Gas detection laser assembly

Abstract

A gas detection laser assembly is disclosed, belonging to the field of gas detection technology. The gas detection laser assembly includes: a housing having a detection chamber with an air inlet; a laser chip disposed within the detection chamber for emitting a detection laser; a detector chip disposed within 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 for diffuse reflection of the laser emitted by the laser chip; the isolation structure prevents the laser emitted by the laser chip from being directly received by the detector chip without diffuse reflection. This disclosure effectively improves the accuracy and performance of the gas detection laser assembly while ensuring its miniaturization and low cost.

Description

Technical Field

[0001] This disclosure relates to the field of gas detection technology, and in particular to a gas detection laser component. Background Technology

[0002] With the development of laser technology, gas detection sensors have gradually shifted 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 fewer false alarms). Laser principle gas detection sensors are based on tunable diode laser absorption spectroscopy (TDLAS) technology. Utilizing the narrow linewidth and wavelength variation of tunable diode lasers with injected current, the laser wavelength is modulated to scan across the absorption peaks of the gas molecules being measured, thereby allowing for the measurement of gas molecule concentration based on the absorption amount.

[0003] In related technologies, laser-based gas detection sensors include a laser, a detector, and a gas chamber, with the laser and detector separately positioned at opposite ends of the gas chamber. The laser emits light in a straight line towards the detector. The laser beam passes through the gas chamber, contacts the gas to be detected, and then enters the detector for detection. The optical path from the laser to the detector is a straight line.

[0004] However, since the longer the optical path in TDLAS technology, the higher the detection accuracy, the optical path from the laser to the detector is a straight optical path. This results in a larger distance between the separately set laser and detector when high accuracy is required, leading to a larger size and higher cost of the gas detection sensor; while when miniaturization and low cost are required, the optical path of the laser is shorter, resulting in lower accuracy of the gas detection sensor. Summary of the Invention

[0005] This disclosure provides a gas detection laser assembly that effectively improves the accuracy and performance of the gas detection laser assembly while ensuring its miniaturization and low cost. The technical solution includes at least the following:

[0006] On one hand, a gas detection laser assembly is provided, comprising: a housing having a detection chamber with an air inlet; a laser chip disposed within the detection chamber for emitting a detection laser; a detector chip disposed within the detection chamber; and an isolation structure disposed between the laser chip and the detector chip; wherein, the inner wall of the detection chamber is provided with a reflective layer for diffuse reflection of the laser emitted by the laser chip; and the isolation structure for preventing 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 reflective layer is made of nickel or gold.

[0009] Optionally, the gas detection laser assembly further includes a dust filter, which is disposed in the detection chamber and located at the air inlet, and the dust filter is made of stainless steel woven metal.

[0010] Optionally, the housing includes a tube base and a tube cap, the tube base being used to support the laser chip, the detector chip, and the isolation structure; the tube cap is disposed on the tube base, and the air inlet is disposed on the tube cap.

[0011] Optionally, the gas detection laser assembly further includes a heat insulation structure and a heating resistor. The heat insulation structure is disposed in the detection chamber and located on the tube seat. The heating resistor is located on the surface of the heat 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 the surface of the heating resistor away from the heat insulation structure.

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

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

[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 of the technical solutions provided in this disclosure include at least the following:

[0017] In this embodiment, by integrating the laser chip, detector chip, and isolation structure into a single detection chamber within the housing, the integration level of the gas detection laser assembly is improved, facilitating miniaturization and cost reduction. The detection chamber has an inlet, allowing the gas to be measured to enter. A reflective layer is provided on the inner wall of the chamber, diffusely reflecting the laser emitted by the laser chip. The isolation structure is positioned between the laser chip and the detector chip, isolating them and preventing the laser emitted from the laser chip from being directly received by the detector chip without diffuse reflection through the reflective layer. This reduces the probability of non-ideal optical path lasers being received by the detector chip, ensuring a high signal-to-noise ratio and good reliability for the gas detection laser assembly. This allows the detection laser emitted by the laser chip to undergo diffuse reflection within the detection chamber, come into contact with the gas to be measured, and ultimately be received by the detector chip. Diffuse reflection effectively increases the optical path of the laser. Since the absorption of light through a gas in TDLAS technology is proportional to the gas concentration and the optical path length, meaning that the longer the optical path length, the higher the detection accuracy, it is possible to effectively improve the accuracy and performance of gas detection laser components while ensuring miniaturization and low cost. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of this disclosure, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this disclosure. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a schematic diagram of the structure of a gas detection laser assembly provided in an embodiment of this disclosure;

[0020] Figure 2 This is a schematic diagram of the optical path of a gas detection laser component provided in an embodiment of this disclosure.

[0021] Figure label:

[0022] 1: Housing; 10: Tube seat; 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: Tube pin. Detailed Implementation

[0023] Unless otherwise defined, the technical or scientific terms used herein shall have the ordinary meaning understood by one of ordinary skill in the art to which this disclosure pertains. The terms “first,” “second,” “third,” and similar terms used in this patent application specification and claims do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Similarly, the terms “an” or “a” and similar terms do not indicate a quantity limitation, but rather indicate the presence of at least one. The terms “comprising” or “including” and similar terms mean that the element or object preceding “comprising” or “including” encompasses the element or object listed following “comprising” or “including” and its equivalents, and do not exclude other elements or objects. The terms “connected” or “linked” and similar terms are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. “Up,” “down,” “left,” “right,” etc., are used only to indicate relative positional relationships, which may change accordingly when the absolute position of the described object changes. A and / or B indicates the presence of three cases: A, B, and A and B.

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

[0025] Figure 1 This is a schematic diagram of the structure of a gas detection laser assembly provided in an embodiment of this disclosure. Figure 1 As shown, the gas detection laser assembly includes: a housing 1, the housing 1 having a detection chamber 21, the detection chamber 21 having an air inlet 22; 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] The inner wall of the detection chamber 21 is provided with a reflective layer (not shown in the figure), which is used to diffusely reflect the laser emitted by the laser chip 30. The isolation structure 50 is used to prevent the laser emitted by the laser chip 30 from being directly received by the detector chip 40 without diffuse reflection.

[0027] In this embodiment, by integrating the laser chip 30, detector chip 40, and isolation structure 50 into the detection chamber 21 of the housing 1, the integration of the gas detection laser component is improved, which is beneficial for miniaturization of the gas detection laser component and for reducing costs.

[0028] Figure 2 This is a schematic diagram of the optical path of a gas detection laser component provided in an embodiment of this disclosure. Figure 2 The arrows in the diagram illustrate the optical path of the laser in detection chamber 21. (See reference...) Figure 1 and Figure 2 The detection chamber 21 is equipped with an air inlet 22, through which the gas to be tested can enter the detection chamber 21. A reflective layer is provided on the inner wall of the detection chamber 21, which diffusely reflects the laser emitted by the laser chip 30. An isolation structure 50 is disposed between the laser chip 30 and the detector chip 40, isolating them and preventing the laser emitted by the laser chip 30 from being directly received by the detector chip 40 without diffuse reflection through the reflective layer. This reduces the probability of non-ideal optical path lasers being received by the detector chip 40, thus ensuring a high signal-to-noise ratio and good reliability for the gas detection laser assembly. In this way, the detection laser emitted by the laser chip 30 undergoes diffuse reflection within the detection chamber 21, comes into contact with the gas to be tested, and is ultimately received by the detector chip 40. Diffuse reflection effectively increases 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 absorption of light through a gas in TDLAS technology is proportional to the gas concentration and the optical path length, meaning that the longer the optical path length, the higher the detection accuracy, it is possible to effectively improve the accuracy and performance of gas detection laser components while ensuring miniaturization and low cost.

[0029] Furthermore, diffuse reflection is not sensitive to optical path displacement, so there is no need to precisely adjust the emission 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 is eventually received by the detector chip 40. Therefore, the assembly difficulty of the gas detection laser component can be effectively reduced and the structure of the gas detection laser component can be simplified.

[0030] For example, the light emission 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, preventing the backlight from being directly received by the detector chip 40 without diffuse reflection through the reflective layer.

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

[0032] For example, the air inlet 22 is located on the top surface of the cap 20 away from the seat 10.

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

[0034] In other embodiments, the housing 1 may also be a one-piece molded structure, and this disclosure does not limit this.

[0035] For example, the gas detection laser component is a transistor outline (TO) packaged component. For instance, the cap 20 can be a hollow cylinder, and when the diameter of the cap 20 is 1 cm, the optical path of the laser can be amplified to 10 cm to 40 cm after diffuse reflection.

[0036] In other embodiments, the shape of the cap 20 can also be set to other shapes as needed. For example, the shape of the cap 20 can be a hollow cuboid or a hollow hemisphere, etc. This disclosure does not limit it.

[0037] Optionally, the volume of the detection chamber 21 is 0.5 mL to 1.5 mL. The smaller volume of the detection chamber 21 ensures the miniaturization of the gas detection laser assembly, which helps to reduce costs.

[0038] For example, the volume of the detection chamber 21 can be 0.5 mL, 1 mL, or 1.5 mL, etc.

[0039] For example, the surface of the reflective layer is a rough surface with multiple protrusions.

[0040] Optionally, the surface roughness of the reflective layer is greater than 1.6 μm. A larger surface roughness of the reflective layer can ensure better diffuse reflection 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 component.

[0041] For example, the surface roughness of the reflective layer can be 1.8 μm, 2 μm, or 2.2 μm, etc.

[0042] Optionally, the reflective layer can be made of nickel or gold. Nickel and gold have high reflectivity, and using nickel or gold to create a rough-surfaced reflective layer can effectively achieve diffuse reflection. For example, a rough-surfaced bright nickel layer or a rough-surfaced gold layer can be plated on the inner wall of the cap 20 to form a reflective layer.

[0043] In other embodiments, the material used to fabricate the reflective layer may also be a highly reflective all-dielectric reflective film material, etc., and this disclosure does not limit this.

[0044] Optionally, the gas detection laser assembly also includes a dust filter 60, which is disposed within the detection chamber 21 and located at the air inlet 22. The dust filter 60 is made of stainless steel woven fabric. When the gas to be tested enters the detection chamber 21 from the air inlet 22, it will be filtered by the dust filter 60. The dust filter 60, made of stainless steel woven fabric, has properties such as acid resistance, alkali resistance, high temperature resistance, and corrosion resistance. It can effectively filter dust and fumes, reducing the probability of dust and fumes entering the detection chamber 21 and interfering with the internal optical path, thereby ensuring good reliability, accuracy, and performance of the gas detection laser assembly.

[0045] For example, the dust filter 60 is press-fitted into the inner wall of the cap 20 and located at the air inlet 22.

[0046] Optionally, the gas detection laser assembly also includes a heat insulation structure 70 and a heating resistor 80. The heat insulation structure 70 is disposed within the detection chamber 21 and located on the tube seat 10. The heating resistor 80 is located on the surface of the heat insulation structure 70 away from the tube seat 10. The isolation structure 50 is a thermistor, and the isolation structure 50 and the laser chip 30 are spaced apart 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 by the heating resistor 80 and sensing by the thermistor can achieve temperature control of the laser chip 30, thereby improving the linearity stability of the laser chip 30 under different ambient temperatures. Furthermore, when high-temperature temperature control is performed by the heating resistor 80 and the thermistor, the high-temperature conditions 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 temperature of the heating resistor 80 and the thermistor on the temperature of the tube seat 10.

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

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

[0049] For example, the detector chip 40 is fixedly connected to the socket 10 by solder or conductive adhesive.

[0050] For example, the solder can be AuSn solder. For instance, soldering can be performed using AuSn solder.

[0051] For example, the conductive adhesive can be silver paste. For instance, silver paste can be used for bonding.

[0052] In this embodiment, the isolation structure 50 is a thermistor that can simultaneously serve as a backlight shield and a temperature control unit. In other embodiments, for example, under stable ambient temperature conditions, the heat insulation structure 70 and the heating resistor 80 may not be provided; the isolation structure 50 may be a light-shielding plate, serving only to shield the backlight. The isolation structure 50 and the laser chip 30 are arranged at intervals on the surface of the tube base 10 near the tube cap 20. This disclosure does not impose any limitations on this arrangement.

[0053] Optionally, the surface of the detector chip 40 is coated with at least one of a waterproof film and a narrowband filter film. 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 non-ideal characteristic spectra such as natural light interfering with the signal-to-noise ratio of the gas detection laser component, thus ensuring better reliability of the gas detection laser component.

[0054] For example, the surface of the detector chip 40 is coated with a layered waterproof membrane and a narrowband filter membrane.

[0055] In other embodiments, the surface of the detector chip 40 may also be coated with only one of a waterproof film and a narrowband filter film, which is not a limitation of this disclosure.

[0056] Optionally, the laser chip 30 is a distributed feedback (DFB) laser chip or a vertical-cavity surface-emitting laser (VCSEL) chip. Both DFB and VCSEL chips can emit a single-wavelength laser with a high side-mode suppression ratio, which is advantageous for selecting an absorption peak that only reacts to the target gas (characteristic gas) and is free from interference from other gases as the laser's peak wavelength. Since the characteristic gas generates a signal based on its spectrum and is insensitive to power, interference from water vapor, oil, and dust on the gas detection laser component can be reduced in practical applications.

[0057] For example, 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 also includes multiple pins 90, which are located on the side of the base 10 away from the cap 20. The placement of the pins 90 facilitates electrical connection between the structure within the detection chamber 21 and external systems.

[0059] In this embodiment of the present disclosure, the gas detection laser component may include 8 pins 90 ( Figure 1 and Figure 2 The diagram shows a cross-sectional structure, with only 6 pins 90 shown. The other 8 pins 90 are electrically connected to the positive and negative terminals of the laser chip 30, detector chip 40, thermistor, and heating resistor 80 via gold wire bonding.

[0060] In other embodiments, the number of pins 90 can be adjusted according to actual needs, such as setting more or fewer pins 90, and this disclosure does not limit this.

[0061] The above description is merely an optional embodiment of this disclosure and is not intended to limit this disclosure. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this disclosure should be included within the protection scope of this disclosure.

Claims

1. A gas detection laser assembly, characterized in that, include: The housing has a detection chamber with an air inlet, and the volume of the detection chamber is 0.5 mL to 1.5 mL. A laser chip is disposed in the detection chamber and is used to emit a detection laser; The detector chip is disposed within the detection chamber; and An isolation structure is disposed between the laser chip and the detector chip; The detection chamber has a reflective layer on its inner wall. The surface of the reflective layer is a rough surface with multiple protrusions, and the roughness of the reflective layer is greater than 1.6 μm. The reflective layer is made of nickel or gold. The reflective layer is used to diffusely reflect the laser emitted by the laser chip multiple times, so that the optical path of the laser after multiple diffuse reflections is amplified to 10 to 40 times the size of the detection chamber. The isolation structure is used to prevent the laser emitted by the laser chip from being received by the detector chip directly along a straight path without diffuse reflection. The detector chip is used to receive the laser emitted by the laser chip after multiple diffuse reflections.

2. The gas detection laser assembly according to claim 1, characterized in that, The gas detection laser assembly also includes a dust filter, which is disposed in the detection chamber and located at the air inlet. The dust filter is made of stainless steel woven metal.

3. The gas detection laser assembly according to claim 1, characterized in that, The housing includes a tube seat and a tube cap. The socket is used to support the laser chip, the detector chip, and the isolation structure; The pipe cap is disposed on the pipe seat, and the air inlet is disposed on the pipe cap.

4. The gas detection laser assembly according to claim 3, characterized in that, The gas detection laser assembly also includes a heat insulation structure and a heating resistor. The heat insulation structure is disposed in the detection chamber and located on the tube seat; The heating resistor is located on the surface of the heat 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 the surface of the heating resistor away from the heat insulation structure.

5. The gas detection laser assembly according to claim 4, characterized in that, The heat insulation structure is fixedly connected to the tube seat 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.

6. The gas detection laser assembly according to any one of claims 1 to 5, characterized in that, The surface of the detector chip is coated with at least one of a waterproof film and a narrowband filter film.

7. The gas detection laser assembly according to any one of claims 1 to 5, characterized in that, The laser chip is a distributed feedback laser chip or a vertical cavity surface-emitting laser chip.

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