MEMS galvanometer and laser radar

Abstract

The invention belongs to the field of laser radars, and particularly relates to an MEMS galvanometer and a laser radar, the MEMS galvanometer comprises a substrate and a mirror body, the mirror body is connected with the substrate through a beam structure, and the mirror body is used for receiving an echo signal and deflecting under the driving of an external force to control the direction of the received echo signal; the back of the mirror body and / or the surface of the substrate are / is provided with an extinction structure, and the back of the mirror body is an opposite surface of the mirror body for receiving echo signals. The extinction structure is arranged on the back face of the mirror body and / or the surface of the substrate, ambient light can be reflected to deviate from the optical axis of a receiving system through the extinction structure, the reflecting capacity of the mirror body and / or the substrate to the ambient light can be reduced through extinction processing, stray light generated by the MEMS galvanometer to an optical system is further reduced, the signal-to-noise ratio of the system is increased, and the system reliability is improved. And the ranging capability of the laser radar is improved.

Description

Technical Field

[0001] The present application relates to the field of laser radar technology, and in particular to a MEMS galvanometer and a laser radar. Background Art

[0002] As a distance measuring device, the distance measuring capability is one of its key indicators. The laser radar is composed of a transmitting system, a receiving system, a scanning system and other parts. The transmitting system transmits a laser signal, which is reflected and swung by a MEMS (Micro-Electro-Mechanical System) galvanometer to achieve a one-dimensional or two-dimensional scan of the space. At the same time, the laser echo signal reflected by the target object enters the receiving system through the galvanometer reflection. The signal processing system analyzes and compares the transmitted laser signal and the echo signal to obtain the three-dimensional spatial information of the target position, speed and other states.

[0003] The ranging capability of LiDAR is often determined by the signal-to-noise ratio of the echo signal. When the signal and noise reach a certain signal-to-noise ratio, the signal processing system can distinguish the signal and obtain ranging information. Generally, the stronger the signal-to-noise ratio, the stronger the ranging capability. In current LiDARs, the stray light generated by the MEMS galvanometer of the scanning system to the optical system reduces the signal-to-noise ratio of the system and affects the ranging capability of LiDAR. Summary of the invention

[0004] The embodiments of the present application provide a MEMS galvanometer and a laser radar, which are intended to reduce the stray light generated by the MEMS galvanometer to the optical system, thereby improving the system signal-to-noise ratio and enhancing the ranging capability.

[0005] To this end, according to one aspect of the present application, a MEMS oscillator is provided for use in a laser radar, wherein the MEMS oscillator includes a substrate and a mirror body, wherein the mirror body is connected to the substrate via a beam structure, and the mirror body is used to receive an echo signal and deflect under external force to control the direction of the received echo signal; an extinction structure is provided on the back side of the mirror body and / or the surface of the substrate, and the back side of the mirror body is the opposite side of the mirror body that receives the echo signal.

[0006] Optionally, the matt structure is a light-guiding structure and / or a matt coating.

[0007] Optionally, the substrate is a silicon substrate, and the mirror body, the beam structure and the silicon substrate are an integrated structure.

[0008] Optionally, an iron core for adjusting the magnetic field distribution is provided on the back of the mirror body, and a coil is provided at a corresponding position of the beam structure. The coil in the magnetic field is deflected by the Lorentz force or electrostatic drive after power is turned on, thereby driving the connected mirror body to deflect.

[0009] Optionally, the light-guiding structure includes an inclined plane, and the inclined plane satisfies: 2α-2θ>β, wherein α is the inclination angle of the inclined plane, θ is the inclination angle of the lens, and β is the field of view angle of the receiving system.

[0010] Optionally, the light-guiding structure comprises chamfers or rounded corners or annular bevel grooves or a plurality of serrated repeating units.

[0011] Optionally, the matte coating is one or more of matte paint, matte film, matte sand and surface ceramicization.

[0012] Optionally, the MEMS oscillating mirror further includes a shading member, and the shading member is used to block non-echo signals from entering the mirror body.

[0013] Optionally, the shading member is located on a side of the mirror body that receives the echo signal and is spaced apart from the substrate, and the shading member is provided with a light-transmitting hole corresponding to the mirror body.

[0014] Optionally, a side of the shading member facing away from the mirror body is provided with a light-guiding structure for reflecting light to a side deviating from the optical axis of a receiving system of the laser radar, and / or performing a light extinction treatment for reducing the reflectivity of the light.

[0015] According to another aspect of the present application, a laser radar is provided, including a laser transceiver system and the MEMS galvanometer as described above, the laser transceiver system including a transmitting system for transmitting a laser signal and a receiving system for receiving an echo signal, the MEMS galvanometer is used to reflect the laser signal and transmit it to a scanning environment, and reflect the echo signal reflected from the scanning environment to the receiving system.

[0016] The beneficial effects of the MEMS galvanometer and laser radar provided by the present application are as follows: compared with the prior art, the MEMS galvanometer of the present application sets an extinction structure on the back of the mirror body and / or the surface of the substrate. The extinction structure can reduce the reflective ability of the back of the mirror body and the surface of the substrate to ambient light, thereby reducing the stray light generated by the MEMS galvanometer to the optical system, improving the system signal-to-noise ratio, and enhancing the ranging capability of the laser radar. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0018] in:

[0019] Figure 1is a schematic diagram of a partial structure of a laser radar shown in an embodiment of the present application;

[0020] Figure 2 is a schematic diagram of the optical path of a laser radar shown in an embodiment of the present application;

[0021] Figure 3 It is a structural schematic diagram of a MEMS galvanometer shown in an embodiment of the present application;

[0022] Figure 4 It is a partial structural schematic diagram of a MEMS galvanometer shown in an embodiment of the present application;

[0023] Figure 5 is a schematic diagram of a MEMS galvanometer in the optical path of a laser radar shown in an embodiment of the present application;

[0024] Figure 6 It is a structural schematic diagram of an iron core of a MEMS galvanometer shown in an embodiment of the present application;

[0025] Figure 7 It is a schematic structural diagram of another iron core of a MEMS galvanometer shown in an embodiment of the present application;

[0026] Figure 8 is a schematic diagram of a light guide structure shown in an embodiment of the present application;

[0027] Fig. 9 It is a schematic structural diagram of a MEMS galvanometer with a shading member according to an embodiment of the present application.

[0028] Description of main component symbols:

[0029] 10. MEMS galvanometer;

[0030] 20. Laser transceiver system;

[0031] 30. Reflector;

[0032] 110. Substrate;

[0033] 120, mirror body;

[0034] 130, beam structure; 131, mounting portion; 132, flexible beam 1; 133, flexible beam 2;

[0035] 200, coil;

[0036] 300, iron core;

[0037] 400, shading member; 401, light transmission hole. DETAILED DESCRIPTION

[0038] In order to facilitate the understanding of the present application, the present application will be described more comprehensively with reference to the relevant drawings below. The preferred embodiments of the present application are provided in the drawings. However, the present application can be implemented in many other different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosure of the present application more thorough and comprehensive.

[0039] It should be noted that when an element is referred to as being "fixed to" or "disposed on" another element, it can be directly on the other element or indirectly on the other element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or indirectly connected to the other element.

[0040] It should be understood that the terms "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0041] In addition, the terms "first", "second", etc. are used for descriptive purposes only and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. In the description of this application, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0042] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those generally understood by those skilled in the art to which the present application belongs. The terms used herein in the specification of the present application are only for the purpose of describing specific embodiments and are not intended to limit the present application. The term "and / or" used herein includes any and all combinations of one or more of the related listed items.

[0043] The present application embodiment provides a laser radar that emits a laser beam to detect characteristic quantities such as the position and speed of a target, such as Figure 1 and Figure 2 As shown, the laser radar includes a laser transceiver system 20, a MEMS galvanometer 10 and a reflector 30. The laser transceiver system 20 includes a transmitting system for transmitting laser signals and a receiving system for receiving echo signals. The laser signal emitted by the transmitting system is reflected to the MEMS galvanometer 10 via the reflector 30. The MEMS galvanometer 10 is used to reflect the laser signal and then emit it to the scanning environment to achieve one-dimensional or two-dimensional scanning of the space. The echo signal reflected back from the scanning environment is reflected to the receiving system via the reflector 30 to achieve signal reception.

[0044] Since the ranging capability of laser radar is often determined by the signal-to-noise ratio of the echo signal, the higher the signal-to-noise ratio, the stronger the ranging capability. In laser radar, the stray light generated by the MEMS galvanometer 10 of the scanning system to the optical system will reduce the signal-to-noise ratio of the system and affect the ranging capability of the laser radar.

[0045] Here, it should be noted that the actual light-transmitting area of ​​the galvanometer is the central swinging surface on the silicon wafer (i.e., the mirror body 120 described below), and the rest will generate stray light, especially the structural parts in the optical path, which will introduce a large amount of stray light. The stray light generated by the galvanometer is mainly divided into two parts, the stray light generated by the structural parts and silicon wafer within the field of view, and the stray light generated by the structure and silicon wafer outside the field of view. The stray light within the field of view is mainly caused by the swing of the mirror body, and the structural parts on the back of the silicon wafer participate in the optical path. The structural parts reflect the ambient light directly into the receiving system along the optical axis to generate a large amount of stray light. The stray light outside the field of view is mainly caused by the diffuse reflection of light from the peripheral structural parts of the optical system directly or indirectly entering the receiving system, generating stray light.

[0046] In the embodiment of the present application, the laser radar improves the MEMS galvanometer 10 by setting an extinction structure on the back side of the mirror body and / or the surface of the substrate to reduce the stray light generated by the MEMS galvanometer 10 to the optical system, improve the system signal-to-noise ratio, and thus enhance the ranging capability of the laser radar.

[0047] In one embodiment, if Figure 2-Figure 3 and Figure 5 As shown, the MEMS galvanometer 10 includes a substrate 110 and a mirror body 120. The mirror body 120 is connected to the substrate 110 via a beam structure 130. The mirror body 120 is used to receive echo signals and deflect under external force to control the direction of the received echo signals. An extinction structure is provided on the back side of the mirror body 120 and / or the surface of the substrate 110. The back side of the mirror body 120 is the opposite side of the mirror body 120 for receiving echo signals.

[0048] In the embodiment of the present application, the MEMS galvanometer 10 is provided with an extinction structure on the back side of the mirror body 120 and / or the surface of the substrate 110. The extinction structure can reduce the reflective ability of the back side of the mirror body 120 and the surface of the substrate 110 to ambient light. By setting as above, the stray light generated by the MEMS galvanometer 10 to the optical system can be reduced, thereby improving the system signal-to-noise ratio and enhancing the ranging capability of the laser radar.

[0049] In a specific embodiment, the matte structure is a light-guiding structure and / or a matte coating.

[0050] The light-guiding structure can reflect ambient light away from the optical axis of the receiving system, and the matte coating can absorb part of the ambient light, thereby reducing the surface's ability to reflect ambient light. Both the light-guiding structure and the matte coating can reduce the stray light generated by the MEMS galvanometer 10 to the optical system, thereby improving the system's signal-to-noise ratio.

[0051] In a specific embodiment, Figure 3 and Figure 4 As shown, the substrate 110 is a silicon substrate, and the mirror body 120, the beam structure 130 and the silicon substrate are an integrated structure.

[0052] By designing the mirror body 120, the beam structure 130 and the silicon substrate as an integrated structure, it is not only convenient for processing and manufacturing, but also helps to improve the connection strength between the components.

[0053] Specifically, the mirror body 120, the beam structure 130 and the silicon substrate can be formed by etching a silicon wafer.

[0054] In a specific embodiment, Figure 2 , Figure 4 and Figure 5 As shown, an iron core 300 for adjusting the magnetic field distribution is provided on the back of the mirror body 120, and a coil 200 is provided at the corresponding position of the substrate 110. The coil 200 in the magnetic field is deflected by the Lorentz force or electrostatic drive after power is turned on, thereby driving the connected mirror body 120 to deflect.

[0055] In order to further reduce the stray light generated by the MEMS galvanometer 10 to the optical system, a light-guiding structure and / or a matte coating is also provided on a side of the core 300 facing the mirror body 120 .

[0056] In a more specific embodiment, Figure 2 and Figure 5 As shown, the light-guiding structure includes an inclined plane, and the inclined plane satisfies: 2α-2θ>β, wherein α is the inclination angle of the inclined plane, θ is the inclination angle of the lens, and β is the field of view angle of the receiving system.

[0057] Assuming that the installation angle of the substrate 110 is θ, at this time, since there is reflected light outside the non-light-transmitting surface of the substrate 110 (i.e., the mirror body 120) and on the side of the iron core 300 on the back of the substrate 110 facing the substrate 110, the light enters the receiving system through the reflector 30.

[0058] When receiving as above, the inclination angle of the inclined plane is α, the angle of the reflected light is 90°+2θ, the angle of the stray light in the field of view is 90°+2θ+2α, and the angle between the two beams of light is 2α. If 2α-2θ>β, the stray light caused by the ambient light reflected by the side of the iron core 300 facing the substrate 110 in the field of view can be greatly reduced.

[0059] It is understandable that the light-guiding structure can be flexibly designed according to the installation and rotation angle of the MEMS galvanometer 10 to ensure the angle relationship of the reflected light.

[0060] For example, in a more specific embodiment, Figure 5 As shown, the light guiding structure adopts a comb-tooth structure, that is, a plurality of repeated units in a sawtooth shape.

[0061] In another more specific embodiment, Figure 6 As shown, the light guide structure adopts a chamfered structure. Of course, the light guide structure can also adopt a rounded structure.

[0062] In yet another more specific embodiment, Figure 7 As shown, the light guiding structure adopts an annular oblique groove structure.

[0063] In other embodiments, the light-guiding structure can also be realized by etching extinction and light-guiding grooves at different angles. The specific structure is as follows: Figure 8 shown.

[0064] In a more specific embodiment, the matte coating is one or more of matte paint, matte film, matte sand and surface ceramicization.

[0065] In one embodiment, if Figure 3 and Figure 4 As shown, the beam structure 130 includes an internally hollow mounting portion 131, a flexible beam 132 and a flexible beam 2 133. The mounting portion 131 is fixed to the substrate 110 through the flexible beam 132, the mirror body 120 is fixed to the inside of the mounting portion 131 through the flexible beam 2 133, and the coil 200 is arranged on the mounting portion 131.

[0066] Specifically, the two flexible beams 132 are respectively connected to the opposite ends of the mounting portion 131 in the horizontal direction, and the two flexible beams 133 are respectively connected to the opposite ends of the mirror body 120 in the vertical direction.

[0067] When a current is applied to the coil 200, a magnetic torque can be generated, and components are generated in two directions along the rotation axis. In order to generate a dual-axis movement, the waveforms of vertical and horizontal movement only need to be simply superimposed. One component of the magnetic torque causes the mounting portion 131 to rotate around its flexible beam 1 132, and the other component causes the mirror body 120 to rotate around the flexible beam 2 133.

[0068] In one embodiment, if Fig. 9 As shown, the MEMS galvanometer 10 further includes a shading member 400 , which is used to block non-echo signals from entering the mirror body 120 .

[0069] Specifically, the shading member 400 is located on a side of the substrate 110 facing the reflective film and is spaced apart from the substrate 110 . The shading member 400 is provided with a light-transmitting hole 401 corresponding to the mirror body 120 .

[0070] By performing light shielding outside the field of view through the shading element 400, the ambient light introduced into the receiving system by the mirror body 120 can be suppressed and the stray light outside the field of view can be reduced.

[0071] The shape of the light-transmitting hole 401 can be set according to the light-transmitting area, and can be circular, rectangular, irregular, etc.

[0072] In a specific embodiment, a side of the shading member 400 facing away from the mirror body 120 is provided with a light-guiding structure for reflecting light to a side deviating from the optical axis of a receiving system of the laser radar, and / or performing a light extinction treatment to reduce the reflectivity of the light.

[0073] It is understandable that the light-guiding structure on the light-shielding member 400 may refer to the above-mentioned light-guiding structure, which will not be described in detail herein.

[0074] Here, it should be noted that the above-mentioned matting treatment includes one or more of spraying matte paint, sticking matte film, spraying matte sand, setting matte grooves and surface ceramicization. Among them, spraying matte paint, sticking matte film or using surface ceramic oxidation process can reduce the reflectivity of the workpiece surface, improve the surface absorption rate of the workpiece, and reduce the reflection of ambient light; spraying matte sand or setting matte grooves can improve the surface roughness of the workpiece, make the workpiece surface closer to Lambertian diffuse reflection, reduce its directional emission light, and reduce the light energy reflected into the receiving system.

[0075] In summary, the MEMS galvanometer and laser radar provided in this embodiment have at least the following beneficial technical effects:

[0076] The MEMS galvanometer of the present application sets an extinction structure on the back side of the mirror body and / or the surface of the substrate. The extinction structure can reduce the reflective ability of the back side of the mirror body and the surface of the substrate to ambient light, thereby reducing the stray light generated by the MEMS galvanometer to the optical system, improving the system signal-to-noise ratio, and enhancing the ranging capability of the laser radar.

[0077] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0078] The above embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the patent application. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent application shall be subject to the attached claims.

Claims

1. A MEMS galvanometer, used in a laser radar, the MEMS galvanometer comprising a substrate and a mirror body, the mirror body being connected to the substrate via a beam structure, the mirror body being used to receive an echo signal and deflect under external force to control the direction of the received echo signal; characterized in that: A light extinction structure is arranged on the back side of the mirror body and / or the surface of the substrate, and the back side of the mirror body is the opposite side of the mirror body for receiving the echo signal.

2. The MEMS galvanometer according to claim 1, characterized in that: The matt structure is a light-guiding structure and / or a matt coating.

3. The MEMS galvanometer according to claim 1, characterized in that: The substrate is a silicon substrate, and the mirror body, the beam structure and the silicon substrate are an integrated structure.

4. The MEMS galvanometer according to claim 1, characterized in that: An iron core for adjusting the magnetic field distribution is provided on the back of the mirror body, and a coil is provided at the corresponding position of the beam structure. The coil in the magnetic field deflects under the action of the Lorentz force or through electrostatic drive after power is turned on, thereby driving the connected mirror body to deflect.

5. The MEMS galvanometer according to claim 2, characterized in that: The light-guiding structure includes an inclined plane, and the inclined plane satisfies: 2α-2θ>β, wherein α is the inclination angle of the inclined plane, θ is the inclination angle of the lens, and β is the field of view angle of the receiving system.

6. The MEMS galvanometer according to claim 5, characterized in that: The light-guiding structure includes chamfers or rounded corners or annular bevel grooves or a plurality of serrated repeating units.

7. The MEMS galvanometer according to claim 2, characterized in that: The matte coating is one or more of matte paint, matte film, matte sand and surface ceramicization.

8. The MEMS galvanometer according to any one of claims 1 to 7, characterized in that: The MEMS oscillating mirror further includes a shading member, which is used to block non-echo signals from entering the mirror body.

9. The MEMS galvanometer according to claim 8, characterized in that: The shading member is located at a side of the mirror body that receives the echo signal and is spaced apart from the substrate. The shading member is provided with a light-transmitting hole corresponding to the mirror body.

10. The MEMS galvanometer according to claim 8, characterized in that: A side of the shading member facing away from the mirror body is provided with a light-guiding structure for reflecting light to a receiving system optical axis deviating from the laser radar, and / or performing a light extinction treatment for reducing the reflectivity of light.

11. A laser radar, characterized in that: include: A laser transceiver system, comprising a transmitting system for transmitting laser signals and a receiving system for receiving echo signals; as well as The MEMS galvanometer as described in any one of claims 1 to 10 is used to reflect the laser signal and then emit it to a scanning environment, and reflect the echo signal reflected back from the scanning environment to the receiving system.

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