Methane telemetering system

Abstract

The invention relates to the technical field of methane telemetering, and particularly provides a methane telemetering system which comprises a DFB laser, a visible light laser, a dichroic mirror, a reflector, a Cassegrain telescope system, a sensor and a data acquisition card, infrared band light and visible light are combined through the dichroic mirror, the combined light is emitted to measured gas through the reflector, and the measured gas is transmitted to the sensor through the Cassegrain telescope system. The combined light passes through the detected gas and then irradiates on a reflecting surface, part of echo reflected light passes through the detected gas again and then enters the Cassegrain telescope system, and after being converged by the Cassegrain telescope system, the sensor acquires an optical signal and converts the optical signal into an analog electric signal; and the analog electric signal is converted into a digital electric signal through the data acquisition card. Visible light is used for assisting in observing the scanning position of infrared band light, the defect that human eyes cannot directly observe the detection position in the methane laser telemetering process is overcome, the light receiving caliber is increased, and the detection signal quality is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of methane telemetry, and in particular relates to a methane telemetry system based on TDLAS technology. Background Art

[0002] Methane telemetry equipment is mainly used to detect the methane content in the air and is widely used in the natural gas industry, coal mine safety and environmental testing. Current detection methods include catalytic combustion detection, semiconductor detection and spectral detection. Among them, the spectral detection method performs well in terms of accuracy and has been widely used in gas detection. TDLAS (tunable semiconductor laser absorption spectroscopy) technology mainly utilizes the narrow line width and wavelength of tunable semiconductor lasers that change with the injected current. By modulating the wavelength of the laser, the wavelength of the laser scans the absorption peak of the gas molecules being measured. Based on the Beer-Lambert law, gas molecules absorb the modulated laser, thereby measuring the concentration of gas molecules based on the absorption amount.

[0003] For telemetry equipment, signal transmission and reception are its main contents. The technical principle requires that the laser signal, after being emitted by the laser, passes through the measured gas and hits the surface of the object, is then diffusely reflected by the surface of the object, passes through the measured gas again and is focused on the detector to read the signal, thereby completing the signal reception.

[0004] Although some methane remote sensing technologies have appeared, there are still many problems with the existing technology. First of all, the existing technology is limited by the lens aperture and the strength of the received signal. When the distance is far, the received signal is weak and is easily interfered by the external environment. Secondly, if the outgoing light and the incident light cannot be coaxial, the optical path will change at different measurement distances. If the equipment is not adjusted, the signal receiving end may not receive the signal or the signal is weak. Finally, because the light of laser remote sensing of methane is generally in the infrared band, it is invisible to the human eye. Therefore, the alignment process needs to be implemented with the help of a color display card. The alignment process is relatively complicated and troublesome, and the scanning position is not intuitive enough. Summary of the invention

[0005] In view of this, the present invention aims to provide a methane telemetry system based on TDLAS technology, which effectively increases the light receiving aperture, improves the maximum telemetry distance, and uses visible light for alignment assistance, thereby reducing the difficulty of aligning the outgoing light path and the incident light path. The outgoing light path and the incident light path are coaxially designed to avoid changes in the detection light path due to changes in the detection distance.

[0006] To achieve the above object, the technical solution created by the present invention is implemented as follows: The present invention provides a methane telemetry system based on TDLAS technology, comprising: A first laser for providing light in the infrared band; a second laser for providing visible light; An optical path component for combining infrared light and visible light and directing it toward the gas to be measured; A reflective telescope system used to collect echo reflected light that passes through the gas being measured.

[0007] Preferably, the first laser is a DFB laser.

[0008] Preferably, it also includes: a host computer, which is used to control the first laser parameters.

[0009] Preferably, the optical path component is a dichroic mirror; One mirror of the dichroic mirror has a reflective effect on infrared light, and the other mirror of the dichroic mirror has a transmissive effect on visible light. Or one mirror surface of the dichroic mirror has a transmission effect on infrared band light, and the other mirror surface of the dichroic mirror has a reflection effect on visible light.

[0010] Preferably, the infrared band light and visible light after being combined by the dichroic mirror are reflected toward the gas to be measured by a reflector, and after passing through the gas to be measured, they are directed toward a surface arranged on the rear optical path of the gas to be measured. The surface reflects part of the combined light again, passes through the gas to be measured, and is directed toward the reflective telescope system.

[0011] Preferably, the reflective telescope system is a Cassegrain telescope system.

[0012] Preferably, the reflector is coaxially arranged with the reflective telescopic system.

[0013] Preferably, it further comprises: a sensor for detecting the echo reflected light collected by the reflective telescope system and converting the optical signal into an analog electrical signal.

[0014] Preferably, it also includes: a data acquisition card, which is used to convert analog electrical signals into digital electrical signals.

[0015] Preferably, it also includes: a collimating mirror, which is arranged on the optical path between the first laser and the dichroic mirror.

[0016] Compared with the prior art, the invention can achieve the following beneficial effects: The present invention adopts a dual laser system and combines infrared band light and visible light through a dichroic mirror. When measuring the methane concentration, visible light is used to assist in marking the detection position of the infrared band light, ensuring that the human eye can intuitively see the laser scanning position, thereby overcoming the disadvantage that the human eye cannot directly observe the detection position during the laser remote sensing of methane. At the same time, during the alignment and adjustment of the outgoing light path and the incident light path, the alignment situation can be directly observed through visible light, without the need to use a color display card to observe the alignment situation, thereby reducing the complexity of the alignment and adjustment.

[0017] The present invention designs a Cassegrain reflection telescope system to receive echo reflected light, thereby increasing the incident aperture of light and improving the light receiving range, thereby enhancing the intensity of the received signal and improving the signal-to-noise ratio, thereby overcoming the defect of insufficient incident aperture of light in previous transmission optical systems.

[0018] The outgoing light path and the incident light path of the present invention adopt a coaxial design, that is, the reflector of the combined light is arranged in the optical axis direction of the Cassegrain reflective telescope system, to ensure that the optical axes of the outgoing combined light and the echo reflected light coincide, thereby avoiding the problem of no signal reception or weak signal due to the coaxiality of the outgoing light path and the incident light path at different distances. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The drawings constituting part of the present invention are used to provide a further understanding of the present invention. The exemplary embodiments and descriptions of the present invention are used to explain the present invention and do not constitute an improper limitation on the present invention. In the drawings: Figure 1 It is a structural diagram of a methane telemetry system based on TDLAS technology provided according to an embodiment of the present invention.

[0020] Reference numerals include: Host computer 1, DFB laser 2, visible light laser 3, first reflector 4, collimator 5, dichroic mirror 6, second reflector 7, measured gas 8, surface 9, reflective telescope system 10, sensor 11, data acquisition card 12. DETAILED DESCRIPTION

[0021] In order to make the purpose, technical scheme and advantages of the invention clearer, the invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the invention and do not constitute a limitation to the invention. Similar components in different embodiments use associated similar component numbers. In the following embodiments, many detailed descriptions are to enable the invention to be better understood. However, those skilled in the art can easily recognize that some of the features can be omitted in different situations, or can be replaced by other components, materials, and methods. In some cases, some operations related to the invention are not shown or described in the specification, in order to avoid the core part of the invention being overwhelmed by too much description, and for those skilled in the art, it is not necessary to describe these related operations in detail, and they can fully understand the related operations according to the description in the specification and the general technical knowledge in the art.

[0022] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other to form various implementation methods. At the same time, the steps or actions in the method description can also be interchanged or adjusted in a manner that is obvious to those skilled in the art. Therefore, the various sequences in the specification and the drawings are only for the purpose of clearly describing a certain embodiment and are not meant to be a necessary sequence, unless otherwise specified that a certain sequence must be followed.

[0023] In the description of the invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the drawings, and are only for the convenience of describing the invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the invention. In addition, the terms "first", "second", etc. are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first", "second", etc. may explicitly or implicitly include one or more of the features. In the description of the invention, unless otherwise specified, the meaning of "multiple" is two or more.

[0024] In the description of the invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installation", "connection" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the invention can be understood according to specific circumstances.

[0025] The present invention will be described in detail below with reference to the accompanying drawings and in combination with embodiments.

[0026] See also Figure 1 In one embodiment of the present invention, a methane telemetry system based on TDLAS technology is provided, comprising: a host computer 1, a DFB laser 2 (first laser), a visible light laser 3 (second laser), a first reflector 4, a collimator 5, a dichroic mirror 6 (optical path component), a second reflector 7, a reflective telescope system 10, a sensor 11 and a data acquisition card 12, wherein the host computer 1 is the control center of the entire system, responsible for sending instructions and processing data, and is connected to the DFB laser 2 to control parameters such as the wavelength and amplitude of the DFB laser 2 to achieve telemetry applications under different conditions. The DFB laser 2 emits a laser of a specific wavelength according to the current instruction output by the host computer 1, so as to detect different gases. The DFB laser 2 can precisely tune the wavelength. Generally, in the process of methane telemetry, it is used to emit infrared band light. The infrared band light emitted by the DFB laser 2 is directed to a side mirror surface of the dichroic mirror 6, and the side mirror surface almost completely reflects the infrared band light. In addition, a collimator 5 is provided on the optical path from the DFB laser 2 to the dichroic mirror 6. The collimator 5 is used to collimate the laser beam emitted by the DFB laser 2 to make it a parallel beam for subsequent transmission and detection.

[0027] In the embodiment of the present invention, in order to solve the problem that the laser scanning point is not easy to observe during the methane remote sensing process, a visible light laser 3 for auxiliary observation is additionally designed. The visible light laser 3 is used to provide visible light that can be directly observed by the human eye to assist in alignment and indicate the laser scanning position. The first reflector 4 is designed to direct the visible light to the other side of the dichroic mirror 6, and the side mirror surface is almost completely transparent to the visible light. It should be noted that the position of the first reflector 4 should be adjusted to ensure that the incident points of the infrared band light and the visible light on the dichroic mirror 6 are the same as much as possible, so as to achieve coaxial beam combination of the infrared band light and the visible light.

[0028] Under the action of the dichroic mirror 6, the infrared band light provided by the DFB laser 2 and the visible light provided by the visible light laser 3 are combined, that is, the optical axes of the infrared band light and the visible light coincide. The combined light is emitted from the dichroic mirror 6 to the second reflector 7, and the second reflector 7 reflects the combined light to the measured gas 8, and irradiates the surface 9 after passing through the measured gas 8. At this time, the laser scanning position can be observed through the visible light in the combined light. When the infrared band light in the combined light passes through the measured gas 8, the methane gas molecules will absorb the infrared band light, and the concentration of the methane gas can be detected by the absorption principle of the laser on the laser of a specific wavelength.

[0029] The combined light beam is diffusely reflected on the surface 9, and a part of the echo reflected light passes through the measured gas 8 again and is directed to the reflective telescope system 10, which is used to converge the reflected infrared laser signal. In an embodiment of the present invention, a Cassegrain telescope system is specifically used. The Cassegrain telescope system is a reflective telescope system that uses two reflectors to collect and focus light, including a large-aperture reflective concave primary mirror. The primary mirror collects and reflects the incoming light onto a reflective concave secondary mirror. The secondary mirror is usually located at the focus of the primary mirror and is used to reflect the light through the light-transmitting hole opened in the center of the primary mirror so that the light can be received by the back-end device. Compared with the traditional transmission signal collection system, the Cassegrain telescope system can effectively increase the incident aperture of the light, that is, the range of the received light, and thus improve the signal-to-noise ratio. The application of the Cassegrain telescope system can effectively improve the signal quality of long-distance methane telemetry and avoid the problem of weak received signals and easy interference from the external environment during long-distance detection. It should be noted that in traditional designs, the optical path of the detection light directed to the measured gas 8 does not coincide with the optical path of the echo reflected light. This off-axis design will cause the receiving end to be unable to receive the echo reflected light when the position and distance between the measured gas 8 and the surface 9 change, resulting in the sensor 11 being unable to collect the signal light. At this time, it is necessary to adjust the receiving end, or align the outgoing optical path and the incident optical path. Among them, the outgoing optical path refers to the optical path of the combined light emitted from the second reflector 7 to the measured gas 8; the incident optical path refers to the optical path of the echo reflected light from the measured gas 8 to the Cassegrain telescope system.

[0030] The signal light processed by the Cassegrain telescope system is directed to the sensor 11. The sensor 11 is an indium gallium arsenide (InGaAs) sensor. The InGaAs sensor is used to detect light signals in the near-infrared and short-wave infrared bands, and convert the infrared laser signal after passing through the measured gas 8 into an analog electrical signal. The data acquisition card 12 is connected to the back end of the InGaAs sensor. The data acquisition card 12 converts the analog electrical signal into a digital electrical signal so that it can be transmitted back to the host computer 1 for signal processing and the concentration of the measured gas 8 can be calculated. Among them, the sensor 11 can be adjusted according to the specific wavelength of the detection light, and different types of sensors can be selected for different wavelengths of light. According to the type of measured gas 8 that needs to be measured for concentration telemetry, the DFB laser 2 and the corresponding sensor 11 are replaced synchronously.

[0031] As a preferred embodiment, the function of the dichroic mirror 6 is to combine the infrared band light provided by the DFB laser 2 and the visible light provided by the visible light laser 3, so other optical path components can be used for combining the beams. In addition, the setting positions of the DFB laser 2 and the visible light laser 3 can also be adjusted appropriately. According to the positions of the DFB laser 2 and the visible light laser 3, the dichroic mirror 6 can also be selected so that one side of the mirror has a transmission effect on the infrared band light and the other side of the mirror has a reflection effect on the visible light, which can also achieve the effect of combining the infrared band light and the visible light.

[0032] In short, the above description is only a preferred embodiment of this specification and is not intended to limit the protection scope of this specification. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of this specification shall be included in the protection scope of this specification.

[0033] The systems, devices, modules or units described in one or more of the above embodiments may be implemented by a computer chip or entity, or by a product having a certain function. A typical implementation device is a computer. Specifically, the computer may be, for example, a personal computer, a laptop computer, a cellular phone, a camera phone, a smart phone, a personal digital assistant, a media player, a navigation device, an email device, a game console, a tablet computer, a wearable device, or a combination of any of these devices.

[0034] It should also be noted that the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, commodity or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, commodity or device. In the absence of more restrictions, the elements defined by the sentence "comprises a ..." do not exclude the existence of other identical elements in the process, method, commodity or device including the elements.

[0035] Each embodiment in this specification is described in a progressive manner, and the same or similar parts between the embodiments can be referred to each other, and each embodiment focuses on the differences from other embodiments. In particular, for the system embodiment, since it is basically similar to the method embodiment, the description is relatively simple, and the relevant parts can be referred to the partial description of the method embodiment.

[0036] The above is a description of a specific embodiment of the specification. Other embodiments are within the scope of the appended claims. In some cases, the actions or steps recorded in the claims can be performed in an order different from that in the embodiments and still achieve the desired results. In addition, the processes depicted in the drawings do not necessarily require the specific order or continuous order shown to achieve the desired results. In some embodiments, multitasking and parallel processing are also possible or may be advantageous.

Claims

1. A methane remote sensing system, characterized in that: include: A first laser for providing light in the infrared band; a second laser for providing visible light; An optical path component for combining infrared light and visible light and directing it toward the gas to be measured; A reflective telescope system used to collect echo reflected light that passes through the gas being measured.

2. The methane remote sensing system according to claim 1, characterized in that: The first laser is a DFB laser.

3. The methane remote sensing system according to claim 1, characterized in that: Also includes: A host computer is used to control the first laser parameters.

4. The methane remote sensing system according to claim 1, characterized in that: The optical path component is a dichroic mirror; One mirror of the dichroic mirror has a reflective effect on infrared light, and the other mirror of the dichroic mirror has a transmissive effect on visible light. Or one mirror surface of the dichroic mirror has a transmission effect on infrared band light, and the other mirror surface of the dichroic mirror has a reflection effect on visible light.

5. The methane remote sensing system according to claim 4, characterized in that: The infrared band light and visible light combined by the dichroic mirror are reflected toward the gas to be measured by a reflector, and after passing through the gas to be measured, they are directed toward a surface arranged on the rear optical path of the gas to be measured. The surface reflects part of the combined light again, passes through the gas to be measured, and is directed toward the reflective telescope system.

6. The methane remote sensing system according to claim 5, characterized in that: The reflective telescope system is a Cassegrain telescope system.

7. The methane remote sensing system according to claim 6, characterized in that: The reflector is coaxially arranged with the reflective telescopic system.

8. The methane remote sensing system according to claim 6, characterized in that: Also includes: The sensor is used to detect the echo reflected light collected by the reflective telescope system and convert the optical signal into an analog electrical signal.

9. The methane remote sensing system according to claim 8, characterized in that: Also includes: A data acquisition card is used to convert analog electrical signals into digital electrical signals.

10. The methane remote sensing system according to claim 4, characterized in that: Also includes: A collimating mirror is arranged on the optical path from the first laser to the dichroic mirror.

Images