CN113030909A

CN113030909A - Laser radar system based on micro-mirror array

Info

Publication number: CN113030909A
Application number: CN201911252558.8A
Authority: CN
Inventors: 马宏
Original assignee: Juexin Electronics Wuxi Co ltd
Current assignee: Juexin Electronics Wuxi Co ltd
Priority date: 2019-12-09
Filing date: 2019-12-09
Publication date: 2021-06-25
Anticipated expiration: 2039-12-09
Also published as: CN113030909B

Abstract

A micro-mirror array based lidar system comprising: a laser light source for emitting a laser beam; a vertical scanning micromirror for deflecting the oscillation along a first rotation axis in a first driving mode to scan the laser beam in a first angular range in a vertical direction; the horizontal scanning micro-mirror array is used for deflecting and vibrating along a second rotating shaft in a second driving mode so as to enable the laser beam to scan in a second angle range in the horizontal direction; a mirror disposed on an optical path between the vertical scanning micromirror and the horizontal scanning micromirror array; the mirror has a mirror transmissive region that just allows the laser beam within the first angular range to pass through.

Description

Laser radar system based on micro-mirror array

Technical Field

The invention belongs to the field of radars, and particularly relates to a laser radar system based on an MEMS micro-mirror array.

Background

Lidar is a high precision distance measuring device. Different from a multi-view camera, the laser radar is not influenced by illumination conditions and has strong anti-interference capability as an active detection device. In addition to applications in the fields of topographic mapping and the like, great attention has been drawn in recent years also in the fields of automatic driving and 3D imaging. The traditional laser radar adopts the design of combining multi-path laser with a mechanical rotating structure, so that the speed is low, the volume is large, the energy consumption is high, and the cost is high. The MEMS micro-mirror is used for replacing a mechanical rotating structure, so that the volume of equipment can be greatly reduced, the scanning frequency is improved, and the energy consumption is less. In addition, the micro mirror can form a one-dimensional scanning mirror surface and can scan in a two-dimensional plane, and the whole observation surface can be detected only by one path of laser. Due to the compact structure design, the laser radar based on the micro mirror can be easily embedded into portable equipment, and the application range of the laser radar is greatly expanded.

The existing laser radar based on the MEMS micro-mirror adopts a scheme that a transmitting light path and a receiving light path are not coaxial. In order to detect echoes in all directions, a receiving light path of the system consists of a wide-angle lens and a detector, a large amount of ambient light is introduced while laser echoes are received, and meanwhile, the system is easily interfered by other laser radar light sources, so that the signal-to-noise ratio of the system is low, and the requirement of remote detection cannot be met.

In order to avoid the above problem, a scheme in which the transmission and reception optical paths are coaxial may be adopted. In this configuration, the detector only receives light signals in the opposite direction to the transmitted pulses, effectively reducing interference from ambient light and other lidar sources. However, the clear aperture of a system with coaxial transmitting and receiving light paths is very limited, which seriously restricts the collection capability of the system to the echo energy, so that the laser radar system can only work in a short-distance occasion.

Disclosure of Invention

In order to solve the above technical problems, the present invention provides a laser radar system based on a micromirror array.

In a first aspect of the present invention, there is provided a lidar system based on a micromirror array, the lidar system comprising: a laser light source for emitting a laser beam; a vertical scanning micromirror for deflecting the oscillation along a first rotation axis in a first driving mode to scan the laser beam in a first angular range in a vertical direction; the horizontal scanning micro-mirror array is used for deflecting and vibrating along a second rotating shaft in a second driving mode so as to enable the laser beam to scan in a second angle range in the horizontal direction; a mirror disposed on an optical path between the vertical scanning micromirror and the horizontal scanning micromirror array; the mirror has a mirror transmissive region that just allows the laser beam within the first angular range to pass through.

Preferably, the area of the reflective transmissive region is much smaller than the total area of the mirror.

Preferably, the reflective transmissive region cylindrical lens structure.

Preferably, the vertical scanning micro-mirror and/or the horizontal scanning micro-mirror array are internally packaged in a high-voltage airtight mode or in an insulating liquid injection mode.

Preferably, capacitive or piezoelectric feedback position sensors are integrated in the vertical scanning micro-mirror and/or the horizontal scanning micro-mirror array.

Preferably, the horizontal scanning micro mirror array is a multi-column structure, and the multi-column structure includes: the beam emergent micro-mirror array is used for deflecting to realize the emergence of the laser beam; the echo light field receiving micro-mirror array is used for receiving the echo light field; the light beam emergent micro-mirror array and the echo light field receiving micro-mirror array are arranged on the same plane; or the light beam emergent micro-mirror array and the echo light field receiving micro-mirror array are arranged in parallel in a staggered mode.

In a second aspect of the present invention, there is provided a lidar system based on a micromirror array, the lidar system comprising: the laser light source is used for emitting laser beams and comprises at least two lasers which are staggered and arranged in parallel on a time domain; a vertical scanning micromirror for deflecting the oscillation along a first rotation axis in a first driving mode to scan the laser beam in a first angular range in a vertical direction; the horizontal scanning micro-mirror array is used for deflecting and vibrating along a second rotating shaft in a second driving mode so as to enable the laser beam to scan in a second angle range in the horizontal direction; the horizontal scanning micro-mirror array comprises column structures, wherein at least two columns in the column structures are arranged in a staggered mode; a mirror disposed on an optical path between the vertical scanning micromirror and the horizontal scanning micromirror array; the mirror has a mirror transmissive region that just allows the laser beam within the first angular range to pass through.

Preferably, the vertical scanning micromirror comprises at least two micromirrors vibrating at the same frequency, phase and amplitude corresponding to the at least two lasers turned on in a staggered manner in the time domain.

Preferably, the mirror comprises a mirror transmissive region; or, the reflector comprises light-transmitting regions corresponding to the at least two lasers which are switched on in a staggered mode in the time domain.

In a third aspect of the present invention, there is provided a lidar system based on a micromirror array, the lidar system comprising: the laser light source is used for emitting laser beams and comprises at least two lasers; a vertical scanning micromirror for deflecting the oscillation along a first rotation axis in a first driving mode to scan the laser beam in a first angular range in a vertical direction; the horizontal scanning micro-mirror array is used for deflecting and vibrating along a second rotating shaft in a second driving mode so as to enable the laser beam to scan in a second angle range in the horizontal direction; the horizontal scanning micro-mirror array comprises column structures, wherein at least two columns in the column structures are arranged in a staggered mode; a mirror disposed on an optical path between the vertical scanning micromirror and the horizontal scanning micromirror array; the reflector is provided with a reflector light-transmitting area which just allows the laser beam in the first angle range to pass through; the two lasers are staggered in time domain and have an angle difference, so that the fields of view formed by the laser beams emitted by the different lasers are spliced to expand the fields of view; and receiving the reflected echo by using a single linear array APD; or the two lasers are simultaneously started in time domain and are incident to different vertical scanning micro mirrors, so that the fields of view formed by the laser beams emitted by the different lasers are spliced; and receive the reflected echoes using a separate APD array.

In a fourth aspect of the present invention, there is provided a lidar system based on a micromirror array, the lidar system comprising: a laser light source for emitting a laser beam; a vertical scanning micromirror for deflecting the oscillation along a first rotation axis in a first driving mode to scan the laser beam in a first angular range in a vertical direction; the horizontal scanning micro-mirror array is used for deflecting and vibrating along a second rotating shaft in a second driving mode so as to enable the laser beam to scan in a second angle range in the horizontal direction; a mirror; the horizontal scanning micro-mirror array is a multi-column structure, comprising: the beam emergent micro-mirror array is used for deflecting to realize the emergence of the laser beam; the echo light field receiving micro-mirror array is used for receiving the echo light field; the light beam emitting micro-mirror array and the echo light field receiving micro-mirror array enable the laser light beams emitted by the laser light source to be parallel to and dislocated with the optical axes of the received echo light beams.

In a fifth aspect of the present invention, there is provided a lidar system based on a micromirror array, the lidar system comprising: a laser light source for emitting a laser beam; a one-dimensional beam expander for causing the laser light to diverge in a vertical direction; the one-dimensional integrator is used for diverging the laser beam diverged by the one-dimensional beam expander; and the horizontal scanning micro-mirror array is used for deflecting and vibrating along the second rotating shaft in a second driving mode so as to enable the laser beam to scan in a second angle range in the horizontal direction.

Preferably, the system further comprises a mirror: the reflecting mirror is used for receiving the echo light beam received by the horizontal scanning micro-mirror array; or the reflecting mirror is arranged on the light path between the vertical scanning micro mirror and the horizontal scanning micro mirror array; the device is provided with a reflector light-transmitting area which just allows the fine light beam expanded by the one-dimensional integrator to pass through.

By adopting the technical scheme, the invention has the following beneficial effects:

first, the use of the MEMS micromirror array can provide a larger clear aperture, which makes up for the limited size of the single micromirror mirror.

Secondly, the coaxial optical path is adopted for transmitting and receiving laser pulses, so that the influence of ambient light can be effectively reduced.

Thirdly, the single-axis scanning MEMS micro-mirror array is adopted, so that the process is simple and a large filling factor is easy to realize.

And fourthly, the linear light detector is adopted, the cost is lower than that of a two-dimensional light detector array, and the signal intensity is higher than that of a single-point detector.

Drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed to be used in the description of the embodiments will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.

Fig. 1 is a schematic diagram of a principle of an optical path of a laser radar according to an embodiment of the present invention.

Fig. 2 is a schematic diagram of an operating state of a laser radar according to an embodiment of the present invention.

Fig. 3 is a schematic diagram of a principle of an optical path of a laser radar according to an embodiment of the present invention.

Fig. 4 is a schematic diagram of a principle of an optical path of a laser radar according to an embodiment of the present invention.

Fig. 5 is a schematic diagram of a principle of an optical path of a laser radar according to an embodiment of the present invention.

Fig. 6 is a schematic diagram of a principle of an optical path of a laser radar according to an embodiment of the present invention.

Fig. 7 is a schematic diagram of a principle of an optical path of a laser radar according to an embodiment of the present invention.

Fig. 8 is a schematic diagram of a principle of an optical path of a laser radar according to an embodiment of the present invention.

Fig. 9 is a schematic diagram of a principle of an optical path of a laser radar according to an embodiment of the present invention.

Fig. 10 is a schematic diagram of a principle of an optical path of a laser radar according to an embodiment of the present invention.

Fig. 11 is a schematic diagram of a principle of an optical path of a laser radar according to an embodiment of the present invention.

Fig. 12 is a schematic diagram of a principle of an optical path of a laser radar according to an embodiment of the present invention.

Fig. 13 is a schematic diagram of a principle of an optical path of a laser radar according to an embodiment of the present invention.

Fig. 14 is a schematic diagram of a principle of an optical path of a laser radar according to an embodiment of the present invention.

Fig. 15 is a schematic diagram of a principle of an optical path of a laser radar according to an embodiment of the present invention.

Fig. 16 is a schematic diagram of a principle of an optical path of a laser radar according to an embodiment of the present invention.

Fig. 17 is a schematic diagram of a principle of an optical path of a laser radar according to an embodiment of the present invention.

Fig. 18 is a schematic diagram of a principle of an optical path of a laser radar according to an embodiment of the present invention.

Fig. 19 is a schematic diagram of a principle of an optical path of a laser radar according to an embodiment of the present invention.

Fig. 20 is a schematic block diagram of a structure of a lidar according to an embodiment of the present invention.

FIG. 21 is a schematic diagram of a micro mirror structure according to an embodiment of the invention.

FIG. 22 is a schematic diagram of a micro mirror structure according to an embodiment of the invention.

Detailed Description

The technical solution in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. It is to be understood that the described embodiments are merely exemplary of the invention, and not restrictive of the full scope of the invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Reference herein to "one embodiment" or "an embodiment" means that a particular feature, structure, or characteristic may be included in at least one implementation of the invention. Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. Moreover, the terms "first," "second," and the like are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order. It is to be understood that the data so used is interchangeable under appropriate circumstances such that the embodiments of the invention described herein are capable of operation in sequences other than those illustrated or described herein.

The first embodiment is as follows:

in view of the above unsolved problems, the present invention provides a laser radar system, which aims to realize long-distance detection with compact structure and high signal-to-noise ratio.

As shown in fig. 1, laser light emitted from a laser 1 is collimated by a collimator lens 2 and then incident on a vertical scanning micromirror 4. The vertical scanning micromirror 4 is an electrostatically driven micromirror operating in a quasi-static mode, deflecting and vibrating about the first rotation axis 3, so that the incident laser beam scans in a certain angle in the vertical direction.

A mirror 5 is arranged in the optical path of the laser beam, which mirror 5 has a reflectivity close to 1 near the laser wavelength. The mirror 5 leaves only a mirror light-transmitting region near the center, which has a transmittance near the laser wavelength of approximately 1 for the laser beam. The mirror transmissive region allows exactly the vertically scanned laser beam to pass through, and has an area much smaller than the total area of the mirror.

The laser beam is transmitted through the transparent region of the mirror and then incident on the horizontal scanning micromirror array 6. The horizontal scanning micromirror array 6 is arranged in a single SOI chip in the vertical direction, is an electrostatically driven micromirror operating in a resonance mode, and deflects and vibrates about a second rotation axis 7. The array units in the horizontal scanning micro-mirror array 6 are driven by static electricity to vibrate in the same frequency and phase and in the same amplitude. In the scanning period, the laser beam is incident on several micromirror units in the center of the horizontal scanning micromirror array 6 in sequence along with the time, and forms a two-dimensional scanning surface after being reflected.

In one specific example, the laser 1 may be an edge-emitting semiconductor laser, a vertical cavity surface emitting laser, a fiber laser, or the like; the wavelengths used may be 850nm, 905nm, 1550nm, etc.

In one specific example, the laser 1 is a fiber laser emitting 1550nm pulsed laser light and incident on the horizontal scanning micromirror array 6.

In one specific example, the mirror light-transmitting region is a stripe-shaped region along the laser scanning direction, the stripe-shaped region just allows the laser beam scanned vertically to pass through, and the area of the stripe-shaped region is much smaller than the total area of the mirror.

In a specific example, the fill factor of the mirror is 0.6 or more. The mirror fill factor refers to the proportion of the effective reflective area of the mirror to the total area of the SOI chip.

As shown in fig. 2, a schematic diagram of the operation of the lidar at a certain time is shown. After passing through the scanning array, the pulse laser is emitted from the window 8 and irradiates an object, scattering occurs on the surface of the object, a part of the light is reflected back to form a reflection echo, and the reflection echo is incident on the horizontal scanning micro-mirror array 6 from the same window 8. Since the flight time of the laser pulse is extremely short, the position change of the micromirror in the horizontal scanning micromirror array 6 is very small and almost negligible within a medium-short distance. Therefore, the echo signals received by the micromirror array will be incident on the mirror 5 along the opposite path of the emitting direction. Since the area of the light-transmitting area of the reflector 5 is very small and much smaller than the total area of the whole reflector 5, only a very small part of the reflected echo passes through the light-transmitting area, and therefore, the return light energy loss caused by transmission on the reflector 5 is not obvious.

The echo pulse is reflected to a receiving light path by a reflector 5, and non-axial stray light is removed through a diaphragm; ambient light of other wavelengths is removed through the filter.

Finally, the filtered reflected echo is focused on a light detector 11 through a converging lens 10, so that the detection of the signal is realized.

In one specific example, non-axial veiling glare is removed by an aperture, and ambient light of other wavelengths is removed by a filter.

In one particular example, the photodetectors 11 are columns of APD lines.

Example two:

in the foregoing embodiments, the vertical scanning micro-mirror 4 and the horizontal scanning micro-mirror array 6 are MEMS micro-mirror devices. The SOI wafer is processed by a semiconductor process. The driving method of the micromirror may be electrostatic driving, piezoelectric driving, electromagnetic driving, electrothermal driving, etc.

The vertical scanning micro-mirror 4 can employ resonant scanning, quasi-static scanning or digital jump scanning.

The vertical scanning micromirror 4 can be selected from an electrostatically driven micromirror using planar comb teeth, or an electrostatically driven micromirror having a vertical comb tooth structure.

In a preferred example, the vertical scanning micromirror 4 is an electrostatically driven micromirror with a vertical comb structure.

The horizontal scanning micromirror array 6 can select an electrostatically driven micromirror using planar comb teeth, or an electrostatically driven micromirror having a vertical comb tooth structure.

In a preferred example, the horizontal scanning micromirror array 6 uses electrostatically driven micromirrors with a planar comb structure.

In one specific example, the scanning frequency of the horizontal scanning micro mirror array 6 is much greater than that of the vertical scanning micro mirror 4, and the two mirrors combine to complete the line-by-line scanning of the laser.

In one specific example, the vertical scanning micromirror 4 can be packaged with an internal high-voltage hermetic package or an insulating liquid injection package to increase the damping of the micromirror to have superior quasi-static or digital scanning characteristics.

In a specific example, a position sensor is integrated in the vertical scanning micro-mirror 4, and the deflection position of the mirror surface is fed back to the signal processing unit in real time by using methods such as capacitance or piezoelectric feedback. The signal processing unit sends driving signals, and closed-loop control of all the micromirror units is realized through the micromirror driving circuit.

In one specific example, the horizontal scanning micromirror array 6 can be packaged with an internal high-voltage hermetic package or an insulating liquid injection package to increase the damping of the micromirrors to have more superior quasi-static or digital scanning characteristics.

In a specific example, a position sensor is integrated in the horizontal scanning micro-mirror array 6, and the deflection position of the mirror surface is fed back to the signal processing unit in real time by using methods such as capacitance or piezoelectric feedback. The signal processing unit sends driving signals, and closed-loop control of all the micromirror units is realized through the micromirror driving circuit.

Example three:

as shown in fig. 3, in this embodiment, the width of the mirror light-transmitting area can be reduced, and a cylindrical mirror is formed on the mirror light-transmitting area, and the cylindrical mirror and the mirror are integrated.

In a preferred example, an antireflection film is deposited on the outer surface of the cylindrical mirror, and a metal reflective layer is deposited in the region other than the cylindrical region.

The cylindrical lens structure can counteract the diffraction effect generated when the laser passes through the light-transmitting area of the reflector, and ensures that the laser beam has good collimation property.

Example four:

as shown in fig. 4, the horizontal scanning micromirror array 6 can be divided into two parts, the central part is a first horizontal scanning micromirror which is common to light emission and light reception, and the light beam transmitted from the light transmission area of the reflecting mirror is vertically scanned on the mirror surface of the micromirror and then reflected to form two-dimensional scanning. A plurality of second horizontal scanning micromirrors for receiving light are distributed on the upper and lower sides of the first horizontal scanning micromirror. The first horizontal scanning micro-mirror and the second horizontal scanning micro-mirror are formed on the surface of the same chip through an MEMS process so as to ensure that the first horizontal scanning micro-mirror and the second horizontal scanning micro-mirror have the same scanning angle. Meanwhile, the structures and the sizes of the first horizontal micro mirror and the second horizontal scanning micro mirror are adjusted, so that the first horizontal micro mirror and the second horizontal scanning micro mirror have basically the same central working frequency, and the first horizontal micro mirror and the second horizontal scanning micro mirror can execute the same-frequency and same-phase constant-amplitude vibration.

In one example, the first horizontal scanning micromirror has a larger width with a larger longitudinal length, and in the present invention, this type of micromirror is also referred to as a type a micromirror. The second horizontal scanning micromirror has a smaller longitudinal length and a larger width, and this type of micromirror is also referred to as a class B micromirror in the present invention.

In a preferred example, the aspect ratio of the first horizontal scanning micromirror is 3 or more and the aspect ratio of the second horizontal scanning micromirror is 3 or less.

The first horizontal scanning micro mirror and the second horizontal scanning micro mirror can have basically the same central working frequency by adjusting the length-width ratio and the specific structure.

Based on the arrangement of the horizontal scanning micro-mirror structure in the embodiment, the micro-mirror array in the horizontal scanning micro-mirror can be ensured to perform the same-frequency and same-phase constant-amplitude vibration.

Example five:

in one embodiment, the horizontal scanning micro mirror array can be divided into two columns, as shown in FIG. 5. The device comprises a light beam emergent row micro-mirror 12 which is used for emergent of laser beams; an echo light field receiving column micromirror 13 is further included for reception of the echo light field.

The reflector 14 is completely opaque, so that the emergent laser light avoids the area where the reflector is located, and then the emergent and received light axes are parallel and staggered, the light axes are parallel and do not coincide, and the possibility that the emergent laser light is scattered into a detector is reduced.

The micromirror for the laser beam to exit may be a column micromirror, such as the beam exiting column micromirror 12 shown in fig. 5, or a single micromirror. As shown in fig. 6, the light beam exits the micromirror a for taking charge of the exit of the laser beam.

When using the light beam exit micromirror a, the vertical scanning micromirror needs to be close to the horizontal scanning micromirror to alleviate the requirement for the length of the horizontal scanning micromirror. The beam exit micromirror a has a similar structure to the first horizontal scanning micromirror, having a larger overall longitudinal length and a smaller width. In a specific example, the aspect ratio thereof is 3 or more.

In some specific examples, the mirror 14 may not be used, and the echo light field received by the micro mirror array 13 may be directly guided to the receiving lens group and finally enter the detector.

Example six:

the horizontal scanning micromirrors can also be in a multi-row structure, as shown in fig. 7, the horizontal scanning micromirror array has a three-row structure, and the light beams emitted from the light-transmitting area of the reflective mirror scan on the B-type micromirrors of which one row has a second horizontal scanning micromirror structure partially or completely.

The multiple rows of micromirrors collectively determine the clear aperture of the echo, and as shown in fig. 8, the light beam emitted through the transmissive region of the reflector may also be incident on one micromirror. The micromirror has a similar structure to the first horizontal scanning micromirror, having a larger longitudinal length and a smaller width. In a specific example, the aspect ratio thereof is 3 or more. As shown in fig. 8, which shows the similar triangular relationship of each device in the optical path, the proportional relationship between the length of the light-transmitting area on the reflector and the length of the class a micromirror is the same as the proportional relationship between the distance between the scanning mirror and the scattering mirror and the distance between the two scanning mirrors.

In addition to the horizontal scanning micromirrors shown in fig. 7 and 8, the micromirror array for receiving the echo light field can be formed by combining and arranging the same type a micromirrors.

In addition to the horizontal scanning micromirrors shown in fig. 7 and 8, the micromirror array for receiving the echo light field can be formed by combining and arranging the same B-type micromirrors.

In addition to the horizontal scanning micromirrors shown in fig. 7 and 8, the micromirror array for receiving the echo light field can also be formed by combining and arranging a type and a type B micromirrors.

The A-type micromirror has a larger longitudinal length and a smaller width, and the B-type micromirror has a smaller longitudinal length and a larger width.

Example seven:

the horizontal scanning micro-mirror can also be a multi-column structure, as shown in fig. 9, where one column 15 at the edge of the horizontal scanning micro-mirror is used for the exit of the laser beam and the other columns are used for the reception of the echo light field.

In this embodiment, the reflector does not have a light-transmitting area, and the emergent laser avoids the area where the reflector is located, and the emergent and received optical axes are parallel and dislocated, so that the optical axes are parallel and do not coincide, and the possibility that the emergent laser is scattered into the detector is reduced.

As shown in fig. 9, the micromirror for laser beam emission may be an array of B-type micromirrors, and the micromirror array for echo light field reception may be an array of a plurality of rows of B-type micromirrors.

As shown in fig. 10, the micromirror for laser beam emission may be a single class a micromirror, and the micromirror array for echo light field reception may be formed by arranging a plurality of columns of class B micromirrors.

As shown in fig. 11, the micromirror for laser beam emission may be a single class a micromirror, and the micromirror array for echo light field reception may be formed by arranging a plurality of columns of class a micromirrors.

Example eight:

in the foregoing embodiment, if a plurality of B-type micromirrors are used to form an array, the vertical scanning is discontinuous due to the spacing between adjacent B-micromirror units, thereby reducing the line density of the vertical scanning.

As shown in fig. 12, the system includes two light sources, namely a first laser and a second laser, and the first laser and the second laser are coherent light sources, that is, the first laser and the second laser can emit parallel lights vibrating in the same frequency, the same phase, and the same amplitude. The light emitted by the first laser and the light emitted by the second laser respectively enter the first vertical scanning mirror and the second vertical scanning mirror, are reflected by the two vertical scanning mirrors, pass through the first light-transmitting area 20 and the second light-transmitting area 21 of the reflecting mirror, and then enter the horizontal scanning micro-mirror array.

The horizontal scanning micro mirror array can be divided into a plurality of columns, wherein the adjacent first vertical scanning micro mirror 18 and second vertical scanning micro mirror 19 are used for reflecting the incident laser to the exit window, and the first horizontal scanning micro mirror 16 and the second horizontal scanning micro mirror 17 are offset in the vertical direction.

The first vertical scanning micro-mirror 18 and the second vertical scanning micro-mirror 19 perform vertical scanning in a manner of same frequency, same phase and same amplitude vibration, and reflected light therefrom scans and is incident on a part of or all of the units of the first horizontal scanning micro-mirror 16 and the second horizontal scanning micro-mirror 17.

The first laser and the second laser are staggered in time domain, when one beam of the started laser is incident to the vertical scanning mirror, the laser is closed, and the other laser is started at the same time. In one possible example, the angle change of the vertical scanning micromirror can be judged by a position sensor integrated on the micromirror, and the laser is controlled to be turned on or off when the vertical scanning micromirror reaches a preset angle. The position sensor may be an electrode formed by a MEMS process at the time of manufacturing the micromirror in relation to the scanning position, reflecting the position of the scanning mirror by the current/voltage conditions in the electrode.

By means of the staggered opening of the first laser and the second laser in the time domain, when one opened laser beam is incident to the position near the edge of the micro mirror, the position sensor feeds back the angle of the micro mirror, the laser is turned off, the other laser is turned on, and when the light beam emitted by the other laser beam is incident to the position near the edge of the mirror surface, the previous laser beam can be incident to the area near the center of the micro mirror. The process is repeated continuously, so that the influence of the interval area of the micro mirror unit can be avoided, continuous vertical scanning is realized, and the scanning vertical linear density is improved.

Example nine:

as shown in fig. 13, the beam emitted from the laser is incident on a one-dimensional beam expander 22, causing the laser light to diverge in the vertical direction. The beam passing through the beam expander passes through a one-dimensional integrator 23, so that the laser is further diffused in the vertical direction, and the energy distribution is more uniform. After passing through the one-dimensional integrator 23, the laser spots become one-dimensional laser lines, and then pass through the light-transmitting area of the reflector and enter an A-type micromirror, and the A-type micromirror rotates to expand the one-dimensional laser lines into a scanning surface, thereby realizing two-dimensional scanning of a target area. The reflected echo is received by the horizontal scanning micro-mirror and reflected to the mirror, and the received optical path thereafter is substantially the same as in the previous embodiment. The horizontal scanning mirror structure can be a multi-column structure composed of a plurality of columns of the B-type micro mirror structures.

Example ten:

as shown in fig. 14, the beam emitted from the laser is incident on a one-dimensional beam expander, causing the laser light to diverge in the vertical direction. The light beam passing through the beam expander passes through a one-dimensional integrator, so that the laser is further diffused in the vertical direction, and the energy distribution is more uniform. The one-dimensional laser line array directly enters the A-type scanning micro-mirror, and the A-type micro-mirror rotates to expand the one-dimensional laser line array into a scanning surface, so that two-dimensional scanning of a target area is realized. The reflected echo is received by the horizontal scanning micro-mirror and reflected to the mirror, and the received optical path thereafter is substantially the same as in the previous embodiment. The horizontal scanning mirror structure can be a multi-column structure composed of a plurality of columns of B-type micro mirror structures, and can also be a multi-column structure composed of a plurality of columns of A-type micro mirror structures. In the embodiment of fig. 14, the exit and receive optical axes are offset or parallel in the plane of the exit and receive optical axes.

At this time, the vertical resolution of the laser radar is determined by the number of vertical pixels of the detector line array and the convergence performance of the optical system.

Example eleven:

as shown in fig. 15, two laser beams are emitted from the first laser and the second laser, respectively, and are incident on the first vertical scanning micromirror 24 and the second vertical scanning micromirror 25, respectively, with a certain angular difference. The first vertical scanning micromirror 24 and the second vertical scanning micromirror 25 are identical and oscillate with the same frequency, phase and amplitude. After being reflected by the first vertical scanning micro-mirror 24 and the second vertical scanning micro-mirror 25, the light beam is incident on the horizontal scanning micro-mirror array via the same mirror light-transmitting area 26 and is reflected by the horizontal scanning micro-mirror array. The angles of the first laser and the second laser are adjusted so that the difference of angles incident to the first vertical scanning micromirror 24 and the second vertical scanning micromirror 25 can be adjusted, and finally the first laser visual field 27 and the second laser visual field 28 reflected by the horizontal scanning micromirror array can be spliced, thereby achieving the visual field doubling.

In one possible embodiment, as shown in FIG. 16, two laser beams are emitted from a first laser and a second laser, respectively, and are incident on the vertical scanning micro-mirrors 24' respectively with a certain angle difference. After being reflected at the vertical scanning micromirror 24 ', the light beam is incident on the horizontal scanning micromirror array via two separate mirror transparent regions 261 ', 262 ' and reflected at the horizontal scanning micromirror array. The angles of the first and second lasers are adjusted so that the angular difference of the beams incident to the vertical scanning micromirror 24 ' can be adjusted and finally the first and second laser fields of view 27 ' and 28 ' reflected by the horizontal scanning micromirror array can be spliced, thereby achieving field doubling.

Two echo light pulse signals can be simultaneously output by using two separate photodetectors 291 'and 292' to respectively detect two laser beams, each photodetector corresponds to a field of view, and thus two lasers can be simultaneously driven, although staggered driving is also possible.

In this embodiment, the example corresponding to fig. 15 uses a multi-line APD detector, and since the detector outputs only one echo optical pulse signal at the same time, the two lasers must be driven in a time domain with a time offset. The example of fig. 16 uses two separate photodetectors, and the two lasers can be driven simultaneously or alternately. Of course, the example of fig. 16 can also use one APD detector in multiple rows, but the two lasers must be driven temporally staggered. Example twelve:

as shown in fig. 17, all micromirrors are arranged on one chip carrier 30. The laser beam is emitted from the laser 31 in the X-axis direction, reflected at the mirror 33 to the first micromirror 32, and dynamically deflected in accordance with the action of the first micromirror 32, and then reflected a second time to the mirror 33, and reflected by the mirror 33 and incident on the second micromirror 34 arranged in the vicinity of the first micromirror 32, and after deflected at the second micromirror 34, exits from the exit window 35. The rotation axis of the first micromirror 32 is along the X-direction, the rotation axis of the second micromirror 34 is along the Y-direction, and the reflecting mirror 33 has a first reflecting surface on the side surface and a second reflecting surface on the bottom surface.

The micromirror array 36 receives the echo light field and reflects it to a light collecting mirror 37, via a diaphragm 38, a filter 39 and a converging lens 40, where the echo signal is finally captured by an APD line column 41. The micromirror units of the micromirror array 36 are sequentially arranged along the Y-axis direction, and the rotation axis vibrates in the same frequency, phase and amplitude as the second micromirror 34 along the Y-axis direction.

The micromirror array 36 can be one or more columns, and the cell composition can be a class a micromirror, a class B micromirror, or a combination thereof, either monolithically or a combination of multiple diced chips.

Of course, in the optical path of the present embodiment, a collimating lens may be further provided. And doubling and beam expanding optics (not shown).

Example thirteen:

as shown in fig. 18, laser 42 emits a laser beam that is directed at a small angle Θ to the-Z axis. The light beam passes through the mirror 43 with the light transmitting area, enters the first micromirror, is deflected at the first micromirror, is reflected to the mirror 43, is reflected again at the mirror 43, is reflected at the second micromirror, is deflected at the second micromirror, and then exits from the exit window.

In this embodiment, since the initial incident direction of the laser deviates from the-Z axis by a small angle Θ, when the laser returns through the first micromirror, the transparent region on the mirror can be avoided, thereby avoiding energy loss. And because the initial incidence direction is very close to the-Z axis, the aberration of the laser radar field of view can be effectively relieved. The problem that the aberration is small but the energy loss is large when the incident light is completely along the-Z axis is avoided.

In one example, the light-passing area of the reflector 43 may be set to be circular, and a spherical lens may be set on the light-passing area to counteract diffraction effect generated when the laser passes through the light-passing area of the reflector, so as to ensure that the laser beam has good collimation.

In one example, the mirror 43 can be replaced by a normal total reflection mirror and moved out of the original incident path of the laser light to reflect only the laser light returning from the first micromirror.

The reflector 43 may have other various structures, and the change of the structure is not beyond the protection scope of the present invention.

Example fourteen:

as shown in fig. 19, light emitted from the laser is incident on a two-dimensional micromirror 44, and the two-dimensional micromirror 44 has two rotation axes along the Y-axis and the X-axis. The micromirror 44 vibrates with the micromirror array 45 along the Y-axis in the same frequency, phase and amplitude.

Example fifteen:

as shown in fig. 20, a schematic block diagram of a laser radar system is shown. The digital signal processing unit outputs a laser driving instruction, and the laser driving instruction is input into a light source driving circuit through a digital-to-analog converter (DAC), and finally the laser is driven to output laser pulses with certain power, pulse width and repetition frequency.

The detector receives the echo signal, and the current signal is subjected to analog-digital conversion after the steps of amplification, filtering and the like. The converted digital signal is calculated by a digital signal processing unit to obtain a flight time result. Here, an analog-digital converter (ADC), a time-digital converter (TDC), or the like can be used as the device.

Meanwhile, the digital signal processing unit outputs a micromirror driving instruction, the micromirror driving instruction is converted into an analog signal through a multi-channel DAC, and the analog signal drives the vertical scanning micromirror and each horizontal scanning micromirror array unit through the micromirror driving circuit respectively. The multi-channel DAC may be formed by a plurality of independent DACs, or may be formed by a high-speed DAC and a Multiplexer (MUX).

The driving circuit of the micromirror array can have independent driving voltage amplitude and phase control, that is, the driving voltage amplitude and phase of each micromirror unit are respectively adjustable; or it may consist of a common phase control combined with a separate drive voltage amplitude control, i.e. all micromirror units share the same phase information, but the drive voltage amplitudes may be adjusted separately.

The position sensor integrated on the micro-mirror chip outputs the feedback signal in real time, and the feedback signal is input into the multi-channel ADC after the steps of amplification, filtering and the like. The ADC device may be composed of a plurality of independent ADCs, or may be composed of a high-speed ADC and a Multiplexer (MUX). And finally, the digital signal processing unit processes and updates the driving instruction of the micromirror to realize closed-loop control of the micromirror, and particularly can realize same-frequency, same-phase and same-amplitude vibration of the micromirror array. In addition, the digital signal processing unit also turns off the power supply of the detector, the amplifier and the filter in the laser pulse detection interval according to the driving time of the laser, so as to reduce the energy consumption. The storage unit provides storage space for the digital signal processing unit, and the power supply supplies power to the digital signal processing unit. And outputting the processed flight time result to an external system for displaying or further calculating.

Example sixteen:

the foregoing embodiments describe the MEMS-based lidar system of the present invention. In the system, pulse laser is emitted by a laser, is collimated by a collimating lens and then enters a vertical scanning micromirror, so that the laser beam scans within a certain angle in the vertical direction. A reflection mirror is arranged on the optical path of the laser beam, the reflectivity of the reflection mirror to the laser beam with the wavelength is close to 1, and only the transmissivity of the strip-shaped area near the center to the laser beam is close to 1. The area of the stripe-shaped region is much smaller than the total area of the mirror. The laser beam scanned in the vertical direction as described above can be transmitted from the stripe region without obstruction and incident on the horizontal scanning micromirror array. The micromirror array is arranged along the vertical direction, and can be formed by combining the cut micromirror units or a single-chip integrated MEMS micromirror array, so that more compact arrangement and larger filling factor are realized. All the units of the micromirror array vibrate at the same frequency and phase with the same amplitude. The laser beam is incident on a part of or all the micro mirror units of the horizontal scanning micro mirror array in sequence along with the time, and forms a two-dimensional scanning surface after being reflected. After the laser pulse irradiates an object, a part of light is reflected back and is incident on the horizontal scanning micro-mirror array, because the flight time of the laser pulse is extremely short, the position change of the horizontal scanning micro-mirror is very small, an echo signal received by the micro-mirror array is incident on the reflecting mirror along a path opposite to the emergent direction, and because the area of a strip-shaped area is very small, the energy loss caused by the reflection is not obvious. The echo pulse is further reflected to a fixed receiving light path, non-axial stray light is removed through a diaphragm, ambient light with other wavelengths is removed through an optical filter, and finally the ambient light is focused on an optical detector through a converging lens, so that signal detection is realized.

The laser can be an edge-emitting semiconductor laser, a vertical cavity surface-emitting laser, a fiber laser and the like; the wavelengths used may be 850nm, 905nm, 1550nm, etc.; of these, 1550nm high power pulsed fiber laser is the best choice for the present invention.

The MEMS micro-mirror device is formed by processing an SOI wafer through a semiconductor process. The driving mode can be electrostatic driving, piezoelectric driving, electromagnetic driving, electrothermal driving and the like. Wherein the vertical scanning micromirror can adopt resonant scanning, quasi-static scanning or digital jump scanning, it is preferable to use the electrostatically driven micromirror with vertical comb tooth structure, but it is not excluded to use the electrostatically driven micromirror with planar comb tooth. The horizontal scanning micromirror array can also adopt resonant scanning, quasi-static scanning or digital jump scanning, and preferably uses electrostatically driven micromirrors with planar comb tooth structures, but does not exclude the use of electrostatically driven micromirrors with vertical comb tooth structures. In the preferred case, the frequency of the horizontal scanning micromirror array is much higher than that of the vertical scanning micromirror array, the two mirrors are combined to complete the line-by-line scanning of the laser, and the vertical scanning micromirror array can adopt internal high-voltage airtight packaging or insulating liquid injection packaging to increase the damping of the micromirror array, so that the micromirror array has more excellent quasi-static or digital scanning characteristics. In addition, the micromirror device is integrated with a position sensor, the deflection position of the mirror surface is fed back to the signal processing unit in real time by adopting methods such as capacitance or piezoelectric feedback, the signal processing unit sends a driving signal, and closed-loop control of all the micromirror units is realized through the micromirror driving circuit.

The reflector with the strip-shaped transmission area can be formed by grooving the mirror surface and penetrating the whole mirror surface, or can be formed by firstly depositing an antireflection film on the surface of glass and then depositing a metal reflection surface and leaving the strip-shaped area without metal deposition. Preferably, the width of the stripe region may be reduced, and a cylindrical mirror may be formed on the stripe region (hereinafter, referred to as a mirror transmissive region), the cylindrical mirror and the mirror forming an integral body, an antireflection film being deposited on an outer surface, and a metal reflective layer being deposited outside the cylindrical region. The structure can counteract the diffraction effect generated when the laser passes through the strip-shaped area, and ensures that the laser beam has good collimation. In addition, the reflecting mirror can be in a plane configuration, and the echo light field is reflected to be parallel light; the reflector can also be in a curved surface configuration, and the reflecting surface can be bent inwards along one or two directions so as to converge the echo light field.

The light detector can be a single-point light detector, a linear light detector or a two-dimensional light detector array. The device type may be a PN or PIN photodiode, an Avalanche Photodiode (APD), a photomultiplier tube, a CCD array, a CMOS array, or a Single Photon Avalanche Diode (SPAD), among others. Preferably, the present invention can use avalanche photodiode arrays to match horizontal scanning micromirror arrays for high precision detection at limited cost. Because the coaxial design of the transmitting-receiving optical path can greatly reduce the influence of environment stray light, the APD line array can be used for fully amplifying weak optical signals without worrying about overhigh noise level.

The horizontal and vertical scanning described above are relative concepts, and merely illustrate that the axes of rotation of the two micromirrors are perpendicular to each other, without limiting the absolute spatial orientation of the system.

Based on the basic system scheme, the horizontal scanning micromirror array can be divided into two parts, the central part is a horizontal scanning micromirror which is shared by emitting light and receiving light, the horizontal scanning micromirror has a larger longitudinal length and a smaller width (the length-width ratio is more than or equal to 3, and is hereinafter referred to as a type A micromirror), and light beams transmitted through a light transmission area of the reflecting mirror vertically scan on the surface of the micromirror and are further reflected to form two-dimensional scanning. The upper and lower sides of the central micromirror are distributed with a plurality of light receiving micromirrors, the micromirrors have a smaller longitudinal length and a larger width (length-width ratio is less than or equal to 3, hereinafter referred to as a class B micromirror), and the two micromirrors have the same scanning angle and central working frequency through design, and execute the same-frequency and same-phase constant-amplitude vibration (hereinafter, the class A and the class B micromirrors both satisfy the condition and are not described again).

Based on the basic system scheme, the horizontal scanning micro-mirror array can be divided into two rows, wherein one row is responsible for emitting laser beams, and the other row is used for receiving echo light fields. The used reflector does not have a light transmission area, the emergent laser avoids the area where the reflector is located, and the emergent and received light axes are subjected to parallel dislocation through receiving and transmitting of different row scanning mirrors, so that the light axes are parallel and do not coincide, and the possibility that the emergent laser is scattered into a detector is reduced. The micromirror for laser beam exit may be a B-type micromirror array or a-type micromirror.

Based on the basic system scheme, the horizontal scanning micro-mirror array can be divided into a plurality of columns, and light beams emitted from the light-transmitting areas of the reflectors scan on part or all of the B-type micro-mirror units in one column. The multiple rows of micromirrors collectively determine the clear aperture of the echoes. The light beam exiting through the transmissive region of the mirror may also be incident on a class a micromirror. The micromirror array for receiving the echo light field can be formed by arranging the same A-type micromirrors, can also be formed by arranging the same B-type micromirrors, and can also be formed by combining and arranging the A-type micromirrors and the B-type micromirrors.

Based on the basic system scheme, the horizontal scanning micro-mirror array can be divided into a plurality of columns, wherein one column is used for emitting laser beams, and the other columns are used for receiving echo light fields. The used reflector does not have a light transmission area, the emergent laser avoids the area where the reflector is located, the emergent and received light axes are subjected to parallel dislocation, the light axes are parallel and do not coincide, and the possibility that the emergent laser is scattered into the detector is reduced. The micromirror for laser beam exit may be a B-type micromirror array or a-type micromirror. The micromirror array for receiving the echo light field can be formed by arranging the same A-type micromirrors, can also be formed by arranging the same B-type micromirrors, and can also be formed by combining and arranging the A-type micromirrors and the B-type micromirrors.

Based on the basic system scheme, the horizontal scanning micromirror array can be divided into a plurality of columns, wherein two adjacent columns of micromirrors are used for laser emission, and the two columns of micromirrors are staggered in the vertical direction. Two beams of parallel laser respectively pass through two identical vertical scanning micro mirrors (same frequency, same phase and same amplitude vibration) and two light-transmitting areas of the reflecting mirror, and are scanned and incident on a part of or all units of the two adjacent rows of micro mirrors. The two lasers are staggered and started in time domain, when one laser beam which is started is incident to the vicinity of the edge of the micro mirror, the laser is closed, and the other laser beam is started at the moment, so that the laser beam can be incident to the vicinity of the center of the micro mirror. The above process is repeated continuously, so that the influence of the interval area of the micro mirror unit can be avoided, continuous vertical scanning is realized, and the vertical linear density is greatly improved.

Based on the basic system scheme, the vertical scanning micro-mirror can be omitted, laser is incident to a one-dimensional beam expander to be diffused in the vertical direction, the laser is further diffused in the vertical direction through a one-dimensional integrator, and the energy distribution is more uniform. At the moment, the laser spots are changed into one-dimensional laser line arrays, and then the laser lines are incident to an A-type micro mirror through a reflector light-transmitting area to realize two-dimensional scanning; the one-dimensional laser line array can also be directly incident to the A-type micro-mirror, and a system scheme that the emitting optical axis and the receiving optical axis are in parallel dislocation is adopted.

Based on the basic system scheme, two beams of laser are emitted from two lasers and then are incident to two identical vertical scanning micro mirrors (same frequency, same phase and same amplitude vibration) with a certain angle difference, and are incident to a horizontal scanning micro mirror array through a light-transmitting area of the same reflector, and the angle difference is properly designed, so that the view fields of the two beams of laser can be spliced, and doubling is realized. In a similar way, two beams of laser are emitted from the two lasers, then are incident on the same vertical scanning micro mirror at a certain angle difference, and are incident on the horizontal scanning micro mirror array through the light transmission areas of the two separated reflectors, so that the same field doubling function can be realized. Two laser beams can be respectively detected by two separate optical detectors, and the two lasers can be driven simultaneously or in a staggered manner between time domains. Alternatively, multiple linear arrays of a single detector may be used, but the two lasers must be driven temporally staggered.

Based on the basic system scheme described above, all micromirrors can be arranged in one plane or in multiple planes parallel to each other. After being scanned by the first micro mirror, the laser beam is reflected by the reflecting mirror and then enters the second micro mirror arranged in the same plane to exit the exit window. The rotation axes of the first and second micromirrors are perpendicular to each other. The micro-mirror array receives the echo light field and reflects the echo light field to a light collecting reflector, and finally the detector captures an echo signal.

In all of the above cases, the amplitude of the micromirror's vibration can be adjusted to achieve independent adjustment of the viewing fields in both horizontal and vertical directions. Under the condition of unchanged scanning frequency, the field of view is reduced, and when the laser modulation frequency is not changed, fine scanning in a small range can be realized, so that the method is suitable for remote detection. When the field of view is enlarged and the laser modulation frequency is not changed, the scanning in a large range can be realized, and the method is suitable for short-distance detection.

The laser radar system provided by the embodiment of the invention is based on the MEMS technology, not only solves the noise influence of an external light field, but also is beneficial to providing sufficient echo light aperture, provides excellent signal-to-noise ratio and greatly expands the effective detection distance.

Example seventeen:

FIG. 21 illustrates one micromirror structure that can be used with embodiments of the present specification, including a mirror plate, a transition frame, three compliant springs, three cantilever beams, and three actuating portions, the compliant springs, cantilever beams, and actuating portions corresponding one-to-one;

the transition frame is arranged on the periphery of the micro mirror, and the micro mirror is connected with the transition frame through a plurality of connecting beams;

the three flexible springs are circumferentially arranged along the outer side of the transition frame at intervals, one end of a cantilever beam is dynamically connected with the transition frame through the flexible springs, and the other end of the cantilever beam is connected with the driving part;

the driving part comprises a torsion beam, two fixed anchor points and a fixed frame, the fixed frame is arranged opposite to the torsion beam, the torsion beam is connected with the cantilever beam, and one sides of two ends of the torsion beam, which are far away from the mirror surface, are respectively connected with the two fixed anchor points through elastic connecting parts;

and one side of the torsion beam opposite to the fixed frame is provided with movable comb teeth, and the fixed frame is provided with static comb teeth matched with the movable comb teeth. The fixed frame is of a strip structure.

The cantilever beams are arc structures of involute vortex lines, the three cantilever beams are arranged along the periphery of the mirror surface in an annular and staggered mode, and one end, connected with the corresponding torsion beam, of each cantilever beam bends towards one side far away from the mirror surface and is perpendicular to the torsion beam.

The movable comb teeth and the static comb teeth form a vertical comb tooth pair, and the vertical comb tooth pair is used for the micro-mirror to perform resonant scanning or quasi-static scanning.

The movable comb teeth and the static comb teeth of the vertical comb tooth pairs are not completely positioned in a plane, namely the vertical comb tooth pairs are of a structure that the movable comb teeth are arranged above the static comb teeth and are staggered completely.

When voltage is applied between the movable comb teeth and the static comb teeth, the movable comb teeth drive the torsion beam to rotate under the driving of the applied voltage, the cantilever beam rotates at the same angle along with the torsion beam, and the cantilever beam drives the mirror surface to vibrate through the flexible spring.

The amplitude of the mirror surface is M times of the amplitude of the movable comb teeth, the arrangement of the cantilever beams enables small-amplitude vibration of the movable comb teeth to be amplified by the lever to be large-amplitude vibration of the mirror surface, the elastic connecting component provides restoring force for vibration of the mirror surface, and M is a positive real number.

The flexible springs and the driving parts can also be asymmetrically distributed around the mirror surface, the included angles of the center lines of the adjacent two flexible springs can also be unequal, and the included angles of the short side directions of the adjacent two driving parts can also be unequal.

The micromirror structure described in this embodiment is only one possible structure for implementing the solution of the present specification, and does not constitute a limitation to the micromirror structure of the present specification.

Example eighteen:

FIG. 22 illustrates a micromirror structure that can be used with embodiments of the present specification, comprising a mirror plate, a transition frame, four compliant springs, four cantilever beams, and four actuating portions, the compliant springs, cantilever beams, and actuating portions corresponding one-to-one;

the four flexible springs are circumferentially arranged along the outer side of the transition frame at intervals, one end of the cantilever beam is dynamically connected with the transition frame through the flexible springs, and the other end of the cantilever beam is connected with the driving part;

and movable comb teeth are arranged on one side of the torsion beam opposite to the fixed frame, and static comb teeth matched with the movable comb teeth are arranged on the fixed frame. The fixed frame is of a strip structure.

The cantilever beams are arc structures of involute vortex lines, the four cantilever beams are arranged along the periphery of the mirror surface in an annular and staggered mode, and one end, connected with the corresponding torsion beam, of each cantilever beam is bent towards one side far away from the mirror surface and is perpendicular to the torsion beam.

The movable comb teeth and the static comb teeth form a plane comb tooth pair, and the plane comb tooth pair is used for the micro mirror to perform resonant scanning.

The amplitude of the mirror surface is M times of the amplitude of the movable comb teeth, the arrangement of the cantilever beams enables small-amplitude vibration of the movable comb teeth to be amplified by the lever to be large-amplitude vibration of the mirror surface, the elastic connecting component provides restoring force for vibration of the mirror surface, and M is a positive real number. An etching groove is formed in the middle of the torsion beam, and the non-uniform deformation of the torsion beam can be reduced through the etching groove. The flexible springs and the driving parts can also be asymmetrically distributed around the mirror surface, the included angles of the center lines of the adjacent two flexible springs can also be unequal, and the included angles of the short side directions of the adjacent two driving parts can also be unequal.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.

Claims

1. A lidar system based on a micro-mirror array, the lidar system comprising:

a laser light source for emitting a laser beam;

a vertical scanning micromirror for deflecting the oscillation along a first rotation axis in a first driving mode to scan the laser beam in a first angular range in a vertical direction;

the horizontal scanning micro-mirror array is used for deflecting and vibrating along a second rotating shaft in a second driving mode so as to enable the laser beam to scan in a second angle range in the horizontal direction;

a mirror disposed on an optical path between the vertical scanning micromirror and the horizontal scanning micromirror array; the mirror has a mirror transmissive region that just allows the laser beam within the first angular range to pass through.

2. The lidar system of claim 1, wherein the area of the mirror transparent region is substantially less than the total area of the mirror.

3. The lidar system of claim 1, wherein the mirror pass region cylindrical lens structure.

4. The lidar system of claim 1, wherein the vertical scanning micro-mirror and/or the horizontal scanning micro-mirror array is encapsulated internally with a high pressure hermetic package or an insulating liquid injection package.

5. The lidar system of claim 1, wherein the vertical scanning micro-mirror and/or the horizontal scanning micro-mirror array has a capacitive or piezoelectric feedback position sensor integrated therein.

6. The lidar system of claim 1, wherein the array of horizontal scanning micro-mirrors is a multi-column structure comprising:

the beam emergent micro-mirror array is used for deflecting to realize the emergence of the laser beam;

the echo light field receiving micro-mirror array is used for receiving the echo light field;

the light beam emergent micro-mirror array and the echo light field receiving micro-mirror array are arranged on the same plane;

or the light beam emergent micro-mirror array and the echo light field receiving micro-mirror array are arranged in parallel in a staggered mode.

7. A lidar system based on a micro-mirror array, the lidar system comprising:

the laser light source is used for emitting laser beams and comprises at least two lasers which are staggered and arranged in parallel on a time domain;

the horizontal scanning micro-mirror array is used for deflecting and vibrating along a second rotating shaft in a second driving mode so as to enable the laser beam to scan in a second angle range in the horizontal direction; the horizontal scanning micro-mirror array comprises column structures, wherein at least two columns in the column structures are arranged in a staggered mode;

8. The lidar system of claim 7, wherein the vertical scanning micromirror comprises at least two micromirrors oscillating at the same frequency, phase and amplitude corresponding to the at least two lasers staggered on in the time domain.

9. The lidar system of claim 7 or 8, wherein the mirror comprises a mirror transmissive region;

or, the reflector comprises light-transmitting regions corresponding to the at least two lasers which are switched on in a staggered mode in the time domain.

10. A lidar system based on a micro-mirror array, the lidar system comprising:

the laser light source is used for emitting laser beams and comprises at least two lasers; a vertical scanning micromirror for deflecting the oscillation along a first rotation axis in a first driving mode to scan the laser beam in a first angular range in a vertical direction;

a mirror disposed on an optical path between the vertical scanning micromirror and the horizontal scanning micromirror array; the reflector is provided with a reflector light-transmitting area which just allows the laser beam in the first angle range to pass through;

the two lasers are staggered in time domain and have an angle difference, so that the fields of view formed by the laser beams emitted by the different lasers are spliced to expand the fields of view; and receiving the reflected echo using a single photodetector;

or,

the two lasers are simultaneously started in a time domain and have an angle difference, so that the fields of view formed by the laser beams emitted by the different lasers are spliced; and a separate photodetector is used to receive the reflected echo.

11. A lidar system based on a micro-mirror array, the lidar system comprising:

a laser light source for emitting a laser beam;

a mirror;

the horizontal scanning micro-mirror array is a multi-column structure, comprising:

the light beam emitting micro-mirror array and the echo light field receiving micro-mirror array enable the laser light beams emitted by the laser light source to be parallel to and dislocated with the optical axes of the received echo light beams.

12. A lidar system based on a micro-mirror array, the lidar system comprising:

a laser light source for emitting a laser beam;

a one-dimensional beam expander for causing the laser light to diverge in a vertical direction;

the one-dimensional integrator is used for homogenizing and further diverging the laser beam diverged by the one-dimensional beam expander;

and the horizontal scanning micro-mirror array is used for deflecting and vibrating along the second rotating shaft in a second driving mode so as to enable the laser beam to scan in a second angle range in the horizontal direction.

13. The lidar system of claim 12, further comprising a mirror:

the reflecting mirror is used for receiving the echo light beam received by the horizontal scanning micro-mirror array;

or,

the reflecting mirror is arranged on a light path between the vertical scanning micro mirror and the horizontal scanning micro mirror array; the laser beam expander is provided with a reflector light-transmitting area which just allows the laser beam expanded by the one-dimensional integrator to pass through.

14. A lidar system based on a micro-mirror array, the lidar system comprising:

a laser light source for emitting a laser beam;

a first scanning micro-mirror for deflecting vibration in a first driving mode to scan the laser beam in a first angular range;

a second scanning micro-mirror for deflecting the vibration in a second driving mode to scan the laser beam in a second angular range;

the first scanning micro-mirror and the second scanning micro-mirror are arranged on the same chip carrier;

the laser beam emitted by the laser source is reflected to the first scanning micro mirror through the first reflecting surface of the first reflecting mirror, is dynamically deflected along with the deflection vibration of the first scanning micro mirror, and is reflected to the second reflecting surface of the first reflecting mirror again; after being reflected by the first reflector, the light is incident to the second scanning micro-mirror;

the vibration directions of the first scanning micro mirror and the second scanning micro mirror are perpendicular to each other.

15. The lidar system of claim 14,

the third scanning micro-mirror array receives the echo light field, reflects the echo light field to the second reflecting mirror and emits the echo light field to the optical receiving unit through a receiving light path;

the third micro-mirror array, the first scanning micro-mirror and the second scanning micro-mirror are arranged along the same direction, and the third scanning micro-mirror array and the second scanning micro-mirror vibrate in the same frequency, in the same phase and at the same amplitude.

16. A lidar system based on a micro-mirror array, the lidar system comprising:

a laser light source for emitting a laser beam;

a mirror disposed between the laser light source and the first scanning mirror, the mirror having a mirror transmissive region;

the first scanning mirror and the second scanning mirror are arranged on the same chip carrier surface, and the chip carrier surface defines a first plane;

a laser beam emitted by the laser light source forms a small angle theta with a normal of the first plane; the laser beam penetrates through the light-transmitting area of the reflector, enters the first scanning micro mirror, is reflected to the reflector after being deflected at the first scanning micro mirror, is reflected again at the reflector, enters the second micro mirror, is deflected at the second micro mirror, and then leaves from the exit window.

17. The lidar system of claim 16, wherein the mirror transmissive region is circular and is provided with a spherical lens.

18. The lidar system of claim 16,

the third scanning micro-mirror array is used for receiving the echo light field, reflecting the echo light field to the second reflecting mirror and enabling the echo light field to be incident to the optical receiving unit through a receiving light path;

19. A lidar system based on a micro-mirror array, the lidar system comprising:

a laser light source for emitting a laser beam;

the two-dimensional micromirror scanning micromirror is used for deflecting and vibrating in a preset driving mode so as to enable the laser beam to scan within a preset angle range;

the third micro mirror array and the two-dimensional scanning micro mirror are arranged on the same chip carrier, and the third scanning micro mirror array and the second scanning micro mirror vibrate in the same frequency, in the same phase and in the same amplitude.