Shear stress microsensor based on lens array optical conduction and packaging method thereof

Abstract

The invention discloses a shear stress microsensor based on lens array optical conduction and a packaging method thereof, and belongs to the technical field of MEMS sensors. Comprising an optical fiber, a transmission lens group, an MEMS chip, a reflection lens group and a photoelectric detector which are sequentially arranged along an optical path, an optical signal transmitted by the optical fiber is transmitted to the MEMS chip through the transmission lens group, the optical signal carrying displacement is reflected through a reflection grating of the MEMS chip, and the reflected optical signal is transmitted to an effective working area of the photoelectric detector through the reflection lens group; optical signals are converted into electric signals through a photoelectric detector, so that displacement information used for calculating shear stress is obtained. According to the invention, the problems of optical fiber displacement and angle deviation which are easy to occur when the optical fiber is fixed by adhesive are effectively avoided, the optical loss is reduced, and the transmission efficiency and stability of optical signals are improved, so that the sensitivity of the sensor is enhanced. The problems of large optical path transmission loss, poor stability and the like are solved.

Description

Technical Field

[0001] The invention belongs to the technical field of MEMS sensors, and in particular relates to a shear stress microsensor based on lens array optical conduction and a packaging method thereof. Background Art

[0002] The shear stress microsensor is a sensor manufactured using microelectromechanical system (MEMS) technology. It has a floating or suspended structure to achieve high-precision and high-sensitivity shear stress measurement. Its core component is a micro floating element, which will produce a slight displacement when subjected to shear stress, and will drive the grating in the floating element to move synchronously, thereby changing the intensity of the reflected light. By accurately monitoring the change in the intensity of the reflected light, the magnitude of the shear stress on the sensor can be calculated. In order to ensure the accuracy of the shear stress measurement, it is particularly important to accurately detect the change in the intensity of the reflected light.

[0003] The optical lens array in the sensor mainly acts on the collimation, focusing and stable transmission of the optical signal, which can greatly improve the performance of the sensor. By collimating and focusing the optical signal, the lens array focuses the light beam emitted by the optical fiber to the grating of the chip floating element, making the sensor more sensitive to tiny displacements, thereby achieving higher measurement sensitivity. At the same time, the collimation and focusing of the lens array can also reduce the scattering and loss of light during the transmission process, reduce the interference of the external environment on the signal, thereby ensuring the stability of signal transmission, especially improving the sensitivity and reliability of the sensor under weak signal conditions.

[0004] In the current related technologies, MEMS sensors that measure shear stress usually use optical fibers to directly glue and align the optical path with the grating, and then measure the change in the intensity of the reflected light to calculate the magnitude of the shear stress on the sensor. Due to the fiber displacement and angle deviation problems that are easy to occur when the optical fiber is fixed with adhesive, the optical fiber will produce a large light loss during the propagation process, weakening the intensity of the light signal, resulting in low sensitivity of the sensor, resulting in poor adaptability of MEMS sensors that use optical fibers to align the optical path with the grating. Summary of the invention

[0005] Technical issues to be solved:

[0006] In order to avoid the shortcomings of the prior art, the present invention provides a shear stress microsensor based on lens array optical conduction and a packaging method thereof, which uses a lens array to focus and collimate the optical fiber beam, and combines a photodetector to measure the optical signal, effectively avoiding the optical fiber displacement and angle deviation problems that are easy to occur when the optical fiber is fixed with adhesive glue, reducing light loss, improving the transmission efficiency and stability of the optical signal, and thus enhancing the sensitivity of the sensor. Overcoming the problems of large optical path transmission loss and poor stability.

[0007] The technical solution of the present invention is: a shear stress microsensor based on lens array optical conduction, comprising an optical fiber, a transmission lens group, a MEMS chip, a reflection lens group, and a photodetector arranged in sequence along an optical path. The optical signal transmitted by the optical fiber is transmitted to the MEMS chip via the transmission lens group, and the optical signal carrying the displacement is reflected by the reflection grating of the MEMS chip. The reflected optical signal is then transmitted to the effective working area of ​​the photodetector via the reflection lens group; the optical signal is converted into an electrical signal by the photodetector, thereby obtaining displacement information for calculating the shear stress.

[0008] A further technical solution of the present invention is: the transmission lens group includes a first lens group, a beam splitter, and a second lens group arranged in sequence along the optical path, and the optical signal output by the optical fiber is completely transmitted to the second lens group through the beam splitter. By setting two groups of lens groups, the optical fiber optical signal is collimated and focused, and a parallel light beam is output to the MEMS chip reflection grating, that is, the optical signal output by the optical fiber can be 100% transmitted to the MEMS chip.

[0009] A further technical solution of the present invention is: each lens group in the transmission lens group is positioned and installed in the light-emitting lens barrel through a pressure ring and a spacer ring, the incident port of the light-emitting lens barrel is coaxially opposite to the optical fiber, and the cross-sectional area of ​​the incident port is larger than the incident area of ​​the optical fiber light signal; the output port of the light-emitting lens barrel is used as a chip placement table for installing a MEMS chip; the light-emitting lens barrel is provided with a through hole on the reflection path of the spectroscope.

[0010] A further technical solution of the present invention is: a square groove is opened on the end surface of the chip placement table to install the MEMS chip, and a plurality of notches are opened axially of the groove to prevent excess high-temperature glue from adhering to the MEMS chip; a square through hole is coaxially opened on the bottom surface of the groove to ensure that all optical signals transmitted by the transmission lens group are received by the MEMS chip.

[0011] A further technical solution of the present invention is: the MEMS chip includes a substrate layer and a device layer, and a reflection grating is arranged on the opposite surface of the substrate layer and the device layer; the reflection grating includes a plurality of groups of floating gratings arranged on the device layer and a plurality of groups of fixed gratings arranged on the substrate layer, wherein a preset offset distance is set between the floating gratings and the fixed gratings, and the two together constitute the reflection grating.

[0012] A further technical solution of the present invention is: the reflective lens group includes a second lens group, a beam splitter, a total reflector, and a third lens group arranged in sequence along the optical path, wherein the second lens group, the beam splitter and the transmission lens group are shared, and the light signal reflected by the MEMS chip is converted into an output light path parallel to the incident light path through two 45-degree reflections by the beam splitter and the total reflector, thereby being incident on the photodetector.

[0013] A further technical solution of the present invention is that the angle between the beam splitting surface of the beam splitter and the output optical axis of the optical fiber is 45 degrees, and the angle between the total reflection mirror and the incident light path and the light path emitted to the photodetector are both 45 degrees.

[0014] A further technical solution of the present invention is: the total reflection mirror and the third lens group in the reflecting lens group are positioned and installed on the returning light tube through a pressure ring and a spacer ring, and the returning light tube is provided with a through hole on the reflection path with the beam splitter; the light signal reflected by the beam splitter is transmitted to the total reflection mirror through the through holes provided on the light emitting tube and the returning light tube.

[0015] A further technical solution of the present invention is: it also includes an outer lens barrel, and the light-emitting lens barrel and the light-returning lens barrel are fixed in parallel in the outer lens barrel through pressure plates and pressure covers at both ends of the outer lens barrel, and the optical fiber and the photoelectric detector are positioned at one end of the outer lens barrel through the pressure plate, so that the optical fiber is coaxially opposite to the light-emitting lens barrel, and the photoelectric detector is coaxially opposite to the light-returning lens barrel; the optical fiber adopts an MPO optical fiber connector to connect with the mounting hole of the outer lens barrel.

[0016] A packaging method for a shear stress microsensor based on lens array optical conduction, the specific steps are as follows:

[0017] Each lens group, beam splitter and total reflector are fixed in the light emitting tube and the light returning tube respectively through a pressing ring and a spacer ring;

[0018] The photoelectric detector and the MPO optical fiber are respectively fixed to one end of the outer lens barrel through a pressing plate;

[0019] The chip placement table, the light-emitting lens barrel, the outer lens barrel, the pressing plate, the light-returning lens barrel, and the pressure cover are assembled and fixed by threaded fasteners;

[0020] Place the MEMS chip at the center of the groove of the chip placement table, adjust the position of the MEMS chip, and when the photodetector detects all the reflected light, apply high-temperature glue in the groove gap to fix the MEMS chip on the chip placement table.

[0021] Beneficial Effects

[0022] The beneficial effects of the present invention are:

[0023] (1) The present invention uses a lens array to collimate and focus the optical fiber beam, reducing the loss of optical signals during transmission and avoiding the common optical fiber displacement and angle deviation problems in the traditional method of fixing optical fibers with adhesives. This design not only improves the transmission efficiency of optical signals, but also ensures the accurate measurement of the change in reflected light intensity, thereby improving the sensitivity and accuracy of the sensor in shear stress measurement.

[0024] (2) The present invention effectively avoids the impact of high temperature on key components by moving components with poor high temperature resistance to the rear end away from the high temperature source, ensuring that the sensor can work stably in a high temperature environment and maintain good light transmission effect and measurement performance. This design improves the reliability of the sensor under high temperature conditions and expands its scope of application in high temperature application scenarios. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 Schematically shows a cross-sectional view of a shear stress microsensor in an exemplary embodiment of the present invention;

[0026] Figure 2 A schematic diagram of a chip placement platform for a shear stress microsensor in an exemplary embodiment of the present invention is schematically shown;

[0027] Figure 3 A cross-sectional view of a light-emitting lens barrel of a shear stress microsensor in an exemplary embodiment of the present invention is schematically shown;

[0028] Figure 4 A schematic diagram of a pressure plate of a shear stress microsensor in an exemplary embodiment of the present invention is schematically shown;

[0029] Figure 5 Schematically shows a cross-sectional view of a light-returning lens barrel of a shear stress microsensor in an exemplary embodiment of the present invention;

[0030] Figure 6 A schematic diagram of a gland of a shear stress microsensor in an exemplary embodiment of the present invention is schematically shown;

[0031] Figure 7 Schematically shows a cross-sectional view of a shear stress microsensor chip in an exemplary embodiment of the present invention;

[0032] Figure 8 Schematically shows a light path propagation diagram of a shear stress microsensor in an exemplary embodiment of the present invention;

[0033] Fig. 9 A flow chart of a packaging method of a shear stress microsensor in an exemplary embodiment of the present invention is schematically shown;

[0034] Explanation of reference numerals: 1. chip placement platform; 10. notch; 11. internal thread; 12. groove; 13. square through hole; 14. positioning hole; 2. light-emitting lens barrel; 20. second pressure ring; 21. second spacer ring; 22. second lens group; 23. spectroscope; 24. first spacer ring; 25. first pressure ring; 26. first lens group; 27. first light-through hole; 28. light-emitting lens barrel fixing hole; 29. ​​chip placement platform positioning hole; 3. outer lens barrel; 4. pressure plate; 40. photodetector Positioning hole; 41, pressure plate positioning hole; 42, MPO fiber interface hole; 5, MPO fiber; 6, photodetector; 7, light-returning mirror tube; 70, second light-through hole; 71, third spacer ring; 72, third pressure ring; 73, third lens group; 74, total reflection mirror; 75, light-returning mirror tube fixing hole; 8, pressure cover; 80, light-emitting mirror tube positioning hole; 81, pressure cover positioning hole; 9, MEMS chip; 90, fixed grating; 91, substrate layer; 92, device layer; 93, floating grating. DETAILED DESCRIPTION

[0035] The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, but should not be construed as limiting the present invention.

[0036] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0037] MEMS sensors based on measuring shear stress have problems of fiber displacement and angle deviation that are easy to occur when fixing optical fibers with adhesive glue. The optical fibers will produce large light losses during propagation, which weakens the intensity of optical signals, resulting in low sensitivity of the sensor, and poor adaptability of MEMS sensors based on optical fiber to achieve alignment of optical paths and gratings. The present invention provides a shear stress microsensor based on lens array optical conduction, comprising an optical fiber, a transmission lens group, a MEMS chip, a reflection lens group, and a photodetector that are sequentially arranged along the optical path. The optical signal transmitted by the optical fiber is transmitted to the MEMS chip via the transmission lens group, and the received optical signal is reflected by the reflection grating of the MEMS chip. The reflected optical signal is then transmitted to the effective working area of ​​the photodetector via the reflection lens group; the optical signal is converted into an electrical signal by the photodetector, thereby obtaining the shear stress measurement result.

[0038] The above technical solution is further described below in conjunction with the accompanying drawings:

[0039] In one embodiment, referring to Figure 1 As shown, a shear stress microsensor based on lens array optical conduction in this embodiment includes: a chip placement platform 1, a light output lens barrel 2, an outer lens barrel 3, a pressure plate 4, an MPO optical fiber 5, a photodetector 6, a light return lens barrel 7, a pressure cover 8 and a MEMS chip 9.

[0040] Reference Figure 2 As shown, the chip placement platform 1 is provided with two through-hole internal threads 11 on the upper surface, and a groove 12 is provided on the upper surface. The depth of the groove 12 is consistent with the thickness of the MEMS chip 9, ensuring that the upper surface of the MEMS chip 9 should be flush with the upper surface of the chip placement platform 1. Four notches 10 are provided at each end of the groove 12 to prevent excess high-temperature glue from sticking to the MEMS chip. A square through hole 13 is provided at the center of the chip placement platform 1. The size of the square through hole 13 is smaller than that of the MEMS chip 9. The size of the square through hole 13 is larger than the reflection grating size of the MEMS chip 9, and is used to focus the optical fiber light beam onto the MEMS chip through lenses 26 and 22. Two positioning holes 14 are provided on the side of the chip placement platform 1, which are used for installing and positioning the chip placement platform 1 and the light-emitting lens barrel 2, ensuring that the chip placement platform 1 will not be offset at an angle during installation;

[0041] Reference Figure 3 As shown, the light emitting lens barrel 2 includes, from left to right: a first pressing ring 25, a first lens group 26, a first spacer ring 24, a beam splitter 23, a first light through hole 27, a light emitting lens barrel fixing hole 28, a second lens group 22, a second spacer ring 21, a second pressing ring 20 and a chip placement platform positioning hole 29. The first pressing ring 25 and the second pressing ring 20 fix the first lens group 26 and the second lens group 22 inside the light emitting lens barrel 2. The first spacer ring 24 and the second spacer ring 21 separate different lenses in the first lens group 26 and the second lens group 22 respectively. The beam splitter 23 deflects the light reflected back by the MEMS chip 9 by 90 degrees and transmits it to the return light lens barrel 7 through the first light through hole 27. The light emitting lens barrel fixing hole 28 is used for positioning and fixing with the outer lens barrel 3. The chip placement platform positioning hole 29 is used in conjunction with the positioning hole 14 to ensure that the chip placement platform 1 will not be offset in angle during installation.

[0042] Reference Figure 1As shown, the outer lens barrel 3 fixes the light-emitting lens barrel and the light-returning lens barrel in parallel therein through the pressure plates and pressure covers at both ends, and the optical fiber and the photoelectric detector are positioned at one end of the outer lens barrel through the pressure plate, so that the optical fiber is coaxially opposite to the light-emitting lens barrel, and the photoelectric detector is coaxially opposite to the light-returning lens barrel; the optical fiber adopts an MPO optical fiber connector to connect with the mounting hole of the outer lens barrel.

[0043] Reference Figure 4 As shown, a pressing plate 4 is provided with a photoelectric detector positioning hole 40, a pressing plate positioning hole 41, and an MPO optical fiber interface hole 42. The photoelectric detector positioning hole 40 is used for positioning and fixing the photoelectric detector 6, the pressing plate positioning hole 41 is used for fixing the outer lens barrel 3, and the MPO optical fiber interface hole 42 is a special interface for the MPO optical fiber 5 to achieve quick plug-in connection;

[0044] Reference Figure 1 As shown, the MPO optical fiber 5 is a multi-core interface, which is plugged into the mounting hole of the outer lens barrel 5.

[0045] The photoelectric detector 6 is of prior art.

[0046] Reference Figure 5 As shown, the light-returning mirror barrel 7 includes, from left to right: a third pressure ring 72, a third lens group 73, a third spacer ring 71, a total reflection mirror 74, a second light-through hole 70, and a light-returning mirror barrel fixing hole 75. The third pressure ring 72 fixes the third lens group inside the light-returning mirror barrel 7, the third spacer ring 71 separates different lenses in the third lens group 73, the total reflection mirror 74 receives the light signal through the second light-through hole 70, and the light signal is deflected 90 degrees to the third lens group 73 after passing through the total reflection mirror 74, and the third lens group 73 aligns the light signal to the effective working area of ​​the photodetector 6 for photoelectric signal conversion.

[0047] Reference Figure 6 As shown, a pressure cover 8 is provided with a light-emitting lens barrel positioning hole 80 and a pressure cover positioning hole 81. The light-emitting lens barrel positioning hole 80 is used to install and fix the light-emitting lens barrel 2 on the outer lens barrel 3, and the pressure cover positioning hole 81 is used to install and fix the pressure cover and the outer lens barrel 3;

[0048] Reference Figure 7 As shown, the MEMS chip 9 includes, from top to bottom, a device layer 92 and a base layer 91. A floating grating 93 is provided on the lower surface of the device layer 92, and a fixed grating 90 is provided on the upper surface of the base layer. The device layer 92 is connected to the base layer 91 by bonding, and the upper surface of the device layer 92 is installed flush with the upper surface of the chip placement platform 1.

[0049] The following is a detailed description of the various parts of the MEMS sensor:

[0050] In one embodiment, reference Figure 2 As shown, the chip placement platform 1 fixes the MEMS chip 9 and the lens package into a whole, a square through hole 13 is set at the center of the chip placement platform 1, a groove 12 is set on the upper surface of the chip placement platform 1, and four notches 10 are set at each end of the groove 12.

[0051] Optionally, the size of the square through hole 13 is smaller than the MEMS chip 9 and is used for placing the MEMS chip 9. The size of the square through hole 13 is larger than the size of the reflection grating of the MEMS chip 9 to ensure that the MEMS chip 9 receives all optical signals.

[0052] Optionally, the depth of the groove 12 should be consistent with the thickness of the MEMS chip 9 to ensure that the upper surface of the MEMS chip 9 is flush with the chip placement platform 1 .

[0053] Optionally, notches 10 are provided at the four ends of the groove 12 so that when the MEMS chip 9 is fixed in the groove 12 , excess high temperature glue can flow out from the notches 10 , thereby avoiding adhesion of excess high temperature glue to the MEMS chip 9 .

[0054] In one embodiment, reference Figure 3 As shown, the light emitting lens barrel 2 collimates and focuses the light beam emitted by the MPO optical fiber 5 onto the reflection grating on the MEMS chip 9 through the first lens group 26 and the second lens group 22, and the beam splitter 23 deflects the reflected light by 90 degrees into the first light hole 27 and transmits it to the total reflection mirror 74 of the light returning lens barrel 7.

[0055] Optionally, the materials of the first lens group 26, the second lens group 22 and the beam splitter 23 are generally glass or quartz glass, which can usually withstand high temperatures of 500-700 degrees.

[0056] In one embodiment, reference Figure 4 As shown, the pressing plate 4 is the lower base plate of the outer lens barrel 3 during the assembly process, and is used to fix the outer lens barrel 3 to the light-emitting lens barrel 2 and the light-returning lens barrel 7. A photodetector positioning hole 40 and an MPO optical fiber interface hole 42 are also provided on the pressing plate 4, which are used to fix and connect the pressing plate 4 to the photodetector 6 and the MPO optical fiber 5.

[0057] Optionally, for ease of installation, the pressure plate positioning hole 41 for fixing with the outer lens barrel 3 is a through hole to facilitate the insertion of threaded fasteners, and the inner diameter of the photodetector positioning hole 40 should be slightly larger than the outer diameter of the signal end of the photodetector 6.

[0058] Optionally, the pressing plate 4 should be made of a material with a high melting point, good thermal conductivity and opacity, and the thermal expansion coefficient should be close to that of the chip, such as molybdenum.

[0059] In one embodiment, reference Figure 5 As shown, the light-returning lens barrel 7 receives the light beam to the total reflector 74 through the second light hole 70, and the total reflector 74 then deflects the reflected light by 90 degrees to the third lens group 73 for collimation and transmits it to the photodetector 6. When the collimated reflected light hits the end face of the photodetector 6, the optical signal is converted into an electrical signal.

[0060] Optionally, the total reflection mirror 74 should be placed at an angle of 45 degrees in the light-returning mirror tube to ensure that the received light signal is deflected 90 degrees and finally transmitted to the effective working area of ​​the photodetector 6.

[0061] Optionally, the second light hole 70 should be aligned with the center of the first light hole 27 to ensure that the light beam is fully transmitted.

[0062] Optionally, the effective working area of ​​the photodetector 6 should be larger than the size of the light spot array after being collimated by the third lens group 73 to ensure that all light signals are accurately received.

[0063] Optionally, the material of the third lens group 73 and the total reflection mirror 74 is generally glass or quartz glass, which can usually withstand high temperatures of 500-700 degrees.

[0064] In one embodiment, reference Figure 6 As shown, the pressure cover 8 is the upper cover plate of the outer lens barrel 3 during the assembly process, and is used to fix the outer lens barrel 3 to the light-emitting lens barrel 2 and the light-returning lens barrel 7 .

[0065] Optionally, for ease of installation, the gland positioning hole 81 for fixing with the outer lens barrel 3 is a through hole to facilitate the insertion of threaded fasteners, and the diameter of the light-emitting lens barrel positioning hole 80 should be slightly larger than the outer diameter of the light-emitting lens barrel 2 .

[0066] Optionally, the pressure cover 8 should be made of a material with a high melting point, good thermal conductivity and opacity, and the thermal expansion coefficient should be close to that of the chip, such as molybdenum.

[0067] In one embodiment, reference Figure 7 As shown, the MEMS chip 9 is a chip with a floating structure made based on the MEMS process, and is used for the incident light transmitted by the MPO optical fiber 5. Each set of reflection gratings of the MEMS chip 9 is composed of a set of floating gratings 93 and a fixed grating 90, and the floating grating 93 and the fixed grating 90 are both composed of a plurality of grating grids, and the floating grating 90 and the fixed grating 90 have a certain offset distance.

[0068] Optionally, the device layer 92 is connected to the base layer 91 by bonding.

[0069] Optionally, the device layer 92 of the MEMS chip 9 may be made of semiconductor materials such as silicon and sapphire, and the base layer 91 may be made of a transparent material such as Borofloat 33 .

[0070] In one embodiment, reference Figure 8 As shown, the light emitted by the light source is transmitted to the MPO connector 5 by the optical fiber, and the light beam passes through the first lens group 26, the beam splitter 23 and the second lens group 22 in sequence and is focused onto the reflection grating of the MEMS chip 9 to form a reflected light cone. The reflected light cone is deflected 90 degrees by the beam splitter 23 to the total reflection mirror 74, and the total reflection mirror 74 then deflects the reflected light cone 90 degrees to the third lens group 73 for collimation and transmission to the photodetector 6. When the collimated reflected light is projected onto the effective working area of ​​the photodetector 6, the displacement signal carried is converted into an electrical signal, and the displacement information is extracted from the voltage signal, thereby calculating the shear stress.

[0071] refer to Fig. 9 The present invention also provides a packaging method for a shear stress microsensor based on lens array optical conduction, which is applied to a shear stress microsensor based on lens array optical conduction of the present invention. The packaging method comprises the following steps:

[0072] S1. Fix the lenses 22, 26, 73, the beam splitter 23 or the total reflector 74 in the light emitting lens barrel 2 and the light returning lens barrel 7 through the pressing rings 20, 25, 72 and the spacers 21, 24, 71.

[0073] Specifically, after the lenses 22, 26, 73, the beam splitter 23 or the total reflector 74 are installed and fixed in the light emitting lens barrel 2 and the light returning lens barrel 7 through the pressing rings 20, 25, 72 and the spacers 21, 24, 71 according to the light path requirements, the optical detection system should be used to detect whether the installation of the lenses meets the light path requirements. If it does not meet the requirements, it should be reinstalled. Only when it meets the requirements can the next step be carried out.

[0074] S2, installing and fixing the photoelectric detector 6 and the MPO optical fiber 5 on the pressing plate 4;

[0075] Specifically, the MPO optical fiber 5 can be quickly plugged and unplugged through the dedicated interface 42 on the pressing plate 4. After the two signal ports of the photodetector 6 pass through the positioning holes 40 on the pressing plate 4, the photodetector 6 and the pressing plate 4 are fixed with glue.

[0076] S3, assembling the chip placement platform 1, the light output lens barrel 2, the outer lens barrel 3, the pressing plate 4, the light return lens barrel 7, and the pressure cover 8 by means of threaded fasteners;

[0077] Specifically, when installing, the light-emitting lens barrel 2 and the light-returning lens barrel 7 need to be positioned and installed with the outer lens barrel 3 through the light-emitting lens barrel fixing hole 28 and the light-returning lens barrel fixing hole 75, respectively, to ensure that the first light-through hole 27 and the second light-through hole 70 thereof are accurately opposite. Then the pressing plate 4 and the pressure cover 8 are connected to the assembled outer lens barrel 3 through threaded fasteners. When installing the chip placement platform 1 and the light-emitting lens barrel 2, it is necessary to pay attention to first passing the positioning pin through the positioning hole 14 and the chip placement platform positioning hole 29, and then connecting them through the threaded fasteners, and it is necessary to ensure that the chip placement platform 1 does not deviate in angle during the installation process.

[0078] S4. Place the MEMS chip 9 at the center of the groove 12 of the chip placement table, adjust the position of the MEMS chip 9, and when the photodetector 6 detects all the reflected light, apply high-temperature glue in the groove notch 10 to fix the MEMS chip 9 on the chip placement table 1.

[0079] Specifically, the upper surface of the MEMS chip 9 after installation should be flush with the upper surface of the chip placement platform 1 to reduce the impact of the pressure gradient on the measurement data and meet the requirements of subsequent testing and use.

[0080] According to a shear stress microsensor based on lens array optical conduction and its packaging method of the present invention, on the one hand, by adopting a lens array to realize the collimation and focusing of the optical fiber light beam, the loss of the optical signal in the conduction process is reduced, and the common optical fiber displacement and angle deviation problems in the traditional method of fixing the optical fiber with adhesive glue are avoided. This design not only improves the transmission efficiency of the optical signal, but also ensures the accurate measurement of the change in the intensity of the reflected light, and improves the sensitivity and accuracy of the sensor in shear stress measurement. On the other hand, by moving components with poor high temperature resistance to the rear end position away from the high temperature source, the influence of high temperature on key components is effectively avoided, ensuring that the sensor can work stably in a high temperature environment and can maintain good light conduction effect and measurement performance. This design improves the reliability of the sensor under high temperature conditions and expands its scope of application in high temperature application scenarios.

[0081] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations on the present invention. A person skilled in the art may change, modify, replace and modify the above embodiments within the scope of the present invention without departing from the principles and intent of the present invention.

Claims

1. A shear stress microsensor based on lens array optical conduction, characterized in that: It includes an optical fiber, a transmission lens group, a MEMS chip, a reflection lens group, and a photodetector arranged in sequence along the optical path. The optical signal transmitted by the optical fiber is transmitted to the MEMS chip through the transmission lens group, and the optical signal carrying the displacement is reflected by the reflection grating of the MEMS chip. The reflected optical signal is then transmitted to the effective working area of ​​the photodetector through the reflection lens group. The optical signal is converted into an electrical signal by a photodetector, thereby obtaining the displacement information used to calculate the shear stress.

2. A shear stress microsensor based on lens array optical conduction according to claim 1, characterized in that: The transmission lens group includes a first lens group, a beam splitter, and a second lens group arranged in sequence along the optical path. The optical signal output by the optical fiber is completely transmitted to the second lens group through the beam splitter. By setting up two groups of lens groups, the optical fiber optical signal is collimated and focused, and a parallel light beam is output to the MEMS chip reflection grating, that is, the optical signal output by the optical fiber can be 100% transmitted to the MEMS chip.

3. A shear stress microsensor based on lens array optical conduction according to claim 2, characterized in that: Each lens group in the transmission lens group is positioned and installed on the light-emitting lens barrel through a pressure ring and a spacer ring. The incident port of the light-emitting lens barrel is coaxially opposite to the optical fiber, and the cross-sectional area of ​​the incident port is larger than the incident area of ​​the optical fiber light signal; the incident port of the light-emitting lens barrel is used as a chip placement table for installing a MEMS chip; the light-emitting lens barrel is provided with a through hole on the reflection path of the spectroscope.

4. A shear stress microsensor based on lens array optical conduction according to claim 3, characterized in that: A square groove is provided on the end surface of the chip placement table to install the MEMS chip. The groove has multiple notches in the axial direction to prevent excess high-temperature glue from sticking to the MEMS chip. A square through hole is coaxially provided on the bottom surface of the groove to ensure that all optical signals transmitted by the transmission lens group are received by the MEMS chip.

5. A shear stress microsensor based on lens array optical conduction according to claim 4, characterized in that: The MEMS chip includes a substrate layer and a device layer, and a reflection grating is arranged on the opposite surface of the substrate layer and the device layer; the reflection grating includes a plurality of groups of floating gratings arranged on the device layer and a plurality of groups of fixed gratings arranged on the substrate layer, wherein a misalignment distance is preset between the floating gratings and the fixed gratings, and the two together constitute the reflection grating.

6. The shear stress microsensor based on lens array optical conduction according to claim 2, characterized in that: The reflective lens group includes a second lens group, a beam splitter, a total reflector, and a third lens group, which are arranged in sequence along the optical path. The second lens group, the beam splitter and the transmission lens group are shared. The optical signal reflected by the MEMS chip is converted into an output optical path parallel to the incident optical path through two 45-degree reflections by the beam splitter and the total reflector, so as to be incident on the photodetector.

7. A shear stress microsensor based on lens array optical conduction according to claim 6, characterized in that: The included angle between the beam splitting surface of the beam splitter and the output optical axis of the optical fiber is 45 degrees, and the included angle between the total reflection mirror and the incident light path and the light path emitted to the photoelectric detector is also 45 degrees.

8. A shear stress microsensor based on lens array optical conduction according to claim 7, characterized in that: The total reflection mirror and the third lens group in the reflecting lens group are positioned and installed on the light-returning lens barrel through a pressure ring and a spacer ring. The light-returning lens barrel is provided with a through hole on the reflection path with the beam splitter; the light signal reflected by the beam splitter is transmitted to the total reflection mirror through the through holes provided on the light-emitting lens barrel and the light-returning lens barrel.

9. The shear stress microsensor based on lens array optical conduction according to claim 2, characterized in that: It also includes an outer lens barrel, and the light-emitting lens barrel and the light-returning lens barrel are fixed in parallel in the outer lens barrel through pressure plates and pressure covers at both ends of the outer lens barrel, and the optical fiber and the photoelectric detector are positioned at one end of the outer lens barrel through the pressure plate, so that the optical fiber is coaxially opposite to the light-emitting lens barrel, and the photoelectric detector is coaxially opposite to the light-returning lens barrel; the optical fiber adopts an MPO optical fiber connector to connect with the mounting hole of the outer lens barrel.

10. A packaging method for a shear stress microsensor based on lens array optical conduction, implemented based on the shear stress microsensor based on lens array optical conduction according to any one of claims 1 to 9; characterized in that The specific steps are as follows: Each lens group, beam splitter and total reflector are fixed in the light emitting tube and the light returning tube respectively through a pressing ring and a spacer ring; The photoelectric detector and the MPO optical fiber are respectively fixed to one end of the outer lens barrel through a pressing plate; The chip placement table, the light-emitting lens barrel, the outer lens barrel, the pressing plate, the light-returning lens barrel, and the pressure cover are assembled and fixed by threaded fasteners; Place the MEMS chip at the center of the groove of the chip placement table, adjust the position of the MEMS chip, and when the photodetector detects all the reflected light, apply high-temperature glue in the groove gap to fix the MEMS chip on the chip placement table.

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