CN117664912A - Laser gas sensor - Google Patents
Laser gas sensor Download PDFInfo
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- CN117664912A CN117664912A CN202311684955.9A CN202311684955A CN117664912A CN 117664912 A CN117664912 A CN 117664912A CN 202311684955 A CN202311684955 A CN 202311684955A CN 117664912 A CN117664912 A CN 117664912A
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- detector
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- air chamber
- gas sensor
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- 238000010438 heat treatment Methods 0.000 claims abstract description 18
- 238000004806 packaging method and process Methods 0.000 claims description 10
- 238000005070 sampling Methods 0.000 claims description 5
- 230000003287 optical effect Effects 0.000 claims description 4
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 abstract description 5
- 230000007613 environmental effect Effects 0.000 abstract description 4
- 230000009286 beneficial effect Effects 0.000 abstract description 3
- 239000007789 gas Substances 0.000 description 34
- 238000010521 absorption reaction Methods 0.000 description 8
- 238000005259 measurement Methods 0.000 description 7
- 238000001514 detection method Methods 0.000 description 6
- 238000009833 condensation Methods 0.000 description 5
- 230000005494 condensation Effects 0.000 description 5
- 238000000041 tunable diode laser absorption spectroscopy Methods 0.000 description 5
- 238000010586 diagram Methods 0.000 description 3
- 238000005516 engineering process Methods 0.000 description 3
- 238000009529 body temperature measurement Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 230000002265 prevention Effects 0.000 description 2
- 238000007789 sealing Methods 0.000 description 2
- 239000004065 semiconductor Substances 0.000 description 2
- 230000008033 biological extinction Effects 0.000 description 1
- 238000007084 catalytic combustion reaction Methods 0.000 description 1
- 230000005518 electrochemistry Effects 0.000 description 1
- 239000002360 explosive Substances 0.000 description 1
- 238000000034 method Methods 0.000 description 1
- 238000011897 real-time detection Methods 0.000 description 1
- 238000005057 refrigeration Methods 0.000 description 1
- 239000000523 sample Substances 0.000 description 1
- 230000035945 sensitivity Effects 0.000 description 1
- 231100000331 toxic Toxicity 0.000 description 1
- 230000002588 toxic effect Effects 0.000 description 1
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- Investigating Or Analysing Materials By Optical Means (AREA)
Abstract
The invention provides a laser gas sensor, which comprises a laser, a measuring air chamber, a detector and a circuit board, wherein the measuring air chamber is arranged on the laser; the detector is packaged with a heating resistor and an NTC temperature sensor; the heating resistor is used for heating the detector; the NTC temperature sensor is used for measuring the temperature of the detector and feeding back to the control system, and the control system controls the temperature of the detector through the temperature control circuit so that the temperature of the detector is above the ambient temperature; the control system is also used for converting the electric signal passing through the adoption module into the concentration of the gas to be detected. The invention uses the common heating resistor to heat the detector end, can lead the temperature of the detector to be higher than the preset environmental temperature, prevents the detector end from generating condensed water in a high-humidity environment and avoids the problem of poor response in a low-temperature environment, simultaneously reduces the application cost and is beneficial to popularization and use.
Description
Technical Field
The invention relates to the field of leakage gas detection, in particular to a laser gas sensor.
Background
Compared with the traditional gas detection technologies such as electrochemistry, catalytic combustion, semiconductors, infrared and the like, the Tunable Diode Laser Absorption Spectroscopy (TDLAS) technology has the advantages of high sensitivity, strong anti-interference performance, high response speed, real-time detection and the like, and is widely applied to detection of flammable and explosive and toxic harmful gases such as industry, public safety, environmental protection and the like.
The Tunable Diode Laser Absorption Spectroscopy (TDLAS) technology uses a laser and a detector as core elements, and is particularly used in a high-humidity environment in the use process of a sensor, the laser is usually provided with a heating module, condensed water cannot appear, but the detector end is communicated with the environment, and in the high-humidity environment, the condensed water is easily generated at the detector end due to the change of the environmental temperature, so that the light path of a product is influenced, and the sensor cannot work normally. Moreover, the detector has low responsivity when used in a low-temperature environment, so that the performance of the whole sensor is poor when the whole sensor works under the low-temperature condition. The Carl Zeiss patent US8253093B2 discloses a photodetector assembly that employs a Peltier element (e.g., a semiconductor refrigeration sheet) to control the photodetector temperature to be maintained above ambient dew point temperature to prevent condensation. Although the Peltier element can obtain good temperature control effect, the cost is high, and the civilian use and popularization of the TDLAS gas sensor are greatly restricted.
Disclosure of Invention
In order to solve the problems, the invention provides a laser gas sensor, which comprises a laser, a measuring air chamber, a detector and a circuit board;
the measuring air chamber is used for flowing air to be measured;
the laser is used for emitting light to the measuring air chamber;
the detector is used for receiving light emitted by the laser and converting an optical signal into an electric signal;
the laser and the detector are electrically connected with the circuit board;
the circuit board is provided with a sampling module, a control system and a temperature control circuit;
the detector is packaged with a heating resistor and an NTC temperature sensor, and the heating resistor is used for heating the detector; the NTC temperature sensor is used for measuring the temperature of the detector and feeding back to the control system, and the control system controls the temperature of the detector through the temperature control circuit so that the temperature of the detector is above the ambient temperature;
the control system is also used for converting the electric signal passing through the sampling module into the concentration of the gas to be detected.
Further, the laser is a DFB laser or a VCSEL laser.
Furthermore, the inner wall of the measuring air chamber adopts frosting treatment to reduce stray light.
Further, the detector is packaged by adopting a flat window or a packaging tube cap with a lens.
Further, the detector is also filled with a gas to be detected with known concentration.
Further, the laser is also packaged with an internal detector filled with a gas to be measured with known concentration.
Further, the concentration range of the gas to be measured with the known concentration is 0-100%.
Further, the laser and the detector are arranged at the same end or opposite ends of the measuring air chamber.
Further, when the laser and the detector are arranged at two opposite ends of the measuring air chamber, the measuring air chamber adopts a straight-through opposite-emission type, single or multiple turn-back type light path air chamber.
Further, when the laser and the detector are disposed at the same end of the measurement air chamber, the measurement air chamber adopts a single or multiple turn-back light path air chamber.
The technical scheme provided by the invention has the beneficial effects that: the invention uses the common heating resistor to heat the detector end, so that the temperature of the detector is higher than the ambient dew point temperature, and when the sensor is used in a high-humidity environment, the detector end is prevented from generating condensed water due to the change of the ambient temperature; when the sensor is used in a low-temperature environment, the problem of poor low-temperature performance of the sensor caused by too low responsivity of the working temperature of the detector can be avoided, the condensation prevention and low-temperature measurement accuracy are ensured, meanwhile, the application cost is reduced, and the popularization and the use are facilitated.
Drawings
The invention will be further described with reference to the accompanying drawings and examples, in which:
FIG. 1 is a schematic diagram of a laser gas sensor in an embodiment of the invention.
Fig. 2 is an internal structural view of a probe in an embodiment of the present invention.
FIG. 3 is a schematic diagram of a laser gas sensor for detecting a gas under test in an embodiment of the invention.
FIG. 4 is a schematic diagram of a laser gas sensor for detecting a gas under test according to another embodiment of the present invention.
Detailed Description
For a clearer understanding of technical features, objects and effects of the present invention, a detailed description of embodiments of the present invention will be made with reference to the accompanying drawings.
Referring to fig. 1, an embodiment of the present invention provides a laser gas sensor applied in a wide temperature environment, in which the environmental temperature is typically-30-70 ℃. The sensor includes: the device comprises a laser, a measuring air chamber, a detector and a circuit board; the measuring air chamber is used for flowing the air to be measured, and the laser is used for emitting light rays to the measuring air chamber; the detector is used for receiving light emitted by the laser and converting an optical signal into an electric signal; the laser and the detector are electrically connected with the circuit board; the circuit board is provided with a sampling module, a control system and a temperature control circuit; by performing temperature control heating on the detector end, the temperature of the detector is higher than the ambient dew point temperature to prevent condensation, and in this embodiment, the packaging structure of the detector shown in fig. 2 is composed of a packaging base 1, a cushion block 2, a light detection chip 3, a heating resistor 4, an NTC temperature sensor 5, a packaging tube cap 6 and the like. The cushion block 2, the heating resistor 4 and the NTC temperature sensor 5 are fixed on the packaging base 1, the light detection chip 3 is fixed on the cushion block 2, the packaging pipe cap 5 is welded with the packaging base 1, components are packaged inside, the heating resistor 4 heats the whole detector through the packaging base 1, the NTC temperature sensor 5 measures the temperature of the base, and the packaging pipe cap 6 can be flat window or lens. When the whole laser gas sensor works in a high-humidity environment and is lower than a preset environment temperature, the sensor control system controls the heating resistor to heat the temperature of the detector through the temperature control circuit, so that the temperature of the detector is higher than the environment temperature, and the condensation of the detector end is prevented.
The laser is typically a DFB laser or a VCSEL laser, with DFB lasers being preferred in this embodiment.
The inner wall of the measuring air chamber adopts an extinction structure to prevent stray light, and in the embodiment, the inside of the air chamber adopts frosting treatment.
The laser and the detector are arranged at the same end or opposite ends of the measuring air chamber, and when the laser and the detector are arranged at the same end of the measuring air chamber, the measuring air chamber adopts a single or multiple foldback light path air chamber; when the laser and the detector are arranged at two opposite ends of the measuring air chamber, the measuring air chamber adopts a straight-through opposite-type, single or multiple turn-back type light path air chamber. Different measuring air chambers are used for configuration according to different application environments and use requirements. In this embodiment, the laser and the detector are disposed at opposite ends of the measurement air chamber, and the measurement air chamber employs a straight-through correlation type optical path air chamber.
In order to realize high-precision measurement, the center wavelength of the laser is required to be exactly aligned with the absorption wavelength of the measured gas, and the factors such as the driving current of the laser, the ambient temperature and the like can cause the drift of the wavelength of the laser. The laser emission wavelength of the current tunable laser gas sensor is generally modulated by the working temperature and the working current, and for a DFB laser, the laser is mainly modulated by the working temperature to obtain the detection wavelength of the gas to be detected.
However, since the temperature of the laser is not a constant value, in the second harmonic wave finally demodulated, the absorption peak will deviate along with the temperature, in order to eliminate the influence caused by the deviation of the absorption peak, the absorption peak of the gas to be detected is locked by encapsulating the gas to be detected with a known concentration in the detector, wherein the concentration range of the gas to be detected with the known concentration is 0% -100%. In another embodiment, as shown in fig. 3, the concentration of the gas to be measured is sealed by the detector to be 25%, and when the light emitted by the laser passes through the measuring air chamber, the light is converted into an electric signal by the detector and then enters the signal demodulation circuit; because the detector is sealed with the standard gas to be detected, the signal demodulation consists of a measurement signal and a gas sealing reference signal, and the gas sealing reference signal can be used for carrying out absorption peak offset correction to eliminate the influence caused by absorption peak offset.
In another embodiment, as shown in fig. 4, the laser has a detector inside, and the detector seals the gas to be measured with a known concentration of 31.25%. Specifically, the light emitted by the laser is divided into two beams in the laser, one beam passes through the measuring air chamber, is converted into an electric signal by the detector and then enters the signal demodulation circuit; the other beam is converted into an electric signal by a detector inside the laser and enters a signal demodulation circuit. Because the detector inside the laser seals the standard gas to be measured to form a reference signal, the gas to be measured enters the measuring air chamber during measurement to obtain a measuring signal, and thus the measuring signal contains the information of the gas to be measured, and the reference signal contains the information of the gas to be measured sealed in the standard gas to be measured. The reference signal can be used to correct the absorption peak offset to eliminate the influence of the absorption peak offset.
The beneficial effects of the invention are as follows: the invention uses the common heating resistor to heat the detector end, so that the temperature of the detector is higher than the ambient dew point temperature, and when the sensor is used in a high-humidity environment, the detector end is prevented from generating condensed water due to the change of the ambient temperature; when the sensor is used in a low-temperature environment, the problem of poor low-temperature performance of the sensor caused by too low responsivity of the working temperature of the detector can be avoided, the condensation prevention and low-temperature measurement accuracy are ensured, meanwhile, the application cost is reduced, and the popularization and the use are facilitated.
The foregoing description is only of the preferred embodiments of the invention and is not intended to limit the invention to the particular embodiments of the invention, but is to be accorded the full scope of the invention as defined by the appended claims.
Claims (10)
1. A laser gas sensor, characterized by: the device comprises a laser, a measuring air chamber, a detector and a circuit board;
the measuring air chamber is used for flowing air to be measured;
the laser is used for emitting light to the measuring air chamber;
the detector is used for receiving light emitted by the laser and converting an optical signal into an electric signal;
the laser and the detector are electrically connected with the circuit board;
the circuit board is provided with a sampling module, a control system and a temperature control circuit;
the detector is packaged with a heating resistor and an NTC temperature sensor, and the heating resistor is used for heating the detector; the NTC temperature sensor is used for measuring the temperature of the detector and feeding back to the control system, and the control system controls the temperature of the detector through the temperature control circuit so that the temperature of the detector is above the ambient temperature;
the control system is also used for converting the electric signal passing through the sampling module into the concentration of the gas to be detected.
2. A laser gas sensor as defined in claim 1, wherein: the laser is a DFB laser or a VCSEL laser.
3. A laser gas sensor as defined in claim 1, wherein: the inner wall of the measuring air chamber adopts frosting treatment to reduce stray light.
4. A laser gas sensor as defined in claim 1, wherein: the detector is packaged by adopting a flat window or a packaging tube cap with a lens.
5. A laser gas sensor as defined in claim 1, wherein: and the detector is filled with gas to be detected with known concentration.
6. A laser gas sensor as defined in claim 1, wherein: the laser is also packaged with an internal detector, and the internal detector of the laser is filled with gas to be measured with known concentration.
7. A laser gas sensor as claimed in any one of claims 5 to 6 wherein: the concentration range of the gas to be measured with the known concentration is 0% -100%.
8. A laser gas sensor as defined in claim 1, wherein: the laser and the detector are arranged at the same end or opposite ends of the measuring air chamber.
9. A laser gas sensor as defined in claim 8, wherein: when the laser and the detector are arranged at two opposite ends of the measuring air chamber, the measuring air chamber adopts a straight-through opposite-type, single or multiple turn-back type light path air chamber.
10. A laser gas sensor as defined in claim 8, wherein: when the laser and the detector are arranged at the same end of the measuring air chamber, the measuring air chamber adopts a single or multiple turn-back light path air chamber.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202311684955.9A CN117664912A (en) | 2023-12-07 | 2023-12-07 | Laser gas sensor |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202311684955.9A CN117664912A (en) | 2023-12-07 | 2023-12-07 | Laser gas sensor |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN117664912A true CN117664912A (en) | 2024-03-08 |
Family
ID=90086092
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202311684955.9A Pending CN117664912A (en) | 2023-12-07 | 2023-12-07 | Laser gas sensor |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN117664912A (en) |
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2023
- 2023-12-07 CN CN202311684955.9A patent/CN117664912A/en active Pending
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