Gas detection laser assembly

Abstract

The invention discloses a gas detection laser assembly, and belongs to the technical field of gas detection. The gas detection laser assembly comprises: a housing having a detection chamber, the detection chamber being provided with a gas inlet; the laser chip is arranged in the detection cavity and is used for emitting detection laser; the detector chip is arranged in the detection cavity; the isolation structure is arranged between the laser chip and the detector chip; wherein the inner wall of the detection chamber is provided with a reflecting layer, and the reflecting layer is used for carrying out diffuse reflection on laser emitted by the laser chip; the isolation structure is used for preventing laser emitted by the laser chip from being directly received by the detector chip without diffuse reflection. The precision and performance of the gas detection laser assembly can be effectively improved while miniaturization and low cost of the gas detection laser assembly are guaranteed.

Description

Technical Field

[0001] The present disclosure relates to the technical field of gas detection, and particularly to a gas detection laser assembly. Background Art

[0002] With the development of laser technology, gas detection sensors have gradually changed from electrochemical catalytic combustion principle gas detection sensors (low accuracy, slow response, and many false alarms) to laser principle gas detection sensors (high accuracy, fast response, and few false alarms). The laser principle gas detection sensor is based on Tunable Diode Laser Absorption Spectroscopy (TDLAS) technology. By using the characteristics of the narrow linewidth and wavelength change with injection current of the tunable semiconductor laser, the wavelength of the laser is modulated to make the wavelength of the laser scan across the absorption peak of the gas molecules to be measured, so as to measure the concentration of gas molecules according to the absorption amount.

[0003] In related technologies, the laser principle gas detection sensor includes a laser, a detector, and a gas chamber. The laser and the detector are separately arranged at both ends of the gas chamber. Among them, the light emitting direction of the laser points straight to the detector. The laser emitted by the laser passes through the gas chamber, contacts the gas to be measured, and then enters the detector for detection. The optical path of the laser from the laser to the detector is a linear optical path.

[0004] However, since the longer the optical path in TDLAS technology, the higher the detection accuracy, and the optical path of the laser from the laser to the detector is a linear optical path, this will result in a large distance between the separately arranged laser and detector when high accuracy needs to be achieved, the size of the gas detection sensor is large, and the cost is high; when miniaturization and low cost need to be achieved, the optical path of the laser is short, and the accuracy of the gas detection sensor is low. Summary of the Invention

[0005] The present disclosure provides a gas detection laser assembly, which can effectively improve the accuracy and performance of the gas detection laser assembly while ensuring the miniaturization and low cost of the gas detection laser assembly. The technical solution at least includes the following solutions:

[0006] On the one hand, a gas detection laser assembly is provided, including: a housing having a detection chamber with an air inlet provided thereon; a laser chip disposed in the detection chamber for emitting detection laser; a detector chip disposed in the detection chamber; and an isolation structure disposed between the laser chip and the detector chip; wherein, a reflection layer is provided on the inner wall of the detection chamber, and the reflection layer is used for diffusely reflecting the laser emitted by the laser chip; the isolation structure is used for blocking the laser emitted by the laser chip from being directly received by the detector chip without diffuse reflection.

[0007] Optionally, the surface roughness of the reflective layer is greater than 1.6 μm.

[0008] Optionally, the material for making the reflective layer is nickel or gold.

[0009] Optionally, the gas detection laser assembly further includes a dust-proof filter screen, which is arranged in the detection chamber and at the air inlet, and the dust-proof filter screen is made of stainless steel metal weaving.

[0010] Optionally, the housing includes a base and a cap. The base is used to carry the laser chip, the detector chip and the isolation structure; the cap is arranged on the base, and the air inlet is arranged on the cap.

[0011] Optionally, the gas detection laser assembly further includes a heat insulation structure and a heating resistor. The heat insulation structure is arranged in the detection chamber and on the base; the heating resistor is located on the surface of the heat insulation structure away from the base; the isolation structure is a thermistor, and the isolation structure and the laser chip are arranged at intervals on the surface of the heating resistor away from the heat insulation structure.

[0012] Optionally, the heat insulation structure is fixedly connected to the base by solder or conductive adhesive; the heating resistor is fixedly connected to the heat insulation structure by solder or conductive adhesive; the isolation structure is fixedly connected to the heating resistor by solder or conductive adhesive; the laser chip is fixedly connected to the heating resistor by solder or conductive adhesive.

[0013] Optionally, at least one of a waterproof film and a narrowband filter film is plated on the surface of the detector chip.

[0014] Optionally, the laser chip is a distributed feedback laser chip or a vertical cavity surface emitting laser chip.

[0015] Optionally, the volume of the detection chamber is 0.5 mL to 1.5 mL.

[0016] The beneficial effects brought by the technical solutions provided by the embodiments of the present disclosure at least include:

[0017] In the embodiments of the present disclosure, by integrally packaging the laser chip, the detector chip, and the isolation structure in the detection chamber of the housing, the integration degree of the gas detection laser component is improved, which is beneficial to the miniaturization of the gas detection laser component and cost reduction. An air inlet is provided on the detection chamber, and the gas to be detected can enter the detection chamber through the air inlet. The inner wall of the detection chamber is provided with a reflective layer, which can diffusely reflect the laser emitted by the laser chip. The isolation structure is arranged between the laser chip and the detector chip, and the isolation structure can isolate the laser chip and the detector chip, blocking the laser emitted by the laser chip from being directly received by the detector chip without being diffusely reflected by the reflective layer, that is, reducing the probability of the laser with a non-ideal optical path being received by the detector chip, thereby ensuring that the gas detection laser component has a relatively high signal-to-noise ratio and good reliability. In this way, the detection laser emitted by the laser chip can pass through the diffuse reflection of the reflective layer in the detection chamber and contact the gas to be detected, and finally be received by the detector chip. The diffuse reflection can effectively increase the optical path of the laser. Since the absorbance of light passing through the gas in the TDLAS technology is proportional to the gas concentration and the optical path, that is, the longer the optical path, the higher the detection accuracy. Therefore, while ensuring the miniaturization and low cost of the gas detection laser component, the accuracy and performance of the gas detection laser component can be effectively improved. Description of the Drawings

[0018] In order to more clearly illustrate the technical solutions in the embodiments of the present disclosure, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the following drawings are only some embodiments of the present disclosure. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0019] Figure 1 FIG. is a schematic structural diagram of a gas detection laser component provided by an embodiment of the present disclosure;

[0020] Figure 2 FIG. is a schematic optical path diagram of a gas detection laser component provided by an embodiment of the present disclosure.

[0021] Reference Signs:

[0022] 1: Housing; 10: Base; 20: Tube Cap; 21: Detection Chamber; 22: Air Inlet; 30: Laser Chip; 40: Detector Chip; 50: Isolation Structure; 60: Dust Filter; 70: Heat Insulation Structure; 80: Heating Resistor; 90: Pin. Detailed Embodiments

[0023] Unless otherwise defined, the technical terms or scientific terms used herein shall have the ordinary meanings as understood by those of ordinary skill in the art to which this disclosure pertains. The terms "first", "second", "third" and similar terms used in the specification and claims of this patent application of the present disclosure do not denote any order, quantity or importance, but are only used to distinguish different components. Similarly, terms such as "a" or "an" do not denote a quantity limitation, but mean that there is at least one. Terms such as "comprising" or "including" mean that the elements or items appearing before "comprising" or "including" cover the elements or items listed after "comprising" or "including" and their equivalents, and do not exclude other elements or items. Terms such as "connected" or "coupled" are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. Terms such as "upper", "lower", "left", "right" are only used to indicate relative positional relationships, and when the absolute position of the object being described changes, the relative positional relationships may also change accordingly. A and / or B means there are three cases: A, B, and A and B.

[0024] To make the objectives, technical solutions and advantages of the present disclosure clearer, the embodiments of the present disclosure will be further described in detail below with reference to the accompanying drawings.

[0025] Figure 1 It is a schematic structural diagram of a gas detection laser assembly provided by an embodiment of the present disclosure. As Figure 1 shown, the gas detection laser assembly includes: a housing 1, the housing 1 having a detection chamber 21, and an air inlet 22 is provided on the detection chamber 21; a laser chip 30, disposed in the detection chamber 21 for emitting detection laser; a detector chip 40, disposed in the detection chamber 21; and an isolation structure 50, disposed between the laser chip 30 and the detector chip 40.

[0026] Wherein, a reflective layer (not shown in the figure) is provided on the inner wall of the detection chamber 21, and the reflective layer is used for diffusely reflecting the laser emitted by the laser chip 30. The isolation structure 50 is used to block the laser emitted by the laser chip 30 from being directly received by the detector 40 chip without diffuse reflection.

[0027] In the embodiment of the present disclosure, by integrally encapsulating the laser chip 30, the detector chip 40 and the isolation structure 50 in the detection chamber 21 of the housing 1, the integration degree of the gas detection laser assembly is improved, which is beneficial to realizing the miniaturization of the gas detection laser assembly and is beneficial to reducing costs.

[0028] Figure 2 It is a schematic optical path diagram of a gas detection laser assembly provided by an embodiment of the present disclosure, Figure 2 and the arrows inFigure 1 and Figure 2 On the detection chamber 21, an air inlet 22 is provided. The gas to be measured can enter the detection chamber 21 from the air inlet 22. The inner wall of the detection chamber 21 is provided with a reflective layer, and the reflective layer can perform diffuse reflection on the laser emitted by the laser chip 30. The isolation structure 50 is arranged between the laser chip 30 and the detector chip 40. The isolation structure 50 can isolate the laser chip 30 and the detector chip 40, and block the laser emitted by the laser chip 30 from being directly received by the detector chip 40 without passing through the diffuse reflection of the reflective layer. That is to say, it reduces the probability that the laser with a non-ideal optical path is received by the detector chip 40, thereby ensuring that the gas detection laser assembly has a relatively high signal-to-noise ratio and good reliability. In this way, the detection laser emitted by the laser chip 30 can pass through the diffuse reflection of the reflective layer in the detection chamber 21 and contact the gas to be measured, and finally be received by the detector chip 40. The diffuse reflection can effectively increase the optical path of the laser. For example, after diffuse reflection, the optical path of the laser can be amplified to 10 to 40 times the size of the detection chamber 21. Since the absorbance of light passing through the gas in the TDLAS technology is proportional to the gas concentration and the optical path, that is, the longer the optical path, the higher the detection accuracy. Therefore, while ensuring the miniaturization and low cost of the gas detection laser assembly, the accuracy and performance of the gas detection laser assembly can be effectively improved.

[0029] Moreover, the diffuse reflection is insensitive to the optical path displacement, and there is no need to precisely adjust the light-emitting angle of the laser chip 30. The laser emitted by the laser chip 30 is diffusely reflected by the reflective layer on the inner wall of the detection chamber 21 and will finally be received by the detector chip 40. Therefore, the assembly difficulty of the gas detection laser assembly can be effectively reduced, and the structure of the gas detection laser assembly can be simplified.

[0030] Exemplarily, the light-emitting direction of the laser chip 30 is away from the isolation structure 50. The isolation structure 50 can isolate the backlight generated by the laser chip 30 and block the backlight from being directly received by the detector chip 40 without passing through the diffuse reflection of the reflective layer.

[0031] Optionally, the housing 1 includes a base 10 and a cap 20. The base 10 is used to carry the laser chip 30, the detector chip 40, and the isolation structure 50. The cap 20 is arranged on the base 10, and the air inlet 22 is arranged on the cap 20. By providing the base 10 and the cap 20, it is beneficial to reduce the assembly difficulty of the gas detection laser assembly.

[0032] Exemplarily, the air inlet 22 is arranged on the top surface of the cap 20 away from the base 10.

[0033] Exemplarily, the cap 20 is fixedly connected to the base 10 by resistance welding.

[0034] In other embodiments, the housing 1 may also be an integrally formed structure, and the present disclosure does not limit this.

[0035] Exemplarily, the gas detection laser assembly is a transistor outline (TO) package assembly. For example, the shape of the tube cap 20 may be a hollow cylindrical shape. When the diameter of the tube cap 20 is 1 cm, the optical path of the laser after diffuse reflection can be amplified to 10 cm to 40 cm.

[0036] In other embodiments, the shape of the tube cap 20 may also be set to other shapes according to needs. For example, the shape of the tube cap 20 may be a hollow cuboid shape or a hollow hemispherical shape, etc., and the present disclosure does not limit this.

[0037] Optionally, the volume of the detection chamber 21 is 0.5 mL to 1.5 mL. The relatively small volume of the detection chamber 21 can ensure the miniaturization of the gas detection laser assembly, which is beneficial to cost reduction.

[0038] Exemplarily, the volume of the detection chamber 21 may be 0.5 mL, 1 mL or 1.5 mL, etc.

[0039] Exemplarily, the surface of the reflective layer is a rough surface with a plurality of protrusions.

[0040] Optionally, the surface roughness of the reflective layer is greater than 1.6 μm. The relatively large surface roughness of the reflective layer can ensure a good diffuse reflection effect of the laser emitted by the laser chip 30, thereby effectively increasing the optical path of the laser and improving the accuracy and performance of the gas detection laser assembly.

[0041] Exemplarily, the surface roughness of the reflective layer may be 1.8 μm, 2 μm or 2.2 μm, etc.

[0042] Optionally, the material for making the reflective layer is nickel or gold. Nickel and gold have relatively high reflectivity. Using nickel or gold to make a rough-surfaced reflective layer can effectively achieve the diffuse reflection effect. For example, a layer of bright nickel with a rough surface or a layer of gold with a rough surface can be plated on the inner wall of the tube cap 20 to form the reflective layer.

[0043] In other embodiments, the material for making the reflective layer may also be a high-reflectivity all-dielectric reflective film material, etc., and the present disclosure does not limit this.

[0044] Optionally, the gas detection laser assembly further includes a dust-proof filter screen 60. The dust-proof filter screen 60 is disposed in the detection chamber 21 and at the air inlet 22. The dust-proof filter screen 60 is made of stainless steel metal woven fabric. When the gas to be detected enters the detection chamber 21 from the air inlet 22, it will pass through the dust-proof filter screen 60 for filtration. The dust-proof filter screen 60 made of stainless steel metal woven fabric has characteristics such as acid resistance, alkali resistance, high temperature resistance, and corrosion resistance, and can effectively filter dust and oil fumes, etc., reducing the probability of dust and oil fumes entering the detection chamber 21 and interfering with the internal optical path, thereby ensuring better reliability, accuracy, and performance of the gas detection laser assembly.

[0045] Exemplarily, the dust-proof filter screen 60 is press-fitted with an interference fit on the inner wall of the tube cap 20 and at the air inlet 22.

[0046] Optionally, the gas detection laser assembly further includes a heat insulation structure 70 and a heating resistor 80. The heat insulation structure 70 is disposed in the detection chamber 21 and on the tube base 10. The heating resistor 80 is located on the surface of the heat insulation structure 70 away from the tube base 10. The isolation structure 50 is a thermistor, and the isolation structure 50 and the laser chip 30 are arranged at intervals on the surface of the heating resistor 80 away from the heat insulation structure 70. Since the peak wavelength of the laser chip 30 may be affected by the ambient temperature, heating is performed through the heating resistor 80, and the temperature is sensed through the thermistor. The two cooperate to achieve temperature control of the laser chip 30, thereby improving the linearity stability of the laser chip 30 at different ambient temperatures. Moreover, when high-temperature control is performed through the heating resistor 80 and the thermistor, the high-temperature condition can reduce the interference of water vapor on the laser emitted by the laser chip 30. The heat insulation structure 70 can reduce the influence of the temperatures of the heating resistor 80 and the thermistor on the temperature of the tube base 10.

[0047] Exemplarily, the heating resistor 80 and the thermistor can perform temperature control on the laser chip 30 so that the laser chip 30 operates at a constant temperature. For example, this constant temperature can be 65 °C.

[0048] Exemplarily, the heat insulation structure 70 is fixedly connected to the tube base 10 through solder or conductive adhesive. The heating resistor 80 is fixedly connected to the heat insulation structure 70 through solder or conductive adhesive. The isolation structure 50 is fixedly connected to the heating resistor 80 through solder or conductive adhesive. The laser chip 30 is fixedly connected to the heating resistor 80 through solder or conductive adhesive. Reliable fixing effects and heat conduction effects can be achieved through solder or conductive adhesive.

[0049] Exemplarily, the detector chip 40 is fixedly connected to the tube base 10 through solder or conductive adhesive.

[0050] Exemplarily, the solder can be AuSn solder. For example, welding can be performed through AuSn solder.

[0051] Exemplarily, the conductive adhesive may be silver paste. For example, bonding can be performed through silver paste.

[0052] In the embodiments of the present disclosure, the isolation structure 50 being a thermistor can simultaneously play the roles of blocking the backlight and temperature control. In other embodiments, for example, under the condition of stable ambient temperature, the heat insulation structure 70 and the heating resistor 80 may not be provided either. The isolation structure 50 is a light-shielding plate, and the isolation structure 50 only plays the role of blocking the backlight. The isolation structure 50 and the laser chip 30 are arranged at intervals on the surface of the header 10 close to the tube cap 20. The present disclosure does not limit this.

[0053] Optionally, at least one of a waterproof film and a narrowband filter film is plated on the surface of the detector chip 40. The waterproof film can reduce the interference of water vapor on the laser received by the detector chip 40, and the narrowband filter film can reduce the probability of interference of non-ideal characteristic spectra such as natural light on the signal-to-noise ratio of the gas detection laser assembly, ensuring better reliability of the gas detection laser assembly.

[0054] Exemplarily, a laminated waterproof film and a narrowband filter film are plated on the surface of the detector chip 40.

[0055] In other embodiments, only one of the waterproof film and the narrowband filter film may also be plated on the surface of the detector chip 40. The present disclosure does not limit this.

[0056] Optionally, the laser chip 30 is a Distributed Feedback (DFB) laser chip or a Vertical-Cavity Surface-Emitting Laser (VCSEL) chip. The DFB laser chip and the VCSEL chip can emit laser with a single wavelength and a high side mode suppression ratio, which is beneficial to selecting an absorption peak that only responds to the gas to be measured (characteristic gas) and has no interference from other gases as the peak wavelength of the laser. Since the characteristic gas generates signals based on spectra and is insensitive to power, interference from water vapor, oil stains, dust, etc. on the gas detection laser assembly can be reduced during actual use.

[0057] Exemplarily, the peak wavelength of the laser chip 30 can be set according to the characteristic spectral absorption peak of the gas to be measured. The gas detection laser can detect various gases to be measured. For example, the gas to be measured can be methane, and the peak wavelength of the laser chip 30 can be the characteristic spectral absorption peak of methane.

[0058] Optionally, the gas detection laser assembly further includes a plurality of pins 90, and the plurality of pins 90 are arranged on the side of the header 10 away from the tube cap 20. Arranging the pins 90 is beneficial for the structure in the detection chamber 21 to be electrically connected to an external system.

[0059] In an embodiment of the present disclosure, the gas detection laser assembly may include eight pins 90 ( Figure 1 and Figure 2 is a schematic cross-sectional structure diagram, and only six pins 90 are shown), and the eight pins 90 are electrically connected to the positive and negative electrodes of the laser chip 30, the detector chip 40, the thermistor, and the heating resistor 80 by wire bonding.

[0060] In other embodiments, the number of pins 90 can be adjusted according to actual needs. For example, a larger or smaller number of pins 90 can be set, etc. The present disclosure does not limit this.

[0061] The above are only optional embodiments of the present disclosure and are not intended to limit the present disclosure. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present disclosure shall be included within the protection scope of the present disclosure.

Claims

1. A gas detection laser assembly, characterized in that: include: A housing, wherein the housing has a detection chamber, and an air inlet is provided on the detection chamber; A laser chip is disposed in the detection chamber and is used to emit detection laser; A detector chip is disposed in the detection chamber; and An isolation structure, disposed between the laser chip and the detector chip; The inner wall of the detection chamber is provided with a reflective layer, and the reflective layer is used to diffusely reflect the laser emitted by the laser chip; the isolation structure is used to prevent the laser emitted by the laser chip from being directly received by the detector chip without diffuse reflection.

2. The gas detection laser assembly according to claim 1, characterized in that The surface roughness of the reflective layer is greater than 1.6 μm.

3. The gas detection laser assembly according to claim 2, characterized in that: The reflective layer is made of nickel or gold.

4. The gas detection laser assembly according to any one of claims 1 to 3, characterized in that: The gas detection laser assembly further comprises a dustproof filter, which is arranged in the detection chamber and located at the air inlet, and is made of stainless steel metal weaving.

5. The gas detection laser assembly according to any one of claims 1 to 3, characterized in that: The shell includes a tube seat and a tube cap. The tube seat is used to carry the laser chip, the detector chip and the isolation structure; The tube cap is arranged on the tube seat, and the air inlet is arranged on the tube cap.

6. The gas detection laser assembly according to claim 5, characterized in that The gas detection laser assembly also includes a heat insulation structure and a heating resistor, The heat insulation structure is arranged in the detection chamber and located on the tube seat; The heating resistor is located on the surface of the thermal insulation structure away from the tube seat; The isolation structure is a thermistor, and the isolation structure and the laser chip are arranged at intervals on a surface of the heating resistor away from the thermal isolation structure.

7. The gas detection laser assembly according to claim 6, characterized in that The heat insulation structure is fixedly connected to the tube seat by solder or conductive glue; The heating resistor is fixedly connected to the thermal insulation structure via solder or conductive adhesive; The isolation structure is fixedly connected to the heating resistor via solder or conductive glue; The laser chip is fixedly connected to the heating resistor via solder or conductive glue.

8. A gas detection laser assembly according to any one of claims 1 to 3 and claims 6 to 7, characterized in that The surface of the detector chip is coated with at least one of a waterproof film and a narrow-band filter film.

9. A gas detection laser assembly according to any one of claims 1 to 3 and claims 6 to 7, characterized in that The laser chip is a distributed feedback laser chip or a vertical cavity surface emitting laser chip.

10. A gas detection laser assembly according to any one of claims 1 to 3 and claims 6 to 7, characterized in that The volume of the detection chamber is 0.5 mL to 1.5 mL.

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