Laser gas sensor and gas detection method

Abstract

The present invention provides a laser gas sensor and a gas detection method, which relates to the field of gas sensor detection. The laser gas sensor includes: a laser, a laser temperature control circuit, a gas chamber, a photodetector, and a processing unit; the laser includes a tube seat, a carrier board, a laser chip, a heating resistor, a second temperature sensor, a thermal insulation layer, and a tube cap; the laser has high and low temperature absorption peak wavelengths for the gas to be measured; the thermal conductivity of the thermal insulation layer is less than the thermal conductivity of the carrier board, so as to achieve rapid heating and heat dissipation of the laser. By designing a low thermal conductivity thermal insulation layer, the heating and heat dissipation speeds are accelerated. The PID fast temperature control method is used to switch the working mode of the laser gas sensor, dynamically select the working mode, reduce the time the laser works at high temperature, and increase the service life of the laser.

Description

Technical Field

[0001] The present invention relates to the field of gas sensor detection, and in particular to a laser gas sensor and a gas detection method. Background Art

[0002] In the field of gas leak detection, tunable semiconductor laser absorption spectroscopy (TDLAS) technology is widely used due to its high sensitivity, good selectivity, fast response speed, and real-time detection. The main principle of TDLAS technology is to control the operating temperature and power of the laser, indirectly control the emission wavelength of the laser, scan the absorption band of the gas to be tested, and then obtain gas concentration information through signal demodulation. The current signal for controlling the power is generally generated by the internal DAC of the microcontroller or the external DA chip. Common scanning signals include sawtooth waves, triangle waves, etc., and the operating temperature of the laser is controlled by a bidirectional temperature-controlled semiconductor cooler (TEC) or a unidirectional temperature-controlled heating resistor, so that the laser can emit a laser of a specific wavelength to measure the gas to be tested.

[0003] At present, although the use of TEC temperature control can achieve precise control of high and low temperatures, the patent CN114199821A discloses a low-power temperature control method for adjusting the wavelength of a QCL laser to match different absorption peaks. Different absorption peaks are selected by adopting a method in which the temperature difference between the ambient temperature and the laser temperature corresponding to the absorption peak is minimized, and the laser wavelength is stabilized at different absorption peaks by TEC, so that the power consumption required by the laser in the entire operating temperature range is minimized, resulting in the reduction of the power consumption of the entire gas sensor. However, the cost of using TEC chips in lasers is very high, which seriously restricts civilian scenarios. Although ordinary heating resistors are low in cost, when facing the detection of gases to be tested with high and low temperature absorption peaks, the laser can be quickly heated to a high temperature target temperature according to the ambient temperature. For example, the patent CN116095891A discloses a laser temperature control device, method and microcontroller, which controls the laser to reach the target operating temperature through a heating wire. In the embodiment of the patent, the target operating temperature of the laser is 60°C. If the laser works at this higher temperature for a long time, the life decay rate is faster than at room temperature, and it will also affect the performance of the sensor. In view of this situation, technicians in this field usually think that the low-temperature absorption peak of the laser can be switched according to the ambient temperature, and accordingly the laser operating temperature needs to be lowered to the low-temperature target temperature. However, since the heating resistor can only actively control the temperature rise in one direction, cooling can only be achieved through passive heat dissipation. This process takes a long time and cannot be detected in time when there is a dangerous gas leak.

[0004] In summary, the technical problem to be solved by the present invention is that when ordinary heating resistors are used as temperature control components of laser gas sensors, the laser is kept at high operating temperature for a long time, which results in the attenuation of the laser life and sensor detection accuracy. Summary of the invention

[0005] The purpose of the present invention is to provide a laser gas sensor and a gas detection method in order to solve the problem that when an ordinary heating resistor is used as a temperature control component of a laser gas sensor, the laser is at a high temperature for a long time, which will cause the laser life and sensor detection accuracy to decay.

[0006] The above object of the present invention is achieved through the following technical solutions:

[0007] A laser gas sensor, characterized in that it comprises: a laser for emitting a laser signal; a laser temperature control circuit, comprising a first temperature sensor, the laser temperature control circuit being connected to the laser and being used to control and adjust the temperature of the laser so that the laser emits a laser signal of a specific wavelength; a gas chamber for allowing the gas to flow; a photoelectric detector, the photoelectric detector being used to convert the laser signal of the gas to be measured that has passed through the gas chamber into an electrical signal; a processing unit, being connected to the photoelectric detector and being used to process the electrical signal converted by the photoelectric detector to obtain a concentration value of the gas to be measured;

[0008] The laser comprises a tube holder, a carrier board, a laser chip, a heating resistor, a second temperature sensor, a heat insulating layer and a tube cap; the laser has high and low temperature absorption peak wavelengths for the gas to be measured;

[0009] The carrier is arranged on the tube holder through a heat insulation layer; the laser chip is arranged on the carrier for emitting an optical signal; the heating resistor is arranged on the carrier for heating the laser chip;

[0010] The thermal conductivity of the material of the heat insulation layer is smaller than that of the material of the carrier plate, so as to realize rapid heating and heat dissipation of the laser; the second temperature sensor is arranged on the carrier plate, and is used for the real-time internal temperature of the laser;

[0011] The first temperature sensor is used to obtain the ambient temperature; the tube cap connected to the tube seat is used to package the laser.

[0012] Optionally, the heat insulation layer of the laser is made of a silicon wafer, silicon oxide or silicate material with low thermal conductivity, and the thickness of the heat insulation layer is 0.2-1 mm.

[0013] Optionally, the laser further includes a reflector, which is placed on the carrier and is used to reflect the light emitted by the laser chip into the air chamber cavity of the sensor.

[0014] Optionally, the laser is a VSCEL laser or a DFB laser.

[0015] Optionally, the air chamber is a counter-reflection air chamber, a single reflection air chamber or a multi-return air chamber.

[0016] Optionally, the laser tube cap is encapsulated with a gas to be tested with a concentration of 0-100% VOL or a pure inert gas.

[0017] Optionally, the tube cap of the photoelectric detector is encapsulated with a gas to be detected with a concentration of 0-100% VOL or a pure inert gas.

[0018] A gas detection method of a laser gas sensor, wherein the laser gas sensor includes at least one high-temperature absorption peak and at least one low-temperature absorption peak for the gas to be detected, characterized in that the method comprises the following steps:

[0019] S1: Get the current ambient temperature T3; set the operating temperature of the laser in the high temperature peak working mode to T1, and the operating temperature in the low temperature peak working mode to T2;

[0020] S2: Determine the working mode of the laser according to the current ambient temperature T3;

[0021] S21: When the laser is in the high temperature peak working mode: if the ambient temperature T3 < the threshold temperature A, the PID fast temperature control method is used to quickly switch the laser to the low temperature peak working mode; if the ambient temperature T3 ≥ the threshold temperature A, the high temperature peak working mode is maintained;

[0022] S22: When the laser is in the low temperature peak working mode: if the ambient temperature T3>threshold temperature B, the laser is quickly switched to the high temperature peak mode by using the PID fast temperature control method; if the ambient temperature T3≤threshold temperature B, the low temperature peak working mode is maintained;

[0023] S3: Obtain the gas to be measured, and detect the gas to be measured by a laser gas sensor according to the working mode of the laser.

[0024] Optionally, the threshold temperature A<threshold temperature B<operating temperature T2.

[0025] Optionally, the PID fast temperature control method is an expert PID control method, and the implementation steps of the PID fast temperature control method are as follows:

[0026] Acquire the real-time internal temperature of the laser through a second temperature sensor;

[0027] Let e(k) = target laser operating temperature - laser internal real-time temperature;

[0028] Define e(k), e(k-1), and e(k-2) to represent the deviation value at the current sampling moment, the deviation value at the previous sampling moment, and the deviation value at the previous two sampling moments, respectively;

[0029] Define de(k) = e(k)-e(k-1) and de(k-1) = e(k-1)-e(k-2) to represent the derivative of the deviation value at the current sampling moment and the derivative of the deviation value at the previous moment, respectively;

[0030] When |e(k)|>M1, it indicates that there is a large deviation in the system. Regardless of whether the deviation change trend increases or decreases, a quick response should be made to the deviation, and the PID controller outputs at full scale to shorten the system response time and minimize the absolute value of the deviation to the greatest extent;

[0031] When e(k)×de(k)>0, it indicates that the deviation has an increasing trend, or when the deviation reaches the preset value, the change trend is zero;

[0032] When |e(k)|>M2, it indicates that the deviation value is large, and stronger control is performed through the system controller to make the absolute value of the deviation tend to decrease in order to achieve the effect of reducing the absolute value of the deviation;

[0033] When |e(k)|<M2, the system controller adopts a general control output;

[0034] When e(k)×de(k)<0, de(k)×de(k-1)>0 or e(k)=0, it indicates that the absolute value of the deviation changes in the decreasing direction, or the system has reached a steady state, and the output of the system controller remains unchanged;

[0035] When e(k)×de(k)<0 and de(k)×de(k-1)<0, it indicates that the deviation is in an extreme value state, as follows:

[0036] If |e(k)|>M2, the system controller adopts a stronger control output;

[0037] If |e(k)|<M2, the system controller adopts a weaker control output; M1 and M2 are preset thresholds.

[0038] The beneficial effects brought by the technical solution provided by the present invention are:

[0039] A laser gas sensor based on a common heating resistor is proposed to realize a gas detection method of fast peak cutting of the laser gas sensor. The working temperature of the laser is changed according to the ambient temperature, switching to the low temperature peak in a low temperature environment and switching to the high temperature peak in a high temperature environment. While meeting the measurement performance, the aging speed of the laser is reduced. The high and low temperature peak switching algorithm is adopted to reduce the aging speed of the laser; at the same time, different linear relationships are used in the two modes to ensure the accuracy of the concentration; in terms of structure, the heating and heat dissipation speeds are accelerated by designing a low thermal conductivity insulation block, and the PID control algorithm is improved to speed up the waiting time to enter the measurement state after switching the mode. After the above improvements, the service life of the laser is effectively increased. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] The present invention will be further described below with reference to the accompanying drawings and embodiments, in which:

[0041] Figure 1 This is a first laser structure diagram of a laser gas sensor in an embodiment of the present invention;

[0042] Figure 2 A second laser structure diagram of the laser gas sensor in an embodiment of the present invention;

[0043] Figure 3 is a step diagram of a rapid peak cutting method of a laser gas sensor in an embodiment of the present invention;

[0044] Figure 4 The rapid peak cutting method of the laser gas sensor in the embodiment of the present invention is Linear graphs of gas concentration in high temperature peak and low temperature peak modes;

[0045] Figure 5 It is a PID fast temperature control logic diagram of the fast peak cutting method of the laser gas sensor in the embodiment of the present invention;

[0046] Figure 6 It is a timing diagram of the PID fast temperature control strategy of the fast peak cutting method of the laser gas sensor in the embodiment of the present invention;

[0047] Figure 7 is a temperature rise control curve diagram of a rapid peak cutting method of a laser gas sensor in an embodiment of the present invention;

[0048] Figure 8 It is a temperature reduction control curve diagram of the rapid peak cutting method of the laser gas sensor in the embodiment of the present invention. DETAILED DESCRIPTION

[0049] In order to have a clearer understanding of the technical features, purposes and effects of the present invention, specific embodiments of the present invention are now described in detail with reference to the accompanying drawings.

[0050] A laser gas sensor in an embodiment of the present invention comprises: a laser for emitting a laser signal; a laser temperature control circuit, comprising a first temperature sensor, the laser temperature control circuit being connected to the laser and being used to control and adjust the temperature of the laser so that the laser emits a laser signal of a specific wavelength; a gas chamber for allowing the gas to flow; a photoelectric detector, the photoelectric detector being used to convert the laser signal of the gas to be measured that has passed through the gas chamber into an electrical signal; a processing unit, being connected to the photoelectric detector and being used to process the electrical signal converted by the photoelectric detector to obtain a concentration value of the gas to be measured;

[0051] The laser comprises a tube holder, a carrier board, a laser chip, a heating resistor, a second temperature sensor, a heat insulating layer and a tube cap; the laser has high and low temperature absorption peak wavelengths for the gas to be measured;

[0052] The carrier is arranged on the tube holder through a heat insulation layer; the laser chip is arranged on the carrier for emitting an optical signal; the heating resistor is arranged on the carrier for heating the laser chip;

[0053] The thermal conductivity of the material of the heat insulation layer is smaller than that of the material of the carrier plate, so as to realize rapid heating and heat dissipation of the laser; the second temperature sensor is arranged on the carrier plate, and is used for the real-time internal temperature of the laser;

[0054] The first temperature sensor is used to obtain the ambient temperature; the tube cap connected to the tube seat is used to package the laser.

[0055] The heat insulation layer of the laser is made of silicon wafer, silicon oxide or silicate material with low thermal conductivity.

[0056] The laser also includes a reflector, which is placed on the carrier and is used to reflect the light emitted by the laser chip into the air chamber of the sensor.

[0057] The air chamber is a counter-reflection air chamber, a single reflection air chamber or a multi-return air chamber.

[0058] The tube cap of the laser is encapsulated with a gas to be tested with a concentration of 0-100% VOL or pure inert gas.

[0059] The tube cap of the photoelectric detector is encapsulated with a gas to be detected with a concentration of 0-100% VOL or a pure inert gas.

[0060] In some specific implementations, the wavelength of the laser can be better locked to the absorption peak of the gas to be measured by encapsulating a certain concentration of the gas to be measured; and the photodetector can be protected from humidity and device oxidation by encapsulating pure inert gas.

[0061] The laser is a VSCEL laser or a DFB laser. In this embodiment, a DFB laser is selected. For the laser structure, please refer to Figure 1 , specifically comprising a tube base 1, a reflector 2, a carrier board 3, a laser chip 4, a heating resistor 5, a second temperature sensor 6, a heat insulation layer 7 and a tube cap 8;

[0062] The carrier board 3 is arranged on the tube base 1 through the heat insulation layer 7; the laser chip 4 is arranged on the carrier board 3 for emitting an optical signal; the heating resistor 5 is arranged on the carrier board 3 for heating the laser chip 4; the reflector 2 is placed on the carrier board 3 for reflecting the light emitted by the laser chip 4 into the air chamber cavity of the sensor;

[0063] The heat insulation layer 7 is made of low thermal conductivity material to achieve rapid heating and heat dissipation of the laser; the second temperature sensor 6 is arranged on the carrier board 3 and is used for the real-time internal temperature of the laser;

[0064] The first temperature sensor is used to obtain the ambient temperature; the tube cap 8 is connected to the tube base 1 to package the laser.

[0065] The heat insulation layer 7 of the laser is made of silicon wafer, silicon oxide or silicate material with low thermal conductivity.

[0066] Specifically, in this embodiment, the thermal insulation layer 7 is made of a low thermal conductivity silicon wafer with a thickness of 0.2-1 mm, preferably 0.4 mm in this embodiment. When the laser switches to the high temperature peak mode based on the ambient temperature, due to the low thermal conductivity effect of the thermal insulation layer 7, it can quickly heat up to the high temperature mode; when the laser switches to the low temperature peak mode based on the ambient temperature, due to the low thermal conductivity effect of the thermal insulation layer 7, the laser can achieve rapid heat dissipation to the environment.

[0067] Specifically, since a heating resistor is used as the temperature control component of the laser, it has a faster response speed when the temperature rises, but can only rely on passive heat dissipation when the temperature drops. Therefore, the sensor can quickly enter the measurement state when switching from the low temperature peak to the high temperature peak, but cannot do so when switching from the high temperature peak to the low temperature peak. It takes a long time to reach the low temperature peak operating temperature, which affects timely detection.

[0068] In another embodiment, in order to reduce the packaging production cost of the laser, the laser omits the reflector 2, such as Figure 2 As shown, the carrier 3, the heat insulating layer 7 and the tube seat 1 are arranged vertically, and the laser chip 4 is arranged on the carrier 3, so that the light emitting direction of the laser chip 4 is perpendicular to the tube seat surface, so the light can be directly emitted into the sensor chamber; the heat insulating layer is made of low thermal conductivity silicon oxide or silicate material, because its thermal conductivity is lower than the thermal conductivity of the material of the carrier 3, it is beneficial to the rapid heating and heat dissipation of the laser.

[0069] The present invention also provides a rapid peak cutting gas detection method based on the above-mentioned laser gas sensor. In this method, the laser gas sensor includes at least one high-temperature absorption peak and at least one low-temperature absorption peak for the gas to be detected, so that the laser gas sensor can be in one of the high-temperature peak working modes or one of the low-temperature peak working modes.

[0070] Please refer to Figure 3 , Figure 3 1 is a step diagram of a gas detection method for rapid peak cutting of a laser gas sensor in an embodiment of the present invention, including: the method includes the following steps:

[0071] S1: Get the current ambient temperature T3; set the operating temperature of the laser in the high temperature peak working mode to T1, and the operating temperature in the low temperature peak working mode to T2;

[0072] S2: Determine the working mode of the laser according to the current ambient temperature T3;

[0073] S21: When the laser is in the high temperature peak working mode: if the ambient temperature T3 < the threshold temperature A, the PID fast temperature control method is used to quickly switch the laser to the low temperature peak working mode; if the ambient temperature T3 ≥ the threshold temperature A, the high temperature peak working mode is maintained;

[0074] S22: When the laser is in the low temperature peak working mode: if the ambient temperature T3>threshold temperature B, the laser is quickly switched to the high temperature peak mode by using the PID fast temperature control method; if the ambient temperature T3≤threshold temperature B, the low temperature peak working mode is maintained;

[0075] S3: Obtain the gas to be measured, and detect the gas to be measured by a laser gas sensor according to the working mode of the laser.

[0076] Specifically, when the laser gas sensor works in a high temperature environment, it can quickly switch to the high temperature peak mode; when the sensor works in a low temperature environment, it can quickly switch to the low temperature peak mode, thereby reducing the time the laser works at high temperature and effectively increasing the service life of the laser gas sensor.

[0077] Specifically, since the heating resistor in the laser can generally only heat up in one direction, passive heat dissipation can only be relied upon to control the laser to switch from high temperature to low temperature. This process is usually relatively long, and when there is a leak of the gas to be tested, it cannot be detected in time. Therefore, the structural design of the laser's rapid heat dissipation and the PID rapid temperature control method are combined to achieve rapid switching of the laser between high and low working modes.

[0078] Specifically, the laser gas sensor designed by the present invention is often used for monitoring the leakage of methane gas in household gas, realizing long-life monitoring of the laser gas sensor. In this application scenario, the ambient temperature is usually -10~60°C. According to the absorption spectrum obtained from the HITRAN (high-resolution transmission molecular absorption database) database, when the operating temperature of the laser is set to 49°C and 74°C, the scanning signal can cover two absorption peaks at 1650.9nm and 1653.7nm respectively, but neither can be covered at the same time.

[0079] Since the size of the absorption peak will change after the laser switches to different working modes, using the same linear relationship to invert the concentration will lead to inaccurate measurement results. Therefore, the sensor needs to switch to different linear relationships according to different modes to ensure the accuracy of the concentration measurement after the mode is switched. In order to meet the above requirements, the sensor will be switched to the high temperature peak and low temperature peak modes for concentration calibration before leaving the factory. The linear relationship is as follows: Figure 4 shown.

[0080] After entering the measurement state, the sensor will select the corresponding linear relationship according to the current mode: high temperature peak mode selects high temperature peak linearity; low temperature peak mode selects low temperature peak linearity. This dynamic switching linearity method is used to ensure the measurement accuracy in both modes.

[0081] Specifically, in order to prevent the sensor from switching back and forth between working modes near a certain ambient temperature, the value of threshold A is usually set to be smaller than the value of threshold B. The threshold temperature A<threshold temperature B<working temperature T2.

[0082] The PID fast temperature control method is an expert PID control method. The temperature control logic is as follows: Figure 5 As shown, the implementation steps of the PID fast temperature control method are as follows:

[0083] Acquiring the real-time internal temperature of the laser by the second temperature sensor;

[0084] Let e(k) = target laser operating temperature - laser internal real-time temperature;

[0085] Define e(k), e(k-1), and e(k-2) to represent the deviation value at the current sampling moment, the deviation value at the previous sampling moment, and the deviation value at the previous two sampling moments, respectively;

[0086] Define de(k) = e(k)-e(k-1) and de(k-1) = e(k-1)-e(k-2) to represent the derivative of the deviation value at the current sampling moment and the derivative of the deviation value at the previous moment respectively;

[0087] When |e(k)| > M1, it indicates that there is a large deviation in the system. Regardless of whether the deviation trend is increasing or decreasing, a quick response should be made to the deviation. The PID controller outputs at full scale to shorten the system response time and minimize the absolute value of the deviation to the greatest extent.

[0088] Specifically, M1 represents a threshold determined according to the internal real-time temperature of the laser and the target temperature deviation. Output at full scale means that if it is heating up, the PID controls the heating resistor to heat at the maximum power; if it is cooling down, the heating resistor does not participate in the work, which is equivalent to cooling down to the greatest extent. At this time, it completely relies on the heat dissipation structure of the laser for heat dissipation.

[0089] When e(k) × de(k) > 0, it indicates that the deviation has an increasing trend, or when the deviation reaches the preset value, the change trend is zero.

[0090] When |e(k)| > M2, it indicates that the deviation value is large. The system controller performs stronger control to make the absolute value of the deviation change in the decreasing direction, achieving the effect of reducing the absolute value of the deviation.

[0091] Specifically, M2 < M1. M2 is the critical value between stronger control output and general control output, and the corresponding resistance temperature control power will be adjusted to prevent overshoot during heating or overshoot during cooling due to continuous heating at the maximum power or cooling at 0 power.

[0092] When |e(k)| < M2, the system controller adopts general control output.

[0093] When e(k) × de(k) < 0, de(k) × de(k - 1) > 0 or e(k) = 0, it indicates that the absolute value of the deviation changes in the decreasing direction, or the system has reached a steady state, and the output of the system controller remains unchanged.

[0094] When e(k) × de(k) < 0 and de(k) × de(k - 1) < 0, it indicates that the deviation is in an extreme value state, as follows:

[0095] If |e(k)| > M2, the system controller adopts stronger control output.

[0096] If |e(k)| < M2, the system controller adopts weaker control output; M1 and M2 are preset thresholds.

[0097] Specifically, improvements have been made to the stronger control part, weakening the role of integration and reducing the overshoot in the initial stage of regulation. The PID fast temperature control method is adopted, as Figure 6 shown.

[0098] In 0-3 seconds, the target temperature is set to 74°C; in 3-6 seconds, the target temperature is set to 49°C.

[0099] Figure 7 The temperature rise curve process control is shown: in the initial stage of control, the strategy number is 0, that is, the strongest control strategy is selected. Under the premise of ensuring that the temperature reaches the target temperature as soon as possible, the role of integration is weakened, the overshoot is reduced, and the highest temperature that can be reached during the adjustment process is controlled within 75°C; when the temperature stabilizes at around 74°C, the strategy number is 2, and the general control strategy is adopted to increase the stability of the control. In order to reduce the overshoot during the temperature rise process, the integral coefficients are set to 80, 100, 120, 150, and 200 respectively. The temperature rise curve is tested and it is found that when the integral coefficient is 200, the highest temperature in the process will exceed 80°C; when the integral coefficient is 80, although there is no overshoot, it takes too long for the temperature to enter the range of 73.8°C-74.2°C; finally, we choose 120 as the final value, and the highest temperature in the adjustment process is 75°C, and it can enter the target range of 73.8°C-74.2°C in 0.8 seconds.

[0100] Figure 8 The control of the cooling curve process is shown: in the early stage of control, the strategy number is 0, that is, the strongest control strategy is selected. Under the premise of ensuring that the temperature reaches the target temperature as soon as possible, the role of integration is weakened, the overshoot is reduced, and the lowest temperature that can be reached during the adjustment process is controlled within 48°C; when the temperature stabilizes at around 49°C, the strategy number is 2, and the general control strategy is adopted to increase the stability of the control. In order to reduce the overshoot during the cooling process, the integral coefficients are set to 80, 100, 120, 150, and 200 respectively. The cooling curve is tested and it is found that when the integral coefficient is 200, the lowest temperature in the process will be close to 46°C; when the integral coefficient is 80, although there is no overshoot, it takes too long for the temperature to enter the range of 48.8°C-49.2°C; finally, we choose 120 as the final value, and the lowest temperature of the adjustment process is 49°C, and it can enter the target range of 48.8°C-49.2°C in 0.8 seconds.

[0101] The present invention also discloses a computer-readable storage medium, which stores a plurality of instructions, and the instructions are suitable for a processor to load to execute the above-mentioned gas detection method of rapid peak cutting of a laser gas sensor.

[0102] The above are only exemplary embodiments of the present disclosure and cannot be used to limit the scope of the present disclosure. That is, any equivalent changes and modifications made according to the teachings of the present disclosure are still within the scope of the present disclosure. After considering the disclosure of the specification and practice, those skilled in the art will easily think of other embodiments of the present disclosure.

[0103] The present invention is intended to cover any variation, use or adaptation of the present disclosure, which follows the general principles of the present disclosure and includes common knowledge or customary technical means in the art not described in the present disclosure. The description and examples are to be regarded as exemplary only, and the scope and spirit of the present disclosure are defined by the claims.

Claims

1. A laser gas sensor, characterized in that: include: A laser, used for emitting a laser signal; A laser temperature control circuit, comprising a first temperature sensor, the laser temperature control circuit being connected to the laser and used to control and adjust the temperature of the laser so that the laser emits a laser signal of a specific wavelength; A gas chamber, used for the flow of the gas to be tested; A photoelectric detector, the photoelectric detector is used to convert the received laser signal of the gas to be measured passing through the gas chamber into an electrical signal; A processing unit, connected to the photoelectric detector, for processing the electrical signal converted by the photodetector to obtain the concentration value of the gas to be measured; The laser comprises a tube holder, a carrier board, a laser chip, a heating resistor, a second temperature sensor, a heat insulating layer and a tube cap; the laser has high and low temperature absorption peak wavelengths for the gas to be measured; The carrier is arranged on the tube seat through the heat insulation layer; the laser chip is arranged on a side of the carrier away from the heat insulation layer, and is used to emit an optical signal; the heating resistor is arranged on a side of the carrier away from the heat insulation layer, and is used to heat the laser chip; The thermal conductivity of the material of the heat insulation layer is less than the thermal conductivity of the material of the carrier; the second temperature sensor is arranged on a side of the carrier away from the heat insulation layer, and is used for the real-time internal temperature of the laser; The first temperature sensor is used to obtain the ambient temperature; the tube cap connected to the tube seat is used to package the laser.

2. A laser gas sensor as claimed in claim 1, characterized in that: The heat insulation layer of the laser is made of silicon wafer, silicon oxide or silicate material with low thermal conductivity.

3. A laser gas sensor as claimed in claim 1, characterized in that: The laser also includes a reflector, which is placed on the carrier and is used to reflect the light emitted by the laser chip into the air chamber of the sensor.

4. A laser gas sensor as claimed in claim 1, characterized in that: The laser is a VSCEL laser or a DFB laser.

5. A laser gas sensor as claimed in claim 1, characterized in that: The air chamber is a counter-reflection air chamber, a single reflection air chamber or a multi-return air chamber.

6. A laser gas sensor as claimed in claim 1, characterized in that: The tube cap of the laser is encapsulated with a gas to be tested with a concentration of 0-100% VOL or pure inert gas.

7. A laser gas sensor as claimed in claim 1, characterized in that: The tube cap of the photoelectric detector is encapsulated with a gas to be detected with a concentration of 0-100% VOL or a pure inert gas.

8. A gas detection method of a laser gas sensor, based on a laser gas sensor according to any one of claims 1 to 7, wherein the laser gas sensor comprises at least one high-temperature absorption peak and at least one low-temperature absorption peak for the gas to be detected, characterized in that: The method comprises the following steps: S1: Get the current ambient temperature T3; set the operating temperature of the laser in the high temperature peak working mode to T1, and the operating temperature in the low temperature peak working mode to T2; S2: Determine the working mode of the laser according to the current ambient temperature T3; S21: When the laser is in the high temperature peak working mode: if the ambient temperature T3 < the threshold temperature A, the PID fast temperature control method is used to quickly switch the laser to the low temperature peak working mode; if the ambient temperature T3 ≥ the threshold temperature A, the high temperature peak working mode is maintained; S22: When the laser is in the low temperature peak working mode: if the ambient temperature T3>threshold temperature B, the laser is quickly switched to the high temperature peak mode by using the PID fast temperature control method; if the ambient temperature T3≤threshold temperature B, the low temperature peak working mode is maintained; S3: Obtain the gas to be measured, and detect the gas to be measured by a laser gas sensor according to the working mode of the laser.

9. A gas detection method for a laser gas sensor as claimed in claim 8, characterized in that: The threshold temperature A<threshold temperature B<operating temperature T2.

10. A gas detection method for a laser gas sensor as claimed in claim 8, characterized in that: The PID fast temperature control method is an expert PID control method.

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