GB2583023A - A gas sensor probe and a detection apparatus based on spiral light path with multiple-point reflection - Google Patents
A gas sensor probe and a detection apparatus based on spiral light path with multiple-point reflection Download PDFInfo
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- G01N21/25—Colour; Spectral properties, i.e. comparison of effect of material on the light at two or more different wavelengths or wavelength bands
- G01N21/31—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry
- G01N21/35—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry using infrared light
- G01N21/3504—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry using infrared light for analysing gases, e.g. multi-gas analysis
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- G01N21/31—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry
- G01N21/39—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry using tunable lasers
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- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
- G01N21/25—Colour; Spectral properties, i.e. comparison of effect of material on the light at two or more different wavelengths or wavelength bands
- G01N21/31—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry
- G01N21/39—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry using tunable lasers
- G01N2021/396—Type of laser source
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Abstract
A gas sensor probe based on a spiral light path with multiple-point reflection comprises block 1, light source 6, spiral light path module 3 and detector 4. The light source emits parallel light and may be a collimated laser. The spiral light path module comprises a plurality of reflectors 2 and a plurality of straight light paths, each straight light path being in communication with an adjacent straight light path and going inward spirally. At least one reflector is detachably fixed between two adjacent straight light paths. The light signal enters the detector and is converted into an electrical signal. The spiral path is configured to increase the optical path length of the light. The probe may have covers and an air inlet with filter, and temperature and pressure sensors 5. The light source may be a tuneable diode laser for TDLAS, such as a VSCEL.
Description
A GAS SENSOR PROBE AND A DETECTION APPARATUS BASED ON SPIRAL LIGHT PATH WITH MULTIPLE-POINT REFLECTION
FIELD OF THE INVENTION
[0001] The present invention relates to the field of laser spectrum gas sensor technologies, and in particular, to a gas sensor probe based on spiral light path with multiple-point reflection.
BACKGROUND OF THE INVENTION
[0002] The statement in this part merely provides a background technology related to the invention, which does not necessarily constitute the prior art.
[0003] In recent years, photoelectric measuring apparatus for measuring gas composition and concentration by means of the principle of infrared laser spectrum absorption is developing toward high sensitivity, full measurement range, small volume and low cost so as to meet the evergrowing requirements of environment safety detection and production safety monitoring. In a tunable diode laser absorption spectrum (TDLAS) technology, the laser wavelength may be precisely aligned with the absorption peak of the gas to be detected by tuning the laser wavelength at the spectrum absorption peak of the gas to be detected according to the features of good tunability and narrow spectrum linewidth of a semiconductor laser, so that fast detection of gas concentration may be realized, and at the same time, interference of other gases on the measurement may be avoided. By utilizing the advanced digital signal processing technology, such a sensor can continuously measure the concentration of a gas to be detected. The novel gas sensor can simultaneously have the functions of automatic diagnosis and selfcorrection, so that such laser spectrum gas sensors can be widely applied to different production processes and safety precaution fields.
[0004] In practical engineering applications, a user often requires to reduce the dimensions of the gas sensor probe under the premise of meeting the measurement precision. For an infrared laser spectrum absorption gas sensor probe, the apparatus having the largest volume is the gas chamber or the gas absorption cell of the gas sensor, wherein the gas chamber of the gas sensor constitutes of the space between the laser source and the detector. Because the measurement optical path length of the laser beam in the gas chamber is proportional to the measurement precision, a high-precision gas sensor requires a long measurement optical path. However, a long measurement optical path will lengthen the gas chamber, which causes the size of the sensor probe to increase. Therefore, when the size of the sensor probe is restricted, in order to increase the total length of the measurement optical path, the light path is reflected in the gas chamber for multiple times via a plurality of mirrors or reflectors, thereby attaining the object of increasing the measurement optical path length and reducing the volume of the gas chamber and the size of the sensing probe. For example, in Chinese patent application No. 2017114551770, a light path module with four through holes is employed, and the beam in the four through holes is reflected by three reflectors to form a "diamond-shaped" measurement light path, thus the size of the sensing probe is reduced. In application publication CN106908412A, a light path module with two reflectors is employed, and the light path is changed by two reflectors, so that the optical path of the gas chamber is more than doubled under the same volume, and the object of reducing the size of the sensing probe can similarly be attained. However, such a light path of the measuring gas chamber mainly has a problem that the measurement optical path is relatively short, and when it is used for measuring a gas requiring a long measurement optical path (for example, CO), it is difficult to improve the measurement precision.
[0005] Therefore, the inventors think that there exist the following problems to be solved: 1) the development trend of miniaturization of the gas sensor probe further reduces the gas chamber, and hence the measurement optical path is further reduced, thus the measurement precision cannot be increased; 2) for combined light path design, the light path needs to be adjusted each time it is used, thus the stability and accuracy of the light path cannot be guaranteed.
SUMMARY OF THE INVENTION
[0006] To overcome the shortages of the prior art, the present invention provides a gas sensor probe and a detection apparatus based on spiral light path with multiple-point reflection, wherein the total length of the measurement optical path is increased in the case that the dimensions of the gas sensor probe is given, so that the measurement precision of gas concentration may be greatly increased, and by embedding the spiral light path in a block of a metal or synthetic material, the possibility of changing the relative position of each element can be greatly reduced, thus the stability and accuracy of the light path system can be increased.
[0007] In order to attain the above object, the invention employs the technical solutions below.
[0008] In a first aspect, the invention provides a gas sensor probe based on spiral light path with multiple-point reflection.
[0009] The gas sensor probe based on spiral light path with multiple-point reflection includes a light source module, a spiral light path module and a detector module, wherein the light source module is configured to emit a parallel light signal, the spiral light path module includes a plurality of reflectors and a plurality of straight light paths, each straight light path is in communication with an adjacent straight light path end to end at a certain angle, and the straight light paths are connected sequentially and go inward spirally, at least one reflector is detachably fixed between two adjacent straight light paths, and the spiral light path module is configured to increase the optical path length of the light signal, the light signal enters the detector module after passing through the spiral light path module, and the detector module converts the light signal received into an electrical signal.
[0010] In some possible embodiments, each straight light path is vertical to an adjacent straight light path.
[0011] In some possible embodiments, a reflector is provided between two adjacent straight light paths, and included angles between the reflector and the two straight light paths are both 45°.
[0012] In some possible embodiments, the reflector for the multiple-point light reflection spiral light path may be a flat reflector pasted on a mirror base plate at a 45° angle with the straight light path, or a reflector surface formed by optically polishing and coating with a reflective film on a mirror base plate, or a reflector surface formed by the reflection plane of a 45° reflector prism.
[0013] In some possible embodiments, the number of the straight light paths is N, and the number of the reflectors is N-1, wherein N is an integer, and NL.5. The head end of the first straight light path is connected with the light source module, the parallel light emitted by the light source module enters the first straight light path parallelly to the inner wall of the first straight light path, and the tail end of the first straight light path is in communication with the head end of the second straight light path, and the rest light paths are connected with each other in the above mode, wherein the tail end of the Nth light path is connected with the sensor module for transmitting the light signal to the sensor module.
[0014] In some possible embodiments, the length of the N straight light paths decreases gradually. That is, the length of the 1' straight light path is less than that the 2nd straight light path, the length of the 2nd straight light path is less than that of the 3rd straight light path, the length of the 3' straight light path is less than that of the 4' straight light path, ... , and the length of the (N-1)°h straight light path is less than that of the Nth straight light path.
[0015] In some possible embodiments, the spiral light path module is manufactured on a block material, the block material may be a metal, an engineering plastic or a synthetic material, and the spiral light path module may be formed via machining or precision injection molding; a first cover plate is further included, wherein the first cover plate is detachably fixed on the top of the spiral light path and is configured to control the in and out of a gas to be detected, and a cavity formed by the spiral light path and the first cover plate is a gas absorption cell for accommodating the gas to be detected.
[0016] In some possible embodiments, the light source module is VCSEL laser collimated light source, which consists of a VCSEL laser source and a parallel light lens. The parallel light beam emitted by the laser collimated light source is received by a photoelectric detector after being reflected by N-1 reflectors to form an electrical signal output during measurement.
[0017] In some possible embodiments, the detector module is a photoelectric detector, and a lens for focusing parallel light onto a detection-sensitive surface is provided in front of the photoelectric detector.
[0018] In some possible embodiments, a second cover plate, a driving circuit module and a signal processing module are further included. The driving circuit module is configured to drive the light source module, and the signal processing module is configured to receive the electrical signal from the detector module and performs signal processing. The driving circuit module and the signal processing module are provided on the bottom of the spiral light path module, and the spiral light path module is provided in a housing enclosed by the first cover plate and the second cover plate.
[0019] In some possible embodiments, the first cover plate is provided with a first air inlet, and the first air inlet is provided with a sintered filter screen, through which a gas to be detected diffuses into the gas absorption cell.
[0020] In some possible embodiments, a bottom of the spiral light path module is provided with a first through hole, which is configured to mount a sensor for measuring the pressure and temperature of the gas chamber.
[0021] In some possible embodiments, the inner wall of the straight light path and the first cover plate is coated with a black coating film for reducing reflected light.
[0022] In some possible embodiments, after the incident laser received by the photoelectric detector is modulated by the gas of a certain concentration to be detected, the output signal thereof carries information indicating the absorption intensity of the gas to be detected at the absorption spectrum thereof.
[0023] In some possible embodiments, the number of times the incident beam is reflected in the multiple-point light reflection spiral light path is determined by the dimensions of the sensor probe and the width of the light path, and the number of times of multiple-point reflection determines the total length of the measurement optical path of the beam in the reflected light path.
[0024] In some possible embodiments, the light source module is connected with the driving module, and the detector module is connected with the signal processing module.
[0025] In some possible embodiments, the photoelectric gas sensor probe according to the invention is arranged in a stainless steel housing with a metal filter screen. [0026] In a second aspect, the invention provides a photoelectric gas detection apparatus.
[0027] The photoelectric gas detection apparatus includes the photoelectric gas sensor probe based on spiral light path with multiple-point reflection according to the invention.
[0028] In comparison with the prior art, the invention has the beneficial effects below: [0029] In the photoelectric gas sensor probe based on spiral light path with multiple-point reflection, the gas absorption cell employs a single two-dimensional spiral light path with multiple-point reflection. Because the whole light path is embedded in an integrated metal or synthetic material module, the possibility of changing the relative position of each element may be reduced, thus the stability and accuracy of the light path system can be improved.
[0030] In the invention, the overall detection optical path is increased in the absorption cell by means of multiple beam reflection of a two-dimensional spiral light path with multiple-point reflection, which is favorable for improving the detection signal-to-noise ratio and measurement precision.
[0031] By the two-dimensional spiral light path with multiple-point reflection according to the invention, the volume of the sensor probe is reduced, so that the measurement response time can be effectively reduced.
[0032] In the invention, by employing a transceiving design of a collimated light source and a photoelectric detector with a focusing lens and utilizing the high precision and dimensional uniformity of precision machining, the precision of incident angle of the mirror plate may be guaranteed, so that the difficulty in adjusting the light path can be reduced in practical production. The overall inventive design of the invention not only reduces the complexity of the production process, but also increases the yield of the product, and it is favorable for large-scale production.
[0033] In the invention, a through hole is provided on the bottom of the spiral light path module for placing a temperature and atmospheric pressure sensor. The temperature and atmospheric pressure sensor is configured to detect the temperature and atmospheric pressure in the gas absorption cell in real time, and the temperature and atmospheric pressure information measured will be used for compensating for the parametric variation due to fluctuation of the ambient temperature and local atmospheric pressure, so that the gas measurement precision can be further improved. [0034] In the invention, each straight light path is vertical to an adjacent straight light path, a reflector is provided between two adjacent straight light paths, and included angles between the reflector and the two straight light paths are both 45°. The design of the light paths vertical to each other and the setting of 45° included angles are favorable for the manufacture of the spiral light paths and the placement of the reflectors to form a standard light path, so that the stability and test accuracy of the light path may be greatly improved.
[0035] In the invention, the number of the straight light paths is N, and the number of the reflectors is N-1, wherein N is an integer, and Na.5, that is, the number of the straight light paths is at least 5, so that the measurement optical path may be effectively increased, and test precision may be improved.
[0036] The top of the upper cover according to the invention is provided with a sintered filter screen, thus dust, impurity and the like can be effectively prevented from entering the absorption cell and polluting the optical elements on the light path.
Moreover, the sintered filter screen may be replaced at any time during maintenance [0037] The spiral light path according to the invention is provided in a housing enclosed by the first cover plate and the second cover plate, and it not only is easy to disassemble for the maintenance of the spiral light path, but also can effectively improve the stability of the light path and reduce the affect of the environment on the light path.
[0038] The inner wall of the gas absorption cell according to the invention is coated with a coating film for reducing reflected light, so that the transmission integrity of the light signal can be effectively guaranteed, and it can ensure, as much as possible, that reflection transmission is only realized via the reflectors.
BRIEF DESCRIPTION OF THE DRAWINGS
[0039] Fig. 1 is a schematic diagram of a spiral light path according to Embodiment 1 of the invention; [0040] Fig. 2 is a side view of the spiral light path according to Embodiment 1 of the invention; [0041] Fig. 3 is a schematic diagram showing the spiral light path according to Embodiment 1 of the invention located in a stainless steel housing; [0042] Fig. 4 is a schematic diagram of a spiral light path according to Embodiment 2 of the invention; [0043] Fig. 5 is a side view of the spiral light path according to Embodiment 2 of the invention; and [0044] Fig. 6 is a schematic diagram showing the spiral light path according to Embodiment 2 of the invention located in a stainless steel housing.
[0045] List of the reference numerals in the drawings: 1: light path block; 2: reflector; 3: spiral light path; 4: photoelectric detector; 5: first through hole; 6: VCSEL laser collimated light source; 7: metal sintered filter screen; 8: first air inlet; 9: upper cover; 10: lower cover; 11: power driving module; 12: photoelectric detector signal processing module
DETAILED DESCRIPTION OF THE EMBODIMENTS
[0046] It should be pointed out that, the detailed illustration below is exemplary only and is provided for further illustrating the invention. Unless otherwise indicated, all technical and scientific terms used herein have the same meanings as commonly understood by one of ordinary skills in the art.
[0047] It should be noted that, the terms used herein are merely provided for describing the specific embodiments, rather than limiting the exemplary embodiments of the invention. As used herein, unless otherwise defined specifically in the context, a single form also intends to encompass the plural form. Additionally, it should be further understood that, when "comprise" and/or "include" are/is used in the invention, it indicates that there exist a characteristic, a step, an operation, an apparatus, a component and/or a combination thereof.
[0048] Embodiment 1 [0049] As shown in Figs.1 to 3, Embodiment 1 of the invention provides a gas sensor probe based on spiral light path with multiple-point reflection, which includes: a light path block 1, a spiral light path module 3 consisting of five reflectors 2 and six straight light paths, an upper cover 9, a lower cover 10, a VCSEL laser collimated light source 6, a photoelectric detector 4, a light source driving circuit 11 and a photoelectric detector signal processing circuit 12. The spiral light path module 3 is manufactured on one light path block 1. Each straight light path is in communication with an adjacent straight light path end to end at a certain angle, and the straight light paths are connected sequentially and go inward spirally. The light path block 1 may be a solid material such as a metal, a plastic or a synthetic material, and the spiral light path module may be formed via machining or precision injection molding.
[0050] The spiral light path module 3 is provided in a stainless steel housing consisting of a probe upper cover 9 and a probe lower cover 10. The upper cover 9 and the lower cover 10 are formed as cylindrical cover plate. The upper cover 9 is provided on the top of the spiral light path, and the lower cover 10 is provided on the bottom of the spiral light path. The upper cover 9 is provided with a first air inlet 8. The cavity between the intracavity of the spiral light path module 3 and the upper cover 9 forms a gas absorption cell. The inner wall of the upper cover 9 and the spiral light path module 3 is coated with a black reflected-light-reducing coating film for reducing the interference of stray light and preventing corrosion. A gas to be detected diffuses into the gas absorption cell via the first air inlet 8 provided with a metal sintered filter screen 7. The metal sintered filter screen 7 is configured to prevent dust, impurity and the like from entering the absorption cell and polluting the optical elements on the light path, and the metal sintered filter screen 7 can be replaced during maintenance for keeping a good dust prevention effect.
[0051] The five reflectors 2 according to this embodiment may be a flat reflector pasted on a mirror base plate at a 45° angle with the straight light path, or a reflector surface formed by optically polishing a mirror base plate and then coating a reflective film, or a reflector surface consisting of the reflection plane of a 45° reflector prism. The five reflectors 2 will reflect an incident collimated laser beam along the straight light path for multiple times. The incident light and the reflected light beam have an included angle of 90°. The beam reflected for multiple times reaches the photoelectric detector 4 and then converges via a focusing lens on the photosensitive surface of the photoelectric detector 4 to form an electrical signal. In the invention, the included angle between the reflector 2 and adjacent two straight light paths may be adjusted as required, so long as that the incident light and the reflected light have an included angle of 90°.
[0052] The light source module according to this embodiment is an intensity adjustable laser collimated light source equiped with a light intensity detector. The laser source may be a low power dissipation vertical cavity surface emitting laser (VCSEL) or a DFB laser. In this embodiment, the light source module is a VCSEL laser collimated light source 6, which consists of a VCSEL laser source and a parallel light lens. The VCSEL laser source has a tunable power source, which may be tuned by a self-equipped tuning circuit. A light intensity detector is mounted in the packaging cap of the VCSEL laser collimated light source 6, and the light intensity detector may detect the light intensity variation of the laser source in real time.
[0053] A parallel light beam emitted by the VCSEL laser collimated light source 6 according to this embodiment is reflected by the five reflectors 2 in the gas absorption cell. Straight light paths of different length exist between the VCSEL laser collimated light source 6 and the first reflector, between every two reflectors and between the last reflector and the detector. The length of the straight light paths decreases gradually, or certain straight light paths therein may have the same length, but the overall trend is that the length of the straight light paths decreases gradually. As shown in Fig. 1, the length of the outermost straight light paths, for example, the first straight light path, the second straight light path and the third straight light path, may be the same or may decrease gradually, and the length of the fourth straight light path, the fifth straight light path and the sixth straight light path may be the same or may decrease gradually. These straight light paths form a spiral light path structure. The length of each straight light path may also be adjusted as practically required to increase the measurement optical path as much as possible, so that the test precision can be improved. The reflected light beam is received by the photoelectric detector 4 after passing through the sixth straight light path. The photoelectric detector 4 is connected with the photoelectric detector signal processing module. After signal processing, the light signal measured and received by the light detector is output from an output signal line in the form of a digital signal.
[0054] The bottom of the spiral light path module 3 is provided with a first through hole 5, and the first through hole 5 is provided with a temperature and atmospheric pressure sensor for detecting the temperature and atmospheric pressure in the gas absorption cell in real time. The temperature and atmospheric pressure information measured will be used for compensating for the parametric variation due to fluctuation of the ambient temperature and local atmospheric pressure, so that the gas measurement precision can be further improved.
[0055] The sensor probe according to this embodiment further includes an electronic processing circuit for modulating the luminous intensity of the laser source and amplifying and adjusting the measurement signal of the light detector. A power driving module 11 and a photoelectric detector signal processing module 12 are placed under the spiral light path module 3 and protected by the lower cover 10.
[0056] The working principle of the gas sensor probe according to Embodiment 1 of the invention is described as follows.
[0057] In the working state, the VCSEL laser collimated light source 6 is tuned and emits a parallel light. The parallel light beam is successively reflected by five reflectors 2 and reaches the photoelectric detector 4, and then is received by the photoelectric detector 4 to form a measurement signal. Because the light signal received by the photoelectric detector is modulated by the gas to be detected, the output signal carries information of the absorption spectrum of the gas to be detected, and is processed by the signal processing module connected with the photoelectric detector to form a measurement signal for measuring the gas concentration. By the design of the spiral light path with multiple-point reflection according to this embodiment, not only the capacity of the absorption cell of the sensor probe is reduced, but also the measurement optical path is increased, and at the same time, the stability and reliability of the light path is greatly improved, thereby lowering the production cost while reducing the debugging difficulty during production.
[0058] The invention further provides a photoelectric gas detection apparatus, which includes the photoelectric gas sensor probe according to Embodiment 1 of the invention.
[0059] Embodiment 2 [0060] As shown in Figs. 4 to 6, Embodiment 2 of the invention provides a gas sensor probe based on spiral light path with multiple-point reflection, which includes: a light path block 1, a spiral light path module 3 consisting of thirteen reflectors 2 and fourteen straight light paths, an upper cover 9, a lower cover 10, a VCSEL laser collimated light source 6, a photoelectric detector 4, a light source driving circuit 11 and a photoelectric detector signal processing circuit 12. The spiral light path module 3 is manufactured on one light path block 1. Each straight light path is in communication with an adjacent straight light path end to end at a certain angle, and the straight light paths are connected sequentially and go inward spirally. The light path block 1 may be a solid material such as a metal, a plastic or a synthetic material, and the spiral light path module may be formed via machining or precision injection molding.
[0061] The spiral light path module 3 is provided in a stainless steel housing consisting of the probe upper cover 9 and the probe lower cover 10. The upper cover 9 and the lower cover 10 are rectangular columnar cover plates. The upper cover 9 is provided on the top of the spiral light path, and the lower cover 10 is provided on the bottom of the spiral light path. The upper cover 9 is provided with a first air inlet 8. the cavity between the intracavity of the spiral light path module 3 and the upper cover 9 forms a gas absorption cell. The inner wall of the upper cover 9 and the spiral light path module 3 is coated with a black reflected-light-reducing coating film for reducing the interference of stray light and preventing corrosion. A gas to be detected diffuses into the gas absorption cell via the first air inlet 8 provided with a metal sintered filter screen 7. The metal sintered filter screen 7 is configured to prevent dust, impurity and the like from entering the absorption cell and polluting the optical elements on the light path, and the metal sintered filter screen 7 can be replaced during maintenance for keeping a good dust prevention effect.
[0062] The thirteen reflectors 2 according to this embodiment may be a flat reflector pasted on a mirror base plate at a 45° angle with the straight light path, or a reflector surface formed by optically polishing a mirror base plate and then coating a reflective film, or a reflector surface consisting of the reflection plane of a 45° reflector prism. The thirteen reflectors 2 will reflect an incident collimated laser beam along the straight light path for multiple times. The incident light and the reflected light beam have an included angle of 90°. The beam reflected for multiple times reaches the photoelectric detector 4 and then converges via a focusing lens on the photosensitive surface of the photoelectric detector 4 to form an electrical signal.
[0063] In the invention, the included angle between the reflector 2 and adjacent two straight light paths may be adjusted as required, so long as that the incident light and the reflected light have an included angle of 90°.
[0064] The light source module according to this embodiment is an intensity adjustable laser collimated light source equipped with a light intensity detector. The laser source may be a low power dissipation vertical cavity surface emitting laser (VCSEL) or a DFB laser. In this embodiment, the light source module is a VCSEL laser collimated light source 6, which consists of a VCSEL laser source and a parallel light lens. The VCSEL laser source has a tunable power source, which may be tuned by a self-equipped tuning circuit. A light intensity detector is mounted in the packaging cap of the VCSEL laser collimated light source 6, and the light intensity detector may detect the light intensity variation of the laser source in real time.
[0065] A parallel light beam emitted by the VCSEL laser collimated light source 6 according to this embodiment is reflected by the thirteen reflectors 2 in the gas absorption cell. Straight light paths of different length exist between the VCSEL laser collimated light source 6 and the first reflector, between every two reflectors and between the last reflector and the detector. The length of the straight light paths decreases gradually, or certain straight light paths therein may have the same length, but the overall trend is that the length of the straight light paths decreases gradually. As shown in Fig. 4, the length of the outermost straight light paths, for example, the first straight light path, the second straight light path and the third straight light path, may be the same or may decrease gradually, and the length of the fourth straight light path and the fifth straight light path may be the same or may decrease gradually, the length of the sixth straight light path and the seventh straight light path may be the same or may decrease gradually, the length of the eighth straight light path and the ninth straight light path may be the same or may decrease gradually, the length of the tenth straight light path and the eleventh straight light path may be the same or may decrease gradually, and the twelfth straight light path and the thirteenth straight light path may be the same or may decrease gradually. These straight light paths form a spiral light path structure.
The length of each straight light path may also be adjusted as practically required to increase the measurement optical path as much as possible, so that the test precision can be improved. The reflected light beam is received by the photoelectric detector 4 after passing through the fourteenth straight light path. The straight light paths according to the invention form a spiral light path structure. The reflected light beam is received by the photoelectric detector 4. The photoelectric detector 4 is connected with the photoelectric detector signal processing module. After signal processing, the light signal measured and received by the light detector is output from an output signal line in the form of a digital signal.
[0066] The bottom of the spiral light path module 3 is provided with a first through hole 5, and the first through hole 5 is provided with a temperature and atmospheric pressure sensor for detecting the temperature and atmospheric pressure in the gas absorption cell in real time. The temperature and atmospheric pressure information measured will be used for compensating for the parametric variation due to fluctuation of the ambient temperature and local atmospheric pressure, so that the gas measurement precision can be further improved.
[0067] The sensor probe according to this embodiment further includes an electronic processing circuit for modulating the luminous intensity of the laser source and amplifying and adjusting the measurement signal of the light detector. A power driving module 11 and a photoelectric detector signal processing module 12 are placed under the spiral light path module 3 and protected by the lower cover 10.
[0068] The working principle of the gas sensor probe according to Embodiment 2 of the invention is described as follows.
[0069] In the working state, the VCSEL laser collimated light source 6 is tuned and emits a parallel light. The parallel light beam is successively reflected by thirteen reflectors 2 and reaches the photoelectric detector 4, and then is received by the photoelectric detector 4 to form a measurement signal. Because the light signal received by the photoelectric detector is modulated by the gas to be detected, the output signal carries information of the absorption spectrum of the gas to be detected, and is processed by the signal processing module connected with the photoelectric detector to form a measurement signal for measuring the gas concentration. By the design of the spiral light path with multiple-point reflection according to this embodiment, not only the capacity of the absorption cell of the sensor probe is reduced, but also the measurement optical path is increased, and at the same time, the stability and reliability of the light path is greatly improved, thereby lowering the production cost while reducing the debugging difficulty during production.
[0070] The invention further provides a photoelectric gas detection apparatus, which includes the photoelectric gas sensor probe according to Embodiment 2 of the invention.
[0071] The above description only shows preferred embodiments of the invention, rather than limiting the scope of the invention. For one skilled in the art, the invention may have various modifications and variations. Therefore, all modifications, equivalent substitutions and improvements made within the spirit and scope of the invention will fall into the protection scope of the invention.
Claims (10)
- WHAT IS CLAIMED IS: 1. A gas sensor probe based on spiral light path with multiple-point reflection, characterized by comprising: a light source module, a spiral light path module and a detector module; wherein the light source module is configured to emit a parallel light signal, and the spiral light path module comprises a plurality of reflectors and a plurality of straight light paths, each straight light path being in communication with an adjacent straight light path end to end at a certain angle, and the straight light paths being connected sequentially and going inward spirally, and at least one reflector being detachably fixed between two adjacent straight light paths; wherein the light signal enters the detector module after passing through the spiral light path module, and the detector module converts the light signal received into an electrical signal.
- 2. The gas sensor probe based on spiral light path with multiple-point reflection according to claim 1, characterized in that, each straight light path is vertical to an adjacent straight light path.
- 3. The gas sensor probe based on spiral light path with multiple-point reflection according to claim 2, characterized in that, a reflector is provided between two adjacent straight light paths, and included angles between the reflector and the two straight light paths are both 45°.
- 4. The gas sensor probe based on spiral light path with multiple-point reflection according to claim 3, characterized in that, the number of the straight light paths is N, and the number of the reflectors is N-1, wherein N is an integer, and W5.
- 5. The gas sensor probe based on spiral light path with multiple-point reflection according to claim 1, characterized in that, the spiral light path module is manufactured on a block, and it further comprises a first cover plate, wherein the first cover plate is detachably fixed on the top of the spiral light path and is configured to control the in and out of a gas to be detected, and a cavity formed by the spiral light path and the first cover plate is a gas absorption cell for accommodating the gas to be detected.
- 6. The gas sensor probe based on spiral light path with multiple-point reflection according to claim 5, further comprising: a second cover plate, a driving circuit module and a signal processing module, wherein the driving circuit module is configured to drive the light source module, the signal processing module is configured to receive the electrical signal from the detector module and performs signal processing, the driving circuit module and the signal processing module are provided on the bottom of bottom the spiral light path module, and the spiral light path module is provided in a housing enclosed by the first cover plate and the second cover plate.
- 7. The gas sensor probe based on spiral light path with multiple-point reflection according to claim 5, characterized in that, the first cover plate is provided with a first air inlet, and the first air inlet is provided with a filter screen, through which the gas to be detected diffuses into the gas absorption cell.
- 8. The gas sensor probe based on spiral light path with multiple-point reflection according to claim 5, characterized in that, a bottom of the spiral light path module is provided with a first through hole, in which a pressure sensor and a temperature sensor are mounted.
- 9. The gas sensor probe based on spiral light path with multiple-point reflection according to claim 5, characterized in that, an inner wall of the gas absorption cell consisting of the straight light path and the first cover plate is coated with a coating film for reducing reflected light.
- 10. A photoelectric gas detection apparatus, comprising the gas sensor probe based on spiral light path with multiple-point reflection according to any one of claims 1-9.
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| CN201910223025.0A CN109839364A (en) | 2019-03-22 | 2019-03-22 | A kind of gas sensor probe and detection device based on multiple spot reflecting helix optical path |
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Also Published As
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| GB2583023B (en) | 2021-10-27 |
| DE102020107632A1 (en) | 2020-09-24 |
| CN109839364A (en) | 2019-06-04 |
| GB202003977D0 (en) | 2020-05-06 |
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