Intermediate infrared sensor for monitoring oil quality

Abstract

The invention provides an intermediate infrared sensor for oil quality monitoring. The intermediate infrared sensor comprises a light source module and a detector module. The light source module comprises a thermal radiation light source and a first focusing reflector, and the first focusing reflector is arranged in the light emitting direction of the thermal radiation light source. The detector module comprises a thermopile detector and a second focusing mirror, and the second focusing mirror is arranged in the light incident direction of the thermopile detector. The first focusing mirror and the second focusing mirror are oppositely arranged, the first focusing mirror is used for focusing mid-infrared light emitted by the thermal radiation light source to form parallel light, and the second focusing mirror is used for focusing the parallel light penetrating through the oil liquid to be detected to the receiving surface of the thermopile detector. The mid-infrared sensor can obtain a high signal-to-noise ratio without a refrigerating system, the transverse size of the sensor is effectively controlled, and the mid-infrared sensor can be conveniently installed on the two sides of a detection section of a bypass detection pipeline.

Description

Technical Field

[0001] The present application relates to the field of display technology, and in particular to a mid-infrared sensor for oil quality monitoring. Background Art

[0002] Oil quality monitoring is a key link to ensure the safe operation of large rotating machinery and equipment. At present, mid-infrared spectroscopy analysis technology has become an important means of oil quality monitoring because it can simultaneously detect multiple characteristic components in oil. When real-time monitoring is performed in oil circulation spaces such as bypass detection pipelines, due to the weak characteristic absorption peaks of the mid-infrared spectrum, traditional mid-infrared sensors need to use low-temperature refrigerated quantum detectors and high-temperature refrigerated thermal radiation light sources to obtain sufficient signal-to-noise ratio. This refrigeration structure not only makes the lateral size of the sensor too large, making it inconvenient to install on the bypass detection pipeline, but also the power consumption of the refrigeration system is usually above 10W, making it difficult for the sensor to achieve long-term stable operation. In addition, the existence of the refrigeration system also increases the volume and weight of the sensor, making the design and fixation of the mounting bracket complicated. Therefore, without reducing the signal-to-noise ratio of spectral measurement, realizing the non-refrigeration and miniaturization of mid-infrared sensors is a technical problem that needs to be solved in the field of oil quality monitoring. Summary of the invention

[0003] The purpose of the present application is to provide a mid-infrared sensor for oil quality monitoring, so as to solve the technical problem that the existing mid-infrared sensor is difficult to perform online real-time monitoring of oil quality in a bypass detection pipeline.

[0004] An embodiment of the present application provides a mid-infrared sensor for oil quality monitoring, the mid-infrared sensor comprising: a light source module, the light source module comprising a thermal radiation light source and a first focusing reflector, the first focusing reflector being arranged in the light emitting direction of the thermal radiation light source; a detector module, the detector module comprising a thermopile detector and a second focusing reflector, the second focusing reflector being arranged in the light incident direction of the thermopile detector; wherein the first focusing reflector is arranged opposite to the second focusing reflector, the first focusing reflector being used to focus the mid-infrared light emitted by the thermal radiation light source to form parallel light, and the second focusing reflector being used to focus the parallel light passing through the oil to be tested onto the receiving surface of the thermopile detector.

[0005] In the above-mentioned mid-infrared sensor, the thermal radiation light source includes a suspended film, a supporting base and a plurality of supporting arms, a hollow cavity is opened on the supporting base, the suspended film is suspended above the hollow cavity through the plurality of supporting arms, and the plurality of supporting arms are evenly arranged along the circumference of the hollow cavity.

[0006] In the above-mentioned mid-infrared sensor, the suspended film includes a first insulating layer, a heating resistor layer and a second insulating layer, the heating resistor layer is sandwiched between the first insulating layer and the second insulating layer, and the edges of the first insulating layer and the second insulating layer are connected to the supporting base through the multiple support arms.

[0007] In the above-mentioned mid-infrared sensor, the heating resistor layer includes a main body part and a lead part. The main body part is arranged in a serpentine pattern in the central area of ​​the suspended membrane, and the lead part extends along the multiple support arms to the supporting base. The supporting base is provided with an electrode pad electrically connected to the lead part.

[0008] In the above mid-infrared sensor, the thermopile detector includes a substrate, a thermocouple array and an absorption layer, a suspended area is provided on the substrate, the thermocouple array is provided in the suspended area, and the absorption layer covers the hot end of the thermocouple array.

[0009] In the above-mentioned mid-infrared sensor, the thermocouple array includes a plurality of thermocouple units, each of the thermocouple units includes a first thermoelectric arm and a second thermoelectric arm, the first thermoelectric arm is made of a first thermoelectric material, the second thermoelectric arm is made of a second thermoelectric material, one end of the first thermoelectric arm and the second thermoelectric arm are connected to form the hot end, and the other ends of the first thermoelectric arm and the second thermoelectric arm respectively extend outside the suspended area and are electrically connected to the lead-out electrode arranged on the substrate to form a cold end.

[0010] In the above-mentioned mid-infrared sensor, the first focusing reflector and the second focusing reflector are both off-axis parabolic reflectors, and the off-axis parabolic reflectors include a base and a reflecting surface, and the reflecting surface is arranged on the base, and the base is provided with an adjusting screw and a locking nut for adjusting the angle of the reflecting surface.

[0011] The above-mentioned mid-infrared sensor also includes a slit diaphragm, which includes an diaphragm substrate and a slit arranged on the diaphragm substrate. Mounting parts for fixing the diaphragm substrate are provided on both sides of the diaphragm substrate, and the mounting parts are detachably connected to the housing of the mid-infrared sensor.

[0012] The above-mentioned mid-infrared sensor also includes a narrow-band optical filter, which includes a substrate layer and a multilayer dielectric film arranged on the substrate layer, and the multilayer dielectric film includes high refractive index layers and low refractive index layers arranged alternately. The narrow-band optical filter is installed in the mid-infrared sensor through a fixed frame arranged at its periphery.

[0013] In the above-mentioned mid-infrared sensor, the center of the emitting surface of the thermal radiation light source is located at the focus of the first focusing reflector, the center of the receiving surface of the thermopile detector is located at the focus of the second focusing reflector, and the optical axis of the first focusing reflector is collinear with the optical axis of the second focusing reflector.

[0014] The mid-infrared sensor provided by the present application realizes the non-cooling of the sensor by adopting a combination of a thermal radiation light source and a thermopile detector. Among them, the emission area of ​​the thermal radiation light source is less than 2mm×2mm, and the power consumption of the thermal radiation light source is reduced by reducing the emission area. At the same time, due to the small emission area, the heat capacity of the thermal radiation light source is also reduced accordingly, so that the thermal radiation light source can achieve rapid heating and stable operation at lower power consumption. The receiving area of ​​the thermopile detector is less than 1mm×1mm. The reduction of the receiving area reduces the heat capacity of the thermopile detector and improves the response speed and sensitivity of the thermopile detector to weak mid-infrared signals. The first focusing reflector focuses the mid-infrared light emitted by the thermal radiation light source into parallel light, ensuring that the mid-infrared light maintains a stable optical path length when passing through the oil to be tested, thereby improving the accuracy of spectral measurement; the second focusing reflector focuses the parallel light passing through the oil to be tested onto the receiving surface of the thermopile detector, and increases the light flux reaching the detector through light beam convergence, thereby improving the signal-to-noise ratio. Due to the adoption of the above technical solution, the mid-infrared sensor of the present application can obtain a high signal-to-noise ratio without a refrigeration system, and the lateral size of the sensor is controlled within 25 mm, so that it can be installed in the detection hole of a standard guide bearing for online real-time monitoring of oil quality. In addition, due to the elimination of the refrigeration system, the total power consumption of the sensor is significantly reduced, which is conducive to the long-term stable operation of the sensor.

[0015] The mid-infrared sensor provided by the present application realizes the non-cooling of the sensor by adopting a combination of a thermal radiation light source and a thermopile detector. The first focusing reflector focuses the mid-infrared light emitted by the thermal radiation light source into parallel light, ensuring that the mid-infrared light maintains a stable optical path length when passing through the oil to be tested in the bypass detection pipeline, thereby improving the accuracy of spectral measurement; the second focusing reflector focuses the parallel light passing through the oil to be tested onto the receiving surface of the thermopile detector, and increases the light flux reaching the detector through light beam convergence, thereby improving the signal-to-noise ratio. Due to the adoption of the above technical solution, the mid-infrared sensor of the present application can obtain a higher signal-to-noise ratio without a refrigeration system, and the lateral size of the sensor is effectively controlled, which is convenient for installation on both sides of the detection section of the bypass detection pipeline. In addition, due to the cancellation of the refrigeration system, the total power consumption of the sensor is significantly reduced, which is conducive to the long-term stable operation of the sensor, and also simplifies the design and fixing method of the mounting bracket. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1It is a schematic diagram of a mid-infrared sensor for oil quality monitoring provided in an embodiment of the present application.

[0017] Figure 2 yes Figure 1 A schematic diagram of a thermal radiation light source in a light source module in a mid-infrared sensor for oil quality monitoring is shown.

[0018] Figure 3 yes Figure 2 Schematic diagram of the suspended membrane in the thermal radiation light source shown. DETAILED DESCRIPTION

[0019] The specific implementation methods of the present application are described in detail below with reference to the accompanying drawings.

[0020] The terms "first", "second" and similar words do not indicate any order, quantity or importance, but are only used to distinguish different technical features. The term "plurality" and similar words mean two or more, unless otherwise clearly defined.

[0021] The mid-infrared sensor of the present invention can be applied to an online oil quality monitoring system. The system includes a main oil pipeline, a bypass detection pipeline, an oil circulation pump and a control unit. The main oil pipeline serves as the main flow channel of the oil, the bypass detection pipeline is connected in parallel with the main oil pipeline, and an oil inlet valve and an oil outlet valve are provided on the bypass detection pipeline to control the oil flow rate.

[0022] The detection section of the bypass detection pipeline is provided with a pair of infrared transparent windows facing each other, and the infrared transparent windows are made of calcium fluoride material to allow mid-infrared light to pass through. The infrared transparent window is sealed and connected to the bypass detection pipeline through a sealing ring, and the sealing ring is made of oil-resistant rubber material. A protective baffle is provided on the outside of the infrared transparent window, and the protective baffle is opened during detection and closed during non-detection to protect the window from contamination and damage.

[0023] The mid-infrared sensor is installed on both sides of the detection section of the bypass detection pipeline 101, and the mid-infrared sensor is fixed by a mounting bracket. The mounting bracket includes a fixing seat and an adjustment mechanism, the fixing seat is welded to the bypass detection pipeline 101, and the adjustment mechanism is used to adjust the spatial position and angle of the mid-infrared sensor.

[0024] The oil circulation pump is arranged on the bypass detection pipeline 101, and is used to drive the oil to flow in the bypass detection pipeline 101. The oil circulation pump adopts a magnetic pump, which does not require a mechanical seal and can prevent oil leakage. The speed of the oil circulation pump is adjustable, and is used to control the oil flow rate so that the oil flows stably during detection. The inlet and outlet of the oil circulation pump are provided with a shock-absorbing hose, which is used to isolate the vibration of the pump.

[0025] The control unit includes a main controller, a data acquisition module and a communication module. The main controller is used to control the detection process, including controlling the start and stop of the oil circulation pump, controlling the switch of the inlet and outlet oil valves, controlling the switch of the protective baffle, etc. The data acquisition module is used to collect the output signal of the thermopile detector 2021 and perform signal processing and analysis. The communication module is used to transmit the detection results to the host computer.

[0026] The bypass detection pipeline 101 is also provided with a temperature sensor and a pressure sensor for monitoring the temperature and pressure of the oil. The output signals of the temperature sensor and the pressure sensor are also transmitted to the data acquisition module.

[0027] The oil inlet and outlet of the bypass detection pipeline 101 are provided with filters for filtering impurities in the oil. The filter adopts a multi-stage filtering structure, including a coarse filter screen and a fine filter element. A pressure differential indicator is provided on the housing of the filter for indicating the degree of blockage of the filter element. A drain valve is provided at the bottom of the filter for regularly discharging the collected impurities.

[0028] The pipeline connection of the whole system adopts flange connection. Metal spiral wound gaskets are used to seal between the flanges. Pressure gauges and temperature gauges are installed at key parts of the system. An oil collecting pan is installed at the bottom of the system to collect possible leaked oil to prevent environmental pollution.

[0029] like Figure 1 , Figure 2 and Figure 3 As shown, an embodiment of the present application provides a mid-infrared sensor for oil quality monitoring, the mid-infrared sensor includes a light source module 201 and a detector module 202, the light source module 201 includes a thermal radiation light source 2011 and a first focusing reflector 2012, the emission area of ​​the thermal radiation light source 2011 is less than 2mm×2mm, the first focusing reflector 2012 is arranged in the light emitting direction of the thermal radiation light source 2011; the detector module 202 includes a thermopile detector 2021 and a second focusing reflector 2022, the thermopile detector The receiving area of ​​2021 is less than 1mm×1mm, and the second focusing reflector 2022 is arranged in the light incident direction of the thermopile detector 2021; the first focusing reflector 2012 and the second focusing reflector 2022 are arranged opposite to each other, the first focusing reflector 2012 is used to focus the mid-infrared light emitted by the thermal radiation light source 2011 to form parallel light, and the second focusing reflector 2022 is used to focus the parallel light passing through the oil to be tested onto the receiving surface of the thermopile detector 2021; the lateral size of the mid-infrared sensor is less than 25mm.

[0030] The thermal radiation light source 2011 is prepared by micro-electromechanical system technology, and the thermal radiation light source 2011 is a micro-MEMS electromechanical integrated infrared light source. The thermal radiation light source 2011 includes a silicon substrate 20116, a suspended film (heating film) 20113, a supporting substrate 20111, a plurality of supporting arms 20112 and a heating wire 20114 arranged on the heating film. The heating wire 20114 is in a zigzag shape and is arranged on the heating film for generating thermal radiation. A cavity is formed between the heating film and the silicon substrate 20116 for achieving thermal isolation. A hollow cavity 20115 is provided on the supporting substrate 20111, and the heating film is suspended above the hollow cavity 20115 by the plurality of supporting arms 20112, and the plurality of supporting arms 20112 are evenly arranged along the circumference of the hollow cavity 20115.

[0031] The support substrate 20111 is made of single crystal silicon material, and the hollow cavity 20115 is formed by an etching process. The side wall of the hollow cavity 20115 is stepped, and the stepped side wall includes an upper vertical section and a lower inclined section. The depth of the upper vertical section is 5-8 microns, and the angle between the lower inclined section and the horizontal plane is 20-70 degrees. The number of the multiple support arms 20112 is four, and the four support arms 20112 are arranged in a cross shape. The length of each support arm 20112 is 100-200 microns and the width is 20-40 microns. The upper surface of the support arm 20112 is provided with a metal wiring layer for laying leads. The material of the metal wiring layer is aluminum or gold, and the thickness of the metal wiring layer is 0.5-1 micron.

[0032] The upper surface of the support base 20111 is provided with a positioning boss, which is arranged around the hollow cavity 20115, and the positioning boss is used to cooperate with the support structure of the first focusing reflector 2012. The positioning boss includes an inner ring and an outer ring, the inner ring is arranged close to the edge of the hollow cavity 20115, and the outer ring is located on the outside of the inner ring. An annular groove is formed between the inner ring and the outer ring, and the annular groove is used to accommodate the bottom of the support structure of the first focusing reflector 2012, so as to achieve accurate positioning of the first focusing reflector 2012. The upper surface of the inner ring is provided with a positioning pin hole, and the positioning pin hole cooperates with the positioning pin on the support structure of the first focusing reflector 2012 to prevent the first focusing reflector 2012 from rotating in a horizontal plane. The upper surface of the outer ring is provided with a plurality of threaded holes, and the threaded holes are used to fix the support structure of the first focusing reflector 2012.

[0033] The bottom of the hollow cavity 20115 is provided with a heat dissipation groove, and the heat dissipation groove includes a main groove and a plurality of branch grooves. The main groove is arranged along the center line of the hollow cavity 20115, and the plurality of branch grooves extend from the main groove to the surroundings. The inner walls of the main groove and the branch groove are provided with fine grooves, and the fine grooves are used to increase the heat dissipation area. An air inlet and an air outlet are provided at both ends of the main groove, and the air inlet and the air outlet are respectively connected to the external environment. A baffle is provided at the end of the branch groove, and the baffle is used to guide the flow direction of the cooling airflow so that the cooling airflow can fully contact the inner wall of the heat dissipation groove to improve the heat dissipation efficiency. The lower surface of the supporting base 20111 is provided with heat dissipation fins, and the heat dissipation fins are radially distributed. The heat dissipation fins include main fins and auxiliary fins, and the main fins extend radially outward from the center, and the auxiliary fins are arranged between adjacent main fins. The surfaces of the main fins and the auxiliary fins are provided with micropore arrays, which are used to form turbulence and enhance the convective heat exchange effect. The height of the main fins gradually decreases from the center to the outside, which is used to form an airflow channel to guide the heat to diffuse outward. The upper surface of the auxiliary fins is provided with an inclined surface, which is used to guide the airflow direction and prevent the formation of airflow dead zones.

[0034] The surfaces of the multiple support arms 20112 are provided with a stress release structure, and the stress release structure includes multiple serpentine bends, and the serpentine bends are used to compensate for thermal stress. The serpentine bends include a main bend section and a secondary bend section, and the main bend section is arranged along the length direction of the support arm 20112, and the secondary bend section is perpendicular to the main bend section. A transition arc is provided at the corner of the main bend section and the secondary bend section, and the transition arc is used to reduce stress concentration. A stress buffer layer is provided on the surface of the serpentine bend, and the stress buffer layer is made of elastic material to further absorb thermal stress.

[0035] The suspended film 20113 includes a first insulating layer 201131, a heating resistor layer 201132 and a second insulating layer 201133, the heating resistor layer 201132 is sandwiched between the first insulating layer 201131 and the second insulating layer 201133, and the edges of the first insulating layer 201131 and the second insulating layer 201133 are connected to the supporting base 20111 through the multiple support arms 20112.

[0036] The first insulating layer 201131 and the second insulating layer 201133 are both made of silicon nitride material, and the thickness of the first insulating layer 201131 and the second insulating layer 201133 are both 200-300 nanometers. The surface roughness of the first insulating layer 201131 is less than 10 nanometers, and the surface roughness of the second insulating layer 201133 is less than 5 nanometers. An adhesion layer is provided between the first insulating layer 201131 and the heating resistor layer 201132, and the adhesion layer is made of titanium dioxide material, and the thickness of the adhesion layer is 10-20 nanometers. The upper surface of the second insulating layer 201133 is provided with an anti-reflection layer, and the anti-reflection layer is composed of a multi-layer dielectric film, which is used to improve the emissivity of the thermal radiation light source 2011 in the 3-5 micron band.

[0037] A reflective protective layer is provided on the upper surface of the first insulating layer 201131, and the reflective protective layer is used to prevent the heat generated by the heating resistor layer 201132 from being conducted downward. The reflective protective layer includes a reflective sublayer and a heat insulating sublayer, wherein the reflective sublayer is located in the upper layer and the heat insulating sublayer is located in the lower layer. The reflective sublayer is made of a high reflectivity material and is used to reflect thermal radiation back to the heating resistor layer 201132 to improve thermal efficiency. The heat insulating sublayer is made of a porous material, and the pores inside the porous material are used to block heat conduction. A transition layer is provided in the edge area of ​​the reflective protective layer, and the transition layer is used to reduce thermal stress.

[0038] The upper surface of the second insulating layer 201133 is provided with an anti-reflection structure, and the anti-reflection structure includes a periodic micro-nano structure array, and the periodic micro-nano structure array is used to improve the emission efficiency in the mid-infrared band. The periodic micro-nano structure array includes a main array area and a transition area, the main array area is located at the center, and the transition area is located at the edge. The main array area includes regularly arranged conical protrusions, and the conical protrusions are used to achieve optical impedance matching. The transition area includes a gradual microstructure, and the gradual microstructure is used to reduce the edge diffraction effect.

[0039] A stress buffer layer is provided between the first insulating layer 201131 and the second insulating layer 201133, and the stress buffer layer is used to reduce the stress caused by the mismatch of thermal expansion coefficients. The stress buffer layer includes an elastic buffer layer and a stress dispersion layer, and the elastic buffer layer is made of a low elastic modulus material and is used to absorb deformation energy, and the stress dispersion layer is made of a multi-layer composite material and is used to disperse stress concentration. An elastic isolation belt is provided at the edge of the stress buffer layer, and the elastic isolation belt is used to prevent stress from being transmitted to the support arm 20112.

[0040] The edge area of ​​the suspended film 20113 is provided with reinforcing ribs, and the reinforcing ribs are used to improve the mechanical strength of the suspended film 20113.

[0041] The reinforcing ribs include annular main ribs and radial secondary ribs, wherein the annular main ribs are arranged along the edge of the suspended membrane 20113, and the radial secondary ribs extend inward from the annular main ribs. The cross section of the annular main ribs is in an I-shape, which is used to provide support forces in both the vertical and horizontal directions. The height of the radial secondary ribs gradually decreases from the outside to the inside, which is used to achieve uniform distribution of stress. A transition zone is provided at the connection between the reinforcing ribs and the suspended membrane 20113, and the transition zone is used to reduce stress concentration.

[0042] The heating resistor is made of platinum, tungsten or polysilicon. The heating resistor is arranged on the suspended membrane 20113 in a serpentine pattern. The line width of the heating resistor is 1-10 microns, and the spacing between adjacent lines is 1-10 microns.

[0043] When the heating resistor is made of platinum material, the thickness of the heating resistor is 100-150 nanometers, and the square resistance of the heating resistor is 2-5 ohms / square; when the heating resistor is made of tungsten material, the thickness of the heating resistor is 80-120 nanometers, and the square resistance of the heating resistor is 1-3 ohms / square; when the heating resistor is made of polysilicon material, the thickness of the heating resistor is 300-500 nanometers, and the polysilicon is doped by ion implantation process to form N-type or P-type semiconductor, and the square resistance of the heating resistor is 50-100 ohms / square. The total resistance value of the heating resistor is 50-200 ohms.

[0044] The serpentine wiring of the heating resistor includes a central heating zone and an edge compensation zone. The line density of the central heating zone is greater than that of the edge compensation zone, so as to achieve uniform distribution of the temperature field. The central heating zone includes a main heating belt and an auxiliary heating belt. The main heating belt is located at the center, and the auxiliary heating belt is arranged around the main heating belt. The main heating belt adopts a double helix wiring method, in which the inner and outer helix wires are arranged alternately, so as to ensure uniform distribution of heat in the central area. The auxiliary heating belt adopts a comb-shaped wiring method, in which the spacing between adjacent wires gradually increases from the inside to the outside, so as to form a temperature gradient that decreases from the inside to the outside.

[0045] The edge compensation zone includes an inner compensation zone and an outer compensation zone, wherein the inner compensation zone is adjacent to the central heating zone and the outer compensation zone is located outside the inner compensation zone. The inner compensation zone adopts a gradient density wiring method, and the width and spacing of the wires are set according to the temperature field distribution to compensate for the edge heat dissipation effect. The outer compensation zone adopts a serpentine wiring method to achieve a smooth transition of the temperature field.

[0046] The corner of the heating resistor is provided with an arc transition portion, which is used to avoid current concentration. The arc transition portion includes an inner arc and an outer arc, and the inner arc and the outer arc are used to make the current density distribution uniform. Both ends of the arc transition portion are provided with a gradual transition section, and the width of the gradual transition section gradually changes along the current direction to reduce current distortion. The surface of the arc transition portion is also provided with a stress release groove to relieve thermal stress concentration.

[0047] The surface of the heating resistor layer 201132 is provided with a passivation protective layer, which is used to prevent the heating resistor from oxidizing at high temperatures. The passivation protective layer includes an inner passivation film and an outer passivation film. The inner passivation film directly covers the surface of the heating resistor and is made of a dense material to block oxygen diffusion. The outer passivation film covers the inner passivation film and is made of a high temperature resistant material to provide mechanical protection. The edge of the passivation protective layer is provided with a step-shaped transition portion to improve the adhesion of the passivation layer.

[0048] The heating resistor also includes a temperature feedback resistor, and the temperature feedback resistor and the control circuit form a closed-loop temperature control system. The temperature feedback resistor is arranged around the central heating area, and the temperature feedback resistor includes a main temperature measuring resistor and a spare temperature measuring resistor. The main temperature measuring resistor adopts a four-terminal wiring method to improve the temperature measurement accuracy. The spare temperature measuring resistor is automatically enabled when the main temperature measuring resistor fails, which is used to improve the system reliability. The temperature feedback resistor is connected to the control circuit through multiple shielded wires to suppress electromagnetic interference.

[0049] The heating resistor layer 201132 includes a main body part and a lead part. The main body part is arranged in a serpentine pattern in the central area of ​​the suspended membrane 20113. The lead part extends along the multiple support arms 20112 to the supporting base 20111. The supporting base 20111 is provided with an electrode pad electrically connected to the lead part.

[0050] The main body includes a plurality of parallel heating units, each of which includes a heating subcircuit and a temperature measurement subcircuit. The heating subcircuit adopts a symmetrical wiring method to ensure uniform current distribution. The temperature measurement subcircuit adopts a distributed layout to achieve accurate monitoring of the temperature field. Each of the heating units can be independently controlled to achieve zoned heating.

[0051] The lead part includes a power lead and a control lead, and the control lead is used to transmit a temperature feedback signal. The power lead adopts a multi-layer parallel structure to improve the current carrying capacity. The control lead adopts a differential transmission method to improve the anti-interference ability of signal transmission. The lead part is also provided with an electromagnetic shielding layer, which separates the power lead and the control lead to prevent mutual interference.

[0052] The electrode pad adopts a multi-layer metal structure, including an adhesion layer, a diffusion barrier layer and a conductive layer. The adhesion layer is used to improve the bonding strength of the pad, and the diffusion barrier layer is used to prevent metal interdiffusion. The adhesion layer is made of a metal material with high surface energy to improve the bonding strength with the substrate. The diffusion barrier layer is made of a metal material with a dense lattice structure to prevent atomic diffusion between adjacent metal layers. The conductive layer is made of a metal material with high conductivity, and an anti-oxidation protective film is provided on the surface of the conductive layer. A stress buffer ring is provided around the electrode pad to absorb the stress generated during the welding process.

[0053] The serpentine trace of the main body includes multiple parallel sections and multiple turning sections, the length of the parallel sections is 100-200 microns, the turning sections are arc transitioned, and the radius of the arc is 5-10 microns. The lead part includes a positive lead and a negative lead, and the positive lead and the negative lead extend along two opposite support arms 20112 respectively. A pad area is provided on the support substrate 20111, and the pad area is provided with multiple layers of metal, which are titanium layer, nickel layer and gold layer from bottom to top, the thickness of the titanium layer is 50-100 nanometers, the thickness of the nickel layer is 100-200 nanometers, and the thickness of the gold layer is 200-300 nanometers.

[0054] The thermopile detector 2021 includes a substrate, a thermocouple array and an absorption layer. A suspended area is provided on the substrate, the thermocouple array is provided in the suspended area, and the absorption layer covers the hot end of the thermocouple array.

[0055] The thermocouple array includes a plurality of thermocouple units, each of which includes a hot end and a cold end, the hot end is located in the central area of ​​the thermocouple unit, and the cold end is located in the edge area of ​​the thermocouple unit, each of which includes a first thermoelectric arm and a second thermoelectric arm, the first thermoelectric arm is made of a first thermoelectric material, the second thermoelectric arm is made of a second thermoelectric material, one end of the first thermoelectric arm and the second thermoelectric arm are connected to form the hot end, and the other ends of the first thermoelectric arm and the second thermoelectric arm respectively extend outside the suspended area and are electrically connected to the lead-out electrodes arranged on the substrate to form the cold end.

[0056] The substrate is made of single crystal silicon material, the suspended area is formed by a wet etching process, and the depth of the suspended area is 100-200 microns. The thermocouple array includes 8×8 thermocouple units, and the spacing between adjacent thermocouple units is 50-100 microns. The absorption layer is made of hafnium nitride material, the thickness of the absorption layer is 100-200 nanometers, and the absorption rate of the absorption layer in the 3-5 micron band is greater than 90%.

[0057] The thermocouple array is made of P-type and N-type semiconductor materials, and the P-type and N-type semiconductor materials are connected in series through a metal interconnection layer. The P-type semiconductor material is made of polysilicon material doped with boron, and the N-type semiconductor material is made of polysilicon material doped with phosphorus, and the thermoelectric conversion efficiency is maximized by optimizing the doping concentration. The metal interconnection layer includes a lower interconnection layer and an upper interconnection layer, the lower interconnection layer is used to connect the cold end of the thermocouple, and the upper interconnection layer is used to connect the hot end of the thermocouple. An electrical insulation layer is provided between the lower interconnection layer and the upper interconnection layer to prevent current leakage. A passivation film is provided on the surface of the metal interconnection layer to prevent metal oxidation and corrosion.

[0058] The surface of the absorption layer is provided with a microcavity structure array, and the microcavity structure array is used to enhance the absorption of mid-infrared light. The microcavity structure array includes a main absorption zone and a transition zone. The main absorption zone is provided with a plurality of pyramid-shaped microcavities, and the inner wall of each microcavity is provided with a multilayer dielectric film to enhance the absorption of light of a specific wavelength. The transition zone is arranged around the main absorption zone, and is provided with a gradient microcavity to reduce edge reflection. The surface of the microcavity structure array is also provided with a plasma resonance layer to further enhance the light absorption efficiency. A reflective layer is provided at the bottom of the microcavity structure to perform secondary absorption of unabsorbed light.

[0059] The substrate is integrated with a signal conditioning circuit, the output end of the thermocouple array is connected to a signal processing circuit arranged on the substrate, and the signal conditioning circuit includes a preamplifier and an analog filter. The cold end of the thermocouple array is in contact with a heat dissipation structure arranged on the substrate, and the heat dissipation structure is used to maintain the temperature of the cold end stable.

[0060] The heat dissipation structure includes a metal heat-conducting layer, a heat-dissipating substrate and a temperature stabilizer. The metal heat-conducting layer is made of a material with a high thermal conductivity coefficient and is used to quickly conduct heat. A microchannel cooling system is provided on the heat-dissipating substrate, including a liquid inlet, a liquid outlet and a serpentine cooling channel. The temperature stabilizer uses a semiconductor refrigeration sheet, which cooperates with a temperature feedback control circuit to control the temperature of the cold end.

[0061] The first focusing reflector 2012 and the second focusing reflector 2022 are both off-axis parabolic reflectors, the focal length of the off-axis parabolic reflector is 5-15mm, the off-axis distance is 3-8mm, the curvature radius of the reflecting surface is 10-30mm, and the off-axis parabolic reflector includes a base and a reflecting surface, the reflecting surface is arranged on the base, and the base is provided with an adjusting screw and a locking nut for adjusting the angle of the reflecting surface.

[0062] The first focusing reflector 2012 and the second focusing reflector 2022 both include a substrate and a reflective layer. The substrate is made of a material with a low thermal expansion coefficient (such as polished glass). The reflective layer is arranged on the curved surface of the substrate and is a metal layer sputtered on the surface of the substrate. The surface roughness of the substrate is less than λ / 20 (λ is the working wavelength), and the surface shape accuracy of the substrate is better than λ / 10. The reflective layer is made of gold material, the thickness of the reflective layer is 200-300 nanometers, and the reflectivity of the reflective layer in the 3-5 micron band is greater than 98%. The focal lengths of the first focusing reflector 2012 and the second focusing reflector 2022 are both 10-15 mm, and the effective apertures of the first focusing reflector 2012 and the second focusing reflector 2022 are both 8-12 mm. The first focusing reflector 2012 and the second focusing reflector 2022 are fixed by a precision optical adjustment frame, and the precision optical adjustment frame has a three-dimensional angle adjustment function.

[0063] The surface of the reflective layer is provided with a protective film, which is used to prevent the reflective layer from being oxidized. The protective film includes an anti-oxidation layer, a stress buffer layer and an anti-corrosion layer. The anti-oxidation layer is made of an inert metal material to block oxygen. The stress buffer layer is made of an elastic material to relieve thermal stress. The anti-corrosion layer is made of a chemically resistant material to prevent environmental corrosion. An edge band is provided at the edge area of ​​the protective film to prevent the protective film from peeling off.

[0064] The back of the base is provided with honeycomb support ribs. The support ribs include a main support grid and a secondary support grid. The main support grid is distributed in a hexagonal shape and is used to provide the main support force. The secondary support grid is located inside the main support grid and is used to provide local reinforcement. The connection of the support ribs is provided with chamfers to reduce stress concentration.

[0065] The first focusing reflector 2012 and the second focusing reflector 2022 are mounted via a flexible support structure, and the flexible support structure is used to compensate for thermal stress and mechanical stress. Position marks are provided on the support structure of the reflector, and the position marks are used to assist in optical path alignment. The reflector assembly also includes a dust cover, and the dust cover is used to protect the reflective surface from contamination.

[0066] The flexible support structure includes an elastic support arm, a shock-absorbing pad and a fine-tuning mechanism. The elastic support arm includes a leaf spring. The shock-absorbing pad is made of a composite damping material for absorbing vibration. A self-locking device is provided on the mounting seat of the flexible support structure for locking the adjusted position.

[0067] The adjusting screws are arranged in three mutually perpendicular directions on the base, and are used to achieve three-dimensional angle adjustment of the first focusing reflector 2012 and the second focusing reflector 2022. An elastic gasket is arranged between the adjusting screws in each direction and the base, and the elastic gasket is used to eliminate mechanical clearance. The locking nut cooperates with the adjusting screws, and is used to fix the angles of the first focusing reflector 2012 and the second focusing reflector 2022 after adjustment. The inner surface of the locking nut is provided with a locking washer. A limiting boss is also arranged on the base, and the limiting boss is used to limit the adjustment range of the first focusing reflector 2012 and the second focusing reflector 2022 to prevent the optical path from deviating due to excessive adjustment. A thermal compensation gasket is arranged between the base and the reflector, and is used to compensate for the position deviation caused by thermal expansion.

[0068] The mid-infrared sensor further includes a slit diaphragm, which includes an diaphragm substrate and a slit arranged on the diaphragm substrate, and mounting portions for fixing the diaphragm substrate are arranged on both sides of the diaphragm substrate, and the mounting portions are detachably connected to the housing of the mid-infrared sensor. The slit diaphragm is arranged in the optical path between the first focusing reflector 2012 and the second focusing reflector 2022, and the opening width of the slit diaphragm is 0.1-0.5 mm, and the opening height is 0.5-2 mm.

[0069] The aperture substrate is made of stainless steel, and the surface of the aperture substrate is gold-plated to improve the infrared reflectivity. The slit is formed by a laser cutting process, and the edge of the slit is chamfered to reduce the diffraction effect. The mounting portion includes a positioning pin and an elastic buckle, the positioning pin is used to ensure the installation position accuracy of the aperture, and the elastic buckle is used to achieve rapid disassembly and assembly of the aperture. An anti-rotation step is also provided on the aperture substrate, and the anti-rotation step cooperates with the housing of the mid-infrared sensor. An identification portion is also provided on the surface of the aperture substrate, and the identification portion is used to indicate the installation direction of the aperture. Gradient transition portions are provided at both ends of the slit, and the gradient transition portions are used to suppress the diffraction effect of light.

[0070] The mid-infrared sensor further includes a plurality of narrow-band optical filters, the narrow-band optical filters including a substrate layer and a multilayer dielectric film disposed on the substrate layer, the multilayer dielectric film including alternating high refractive index layers and low refractive index layers, and the narrow-band optical filters are installed in the mid-infrared sensor via a fixed frame disposed at the periphery thereof. The narrow-band optical filter is disposed between the second focusing reflector 2022 and the thermopile detector 2021, and the central wavelength of the narrow-band optical filter is 2800-3200nm, and the full width at half maximum is 50-200nm.

[0071] The mid-infrared sensor also includes a filter wheel and a drive motor. The multiple narrow-band optical filters are evenly arranged along the circumference of the filter wheel, each of the filters corresponds to a specific wavelength, and the central wavelengths of the multiple filters are respectively located at different positions within the 3-5 μm band. The drive motor is used to drive the filter wheel to rotate so that the multiple filters enter the optical path in sequence.

[0072] The filter wheel includes a wheel body, a plurality of light holes and a plurality of fixing rings. The wheel body is made of aluminum alloy material, and has the characteristics of light weight and good heat dissipation. The plurality of light holes are evenly arranged along the circumference of the wheel body, and the inner wall of each light hole is provided with a positioning step. The plurality of fixing rings are respectively arranged in the plurality of light holes, and cooperate with the positioning steps to fix the plurality of filters. The fixing ring is made of elastic material, and can compensate for thermal stress.

[0073] The substrate layer is made of potassium bromide material, and the surface of the substrate layer is polished. The high refractive index layer is made of zinc sulfide material, and the low refractive index layer is made of calcium fluoride material. The multilayer dielectric film is prepared by electron beam evaporation process, and the number of layers of the multilayer dielectric film is greater than fifty. The fixed frame is made of Invar alloy to reduce the stress caused by temperature changes. An elastic sealing ring is provided between the fixed frame and the substrate layer, and the elastic sealing ring is used to prevent oil from penetrating. The fixed frame is provided with an anti-rotation positioning groove, and the anti-rotation positioning groove cooperates with the housing of the mid-infrared sensor. The surface of the narrow-band optical filter is also provided with an anti-reflection film, and the anti-reflection film is used to reduce surface reflection losses.

[0074] The center of the emitting surface of the thermal radiation light source 2011 is located at the focus of the first focusing reflector 2012, the center of the receiving surface of the thermopile detector 2021 is located at the focus of the second focusing reflector 2022, and the optical axis of the first focusing reflector 2012 is collinear with the optical axis of the second focusing reflector 2022. The distance between the thermal radiation light source 2011 and the first focusing reflector 2012 is equal to the focal length of the first focusing reflector 2012, and the distance between the thermopile detector 2021 and the second focusing reflector 2022 is equal to the focal length of the second focusing reflector 2022.

[0075] The thermal radiation light source 2011 is installed on a position adjustment platform, and the precision position adjustment platform includes a three-dimensional mobile platform and an angle adjustment seat. The three-dimensional mobile platform is used to adjust the spatial position of the thermal radiation light source 2011, and the angle adjustment seat is used to adjust the inclination angle of the thermal radiation light source 2011. The thermopile detector 2021 is installed on a flexible support, and the flexible support is used to compensate for thermal stress. An auxiliary laser and a four-quadrant detector are provided between the first focusing reflector 2012 and the second focusing reflector 2022 for real-time monitoring of optical path deviation.

[0076] The mid-infrared sensor also includes a protective component, which includes a dust cover, an oil cover and an anti-vibration pad. The dust cover is arranged between the thermal radiation light source 2011 and the first focusing reflector 2012 to prevent dust from entering the optical path. The oil cover is arranged in the optical path area between the first focusing reflector 2012 and the second focusing reflector 2022 to prevent oil splashing. The anti-vibration pad is arranged at the bottom of the mid-infrared sensor to reduce the influence of external vibration. The dust cover and the oil cover are both made of infrared transparent materials, and the surfaces of the dust cover and the oil cover are provided with anti-reflection films. The oil cover includes an upper cover plate and a lower cover plate, which are connected by a sealing strip to form a closed space. The upper cover plate and the lower cover plate are both made of infrared transparent materials, and the material is calcium fluoride crystal. The sealing strip is made of fluororubber material. The edge of the oil cover is provided with an oil collecting groove and an oil drain hole to discharge splashed oil.

[0077] The anti-vibration pad is made of a multi-layer composite material, including a metal elastic layer and a damping layer. The metal elastic layer is used to support the sensor body, and the damping layer is used to absorb vibration energy.

[0078] The anti-vibration pad adopts a multi-layer composite structure, which is composed of an upper covering layer, a metal elastic layer, a damping layer and a lower supporting layer from top to bottom. The upper covering layer adopts a wear-resistant material to prevent surface damage. The metal elastic layer adopts a corrugated plate design and has good elastic deformation ability. The damping layer adopts a viscoelastic material to effectively absorb vibration energy. The lower supporting layer adopts an anti-slip material to increase the friction with the installation plane.

[0079] The three-dimensional mobile platform includes an X-axis mobile unit, a Y-axis mobile unit and a Z-axis mobile unit, and each mobile unit includes a linear guide rail and a micro-adjustment mechanism. The linear guide rail includes a guide rail seat and a sliding part, the guide rail seat is fixed on the bottom plate, and the sliding part and the guide rail seat are matched with a dovetail groove. The upper surface and the lower surface of the guide rail seat are both provided with a V-shaped slide groove. Slide blocks matching the V-shaped slide groove are provided on both sides of the sliding part, and the slide blocks are made of wear-resistant alloy material. A dustproof sealing belt is provided between the guide rail seat and the sliding part, and the two ends of the dustproof sealing belt are fixed on the guide rail seat.

[0080] The micro-adjustment mechanism includes a driving wheel, a driven wheel, a transmission shaft and a reducer. The driving wheel is coaxially connected to the adjustment handwheel, and the outer peripheral surface of the driving wheel is provided with a toothed structure. The driven wheel is fixed to one end of the transmission shaft, and the driven wheel is meshed with the driving wheel for transmission. The other end of the transmission shaft is connected to the input end of the reducer, and the output end of the reducer is connected to the moving slider. The transmission shaft is supported by a bearing seat, and the bearing seat is fixed to the bottom plate.

[0081] The X-axis moving unit is located at the lower layer, and the Y-axis moving unit is located at the upper layer. The guide rail seat of the X-axis moving unit is connected to the bottom plate through a fixed seat, and the fixed seat adopts an L-shaped structure. The guide rail seat of the Y-axis moving unit is connected to the sliding part of the X-axis moving unit through a connecting plate, and reinforcing ribs are provided at both ends of the connecting plate.

[0082] The guide rail seat of the Z-direction moving unit is fixed on the sliding part of the Y-direction moving unit. The sliding part of the Z-direction moving unit is connected to the stage, and the stage is used to install the thermal radiation light source 2011. A limit block is provided on the guide rail seat of the Z-direction moving unit to limit the moving range of the sliding part.

[0083] The axial direction of the adjusting hand wheel is provided with a locking nut for locking the adjusting position. The inner surface of the locking nut is provided with an anti-loosening washer, and the anti-loosening washer adopts a toothed structure.

[0084] The upper surface of the movable slider is provided with a T-shaped groove for installing a connecting piece. The side surface of the movable slider is provided with an adjusting screw for eliminating the gap between the movable slider and the guide rail.

[0085] The bottom plate is provided with mounting holes around it for fixing on the workbench. The bottom surface of the bottom plate is provided with a shock-absorbing pad, which is made of metal rubber material.

[0086] The guide rail seats of the X-axis moving unit, the Y-axis moving unit and the Z-axis moving unit are all provided with lubricating oil nozzles for injecting lubricating oil. The lubricating oil nozzles are designed with a one-way valve to prevent the lubricating oil from flowing back. The guide rail seat is provided with a lubricating oil groove for storing lubricating oil. The slider is provided with a capillary oil hole for conveying lubricating oil to the friction surface.

[0087] The angle adjustment seat includes a pitch adjustment component and a horizontal rotation component. The pitch adjustment component includes a support frame, a rotating shaft assembly and an adjustment arm. The support frame adopts a U-shaped structure, and bearing seats are respectively provided on the two side walls of the support frame. The rotating shaft assembly includes a main shaft and a secondary shaft, and the main shaft and the secondary shaft are respectively installed in the bearing seats on both sides. The main shaft is fixedly connected to the adjustment arm, and the secondary shaft is connected to the balance block. A double-row angular contact ball bearing is provided in the bearing seat, and the inner ring of the bearing is interference fit with the rotating shaft, and the outer ring is transition fit with the bearing seat.

[0088] The adjustment arm includes a connecting portion and an operating portion, wherein the connecting portion is connected to the spindle key, and the operating portion is provided with an anti-slip handle. An arc guide groove is provided on the adjustment arm, and a slider is provided in the arc guide groove. A locking bolt that cooperates with the slider is provided on the support frame, and the pitch angle can be fixed by tightening the locking bolt.

[0089] The horizontal rotating component includes a base, a turntable and a transmission mechanism. The base is fixed on a three-dimensional mobile platform, and an annular slide rail is provided on the upper surface of the base. The turntable is connected to the base through a ball support ring, and the balls in the ball support ring are evenly distributed.

[0090] The transmission mechanism includes a worm wheel, a worm and a transmission box. The worm wheel is fixed to the outer periphery of the turntable, and the worm is installed in the transmission box. The transmission box is fixed to the base, and a bearing support seat is arranged in the transmission box. One end of the worm is connected to the hand wheel, and the other end is meshed with the worm wheel.

[0091] The center of the turntable is provided with a mounting hole for fixing the support frame of the pitch adjustment component. A plurality of positioning pin holes are provided around the mounting hole for ensuring the angular position of the installation.

[0092] The mid-infrared sensor provided by the present application realizes the non-cooling of the sensor by adopting a combination of a thermal radiation light source 2011 and a thermopile detector 2021. Among them, the emission area of ​​the thermal radiation light source 2011 is less than 2mm×2mm, and the power consumption of the thermal radiation light source 2011 is reduced by reducing the emission area. At the same time, due to the small emission area, the heat capacity of the thermal radiation light source 2011 is also reduced accordingly, so that the thermal radiation light source 2011 can achieve rapid heating and stable operation at low power consumption. The receiving area of ​​the thermopile detector 2021 is less than 1mm×1mm. The reduction of the receiving area reduces the heat capacity of the thermopile detector 2021, and improves the response speed and sensitivity of the thermopile detector 2021 to weak mid-infrared signals. The first focusing reflector 2012 focuses the mid-infrared light emitted by the thermal radiation light source 2011 into parallel light, ensuring that the mid-infrared light maintains a stable optical path length when passing through the oil to be tested in the bypass detection pipeline 101, thereby improving the accuracy of spectral measurement; the second focusing reflector 2022 focuses the parallel light passing through the oil to be tested onto the receiving surface of the thermopile detector 2021, and increases the light flux reaching the detector through light beam convergence, thereby improving the signal-to-noise ratio. Due to the adoption of the above technical solution, the mid-infrared sensor of the present application can obtain a high signal-to-noise ratio without a refrigeration system, and the lateral size of the sensor is effectively controlled, which is convenient for installation on both sides of the detection section of the bypass detection pipeline 101. In addition, due to the elimination of the refrigeration system, the total power consumption of the sensor is significantly reduced, which is conducive to the long-term stable operation of the sensor, and also simplifies the design and fixing method of the mounting bracket.

[0093] The embodiments of the present application are described in detail above, and the contents of this specification should not be construed as limiting the scope of protection of the present application.

Claims

1. A mid-infrared sensor for oil quality monitoring, characterized in that: The mid-infrared sensor comprises: A light source module, the light source module comprising a thermal radiation light source and a first focusing reflector, wherein the first focusing reflector is arranged in a light emitting direction of the thermal radiation light source; A detector module, the detector module comprising a thermopile detector and a second focusing reflector, wherein the second focusing reflector is arranged in a light incident direction of the thermopile detector; Among them, the first focusing reflector and the second focusing reflector are arranged opposite to each other, the first focusing reflector is used to focus the mid-infrared light emitted by the thermal radiation light source to form parallel light, and the second focusing reflector is used to focus the parallel light passing through the oil to be tested onto the receiving surface of the thermopile detector.

2. The mid-infrared sensor according to claim 1, characterized in that: The thermal radiation light source includes a suspended film, a supporting base and a plurality of supporting arms, the supporting base is provided with a hollow cavity, the suspended film is suspended above the hollow cavity through the plurality of supporting arms, and the plurality of supporting arms are evenly arranged along the circumference of the hollow cavity.

3. The mid-infrared sensor according to claim 2, characterized in that: The suspended membrane includes a first insulating layer, a heating resistor layer and a second insulating layer. The heating resistor layer is sandwiched between the first insulating layer and the second insulating layer. The edges of the first insulating layer and the second insulating layer are connected to the supporting base through the multiple supporting arms.

4. The mid-infrared sensor according to claim 3, characterized in that: The heating resistor layer includes a main body and a lead part. The main body is arranged in a serpentine pattern in the central area of ​​the suspended membrane. The lead part extends along the multiple support arms to the support base. The support base is provided with an electrode pad electrically connected to the lead part.

5. The mid-infrared sensor according to claim 1, characterized in that: The thermopile detector comprises a substrate, a thermocouple array and an absorption layer. A suspended area is arranged on the substrate, the thermocouple array is arranged in the suspended area, and the absorption layer covers the hot end of the thermocouple array.

6. The mid-infrared sensor according to claim 5, characterized in that: The thermocouple array includes a plurality of thermocouple units, each of which includes a first thermoelectric arm and a second thermoelectric arm, the first thermoelectric arm is made of a first thermoelectric material, the second thermoelectric arm is made of a second thermoelectric material, one end of the first thermoelectric arm and the second thermoelectric arm are connected to form the hot end, and the other ends of the first thermoelectric arm and the second thermoelectric arm respectively extend outside the suspended area and are electrically connected to the lead-out electrode arranged on the substrate to form a cold end.

7. The mid-infrared sensor according to claim 1, characterized in that: The first focusing reflector and the second focusing reflector are both off-axis parabolic reflectors, and the off-axis parabolic reflector comprises a base and a reflecting surface, the reflecting surface is arranged on the base, and the base is provided with an adjusting screw and a locking nut for adjusting the angle of the reflecting surface.

8. The mid-infrared sensor according to claim 1, characterized in that: It also includes a slit diaphragm, which includes an diaphragm substrate and a slit arranged on the diaphragm substrate. Mounting parts for fixing the diaphragm substrate are provided on both sides of the diaphragm substrate, and the mounting parts are detachably connected to the housing of the mid-infrared sensor.

9. The mid-infrared sensor according to claim 1, characterized in that: It also includes a narrow-band optical filter, which includes a substrate layer and a multilayer dielectric film arranged on the substrate layer, the multilayer dielectric film includes high refractive index layers and low refractive index layers arranged alternately, and the narrow-band optical filter is installed in the mid-infrared sensor through a fixed frame arranged at its periphery.

10. The mid-infrared sensor according to claim 1, characterized in that: The center of the emitting surface of the thermal radiation light source is located at the focus of the first focusing reflector, the center of the receiving surface of the thermopile detector is located at the focus of the second focusing reflector, and the optical axis of the first focusing reflector is collinear with the optical axis of the second focusing reflector.

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