CN113030909B

CN113030909B - Laser radar system based on micromirror array

Info

Publication number: CN113030909B
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: 2024-05-28
Anticipated expiration: 2039-12-09
Also published as: CN113030909A

Abstract

A micro-mirror array based lidar system comprising: a laser light source for emitting a laser beam; a vertical scanning micromirror for deflecting vibration along a first rotation axis in a first driving mode so that the laser beam is scanned in a first angular range in a vertical direction; a horizontal scanning micromirror array for deflecting and vibrating along a second rotation axis in a second driving mode so that the laser beam scans in a second angle range in a horizontal direction; a mirror disposed in an optical path between the vertical scanning micromirror and the horizontal scanning micromirror array; the mirror has a mirror light transmission region that allows passage of the laser beam within exactly the first angular range.

Description

Laser radar system based on micromirror 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 measurement device. Different from a multi-view camera, the laser radar is not influenced by illumination conditions and has stronger 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 paid in recent years to the fields of autopilot and 3D imaging. The traditional laser radar uses the design of combining multiple paths of lasers with a mechanical rotating structure, so that the speed is low, the size 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 equipment volume can be greatly reduced, the scanning frequency can be 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 plane can be detected by only one laser. The compact design of the structure ensures that the laser radar based on the micro mirror is easy to be embedded into the portable equipment, thereby greatly widening the application situations.

The existing laser radar based on MEMS micro-mirrors adopts a scheme that transmitting and receiving light paths 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 receiving laser echoes, 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 long-distance detection requirement cannot be met.

To avoid the above problems, a scheme in which the transmission and reception optical paths are coaxial may be adopted. With this configuration, the detector receives only the light signal in the opposite direction to the emitted pulse, thereby effectively reducing interference of ambient light and other lidar light sources. However, the coaxial system clear aperture of the transmitting and receiving light paths is very limited, so that the capability of the system for collecting echo energy is severely restricted, and the laser radar system can only work in a short-distance occasion.

Disclosure of Invention

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

In a first aspect of the present invention, there is provided a laser radar system based on a micromirror array, the laser radar system comprising: a laser light source for emitting a laser beam; a vertical scanning micromirror for deflecting vibration along a first rotation axis in a first driving mode so that the laser beam is scanned in a first angular range in a vertical direction; a horizontal scanning micromirror array for deflecting and vibrating along a second rotation axis in a second driving mode so that the laser beam scans in a second angle range in a horizontal direction; a mirror disposed in an optical path between the vertical scanning micromirror and the horizontal scanning micromirror array; the mirror has a mirror light transmission region that allows passage of the laser beam within exactly the first angular range.

Preferably, the area of the reflective light-transmitting region is much smaller than the total area of the mirror.

Preferably, the reflective light-transmitting zone is a cylindrical lens structure.

Preferably, the vertical scanning micro-mirror and/or the horizontal scanning micro-mirror array are packaged by high-pressure air-tight packaging or insulating liquid injection.

Preferably, capacitive or piezoelectric feedback position sensors are integrated into the vertical scanning micro-mirrors 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 comprises: the beam emergent micro-mirror array is used for deflecting to realize the emergent of laser beams; the echo light field receiving micro mirror array is used for receiving the echo light field; the beam emergent micro-mirror array and the echo light field receiving micro-mirror array are arranged on the same plane; or the beam emergent micro-mirror array and the echo light field receiving micro-mirror array are arranged in parallel and staggered.

In a second aspect of the present invention, there is provided a laser radar system based on a micromirror array, the laser radar system comprising: the laser light source is used for emitting laser beams and comprises at least two lasers which are staggered in time domain and are arranged in parallel; a vertical scanning micromirror for deflecting vibration along a first rotation axis in a first driving mode so that the laser beam is scanned in a first angular range in a vertical direction; a horizontal scanning micromirror array for deflecting and vibrating along a second rotation axis in a second driving mode so that the laser beam scans in a second angle range in a horizontal direction; the horizontal scanning micro mirror array comprises a column structure, and at least two columns in the column structure are arranged in a staggered manner; a mirror disposed in an optical path between the vertical scanning micromirror and the horizontal scanning micromirror array; the mirror has a mirror light transmission region that allows passage of the laser beam within exactly the first angular range.

Preferably, the vertical scanning micro-mirror is composed of at least two micro-mirrors vibrating in the same frequency, in the same phase and in the same amplitude corresponding to the at least two lasers which are staggered and started in the time domain.

Preferably, the mirror comprises a mirror light transmission region; or the reflecting mirror comprises a light transmission area corresponding to the at least two lasers which are turned on in a staggered mode in the time domain.

In a third aspect of the present invention, there is provided a laser radar system based on a micromirror array, the laser radar system comprising: a laser light source for emitting a laser beam comprising at least two lasers; a vertical scanning micromirror for deflecting vibration along a first rotation axis in a first driving mode so that the laser beam is scanned in a first angular range in a vertical direction; a horizontal scanning micromirror array for deflecting and vibrating along a second rotation axis in a second driving mode so that the laser beam scans in a second angle range in a horizontal direction; the horizontal scanning micro mirror array comprises a column structure, and at least two columns in the column structure are arranged in a staggered manner; a mirror disposed in an optical path between the vertical scanning micromirror and the horizontal scanning micromirror array; the reflecting mirror is provided with a reflecting mirror light transmission area which exactly 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 fields formed by laser beams emitted by different lasers are spliced to enlarge the fields; and receiving the reflected echo using a single line APD; or the two lasers are simultaneously started in the time domain and are incident to different vertical scanning micromirrors so that the fields of view formed by the laser beams emitted by the different lasers are spliced; and receives the reflected echoes using a separate APD array.

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

In a fifth aspect of the present invention, there is provided a laser radar system based on a micromirror array, the laser radar system comprising: a laser light source for emitting a laser beam; a one-dimensional beam expander for causing the laser to diverge in a vertical direction; a one-dimensional integrator for dispersing the laser beam dispersed by the one-dimensional expander; and 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 scan the laser beam in a second horizontal angle range.

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 mirror is arranged in the optical path between the vertical scanning micro mirror and the horizontal scanning micro mirror array; the light-transmitting area of the reflecting mirror is provided, and the light-transmitting area of the reflecting mirror just allows the refined light beam after being expanded by the one-dimensional integrator to pass through.

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

first, the MEMS micro-mirror array can provide a larger aperture, which overcomes the defect of limited mirror surface size of a single micro-mirror.

Second, the laser pulse is transmitted and received by adopting a coaxial light path, so that the influence of ambient light can be effectively reduced.

Third, the MEMS micro-mirror array is scanned by adopting a single axis, so that the process is simple and the larger filling factor is easy to realize.

Fourth, the cost is lower than that of a two-dimensional photodetector array, and the signal intensity is higher than that of a single-point detector.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for the description of the embodiments will be briefly described below, and it is apparent that the drawings in the following description are only some embodiments of the present invention, and other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

Fig. 19 is a schematic view of an optical path principle of a lidar according to an embodiment of the present invention.

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

Fig. 21 is a schematic diagram of a micromirror structure according to an embodiment of the invention.

Fig. 22 is a schematic diagram of a micromirror structure according to an embodiment of the invention.

Detailed Description

The technical solutions 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 will be apparent that the described embodiments are only some, but not all, embodiments of the invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the 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 the like, are used for descriptive purposes only and are not to be construed as indicating or implying a relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defining "a first" or "a second" may include one or more of the feature, either explicitly or implicitly. Moreover, the terms "first," "second," and the like, are used for distinguishing between similar objects and not necessarily for describing a particular sequential or chronological order. It is to be understood that the data so used may be interchanged where appropriate such that the embodiments of the invention described herein may be implemented in sequences other than those illustrated or otherwise described herein.

Embodiment one:

in view of the above unsolved problems, the present invention provides a lidar system, which aims to realize remote 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 enters a vertical scanning micromirror 4. The vertical scanning micromirror 4 is an electrostatically driven micromirror operating in a quasi-static mode, and deflects and vibrates about the first axis of rotation 3 such that an incident laser beam is scanned within a certain angle in the vertical direction.

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

The laser beam passes through the mirror light-transmitting region and then is 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 resonant mode, and deflects and vibrates about the second axis of rotation 7. The array units in the horizontal scanning micro mirror array 6 are driven by static electricity to vibrate in the same frequency and in the same phase with the same amplitude. In the scanning period, the laser beams are sequentially incident on a plurality of micromirror units in the center of the horizontal scanning micromirror array 6 along with the passage of time, and form a two-dimensional scanning surface after being reflected.

In a 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 that emits 1550nm pulsed laser light and is incident on a horizontal scanning micro-mirror 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 vertically scanned laser beam 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 ratio of the effective reflective area of the mirror to the total area of the SOI chip.

As shown in fig. 2, which shows a schematic diagram of the operation of the lidar at a certain moment. After passing through the scanning array, the pulsed laser light exits from the window 8 and irradiates the object, scattering occurs on the surface of the object, and a part of the light is back-reflected to form a reflected echo, and 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 micromirrors in the horizontally scanned micromirror array 6 is small and almost negligible in the middle-short distance. Thus, the echo signals received by the micromirror array will be incident on the mirror 5 along a path opposite to the exit direction. Since the area of the light-transmitting area of the reflecting mirror 5 is very small, which is far smaller than the total area of the whole reflecting mirror 5, only a very small part of the reflected echo is transmitted through the light-transmitting area, and therefore, the energy loss of the echo light due to the transmission on the reflecting mirror 5 is not obvious.

The echo pulse is reflected to a receiving light path by a reflecting mirror 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 the photodetector 11 through the converging lens 10, so as to realize the detection of signals.

In one specific example, non-axial parasitic light is removed by a diaphragm and ambient light of other wavelengths is removed by a filter.

In one specific example, the photodetector 11 is an APD line train.

Embodiment two:

In the foregoing embodiment, the vertical scanning micromirror 4 and the horizontal scanning micromirror array 6 are MEMS micromirror devices. The SOI wafer is processed by a semiconductor process. The driving mode of the micromirror can be electrostatic driving, piezoelectric driving, electromagnetic driving, electrothermal driving, etc.

The vertical scanning micromirror 4 may employ resonant scanning, quasi-static scanning, or digital jump scanning.

The vertical scanning micromirror 4 may be an electrostatically driven micromirror using a planar comb, or an electrostatically driven micromirror having a vertical comb 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 may alternatively use electrostatic driven micromirrors of planar comb teeth or electrostatic driven micromirrors having a vertical comb tooth structure.

In a preferred example, the horizontally 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 progressive scanning of the laser light.

In a specific example, the vertical scanning micro-mirror 4 may employ an internal high pressure hermetic package or an insulating liquid injection package to increase the damping of the micro-mirror to provide it with 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 position of the deflection of the mirror surface is fed back to the signal processing unit in real time by adopting a method such as capacitance or piezoelectric feedback. The signal processing unit sends a driving signal, and closed-loop control of all the micro mirror units is realized through the micro mirror driving circuit.

In a specific example, the horizontal scanning micromirror array 6 can employ an internal high pressure hermetic package or an insulating liquid injection package to increase the damping of the micromirrors to have 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 position of the mirror deflection is fed back to the signal processing unit in real time by adopting a method such as capacitance or piezoelectric feedback. The signal processing unit sends a driving signal, and closed-loop control of all the micro mirror units is realized through the micro mirror driving circuit.

Embodiment III:

as shown in fig. 3, in this embodiment, it is possible to reduce the width of the light transmitting region of the reflecting mirror and form a cylindrical mirror on the light transmitting region of the reflecting mirror, the cylindrical mirror being integral with the reflecting mirror.

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

The cylindrical lens structure can counteract diffraction effect of laser passing through the light transmission area of the reflecting mirror, and good collimation of the laser beam is ensured.

Embodiment four:

As shown in fig. 4, the horizontal scanning micro-mirror array 6 may be divided into two parts, wherein the central part is a first horizontal scanning micro-mirror shared by the emergent light and the light receiving light, and the light beam transmitted through the light transmitting area of the mirror performs vertical scanning on the micro-mirror surface, and then is reflected to form two-dimensional scanning. The upper and lower sides of the first horizontal scanning micro-mirror are distributed with a plurality of second horizontal scanning micro-mirrors for light receiving. The first horizontal scanning micro-mirror and the second horizontal scanning micro-mirror are formed on the same chip surface through MEMS technology, so that the first horizontal scanning micro-mirror and the second horizontal scanning micro-mirror can have the same scanning angle. And simultaneously, 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 therefore 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 length in the longitudinal direction and a smaller width, and this type of micromirror is also referred to herein as a class 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 herein as a class B micromirror.

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 aspect ratios of the first horizontal scanning micromirror and the second horizontal scanning micromirror and the specific structure can be adjusted so that they have substantially the same center operating frequency.

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 execute the same-frequency and same-phase constant-amplitude vibration.

Fifth embodiment:

As shown in fig. 5, in one particular embodiment, the horizontal scanning micro mirror array may be divided into two columns. The micro-mirror 12 is used for taking charge of the emission of laser beams; also included is an echo light field receiving column micromirror 13 for receiving the echo light field.

The reflecting mirror 14 is set to be completely opaque, so that the outgoing laser avoids the area where the reflecting mirror is located, and the outgoing optical axis and the received optical axis are further parallel and misplaced, so that the optical axes are parallel and are not coincident, and the possibility that the outgoing laser is scattered into the detector is reduced.

The micromirrors for emitting the laser beam may be column micromirrors such as the beam emitting column micromirrors 12 shown in fig. 5, or may be single micromirrors. As shown in fig. 6, a beam-emitting micromirror a is responsible for the emission of a laser beam.

When the beam-exit micromirror a is used, it is necessary to bring the vertical scanning micromirror close to the horizontal scanning micromirror in order to alleviate the requirement for the length of the horizontal scanning micromirror. The beam-emitting micromirror a has a similar structure to the first horizontal scanning micromirror, with a larger length in the longitudinal direction and a smaller width. In a specific example, the aspect ratio is 3 or more.

In some specific examples, the reflected light field received by the micromirror array 13 may be directed directly into the receiving lens group without using the mirror 14, and finally into the detector.

Example six:

The horizontal scanning micro mirrors may also have a multi-column structure, as shown in fig. 7, in which the horizontal scanning micro mirror array has a three-column structure, and the light beam emitted from the light transmitting area of the mirror scans on the B-type micro mirrors having the second horizontal scanning micro mirror structure in part or all of one column.

The entire plurality of rows of micromirrors determines the clear aperture of the echo, and as shown in fig. 8, the light beam exiting through the transparent region of the mirror may also be incident on one micromirror. The micromirror has a similar structure to the first horizontal scanning micromirror, with a larger length in the longitudinal direction and a smaller width. In a specific example, the aspect ratio is 3 or more. As shown in fig. 8, which shows a similar triangular relationship of each device in the optical path, the proportional relationship of the length of the light transmitting region on the reflecting mirror and the length of the class a micromirror is the same as the proportional relationship of 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 may 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 may 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 may be formed by combining and arranging a class a and a class B micromirrors.

Wherein, the class A micromirror has a larger longitudinal length and a smaller width, and the class B micromirror has a smaller longitudinal length and a larger width.

Embodiment seven:

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

In this embodiment, the reflecting mirror does not have a light-transmitting area, the outgoing laser avoids the area where the reflecting mirror is located, and the outgoing optical axis and the received optical axis are parallel and dislocated, so that the optical axes are parallel and not overlapped, and the possibility that the outgoing laser is scattered into the detector is reduced.

As shown in fig. 9, the micromirrors for emitting the laser beam may be an array of B-type micromirrors, and the micromirror array for receiving the echo light field may be formed by arranging a plurality of columns of B-type micromirrors.

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

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

Example eight:

In the foregoing embodiment, if a plurality of B-type micromirrors are used to form an array, the line density of the vertical scanning is reduced due to the discontinuity of the vertical scanning caused by the interval between the adjacent B-type micromirror units.

As shown in fig. 12, the system includes two light sources, i.e., a first laser and a second laser, which are coherent light sources, that is, the first and second lasers can emit parallel light with the same frequency, the same phase, and the same amplitude. Light emitted from the first laser and the second laser is incident on the first vertical scanning mirror and the second vertical scanning mirror, respectively, passes through the first light-transmitting region 20 and the second light-transmitting region 21 of the reflecting mirror by reflection of the two vertical scanning mirrors, and then is incident on the horizontal scanning micro mirror array.

The array of horizontal scanning micromirrors can be divided into a plurality of columns wherein adjacent first 18 and second 19 vertical scanning micromirrors are used to reflect the incident laser light to the exit window, the first 16 and second 17 horizontal scanning micromirrors being 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 mode of vibration of the same frequency, the same phase and the same amplitude, and reflected light passing through the vertical scanning micro mirrors scans and is incident on a part 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 laser is incident to the vertical scanning mirror, the laser is turned off, and the other laser is turned on. In one possible example, the angular variation of the vertical scanning micromirror can be determined 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 associated with the scanning position formed by a MEMS process at the time of manufacturing the micromirror, reflecting the position of the scanning mirror by the current/voltage conditions in the electrode.

By staggering the first laser and the second laser in time domain, it can be realized that when one beam of laser is started and is incident near the edge of the micro-mirror, the position sensor feeds back the angle of the micro-mirror, at this time, the laser is turned off, and the other laser is started, and when the beam emitted by the other laser is incident near the edge of the mirror, the previous laser beam can be just incident near the center of the micro-mirror. The above process is repeated continuously, so that the influence of the interval area of the micro mirror units can be avoided, continuous vertical scanning is realized, and the vertical line density of scanning is improved.

Example nine:

As shown in fig. 13, the laser beam is incident on a one-dimensional beam expander 22, causing the laser beam to diverge in the vertical direction. The beam passing through the beam expander passes through a one-dimensional integrator 23, so that the laser light 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, then pass through the light transmission area of the reflector and are incident into an A-type micro mirror, and the A-type micro mirror rotates to expand the one-dimensional laser lines into a scanning surface, so that two-dimensional scanning of a target area is realized. The reflected echo is received by the horizontal scanning micromirror and reflected to the mirror, and the received light path thereafter is substantially the same as in the previous embodiment. The horizontal scanning mirror structure may be a multi-column structure consisting of a plurality of columns of class B micromirror 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 to diverge in the vertical direction. The beam passing through the beam expander passes through a one-dimensional integrator, so that the laser is further dispersed in the vertical direction, and the energy distribution is more uniform. The one-dimensional laser line is directly incident to the A-type scanning micro mirror, and the A-type micro mirror rotates to expand the one-dimensional laser line into a scanning surface, so that two-dimensional scanning of a target area is realized. The reflected echo is received by the horizontal scanning micromirror and reflected to the mirror, and the received light path thereafter is substantially the same as in the previous embodiment. The horizontal scanning mirror structure may be a multi-column structure composed of a plurality of columns of B-type micromirror structures, or may be a multi-column structure composed of a plurality of columns of a-type micromirror structures. In the corresponding embodiment of fig. 14, the exit and receiving optical axes are parallel and offset, or the planes of the two are parallel.

At this time, the vertical resolution of the lidar is determined by the number of vertical pixels of the detector line 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 angle difference. The first vertical scanning micromirror 24 and the second vertical scanning micromirror 25 are identical and vibrate at the same frequency, in phase, and constant amplitude. After being reflected at 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 region 26 and reflected on the horizontal scanning micro mirror array. The angles of the first and second lasers are adjusted so that the angle difference incident to the first and second vertical scanning micromirrors 24, 25 can be adjusted, and finally the first and second laser fields of view 27, 28 reflected by the horizontal scanning micromirror array can be spliced, thereby achieving field doubling.

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

Two echo light pulse signals can be simultaneously output by detecting two lasers respectively using two separate photodetectors 291 'and 292', each corresponding to one field of view range, so that two lasers can be driven simultaneously, although staggered driving is also possible.

In this embodiment, the example shown in fig. 15 uses a multi-line APD detector, and since the detector outputs only one echo optical pulse signal at a time, two lasers must be driven in a time domain with a staggered arrangement. The example corresponding to fig. 16 uses two separate photo detectors, and the two lasers can be driven simultaneously or time-staggered. Of course, the example corresponding to fig. 16 may also use one APD detector of multiple columns, but two lasers must be driven staggered in time domain. Embodiment 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 to the first micromirror 32 at the mirror 33 and dynamically deflected in accordance with the action of the first micromirror 32, then reflected to the mirror 33 a second time, reflected by the mirror 33 and incident on the second micromirror 34 arranged near the first micromirror 32, deflected at the second micromirror 34 and exits from the exit window 35. Wherein, the rotation axis of the first micro mirror 32 is along the X direction, the rotation axis of the second micro mirror 34 is along the Y direction, and the reflecting mirror 33 is provided with a first reflecting surface positioned at the side surface and a second reflecting surface positioned at the bottom surface.

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

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

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

Embodiment thirteen:

as shown in fig. 18, the laser 42 emits a laser beam in a direction at a small angle theta to the-Z axis. The light beam passes through the mirror 43 with a 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 to the second micromirror, is deflected at the second micromirror, and then leaves from the exit window.

In this embodiment, since the initial incident direction of the laser beam deviates from the-Z axis by a small angle Θ, the light-transmitting region on the mirror can be avoided when returning through the first micromirror, 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 problems of small aberration but large energy loss of incident light when the incident light is completely along the-Z axis are avoided.

In one example, the light-transmitting region of the reflector 43 may be configured as a circle, and the light-transmitting region may be configured as a spherical lens to counteract the diffraction effect of the laser beam passing through the light-transmitting region of the reflector, so as to ensure good collimation of the laser beam.

In one example, the mirror 43 may be replaced with a common total reflection mirror and the laser light returned from the first micromirror is reflected only off the original incident path of the laser light.

The reflecting mirror 43 can have other various structures, and the different structures can be changed without exceeding the protection scope of the invention.

Fourteen examples:

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

Example fifteen:

As shown in fig. 20, a functional block diagram of one construction of a lidar system is shown. The digital signal processing unit outputs a laser driving instruction, inputs the laser driving instruction to the light source driving circuit through a digital-to-analog converter (DAC), and finally drives the laser 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 amplifying, filtering and other steps. The converted digital signal is calculated by a digital signal processing unit to obtain a flight time result. Here, the device that can be adopted is an analog-to-digital converter (ADC) or a time-to-digital converter (TDC), or the like.

Meanwhile, the digital signal processing unit outputs a micromirror driving instruction, converts the micromirror driving instruction into an analog signal through a multi-channel DAC, and respectively drives the vertical scanning micromirror and each horizontal scanning micromirror array unit through a micromirror driving circuit. The multi-channel DAC may be composed of a plurality of independent DACs or may be composed of 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 can be respectively adjusted; it may also consist of a common phase control combined with separate drive voltage amplitude control, i.e. all micromirror units share the same phase information, but the drive voltage amplitude can be adjusted separately.

The position sensor integrated on the micro-mirror chip outputs feedback signals in real time, and inputs the feedback signals into the multichannel ADC after the steps of amplifying, 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 micromirror driving instruction to realize closed-loop control of the micromirrors, and particularly can realize the same-frequency, same-phase and constant-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 gap 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 flight time result obtained by processing to an external system for display or further calculation.

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, collimated by a collimating lens and then enters a vertical scanning micro-mirror, so that the laser beam is scanned within a certain angle in the vertical direction. A reflecting mirror is arranged on the optical path of the laser beam, the reflecting mirror has a reflectivity of approximately 1 for the laser beam with the wavelength, and only a strip-shaped area near the center is left to have a transmissivity of approximately 1 for the laser beam. The area of the strip-shaped area is much smaller than the total area of the mirror. The laser beam scanned in the vertical direction described above can be transmitted through 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 can be a monolithically integrated MEMS micromirror array, so as to realize more compact arrangement and larger filling factor. All units of the micromirror array vibrate in the same frequency and same phase with the same amplitude. The laser beams are sequentially incident on a part or all of the micromirror units of the horizontal scanning micromirror array along with the time, and a two-dimensional scanning surface is formed after reflection. After the laser pulse irradiates an object, a part of light is reflected back and is incident on the horizontal scanning micro mirror array, and because the flight time of the laser pulse is extremely short, the position change of the horizontal scanning micro mirror is very small, so that an echo signal received by the micro mirror array is incident on the reflecting mirror along a path with opposite emergent directions, and because the area of a strip-shaped area is very small, the energy loss caused by the echo signal is not obvious. The echo pulse is 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 echo pulse is focused on a light detector through a converging lens, so that signal detection is realized.

The laser may be an edge-emitting semiconductor laser, a vertical cavity surface emitting laser, an optical fiber laser, or the like; the wavelength used may be 850nm, 905nm, 1550nm, etc.; of these, 1550nm high-power pulsed fiber lasers are 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 may employ resonant scanning, quasi-static scanning, or digital jump scanning, preferably using an electrostatically driven micromirror with a vertical comb structure, but the use of an electrostatically driven micromirror with planar comb is not precluded. The horizontal scanning micromirror array may also employ resonant scanning, quasi-static scanning, or digital jump scanning, preferably using electrostatically driven micromirrors with planar comb structures, but the use of electrostatically driven micromirrors with vertical comb structures is not precluded. Under the preferred condition, the frequency of the horizontal scanning micro-mirror array is far higher than that of the vertical scanning micro-mirror, the two mirror surfaces are combined to finish the progressive scanning of the laser, and at the moment, the vertical scanning micro-mirror can adopt an internal high-pressure airtight package or an insulating liquid injection package so as to increase the damping of the micro-mirror and enable the micro-mirror to have 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 a method such as capacitance or piezoelectric feedback, the signal processing unit sends a driving signal, and the closed-loop control of all the micromirror units is realized through the micromirror driving circuit.

The reflecting mirror with the strip-shaped transmission area can be formed by grooving on the mirror surface and penetrating the whole mirror surface, or can be formed by depositing an antireflection film on the surface of glass, then depositing a metal reflecting surface, and leaving the strip-shaped area free from metal deposition. Preferably, the width of the stripe-shaped region may be reduced, and a cylindrical mirror may be formed on the stripe-shaped region (hereinafter, referred to as a mirror light-transmitting region), the cylindrical mirror being integrated with the mirror, an anti-reflection film being deposited on an outer surface, and a metal reflective layer being deposited outside the cylindrical region. The structure can counteract diffraction effect generated when 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 parallel light after being reflected; the mirror may also be curved in configuration and the reflecting surface may be curved inwardly in one or both directions to converge the echo light field.

The light detector may be a single-point light detector, a line-up light detector, or a two-dimensional light detector array. The device type may be PN or PIN photodiodes, avalanche Photodiodes (APDs), photomultiplier tubes, CCD arrays, CMOS arrays, single Photon Avalanche Diodes (SPAD), or the like. Preferably, the present invention can use avalanche photodiode arrays, matched to a horizontally scanned micromirror array, to achieve high precision detection at limited cost. Because the coaxial design of the receiving and transmitting optical paths can greatly reduce the influence of ambient parasitic light, weak optical signals can be fully amplified by using the APD line array without worrying about overhigh noise level.

The horizontal and vertical scanning described above are relative concepts that merely illustrate that the axes of rotation of the two micromirrors are perpendicular to each other and do not limit the absolute spatial orientation of the system.

Based on the above basic system scheme, the horizontal scanning micro-mirror array can be divided into two parts, the central part is a horizontal scanning micro-mirror shared by emergent light and light receiving, which has a larger longitudinal length and a smaller width (the aspect ratio is more than or equal to 3, hereinafter referred to as a type-a micro-mirror), and the light beam transmitted from the light transmitting area of the reflecting mirror is vertically scanned on the micro-mirror surface, so that the two-dimensional scanning is formed by reflection. The upper and lower sides of the central micromirror are distributed with a plurality of light-receiving micromirrors, the micromirrors have smaller longitudinal length and larger width (the length-width ratio is less than or equal to 3, hereinafter referred to as class-B micromirrors), and through designing that the two micromirrors have the same scanning angle and central working frequency, the same-frequency and same-phase constant-amplitude vibration is executed (hereinafter, class-A micromirrors and class-B micromirrors meet the conditions and are not repeated).

Based on the basic system scheme, the horizontal scanning micro mirror array can be divided into two columns, wherein one column is responsible for the emergence of laser beams, and the other column is used for the reception of echo light fields. The reflector used at the moment is not provided with a light transmission area, the emergent laser avoids the area where the reflector is positioned, and the emergent laser and the received optical axis are subjected to parallel dislocation through the receiving and transmitting of the scanning mirrors in different rows, so that the optical axes are parallel and are not overlapped, and the possibility that the emergent laser is scattered into the detector is reduced. The micro-mirror used for emitting the laser beam can be a B-type micro-mirror array or an A-type micro-mirror.

Based on the basic system scheme, the horizontal scanning micro-mirror array can be divided into a plurality of columns, and the light beams emitted from the light transmission area of the reflecting mirror scan on part or all of B-type micro-mirror units in one column. The entire array of micromirrors determines the clear aperture of the echo. The light beam exiting through the light transmitting 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 class A micromirrors, can be formed by arranging the same class B micromirrors, and can be formed by combining and arranging the class A micromirrors and the class B 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 reflector used at the moment is not provided with a light transmission area, the emergent laser avoids the area where the reflector is positioned, the emergent optical axis and the received optical axis are subjected to parallel dislocation, the optical axes are parallel and are not overlapped, and the possibility that the emergent laser is scattered into the detector is reduced. The micro-mirror used for emitting the laser beam can be a B-type micro-mirror array or an A-type micro-mirror. The micromirror array for receiving the echo light field can be formed by arranging the same class A micromirrors, can be formed by arranging the same class B micromirrors, and can be formed by combining and arranging the class A micromirrors and the class B micromirrors.

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

Based on the basic system scheme, the vertical scanning micro mirror can be omitted, laser is incident to one-dimensional beam expander, so that the laser is diffused in the vertical direction, and then the laser is further diffused in the vertical direction through one-dimensional integrator, and the energy distribution is more uniform. At the moment, the laser spots become one-dimensional laser lines, and then enter an A-type micro mirror through a light transmission area of the reflecting mirror to realize two-dimensional scanning; the one-dimensional laser line can also directly enter the A-type micro mirror, and a system scheme that the emergent optical axis and the receiving optical axis are parallel and misplaced is adopted.

Based on the basic system scheme, after two laser beams are emitted from two lasers, two identical vertical scanning micro mirrors (with the same frequency, the same phase and the same amplitude vibration) are incident on the horizontal scanning micro mirror array through the same reflector light transmission area with a certain angle difference, and the angle difference is properly designed, so that the fields of view of the two laser beams can be spliced, and doubling is realized. Similarly, after two laser beams are emitted from the two lasers, the two laser beams are incident on the same vertical scanning micro-mirror with a certain angle difference, and are incident on the horizontal scanning micro-mirror array through two separated reflector light transmission areas, so that the same field doubling function can be realized. At this time, two separate light detectors can be used to detect two laser beams respectively, and the two laser beams can be driven simultaneously or in a time-domain staggered manner. Alternatively, a single detector of multiple columns may be used, but two lasers must be driven in time domain with an error.

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

In all the above cases, the vibration amplitude of the micromirror can be adjusted to realize independent adjustment of the field of view in both the 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, and the method is suitable for long-distance detection. When the field of view is increased and the laser modulation frequency is not changed, scanning in a large range can be realized, and the method is suitable for short-distance detection.

The laser radar system of 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 clear aperture, providing superior signal to noise ratio and greatly expanding effective detection distance.

Example seventeenth:

FIG. 21 illustrates one type of micromirror structure that may be used in embodiments of the present disclosure, including a mirror, a transition frame, three flexible springs, three cantilever beams, and three driving sections, which are in one-to-one correspondence;

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

the three flexible springs are arranged at intervals along the circumferential direction of the outer side of the transition frame, 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;

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 side, far away from the mirror surface, of the two ends of the torsion beam is respectively connected with the two fixed anchor points through an elastic connecting part;

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

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

The movable comb teeth and the static comb teeth form vertical comb teeth pairs, and the vertical comb teeth pairs are used for carrying out resonance scanning or quasi-static scanning on the micro mirrors.

The movable comb teeth and the static comb teeth of the vertical comb tooth pair are not completely in the same plane, namely the vertical comb tooth pair is in a structure that the movable comb teeth are arranged below the static comb teeth, and the movable comb teeth and the static comb teeth are completely staggered.

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 drive of the applied voltage, the cantilever beam rotates with the torsion beam at the same angle, 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 cantilever beams are arranged to enable small vibration of the movable comb teeth to be amplified into large vibration of the mirror surface by the lever, and the elastic connecting component provides restoring force for the vibration of the mirror surface, wherein M is a positive real number.

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

The micromirror structure described in this embodiment is only one possible structure for implementing the technical solution of this specification, and is not limited to the micromirror structure of this specification.

Example eighteenth:

FIG. 22 illustrates one type of micromirror structure that may be used in embodiments of the present disclosure, including a mirror, a transition frame, four flexible springs, four cantilever beams, and four driving sections, which are in one-to-one correspondence;

The four flexible springs are circumferentially arranged at intervals along the outer side of the transition frame, 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;

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

The cantilever beams are of arc structures of involute vortex lines, four cantilever beams are arranged in a staggered mode along the periphery of the mirror face in a circumferential direction, and one end, connected with the corresponding torsion beam, of each cantilever beam is bent towards one side, far away from the mirror face, of each torsion beam 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 carrying out resonance scanning on the micromirror.

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

The foregoing description of the preferred embodiments of the invention is not intended to limit the invention to the precise form disclosed, and any such modifications, equivalents, and alternatives falling within the spirit and scope of the invention are intended to be included within the scope of the invention.

Claims

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

a laser light source for emitting a laser beam;

A vertical scanning micromirror for deflecting vibration along a first rotation axis in a first driving mode so that the laser beam is scanned in a first angular range in a vertical direction;

A horizontal scanning micromirror array for deflecting and vibrating along a second rotation axis in a second driving mode so that the laser beam scans in a second angle range in a horizontal direction;

a mirror disposed in an optical path between the vertical scanning micromirror and the horizontal scanning micromirror array; the reflecting mirror is provided with a reflecting mirror light transmission area which exactly allows the laser beam in the first angle range to pass through;

a cylindrical mirror is formed on the light transmission area of the reflecting mirror, and the cylindrical mirror and the reflecting mirror form a whole;

and depositing an antireflection film on the outer surface of the cylindrical mirror, and depositing a metal reflecting layer in the cylindrical mirror except for the cylindrical area.

2. The lidar system of claim 1, wherein the area of the light-transmissive region of the mirror is substantially smaller than the total area of the mirror.

3. The lidar system according to claim 1, wherein the vertical scanning micro-mirror and/or the horizontal scanning micro-mirror array are internally encapsulated with a high-pressure gas-tight package or an insulating liquid injection package.

4. The lidar system according to claim 1, wherein capacitive or piezoelectric feedback position sensors are integrated in the vertical scanning micro-mirror and/or the horizontal scanning micro-mirror array.

5. The lidar system of claim 1, wherein the horizontally scanning micro-mirror array is a multi-column structure comprising:

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

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

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

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

6. A micro-mirror array based lidar system, the lidar system comprising:

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

A horizontal scanning micromirror array for deflecting and vibrating along a second rotation axis in a second driving mode so that the laser beam scans in a second angle range in a horizontal direction; the horizontal scanning micro mirror array comprises a column structure, and at least two columns in the column structure are arranged in a staggered manner;

7. The lidar system of claim 6, wherein the vertical scanning micromirror consists of at least two micromirrors vibrating at the same frequency, in phase, and with the same amplitude corresponding to the at least two lasers that are staggered in time domain.

8. The lidar system according to claim 6 or 7, wherein the mirror comprises a mirror light-transmitting region;

Or the reflecting mirror comprises a light transmission area corresponding to the at least two lasers which are turned on in a staggered mode in the time domain.

9. A micro-mirror array based lidar system, the lidar system comprising:

A laser light source for emitting a laser beam comprising at least two lasers; a vertical scanning micromirror for deflecting vibration along a first rotation axis in a first driving mode so that the laser beam is scanned in a first angular range in a vertical direction;

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

Or alternatively

The two lasers are simultaneously started in the time domain and have an angle difference, so that the fields of view formed by the laser beams emitted by different lasers are spliced; and receiving the reflected echo using a separate light detector;

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

a laser light source for emitting a laser beam;

the horizontal scanning micro mirror array is of a multi-column structure and comprises:

The beam emergent micro-mirror array and the echo light field receiving micro-mirror array enable the laser beam emitted by the laser light source to be parallel and dislocated with the optical axis of the received echo light beam;