to the field of systems for sensing and monitoring gases.

Background Art

[0002] Gas leakage can lead to serious consequences, including explosions, fires, and health hazards. Therefore, the detection and visualization of gas leakage are essential for public safety. Conventional gas sensors can detect the presence of gases, but they do not provide visual information regarding the location and severity of the leak. Therefore, there is a need for a gas detection system that combines a gas sensing function and a gas imaging function.

[0003] In the past, various gas sensing systems have been developed, including Fourier transform infrared (FTIR) spectroscopy, differential optical absorption spectroscopy (DOAS), electrochemical detection, and laser-induced fluorescence (LIF). However, these conventional gas sensing systems have several limitations, such as low sensitivity, direction dependence, and susceptibility to interference from other gases and environmental factors.

[0004] In recent years, tunable diode laser absorption spectroscopy (wavelength tunable diode laser absorption spectroscopy: TDLAS) has emerged as a promising technology for gas sensing. TDLAS uses a narrowband laser beam tuned to match the absorption line of the target gas. When the laser beam passes through the gas, a very small amount of light is absorbed by the gas particles or gas molecules, and the remaining light is detected by a photodetector. TDLAS has several advantages over conventional gas sensors, such as high sensitivity, selectivity, speed, accuracy, and an inherent remote sensing or standoff detection function. Furthermore, it is known that distance measurement can be achieved simultaneously with TDLAS, for example, via triangulation, or via careful modulation and demodulation of the narrowband signal, or via a modulation and phase detection scheme.

[0005] Another challenge with gas sensing systems is the need to visualize gas leaks. Conventional methods for gas visualization include infrared cameras. However, these methods are not effective in certain environments such as outdoors or industrial areas, and require a strong IR light source, whether artificial or natural. The environments in which the disclosed systems are used typically involve flammable gases, or the risk of explosion or fire. In these scenarios, TDLAS devices can also remotely provide information on the emission of smoke or particulate matter to the user to provide an early warning system, whereas conventional remote sensors rely on the presence of light, whether artificial or natural, to detect the presence of smoke, for example, in darkness. [Prior art documents] [Patent Documents]

[0006] [Overview of the project] [Problems that the invention aims to solve]

[0007] Existing gas sensing systems have several limitations, including low sensitivity, directional dependence, susceptibility to interference from other gases, crosstalk, sensor poisoning, and environmental factors. Furthermore, conventional gas visualization methods, such as infrared cameras, are not effective in certain environments, such as outdoors or industrial areas. In addition, conventional gas sensing systems do not provide high-quality visual information regarding the location and severity of leaks. Therefore, there is a need for a gas detection system that combines gas sensing and gas imaging capabilities in a compact, reliable, and cost-effective manner, and that can also provide distance information to the target volume being sensed, as well as the presence of elevated smoke or particle levels within the target volume. [Means for solving the problem]

[0008] Abstract In a first aspect of this disclosure, a gas sensing monitoring system is provided, which includes a housing configured to house a camera and a tunable diode laser absorption spectroscopy (TDLAS) sensor system. The housing includes an optical window. [Modes for carrying out the invention]

[0009]

[0010] Optionally, the TDLAS sensor system includes a light source and a photodetector. This configuration allows for simultaneous monitoring of visual and gas data, providing a comprehensive monitoring solution.

[0011] As an option, in some examples, the optical window is made of tempered glass. This configuration improves the system's durability and ensures that the optical window can withstand harsh environmental conditions and potential impacts without compromising its functionality.

[0012] As an option, in some examples, the light source and photodetector of the TDLAS sensor system are separated into different compartments within the housing. This separation prevents potential interference between the light source and detector, thereby improving the accuracy and reliability of the gas sensing data.

[0013] As an option, in some examples, refractive index matching gels are used to mount a light source or photodetector to an optical window. This mounting method enhances the optical coupling between components, improving the efficiency and performance of the system.

[0014] Optionally, in some examples, the system further includes hardware subtraction or normalization circuits to eliminate the effect of direct back reflection of the laser beam from the optical window to the detector. This configuration can significantly reduce noise within the system, resulting in more accurate and reliable gas detection data.

[0015] Optionally, in some examples, the optical window may include an ultrasonic transducer actuator, piezoelectric actuator, linear actuator, or linear motor used to generate dithering motion that reduces optical interference. This configuration can further improve the quality of gas sensing data by minimizing the effects of optical interference.

[0016] Optionally, in some examples, the optical window includes a band-pass filter to selectively filter out wavelengths of light emitted by the TDLAS sensor system. This configuration enhances the specificity of gas sensing data, enabling the detection and identification of specific gases.

[0017] As an option, in some examples, the band-pass filter is positioned to be used as a separate accessory that can be attached to the camera and is designed to be easily replaceable. This design allows for easy and cost-effective filter replacement, simplifying system maintenance and extending the system's lifespan.

[0018] As an option, in some examples, the band-pass filter is optimized for a specific gas type or gas mixture. This configuration enables targeted detection and identification of specific gases, improving the system's versatility and applicability.

[0019] As an option, in some examples, the system may further include a polarizer or lens. These components can improve the quality of the visual data captured by the camera and enhance the overall monitoring capabilities of the system.

[0020] As an option, in some examples, the system further includes a distance sensing function for the TDLAS sensor system. This configuration can provide valuable information regarding the location and spread of the detected gas, enhancing the system's ability to monitor and respond to gas-related accidents.

[0021] As an option, in some examples, the distance sensing function is configured to determine the distance and / or location of the detected gas. This configuration can provide accurate and detailed information regarding the location of the detected gas(es), facilitating more effective monitoring and response strategies.

[0022] As an option, in some examples, the distance sensing function is achieved via a modulation waveform with respect to a light source. This approach can provide accurate and reliable distance data, enhancing the system's ability to monitor and respond to gas-related accidents.

[0023] As an option, in some examples, the distance sensing function is achieved via triangulation using combined information between TDLAS sensor systems and cameras arranged at different positions(s) and angles(s). This approach can provide extremely accurate and detailed position data, further enhancing the system's monitoring and response functions.

[0024] As an option, in some examples, the TDLAS sensor system and / or camera are configured to detect particulate matter or smoke. This configuration extends the system's monitoring function, enabling it to monitor a wider range of potential hazards.

[0025] As an option, in some examples, the output of the camera and the output of the TDLAS sensor system are combined to detect gas. This configuration enables the correlation of visual data and gas data, providing a more comprehensive understanding of the monitored environment and enhancing the system's ability to detect and respond to gas-related accidents.

[0026] In a first aspect, the present disclosure is a gas sensing monitoring system that combines a camera and a gas sensing detector to detect and visualize gas leaks. The system includes a housing configured to accommodate both the camera and the detector, and the housing includes an optical window for protecting the components from external elements. The TDLAS sensor system can include a light source and a light detector separated into different compartments within the housing. The optical window can include an ultrasonic transducer, a linear actuator, a linear motor, or a piezoelectric actuator, etc., to generate a dithering motion that reduces optical interference and reduces the adhesion of dust, dirt, and moisture to the optical window. The optical window can also include a notch filter, a band-pass filter, an interference filter, a color filter, or a liquid crystal-based filter to selectively filter out the wavelength of the light emitted by the TDLAS sensor system. As an optional configuration, a refractive index matching gel can be used to attach the light source or the light detector to the optical window, a polarizer or a lens can be used to further enhance the performance of the gas leak detection system, and a focus mechanism for the directionality of the sensor field of view and the focusing operation can be included. Such a focus mechanism can include one or more lens packages coupled to a mechanical actuator, a MEMS device, a liquid lens, or a spatial light modulator. Further, the TDLAS sensor can include a hardware configuration and a software configuration, which enable remote gas sensing to sense distance and particulate matter or smoke simultaneously or sequentially.

[0027] The present disclosure will be described in more detail below in connection with the accompanying drawings. [Brief explanation of the drawing]

[0028] [Figure 1] This is a schematic diagram of the gas sensing and monitoring system 10, showing a housing 40 configured to accommodate a camera 30 and a tunable diode laser absorption spectroscopy (TDLAS) sensor system 20. [Figure 2] Figures 2a and 2c show detailed diagrams of the TDLAS sensor system 20, respectively, illustrating separate compartments for the light source 60 and the detector 70, along with an optional refractive index matching gel used to mount the light source 60 to the optical window 50, and a hardware subtraction or normalization circuit used to eliminate the effect of direct back reflection of the laser light from the optical window 50 to the detector 70. [Figure 3] This is a detailed view of the optical window 50, showing an actuator used to generate dithering motion and reduce optical interference, a focusing mechanism, and a band-pass filter 100 used to selectively filter out the wavelength of light emitted by the TDLAS sensor system 20. [Figure 4] This diagram shows an example of how the TDLAS sensor system 20, which has distance sensing capabilities, operates. [Figure 5] This shows an example of a dichroic mirror used to separate the synchrotron radiation from the TDLAS system from the incident light entering the camera. [Examples]

[0029] Detailed explanation The present disclosure will be described in detail below in relation to exemplary embodiments. It should be understood that these exemplary embodiments are provided for illustrative purposes only and are not intended to limit the scope of the present disclosure.

[0030] Gas sensing monitoring system According to one embodiment illustrated in Figure 1, the gas sensing monitoring system 10 includes a housing 40 configured to house both a camera 30 and a tunable diode laser absorption spectroscopy (TDLAS) sensor system 20. The housing 40 is designed to have internal dimensions, supports, and enclosure for securing and protecting both components. In addition, the housing 40 includes a power and control system for coordinating and coordinating the functions of both the camera 30 and the TDLAS sensor system 20.

[0031] Figure 2a shows a diagram of one embodiment of the TDLAS sensor system 20, including a light source 60 and a photodetector 70. As illustrated in the embodiment of Figure 2c, the TDLAS sensor system 20 can be housed in a compartment away from the camera 30 to prevent any interference, and the light source 60 is optionally mounted to the optical window 50 using refractive index matching gel to guide the laser beam without any energy loss due to reflection. Alternatively, the light source assembly is optically separated from the detector assembly via a mechanical compartment or mechanical beam-blocking mechanism to prevent back reflection from the light source to the detector. Hardware subtraction or normalization circuits can be used to eliminate the effect of direct back reflection of the laser light from the optical window to the detector, thereby improving the sensitivity and accuracy of the gas leak detection system.

[0032] Figure 3 shows a detailed diagram of one embodiment of the optical window 50, including an actuator for generating dithering motion and reducing optical interference. The band-pass filter 100 is used to selectively filter out wavelengths of light emitted by the TDLAS sensor system 20, reducing any overlap or interference between the two systems. The band-pass filter 100 can be made of a special optical material having high rejection rates over multiple wavelength ranges and a narrow transmission bandwidth centered on the wavelength of interest, designed for a specific gas type or gas mixture and optimized for different target gases and different environments. The band-pass filter 100 can be incorporated into a housing structure, optical dome, optical window, or as a separate accessory attached to a camera. The band-pass filter 100 can also be combined with other optical components such as polarizers and lenses to improve the performance of the gas leak detection system.

[0033] Figure 4 shows an example schematic diagram of how the TDLAS sensor system 20, which has distance sensing capabilities, operates. In this example, the TDLAS sensor system 20 emits a modulated laser beam onto the target area, and the light absorbed by gas molecules is detected by the photodetector 70. Using the same photodetector, the TDLAS sensor system can simultaneously determine the gas concentration and the distance of the detected gas plume. At the same time, the surrounding environment and the gas plume (visible to the camera) are imaged by the camera. The distance information, gas composition information, and video information are then combined and analyzed to provide information about the location, size, and shape of the gas plume.

[0034] TDLAS Sensor System While this disclosure discusses the use of the TDLAS sensor system 20, the gas detection system can be understood to include alternative configurations of the gas detection device, including a device with a light source 60 such as a tunable diode laser, a narrowband or broadband multimode light source, a high-power multimode diode laser, a high-power multimode fiber laser, a high-power taper amplifier based on a tunable single-mode diode laser, a high-power fiber amplifier based on a tunable single-mode diode laser, a high-power tunable CO2 or solid crystal laser, or a non-coherent light source. The photodetector 70 may be of the complementary metal-oxide-semiconductor (CMOS) sensor, charge-coupled device (CCD) sensor, semiconductor photodiode, pn junction detector, avalanche photodiode, photomultiplier tube detector, pyroelectric detector, or polycrystalline sensor type, equipped with a lens arrangement 90. The lens arrangement 90 is configured to focus light onto the sensor. The lens arrangement 90 may be adjustable to adjust the focus and increase the sensitivity of the system. The photodetector 70 may further include an optical filter or polarizer to increase the contrast and signal-to-noise ratio of the captured image and to remove unwanted background light. The sensor is configured to transmit one or more signals to the controller.

[0035] Therefore, the TDLAS sensor system will combine data from camera 30 with gas content information and, optionally, distance information of the examined volume. In one variation, the TDLAS sensor system may be configured to provide only distance information or only gas content information. In other variations, the TDLAS sensor system may simultaneously provide information on the presence of elevated particulate matter levels or smoke levels within the examined volume.

[0036] In this way, the TDLAS sensor system 20 includes a light source 60 and a photodetector 70. Both the light source 60 and the photodetector 70 are mounted within the housing 40. As previously described, the light source 60 and the photodetector 70 can be mounted within the same housing compartment or in separate housing compartments within the housing 40.

[0037] camera In some embodiments, the gas sensing monitoring system 10 includes a camera 30. The camera 30 can be selected from a group of cameras including high-resolution RGB cameras, night vision cameras, outdoor weatherproof cameras, pan-tilt-zoom (PTZ) cameras, wide-angle view cameras, infrared cameras, network-connected cameras, and smart cameras with artificial intelligence (AI) capabilities. The camera 30 can provide additional visual information and context to the gas leak detection system. The specific type of camera 30 selected may depend on the specific implementation and requirements of the gas sensing monitoring system 10.

[0038] Alternative camera configurations may include thermal imaging cameras, hyperspectral cameras, and multispectral cameras. Thermal imaging cameras can detect temperature differences and infrared absorption caused by gas leaks and can be used to create visual images of gas clouds. Hyperspectral cameras can capture detailed spectral information over a wide range of wavelengths, enabling highly accurate identification of gas leaks based on their unique spectral signatures. Multispectral cameras can capture information over multiple wavelengths but have lower spectral resolution than hyperspectral cameras, enabling faster detection and localization of gas leaks in real time.

[0039] housing In some embodiments, the housing 40 of the gas leak detection system may have a length of 10 to 30 cm, a width of 10 to 20 cm, and a height of 10 to 20 cm. The material used is non-conductive and non-reactive and has a thickness of 0.5 to 1 cm. The housing 40 also has at least two openings for maintenance and inspection and, for safety purposes, an optional but recommended locking mechanism. The housing 40 is designed to securely hold and surround the two components and is protected from external elements that may interfere with their function.

[0040] The housing 40 can be designed as a protective barrier against external elements, preventing dust and debris from interfering with the TDLAS sensor system 20, providing shock protection against nearby explosions or blasts resulting from, for example, gas leaks, shielding the TDLAS sensor system 20 from extreme temperatures, humidity, moisture, electromagnetic interference (EMI), and radio frequency interference (RFI), reducing the impact of external vibrations and seismic activity, preventing sunlight from interfering with spectral analysis, minimizing the risk of tampering and sabotage, and improving the lifespan and durability of the TDLAS sensor system 20.

[0041] The power system and control system within the housing 40 can coordinate and synchronize the functions of both the camera 30 and the TDLAS sensor system 20. The power system can be configured to supply sufficient power to both systems, while the control system can manage the flow of data and control signals between them.

[0042] Optical window In some embodiments, the gas sensing monitoring system 10 may include an optical window 50 that is particularly robust to protect against explosions. The optical window 50 may be made of tempered glass or polycarbonate material and may be designed to have a thickness of 1-2 cm. However, using a thick optical window 50 may cause direct back reflection of light emitted by the light source 60 to the detector, which may result in detector saturation or undesirable light guiding.

[0043] In some embodiments, the optical window 50 includes a front lens of the TDLAS instrument. The front lens may be particularly robust to protect against explosions and environmental factors and may be designed to have a thickness of 1-2 cm. Optionally, the optical window 50 may be positioned in front of only one of the photodetector 70 or the light source 60, with the other optical aperture covered by the front lens.

[0044] Separate compartments To overcome this problem, the housing 40 may include separate compartments for the light source 60 and the photodetector 70. This would overcome the problem of direct back reflection. Furthermore, this would prevent interference from other components or external sources. Optionally, the light source could be collimated and housed in a mechanical cylinder with a separate windshield optical window. This would prevent direct feedback to the photodetector 70. While the light source 60 and the photodetector 70 can be mounted in separate compartments of the housing 40, in other examples, the light source 60 and the photodetector 70 can be mounted in the same compartment. For example, the light source 60 and the photodetector 70 can be mounted in the same compartment but separated by the inner wall or internal mechanism (or internal components) of the housing 40.

[0045] Optical Interference Using a thick optical window 50 can sometimes cause optical interference from the optical window 50, which affects the spectral performance of the TDLAS sensor system 20. To reduce the effect of optical interference, dithering can be used to introduce vibrations into the optical window 50.

[0046] Dithering method In some embodiments, dithering can be used to minimize optical interference within the gas detection system. Dithering can be implemented using a circuit and controller. To achieve this, ultrasonic transducers can be provided in the optical window 50 to provide vibrations that prevent condensation or ice buildup that could interfere with gas detection. These transducers can be designed to generate vibrations or dithering motions that reduce the effects of optical interference, resulting in improved spectral performance of the TDLAS sensor system 20. Alternatively, piezoelectric dithering devices can be used, which utilize actuators commonly found as compact, high-capacity, and cost-effective haptic feedback devices. Alternatively, linear actuators or linear motors can be used to provide mechanical motions that minimize optical interference and adhesion on optical elements.

[0047] Bandpass filter In some embodiments, the gas sensing and monitoring system 10 further includes a band-pass filter 100 positioned in front of the camera 30 to enhance the sensitivity and specificity of the gas leak detection system. These band-pass filters 100 are specifically designed to selectively filter out wavelengths of light emitted by the TDLAS sensor system 20, thereby reducing any overlap or interference between the two systems. The band-pass filters 100 can be made of special optical materials having high rejection rates across multiple wavelength ranges, but with a narrow transmission bandwidth centered on the wavelengths of interest of the TDLAS sensor system 20. In addition, these filters can be easily replaced or optimized for specific gas types or gas mixtures, enabling the system to be customized for different target gases and different environments. Easily replaceable means that the band-pass filters 100 can be positioned or mounted on the camera 30 or other optical components of the gas sensing and monitoring system 10 without disassembling or reassembling other components of the gas sensing and monitoring system 10. For example, the band-pass filters 100 can be fastened to existing components. For example, other types of mounting devices, such as screw mounting and bayonet mounting, are also available. In some cases, mounting the band-pass filter 100 is a tool-free operation. The band-pass filter 100 can be integrated into a housing structure, optical dome, or optical window, or it can be used as a separate accessory that can be attached to a camera, and it can be combined with other optical components or image processing techniques to further enhance the performance of the gas leak detection system.

[0048] In some examples, the gas sensing monitoring system 10 optionally includes a multiband bandpass filter. A multiband bandpass filter is a type of filter that allows only specific frequency bands to pass through, while attenuating frequencies outside those bands. The multiband bandpass filter is designed to divide the signal into multiple frequency bands, allowing each band to be processed independently.

[0049] In some cases, a multiband bandpass filter includes multiple individual filters, each tuned to pass a specific frequency band. Each bandpass filter allows only the desired frequency range to pass through, blocking other frequencies. A multiband bandpass filter may also include a crossover, which is used to split the signal into different frequency bands before it enters the bandpass filter. Crossovers are designed to split a signal into two or more frequency ranges based on their frequency response characteristics. A multiband bandpass filter may also include an add-on amplifier used to combine the outputs of different bandpass filters. The add-on amplifier receives the filtered signals from each bandpass filter and recombines them to produce the final multiband output.

[0050] In addition to separating compartments, the optical window 50 may include a thin layer of optically black or optically dense material between the glass layers of the sandwich-like optical window 50. This reduces optical interference and improves performance. Furthermore, a cylinder of bonded black glass or black substrate can surround the central part (where the light from the light source is emitted) relative to the coaxial orientation of the light source 60 and the detector, and this cylinder can directly prevent back reflection.

[0051] The gas sensing monitoring system 10 may further include a focusing mechanism for controlling the direction and focusing of the sensor field of view. The focusing mechanism may include one or more lens packages coupled to a mechanical actuator, a MEMS (micro electro-mechanical systems) device, a liquid lens, or a spatial light modulator. The focusing mechanism can be used to adjust the direction and focus of the gas leak detection system, enabling targeted detection and localization of gas leaks within a specific area. The focusing mechanism may also be controlled by a circuit and controller, for example, by a controller that transmits control signals to the actuator of the focusing mechanism, thereby adjusting the focus of the gas sensing monitoring system 10.

[0052] Mechanical actuators may include linear or rotary motors, or piezoelectric actuators, that can move the lens package or TDLAS sensor system in a specific direction to adjust the system's focus. MEMS devices, liquid lenses, or spatial light modulators may use electrical signals to manipulate the shape or position of the lens, providing a more precise and rapid method of adjusting the system's focus.

[0053] Refractive index matching gel In the embodiment shown in Figure 2b, the gas sensing and monitoring system 10 may include a configuration in which a light source 60 or a photodetector 70 is attached to the optical window 50 using a refractive index matching gel. These gels have a refractive index similar to that of the contacting material, allowing the laser beam to be guided through the optical window 50 without any energy loss due to reflection. This improves the accuracy and sensitivity of the gas leak detection system by directing more laser energy to the target area.

[0054] Hardware subtraction and normalization circuits Figure 2c shows one embodiment in which a hardware subtraction or normalization circuit is used to eliminate the effect of direct back reflection of laser light from the optical window 50 to the detector, which can saturate the detector and cause erroneous readings. This circuit functions by including a reference detector in the same compartment as the main detector. This reference detector detects the amount of light directly reflected from the optical window 50 and generates a signal proportional to that amount of light. The signal from the reference detector is then subtracted from the signal of the main detector, or the signal from the reference detector is used to normalize the main detector signal, for example, by division which eliminates the effect of the direct back reflection component from the gas absorption spectrum and overcomes the effect of saturation in the analog and digital electronics prior to the signal processing step.

[0055] In some examples, the circuit includes a controller (not shown) with a processor and associated memory, configured to control one or more functions of the TDLAS sensor system 20. For example, the controller is configured to activate the light source 60 and the photodetector 70 during gas detection. The controller is also configured to receive one or more signals from the photodetector 70 and to process the received sensor signals to determine the presence of gas using process, algorithm, and method steps, such as those discussed herein. The controller is also configured to control other components of the TDLAS sensor system 20 as needed.

[0056] TDLAS distance sensing function In some embodiments, the TDLAS sensor system 20 may also have the ability to measure the distance of a detected gas via triangulation, or via modulation and demodulation of a narrowband signal, or via a modulation and phase detection scheme. This distance sensing function can be achieved by using a modulated waveform for the light source 60. The modulated light can be detected by a detector arrangement and demodulated in hardware or software to acquire (detect) distance information of the detected light simultaneously with the gas composition. Modulation can be added as a component of the propagated light, enabling simultaneous detection of the gas signal in direct absorption mode, wavelength-modulated spectral mode, or frequency-modulated spectral mode. Optionally, distance sensing and gas sensing can be performed sequentially. Optionally, the modulation can be a simple on / off or square wave-like signal, and demodulation includes identifying the flank delay (rise / fall flank delay) between the modulated radiated light and the modulated received light. The controller is configured to perform various distance sensing functions as considered herein.

[0057] Alternatively, distance sensing can be achieved via triangulation, which involves using combined data from a camera or a separate 1D or 2D optical sensor and the TDLAS instrument. By knowing the angle of the light source, the separation distance between the TDLAS light source and the optical axis of the second sensor, and optionally the depth of field of the second sensor, it is possible to calculate the distance to the object by creating a distance-to-pixel-number map.

[0058] This distance sensing function enables the TDLAS sensor system 20 to not only detect gas leaks but also to determine and quantify the location of gas leaks, as well as provide the size and shape of the gas plume in three dimensions.

[0059] Furthermore, the TDLAS sensor system 20 can distinguish between multiple gas leaks that may occur simultaneously in different locations. This is achieved by using a combination of distance sensing and spectral analysis, which enables a system that can identify and distinguish between different gas leaks based on their chemical composition and location.

[0060] Smoke detection In one embodiment, the TDLAS system of this disclosure is configured to simultaneously detect and provide information regarding the presence of elevated particulate matter levels or smoke within a volume(s) being examined, along with information on the gas and distance. This can be achieved by a controller that analyzes the scattering and absorption characteristics of the emitted and received laser light. The presence of particulate matter or smoke within the volume(s) being examined causes a change in the intensity and spectral characteristics of the received light, and this change can be used to identify the presence of smoke or elevated particulate matter levels. Similarly, the camera 30 can resolve and detect smoke depending on the lighting environment and camera type.

[0061] The ability to detect smoke or elevated particulate matter levels can provide an early warning system for potential fire hazards, enabling timely intervention and preventing further damage and risk. In addition, this information can be combined with gas leak detection data to provide a comprehensive environmental assessment, which helps identify potential hazards and ensure public safety.

[0062] Dichroic mirror In one embodiment illustrated in Figure 5, a dichroic mirror is used to separate the light emitted from the TLDAS system from the light incident on the camera. A dichroic mirror is an optical filter that reflects light of a specific wavelength and transmits light of other wavelengths, and can be used to separate the spectral bands of interest of both systems. The dichroic mirror can be positioned at a specific angle with respect to the camera to overlap the optical axis of the TDLAS system with the optical axis of the camera, and can be configured to ensure optimal transmission for light directed to the camera at the required wavelengths, while simultaneously reflecting light from the TLDAS light source toward the gas to be detected. Exemplary wavelengths for transmission to the camera may include visible or infrared light, but the wavelengths for reflection may be specific to the gas being detected, for example, approximately 1650 nm for methane detection and approximately 760 nm for oxygen detection. This enables simultaneous detection of both gas content and visual information, reducing interference or overlap between the two systems and eliminating parallax because the TDLAS light source is narrowband and does not cause distortion within the spectral region (one or more) being imaged for the camera.

[0063] In some examples, the TDLAS sensor system 20 is configured to sense multiple gases. Thus, the TDLAS sensor system 20 can use a single light source 60 and a single photodetector 70 to detect different gases. In some examples, the light source 60 and photodetector 70 can be adjusted to a predetermined response frequency depending on the specific gas to be detected. The controller is configured to adjust the configuration of the light source 60 and / or photodetector 70 depending on the predetermined gas to be detected.

[0064] In some examples, the TDLAS sensor system 20 includes a temperature sensor for detecting the ambient temperature of the TDLAS sensor system 20. The temperature sensor is configured to transmit a sensor signal to the controller. Depending on the received temperature, the controller can determine the operating parameters of the TDLAS sensor system 20. In some examples, the controller can transmit one or more control signals to adjust the operation of the TDLAS sensor system 20 as needed. For example, if the controller determines that the TDLAS sensor system 20 is operating outside the recommended temperature range, the controller can transmit a control signal to deactivate the TDLAS sensor system 20 until it is cooled down. In addition to or instead of this, the controller can transmit a control signal to a cooling mechanism for actively cooling the TDLAS sensor system 20. For example, the cooling mechanism may include a motor fan assembly that generates airflow through the TDLAS sensor system 20. The cooling mechanism can be any arrangement suitable for cooling the TDLAS sensor system 20. In some examples, the cooling mechanism can be a water cooling system. In some cases, the cooling mechanism, such as a fan, is always on, but the controller can send control signals to determine the speed at which the fan rotates. In this way, the controller can adjust the airflow and cooling rate (or cooling speed) of the TDLAS sensor system 20.

[0065] Furthermore, in some examples, the controller is configured to determine the ambient temperature based on the gas signature profile. In other words, the controller can evaluate the ambient temperature near the gas based on the analysis data received from the photodetector 70. This improves the accuracy and precision of the analysis results.

[0066] In some cases, the controller can be configured to correlate gas signatures with known temperature patterns. For example, the controller may be configured to analyze historical data of gas signatures (characteristic data) and their corresponding external temperatures. In this way, the controller establishes a correlation between the two variables and stores that correlation in memory. The controller also uses this correlation to predict the external temperature based on the current gas signature profile.

[0067] In addition, or alternatively, the controller is configured to use mathematical models to predict the external temperature. These models may be based on the principles of thermodynamics, heat transfer, and gas behavior to assess the temperature.

[0068] In addition, or alternatively, the controller is configured to use a machine learning algorithm. The controller is configured to train the algorithm to predict temperature based on the gas profile. The algorithm learns patterns and relationships between two variables to provide an accurate temperature assessment.

[0069] In addition, or alternatively, the controller is configured to use a calibration process with one or more external temperature sensors. The controller performs calibration using external temperature sensors to establish a direct relationship between the gas signature and temperature. This calibration will enable real-time monitoring and adjustment of temperature assessments based on the gas profile.

[0070] In some examples, the controller is configured to perform an automatic gain control (AGC) function using the photodetector 70. The controller is configured to adjust the signal gain to ensure optimal signal quality. In some examples, the controller automatically adjusts the system gain in real time to maintain a constant output level regardless of changes in input signal intensity.

[0071] The controller may optionally include an analog-to-digital converter (ADC). The ADC is configured to convert the analog signal received from the detector into a digital format that the system can process. The controller may further include a gain control amplifier configured to adjust the system's gain based on the input signal strength. The gain control amplifier receives feedback from the system to determine the appropriate gain level required to maintain a constant output level.

[0072] The controller is configured to apply signal processing to the digital signal received from the ADC, and applies the gain adjustment determined by the gain control amplifier.

[0073] When the controller performs an automatic gain control function in conjunction with the photodetector 70, the controller continuously monitors the input signal intensity and dynamically adjusts the system gain to maximize signal quality. This enables a system that maintains a stable output level even in the presence of noise or signal fluctuations.

[0074] During a single sweep or ramp of the detector, the controller performing the AGC function can rapidly adjust the gain to optimize signal quality without requiring manual intervention. This real-time adjustment ensures that the detector operates efficiently under various signal conditions, providing accurate and reliable measurements.

[0075] example Example 1: A gas sensing and monitoring system comprising a housing configured to accommodate a camera and a tunable diode laser absorption spectroscopy (TDLAS) sensor system, wherein the housing includes an optical window, and the TDLAS sensor system includes a light source and a photodetector. Example 2: The gas sensing and monitoring system described in Example 1, wherein the optical window is made of tempered glass. Example 3: A gas sensing and monitoring system according to Example 1 or 2, wherein the TDLAS sensor system includes a light source and a photodetector separated into different compartments within the housing. Example 4: A gas sensing and monitoring system according to any of Examples 1 to 3, wherein a refractive index matching gel is used to attach the light source or the photodetector to the optical window. Example 5: A gas sensing and monitoring system according to any of Examples 1 to 4, further comprising a hardware subtraction or normalization circuit for eliminating the effect of direct back reflection of laser light from the optical window to the detector. Example 6: A gas sensing and monitoring system according to any of Examples 1 to 5, wherein the optical window includes an ultrasonic transducer actuator, a piezoelectric mechanical actuator, a linear actuator, or a linear motor used to generate dithering motion that reduces optical interference. Example 7: A gas sensing and monitoring system according to any of Examples 1 to 6, wherein the optical window includes a band-pass filter for selectively filtering out the wavelength of light emitted by the TDLAS sensor system. Example 8: A gas sensing and monitoring system as described in Example 7, wherein the band-pass filter is provided to be used as a separate accessory that can be attached to the camera and is designed to be easily replaceable. Example 9: A gas sensing and monitoring system as described in Example 7 or 8, wherein the band-pass filter is optimized for a specific gas type or gas mixture. Example 10: A gas sensing and monitoring system as described in Example 7, 8, or 9, further comprising a polarizer or lens. Example 11: A gas sensing and monitoring system according to any of Examples 1 to 10, further comprising a distance sensing function for the TDLAS sensor system. Example 12: A gas sensing and monitoring system as described in Example 11, wherein the distance sensing function is configured to determine the distance and / or location of the detected gas. Example 13: A gas sensing and monitoring system according to Example 11 or 12, wherein the distance sensing function is achieved via a modulated waveform with respect to the light source. Example 14: A gas sensing monitoring system according to Example 11 or 12, wherein the distance sensing function is achieved via triangulation using combined information between the TDLAS sensor system and the camera, which are positioned at different locations and angles. Example 15: A gas sensing and monitoring system according to any of Examples 1 to 14, further comprising the TDLAS sensor system and / or the camera configured to detect particulate matter or smoke. Example 16: A gas sensing and monitoring system according to any of Examples 1 to 15, wherein the output of the camera and the output of the TDLAS sensor system are combined to detect gas. [Explanation of Symbols]

[0076] 10. Gas Sensing Monitoring System 20 TDLAS Sensor System 30 Cameras 40 Housing 50 Optical windows 60 light source 70 Photodetector 90 Lens Arrangement 100 Bandpass Filter

Claims

1. A gas sensing monitoring system (10) comprising a housing (40) configured to house a camera (30) and a tunable diode laser absorption spectroscopy (TDLAS) sensor system (20), wherein the housing (40) includes an optical window (50), and the TDLAS sensor system (20) includes a light source (60) and a photodetector (70).

2. A gas sensing monitoring system (10) according to claim 1, wherein the optical window (50) is made of tempered glass.

3. A gas sensing monitoring system (10) according to any of the above claims, characterized in that the light source (60) and the photodetector (70) are separated into different compartments within the housing (40).

4. A gas sensing monitoring system (10) according to any of the above claims, wherein the TDLAS sensor system (20) includes a light source (60) and a photodetector (70), and a refractive index matching gel is used to attach the light source (60) or the photodetector (70) to the optical window (50).

5. A gas sensing monitoring system (10) according to any of the preceding claims, further comprising a hardware subtraction or normalization circuit for eliminating the effect of direct back reflection of laser light from the optical window (50) to the detector (70).

6. A gas sensing monitoring system (10) according to any of the above claims, wherein the optical window (50) includes an ultrasonic transducer actuator, a piezoelectric mechanical actuator, a linear actuator, or a linear motor used to generate dithering motion that reduces optical interference.

7. A gas sensing monitoring system (10) according to any of the above claims, wherein the optical window (50) includes a band-pass filter (100) for selectively filtering out the wavelength of light emitted by the TDLAS sensor system (20).

8. A gas sensing monitoring system (10) according to claim 7, wherein the band-pass filter (100) is provided to be used as a separate accessory that can be attached to the camera (40) and is easily replaceable.

9. A gas sensing and monitoring system (10) according to claim 7, wherein the band-pass filter (100) is optimized for a specific gas type or gas mixture.

10. A gas sensing monitoring system (10) according to claim 7, further comprising a polarizer or lens.

11. A gas sensing monitoring system (10) according to any of the above claims, further comprising a distance sensing function for the TDLAS sensor system (20).

12. A gas sensing monitoring system (10) according to claim 11, wherein the distance sensing function is configured to determine the distance and / or location of the detected gas.

13. A gas sensing monitoring system (10) according to claim 11 or 12, characterized in that the distance sensing function is achieved via a modulated waveform with respect to the light source (60).

14. A gas sensing monitoring system (10) according to claim 11 or 12, wherein the distance sensing function is achieved via triangulation using combined information between the TDLAS sensor system (20) and the camera (30) arranged at different positions and angles.

15. A gas sensing monitoring system (10) according to any of the preceding claims, further comprising the tunable diode laser absorption spectroscopy (TDLAS) sensor system (20) and / or the camera (30) configured to detect particulate matter or smoke.

16. A gas sensing monitoring system (10) according to any of the above claims, characterized in that the output of the camera (30) and the output of the tunable diode laser absorption spectroscopy (TDLAS) sensor system (20) are combined to detect a gas.

Images