KR20220039631A - Laser Optical System for LiDAR - Google Patents

Abstract

The present invention relates to a LIDAR optical system. The present invention is to separate driving of a high-speed axis and low-speed axis by using two horizontal scanners or vertical scanners and to improve a detection function by using a biaxial optical system including a big mirror in a horizontal direction. In addition, the present invention can improve valid resolution through phase control of two directional scanners when there is an interested measurement location.

Description

Laser Optical System for LiDAR

The present invention relates to a laser optical system for LiDAR including a scanner for LiDAR (Light Detection & Ranging), which is a three-dimensional recognition sensor.

LiDAR (Laser Detection And Ranging) is a core sensor for autonomous driving, etc., and can measure three-dimensionally. The main performance includes resolution, measurement range, measurement distance, frame rate, etc. In addition, size and price are also very important. As a measurement principle, the Time of Flight (ToF) method including a signal processing unit that converts the time it takes for the laser pulse reflected from the target to return to the detector into a distance is the most used (Fig. One).

To obtain a three-dimensional lidar image, a two-dimensional scan of the target with a laser is required (Method A). 1 shows a two-dimensional scanning method using a high-speed scanner in a vertical direction and a low-speed rotating motor in a horizontal direction. This method can measure 360 degrees in the horizontal direction, but since it uses a motor manufactured by an assembly process of parts, it is weak to shock, and it is difficult to reduce the price in mass production (see Non-Patent Document 1).

As another two-dimensional scanning method, as shown in FIG. 2 , a scanner may be used for the horizontal axis and a one-dimensional laser array and a two-dimensional detector array may be used for the vertical direction (Method B) (see Non-Patent Document 2).

On the other hand, in the optical configuration of LIDAR, there is a coaxial or co-axial scheme in which the optical axes of transmission and reception coincide, and a bi-axial scheme in which the optical axis is not identical. In general, the optical configuration and the scanning scheme can be independently selected can

Although the optical configuration of the coaxial method is simple, it has a characteristic that it is difficult to design an optical system with good performance. For example, in the case of making a small mirror in order to increase the driving speed in the vertical direction in a coaxial optical system including a fast-axis vertical scanner and a slow-axis horizontal scanner there is However, since the diameter of the laser beam in transmission is generally small, there is no problem even if the diameter of the scanner mirror and lens is small. However, there is a problem in that the received light cannot be sufficiently received in the optical system in which transmission and reception are shared in such a coaxial manner. In the final stage of the coaxial method, the received light must be separated and sent to the detector. For this purpose, a Polarizing Beam Splitter (PBS) is often used between the laser light source and the scanner. However, the use of expensive PBS causes an increase in cost, and the alignment process of the optical axis is also very difficult.

In addition, in the biaxial method of FIG. 2 , since the transmission optical system does not share reception, the sensitivity can be improved by increasing the aperture of the reception optical system. However, there is a disadvantage that the system becomes complicated because several lasers and detectors are needed to increase the resolution in the vertical direction.

3 uses a method in which two mirror surfaces 51 and 52 are rotated in the same direction for 360 degree measurement (Method C1). Here, when multiple lasers are used, images can be acquired even in the vertical direction, but the structure is complicated because the detector must be located inside the rotation motor (refer to Patent Document 1).

Fig. 4 is a modified embodiment of Fig. 3, in which a uniaxial scanner is used in the vertical direction instead of multiple lasers, and a polygon mirror is used for the horizontal scan (Method C2). Although this method cannot measure the entire 360 degree range in the horizontal direction, it is possible to obtain a 3D image at an improved image speed by rotating only the polygon mirror. Here, since the distance to the target (up to 150 m) is much larger than the distance (~cm) between the two scanners, it can be assumed that the transmit and receive light paths to and from the target are practically almost parallel except when the target is close ( See Patent Document 2).

Here, when the surface of a polygon mirror used for transmission and reception has a 90 degree angle difference, the received light can be transmitted to the detector opposite to the laser regardless of the horizontal position of the transmitted laser beam. It should be noted here that, when the distance is long, the received light is incident perpendicular to the detector surface regardless of the rotation angle of the two mirror surfaces, so that efficient detection is possible. There is a disadvantage in that it cannot enter into the optical system or it is deflected to one side (off-set) depending on the design of the optical system.

On the other hand, since this method uses a bi-axial optical system, a large receiving lens can be used, and thus the sensitivity can be increased as the amount of received light increases. In addition, in the vertical direction, the signal-to-noise ratio can be improved by increasing the selectivity by using a one-dimensional detector array. However, since a rotation motor similar to the rotor of FIG. 1 is used, it is weak to shock, and it is difficult to reduce the price in mass production.

To solve this problem, a micro-scanner using semiconductor-based silicon (Si) MEMS (MicroElectroMechanical System) technology can be used for vertical scanning. In this case, the rotational speed of the actuator including the mirror is very small, so can increase 5 is a lidar optical system using two independent two-axis MEMS scanners, in which the two scanners arranged symmetrically are synchronized and driven (Method D). Although it is abstractly described as “predetermined synchronization” in the specification and claims of the patent, it can be seen that the received light is normally transmitted to the detector only when driven in the same phase (see Patent Document 3) ).

6 shows two 2-axis MEMS scanners arranged on the same plane, and similarly to FIG. 5, the scanners are driven in a synchronized state. When the MEMS scanner for lidar used in FIGS. 5 and 6 is operated in a quasi-static mode, the driving angle is small and the driving speed is often low. Therefore, in order to increase the driving angle and the driving frequency, it is preferable to drive in the resonance mode (see Non-Patent Document 3).

In this way, when two MEMS scanners are driven at a resonant frequency, scanners having the same resonant frequency or very close to each other must be used for efficient synchronized driving. The reason is that, when two scanners having slightly different resonant frequencies are used as shown in FIG. 7 , when driven at one resonant frequency (yellow dotted line), the other scanner has a large driving angle loss (dA). Meanwhile, in the vicinity of the resonance frequency, since the phase difference responds sensitively to the frequency, it is difficult to drive in the same phase because the phase difference occurs by df, and a separate phase control circuit is required to solve this problem.

As described so far, when a rotary motor is used for laser scanning in lidar, it has the advantage of being able to measure 360 degrees, but it is bulky, slow, and it is difficult to lower the price in mass production. is becoming

In addition, in the case of a synchronized scanner, since a high-speed vertical scanner uses a two-axis scanner placed inside a low-speed horizontal scanner, there is a problem in that it is difficult to simultaneously improve the vertical driving speed and the sensing sensitivity of the detector.

WO 2017/168500 (published on October 5, 2017) KR 10-2155425 (2020.09.11. Announcement) US 2018/0231640 Al (published on August 16, 2018)

Micromachines 2017, 8, 120; doi:10.3390/mi8040120 Elektrotechnik & Informationstechnik (2018) 135/6: 408?415. https://doi.org/10.1007/s00502-018-0635-2 Proc. of SPIE Vol. 11293 112930B-2 on 09 Sep 2020 (https://www.spiedigitallibrary.org/conference-proceedings-of-spie)

An object of the present invention is to provide a laser optical system for lidar including a MEMS scanner that is small in volume, can perform high-speed scanning, and can be mass-produced using MEMS technology.

Another object of the present invention is to provide a laser optical system for lidar that can reduce the horizontal rotational inertia mass of the MEMS scanner to improve the driving speed and to be less affected by external vibrations.

In addition, an object of the present invention is to provide a laser optical system for lidar in which the reception sensitivity and noise characteristics of a detector are improved through phase control of two scanners.

In addition, the present invention can maximize the measurement range by minimizing each dead zone of the optical scan range and the detection range.

A laser optical system for lidar according to the present invention is a laser optical system for lidar that transmits and receives laser light, comprising: a laser light source; Two transmit scanners capable of two-dimensional laser scanning; two receiving scanners for receiving laser light reflected from the target; and a detector that receives the laser beam reflected from the receiving scanner and generates an electrical signal. includes

In addition, a lens may be included in front of the laser light source and the detector of the laser optical system for lidar according to the present invention.

Also, the transmitting scanner and the receiving scanner may be rotated while having the same phase.

In addition, a spring-connected electrode may be added between the springs of the two scanners so that the phases of the transmitting scanner and the receiving scanner are linked and rotated.

In addition, a mirror linkage electrode may be added between the mirrors of the two scanners so that the phases of the transmitting scanner and the receiving scanner are linked and rotated.

In addition, a wing linkage electrode may be added between a wing formed in each mirror of the two scanners and a neighboring driving electrode so that the phases of the transmitting scanner and the receiving scanner are linked and rotated.

In addition, a spring link lever and a hinge may be added between the springs of the two scanners so that the phases of the transmitting scanner and the receiving scanner are linked and rotated.

In addition, a mirror linkage lever and a hinge may be added between the mirrors of the two scanners so that the phases of the transmitting scanner and the receiving scanner are linked and rotated.

In addition, a comb structure having a step difference may be formed on both sides of the spring-connected electrode between the springs of the transmitting scanner and the receiving scanner.

In this case, the ground electrode formed on each spring of the transmitting scanner and the receiving scanner is adjacent to the spring-connected electrode, and comb electrodes having no step difference are formed on both sides of the ground electrode, and driving adjacent to the ground electrode A step may be formed between the electrode and the ground electrode.

Alternatively, the ground electrode formed on each spring of the transmitting scanner and the receiving scanner is adjacent to the spring-connected electrode, and comb electrodes having a step difference are formed on both sides of the ground electrode, and adjacent to the ground electrode A step may also exist between the driving electrode and the ground electrode.

In addition, comb electrodes having no step difference are formed on both of the wing linkage electrodes of the transmitting scanner and the receiving scanner, and a step may be formed between the driving electrode adjacent to the wing linkage electrode and the wing linkage electrode.

In addition, a comb electrode having a step difference is formed on both of the wing linkage electrodes of the transmitting scanner and the receiving scanner, and a step may be formed between the driving electrode adjacent to the wing linkage electrode and the wing linkage electrode.

In addition, the transmitting scanner and the receiving scanner are driven in the middle of their respective resonant frequencies, and the phase difference may be compensated for by an input voltage for driving.

In addition, according to the measurement direction and distance of interest, a variable focus lens can be used in the transmission optical system.

In addition, the reception scanner may be driven by compensating for a phase difference in the time domain due to the optical transmission/reception distance with respect to the transmission scanner.

Also, the receiving scanner may be driven by compensating for a phase difference in a spatial domain due to a gaze error with respect to the transmitting scanner.

In addition, according to the measurement direction and distance of interest, it is possible to compensate for the phase difference occurring in the time domain and the spatial domain to the rotation angle of the receiving scanner.

In addition, the laser light source and the detector may be disposed to face each other, and the transmitting scanner and the receiving scanner may be driven with a 90 degree phase difference.

Also, depending on the measurement distance of interest, one can adjust the laser power in inverse proportion to the square of the distance or increase the pulse rate linearly.

The present invention configured as described above uses MEMS technology to manufacture a MEMS scanner of a laser optical system for LiDAR, so that the volume is small, high-speed scanning is possible, and mass production is possible.

In addition, by separately separating the vertical scanner and the horizontal scanner, the rotational inertia mass in the horizontal direction can be reduced to improve the driving speed and can be less affected by external vibration.

In addition, it is possible to improve the reception sensitivity and noise characteristics of the detector by configuring a biaxial optical system including a large mirror in the horizontal direction and separating the horizontal scanner into two for transmitting and one for receiving, but driving them in the same phase.

In addition, it is possible to maximize the measurement range by minimizing each dead zone of the light scan range and the detection range by configuring the rotation angle of the receiving scanner to be vertically incident when the received light enters the detector.

1 to 6 are diagrams showing the structure and operating principle of a conventional lidar scanner;
7 is a graph showing the driving characteristics of a conventional resonant scanner;
8 is a view showing a measurement range according to the characteristics of a laser and a detector;
9 to 12 are diagrams showing the structure of an optical system for lidar according to an embodiment of the present invention;
13 is a view showing another embodiment of the optical system for lidar according to the present invention;
14 is a diagram showing a structure in which two uniaxial scanners linked by electrostatic force are arranged;
15 is a diagram for explaining a driving voltage applied to the structure of FIG. 14;
16 to 17 are diagrams showing another structure in which two uniaxial scanners linked by electrostatic force are arranged;
18 and 19 are diagrams showing a structure in which two uniaxial scanners linked by a lever are arranged;
20 is a view showing the structure of a lever composed of a hinge spring;
21 is a diagram showing a structure in which two single-axis scanners are arranged in the vertical direction;
22 is a diagram showing the phase difference in the time domain occurring in two scanners;
23 is a diagram illustrating a phase difference in a spatial domain generated by two scanners;
24 is a diagram illustrating an optical system for lidar having a phase difference of 90 degrees.

Hereinafter, an embodiment of the present invention will be described in detail with reference to FIGS. 8 to 24 .

First, in FIG. 8, the reference distance L, which is the interval between the laser light source 11 and the detector 18, the optical scan range determined by the laser scan range (FoI: Field of Illumination; θ ₁ ), and the acceptance angle of the detector ( The detection range (FoV: Field of view; θ ₂ ) determined from the acceptance angle is shown. Preferably, the measurement range can be maximized by making the reference distance L equal to 0, and the optical scan range θ ₁ and the detection range θ ₂ coincide with each other. However, from the existence of the reference distance L and the difference between the optical scan range (θ ₁ ) and the detection range (θ ₂ ), there is a dead zone, a range in which target measurement is impossible, and the two ranges overlap with other areas. The area corresponds to the measurement range.

The basic structure of the lidar optical system of the present invention is shown in FIGS. 9 to 12 . 9 to 12, the laser light (red) emitted from the laser light source 11 is scanned vertically (y-direction) through the mirror of the MEMS vertical scanner 51 for transmission, and then the MEMS for transmission horizontally It is scanned in the horizontal (x-direction) while being reflected from the horizontal mirror of the scanner 52 to complete the two-dimensional scan.

The energy of the laser light reflected from the target 24 has a significantly smaller value compared to the initial value, and the received light (yellow) is first reflected by the mirror of the receiving MEMS horizontal scanner 52a, and then the receiving MEMS vertical scanner 51a ) is input to the detector through the mirror. The very close lines in the front view of FIG. 11 and the side view of FIG. 12 almost overlap in reality, but are shown slightly separated for convenience in order to show the figure in detail.

Two mirrors for vertical scanning are manufactured on a single silicon chip (Si chip) on the same plane so that additional assembly and optical alignment processes are not required. Two mirrors for horizontal scanning are also present on the same plane, and the vertical and horizontal scanners can be synchronized and driven in the same phase. In another embodiment, only one mirror for vertical scanning may be used, and in this case, synchronization in the vertical direction is not required.

Since the LIDAR optical system of the present invention separates the high-speed scanner in the vertical direction and the low-speed scanner in the horizontal direction separately, the inertia mass in the horizontal direction is reduced, so that the resonance frequency can be increased. Accordingly, the horizontal scanner can reduce the effect of disturbance and increase the image speed by increasing the driving speed.

In addition, in order to improve the reception sensitivity and noise characteristics of the detector, it is composed of a biaxial optical system using a large mirror in the horizontal direction. That is, the horizontal scanner is divided into two for transmitting and one for receiving, but driven in the same phase.

In other words, a Si MEMS scanner for speeding up, downsizing, and low-cost LiDAR is used, but two single-axis scanners with separate horizontal and vertical scans are used to improve the output signal of the detector.

11 shows the structure of the LIDAR optical system of the present invention, and consists of a laser light source 11, a detector 18, two high-speed vertical scanners (51, 51a), and two low-speed horizontal scanners (52, 52a). Consists of.

When the scanner is used in a pseudo-static mode in which frequency selection is relatively free in horizontal driving, control for driving two horizontal scanners in the same phase may be performed.

Since the laser beam reaching the vertical scanner from the light source does not move, the mirror shape and size of the vertical scanner are similar to that of the beam cross-section, but slightly larger. However, the mirror of the horizontal scanner can be made into a long oval in the vertical direction because the scan length according to the movement of the vertical mirror must be reflected. Although the mirror size of the horizontal scanner is relatively large, since the long axis of the ellipse is the center of rotation, the rotational inertia is small and the driving speed is not significantly reduced.

An optical system for transmission may be added between the laser light source 11 and the MEMS vertical scanner 51 for transmission in order to maintain a constant diameter in the transmission laser beam (collimation). Similarly, a receiving optical system can be added between the receiving MEMS vertical scanner 51a and the detector 18 so that the detector 18 can receive a large amount of light. If the receiving optical system has a convex lens characteristic, the received light that is not on the optical axis may have a shift in the distance from the detector position. In order to solve this problem, a detector having a large reception area must be used, but as described above, there is a problem in that noise increases and response speed decreases.

On the other hand, as shown in FIG. 13 , the driving angle magnifying lens 56 may be used past the horizontal scanner 52 for transmission in order to enlarge the driving angle. In addition, in order to improve light collection efficiency by increasing the amount of received light, a wide-angle lens 57 may be additionally used before the horizontal scanner 52a for reception. In this case, the reception angle of the detector 18 is linked to the optical system in front of the detector 18 It is desirable to be designed for

14, 16, and 17 show the structure of a MEMS scanner that can be driven in a state in which the phases are linked.

14 is a state in which two uniaxial MEMS scanners are arranged sideways, and a spring-connected electrode 66 is added between the driving electrodes of the two scanners. Here, the second and fourth positioned mirror electrodes are the ground electrodes 61 , and ground can be connected to this electrode, and a driving voltage can be applied to the third positioned spring-connected electrode 66 , thereby driving two scanners. When a phase difference occurs in each angle, it can be suppressed.

On the other hand, the driving angle of the mirror can be increased by applying a driving voltage to the driving electrode 62, which is the first and fifth electrodes, in a state where no voltage is applied to the spring-connected electrode 66 (see FIG. 15). In this case, as shown in the cross-sectional view of FIG. 14 , a step G (a difference in height between the two electrodes) exists in the comb electrode 63 on both sides of the connecting electrode 66, which is the third electrode, but the second and fourth There is no step difference between the comb electrodes 63 on both sides of the first electrode, and between the other neighboring driving electrodes (the first electrode and the second electrode, the second electrode and the third electrode, the third electrode and the fourth electrode, 4 It is preferable to form a step difference between the second electrode and the fifth electrode).

14, in order to lower the driving voltage of the mirror, there is a step difference between the comb electrodes 63 on both sides of the second electrode and the fourth electrode, and between the other neighboring driving electrodes (the first electrode and the second electrode) A step may be formed in the second electrode, the second electrode and the third electrode, the third electrode and the fourth electrode, and the fourth electrode and the fifth electrode).

In FIG. 16, an effect similar to that of FIG. 14 can be obtained by adding the mirror linkage electrode 67 at the position closest to the two mirrors of FIG. In this case, different voltages may be applied to the second and fourth electrodes.

17 is an embodiment that can be driven by forming wings 68 on two mirrors and forming a wing link electrode 69 of a comb structure on the wings 68 to match the comb structure of the neighboring driving electrode 62 shows an example. The step difference of the comb structure connected to the wing connection electrode 69 may be applied similarly to the case of the spring connection electrode 66 .

18 and 19 show an embodiment different from FIGS. 14, 16 and 17 as a MEMS scanner that can be driven in a state in which the phases are linked. 18 shows that the spring link lever 71 added between the two scanner springs induces the two scanners to operate in the same phase. 20 shows the detailed structure of the hinge 76 and the spring link lever 71 connected between the spring or the mirror. In general, the thickness of this structure is uniform throughout, and the part with the narrowest width is called a hinge, and greater torsional deformation occurs than other parts. Therefore, as shown in FIG. 18 , the length of the spring-linked lever 71 is long and the torsional deformation of the hinge 76 easily occurs, so that the reciprocating rotational movement of the link-linked lever is possible. This movement of the link lever induces the two mirrors to be driven in the same phase.

19 shows that a mirror link lever 72 is added between two mirrors, and a scanner is configured as another embodiment in case the two scanners need to synchronize in opposite phases. In this case, since the length of the mirror link lever 72 is short, too large deformation is required to drive in the same phase. Therefore, it can be seen that the driving freedom of the two mirrors exists only in opposite phases. In this case, it is preferable that the step direction of both comb structures connected to the third driving electrode is the same.

21 shows a structure in which two uniaxial MEMS scanners are arranged in the vertical direction, and since the driving axes of the two mirrors are the same, co-phase driving is very easy. The lidar optical system suitable for this may be arranged in the vertical direction instead of left and right, and the method described above may be similarly applied.

In addition, in order to maintain optimal image resolution according to distance, a tunable lens may be used in the transmission optical system according to the measurement direction and distance of interest.

On the other hand, when the phase of the receiving scanner completely coincides with that for transmission, the angle of incidence of the received light entering the detector is not perpendicular or a deviation occurs while passing through the receiving optical system, and thus the image may be deteriorated.

Therefore, as a way to improve the image, we propose a quasi-synchronization method in which the phase of the receiving scanner is slightly different from that of the transmitting one.

That is, as shown in FIG. 22 , when two scanners are operated in a synchronized state, based on the rotation angle (solid red line) when transmitting the laser beam, the laser beam reciprocates to and from the target. The rotation angle (yellow dotted line) when receiving the beam is different. The phase difference Φt in the time domain is expressed by the following equation, and for this reason, a received light deviation that does not allow the received light (yellow dotted line) to enter the detector 18 occurs or a good signal cannot be obtained.

Length of light path L = z _p + (z _p +b)

time delay t _d = L / c (c: speed of light)

Time domain phase difference Φ _t = 360° t _d / f (f: scanner driving frequency)

Also, as shown in FIG. 23, as the target is closer and further away in the lateral direction of the on-axis, the line-of-sight error as shown in the following equation increases, resulting in a phase difference in the spatial domain. As a result, the received light deviation occurs.

Spatial phase difference Φ _s = α - β

Φ _s = tan-1 (x _p /z _p ) -tan-1 {(x _p -a)/(z _p +b)}

Due to the phase difference in the temporal and spatial domains, effective resolution may be lowered, and a detector having a large area may be used to improve this, but this method has a disadvantage in that noise increases and reaction speed becomes slow.

As a method to solve this problem, a detector with a small area is used, but in order to accurately receive the signal reflected from the target, the phase difference occurring in the time domain and the spatial domain can be reduced by compensating the rotation angle b(t) of the receiving scanner as shown in the following equation. there is.

transmission rotation angle α(t) = A sin (2πf t) (A: 1/2 of the driving angle)

x _p (t) = z _p tan {α(t)}

Sum of phase difference Φ _ts (t) = Φ _t + Φ _s (t)

Receive rotation angle β(t) = A sin {2πf t - Φ _ts (t)}

Since this method can be applied when the location and distance of the target are known, it can be applied accordingly when the ROI in the 3D space is changed as needed.

24, when it is necessary to arrange the laser light source 11 and the detector 18 to face each other from both sides, the two mirrors can be driven with a phase difference of 90 degrees, and the content of the invention related to the phase described so far can also be applied here.

In addition, the contents of the present invention described so far can be applied to both vertical and horizontal scanners, and can also be applied to a non-mirror lens scanner or a laser light source of a phased array concept.

On the other hand, the amount of light reflected back from a nearby target is relatively large, which may saturate the detector. Therefore, when the measurement range of interest is determined, the measurement range for a close distance can be expanded by adjusting the laser power in inverse proportion to the square of the distance, and the image speed can be improved by increasing the pulse rate.

The above description is merely illustrative of the technical spirit of the present invention, and various modifications, changes and substitutions will be possible without departing from the essential characteristics of the present invention by those skilled in the art to which the present invention pertains. . Accordingly, the present embodiment is intended to explain, not to limit the technical spirit of the present invention, and the scope of the technical spirit of the present invention is not limited by these embodiments. The protection scope of the present invention should be construed by the following claims, and all technical ideas within the scope equivalent thereto should be construed as being included in the scope of the present invention.

11: laser light source
18: detector
24: target
L: standard length
θ ₁ : optical scan range
θ ₂ : detection range
51, 51a: MEMS vertical scanner
52, 52a: MEMS horizontal scanner
56: magnifying lens
57: wide angle lens
60: horizontal mirror
61: ground electrode
62: driving electrode
63: comb electrode
64: scanner spring
66: spring-connected electrode
67: mirror connection electrode
68: wing
69: wing linkage electrode
O: center rotation
G: step
r: turning radius
71: spring link lever
72: mirror linkage lever
76: hinge
78: hinge fixture
80: region of interest
81: send scanner when sending
82: send scanner when receiving
83: Receive scanner when sending
84: receive scanner when receiving
a: x-axis reference distance
b: z-axis reference distance
x _p : the x-axis position of the target
z _p : the z-axis position of the target
89: time phase difference
92: spatial phase difference
94: received light deviation

Claims (20)

In the laser optical system for lidar that transmits and receives laser light,
laser light source;
Two transmit scanners capable of two-dimensional laser scanning;
two receiving scanners for receiving laser light reflected from the target; and
a detector that receives the laser beam reflected from the receiving scanner and generates an electrical signal;
Laser optical system for lidar, characterized in that it comprises a. According to claim 1,
A laser optical system for lidar, characterized in that a lens is included in front of the laser light source and the detector. The method of claim 1,
The laser optical system for lidar, characterized in that the transmitting scanner and the receiving scanner are rotated while having the same phase. 4. The method of claim 3,
A laser optical system for lidar, characterized in that a spring-connected electrode is shared between the springs of the two scanners so that the phases of the transmitting scanner and the receiving scanner are linked and rotated. 4. The method of claim 3,
A laser optical system for lidar, characterized in that a mirror linkage electrode is added between the mirrors of the two scanners so that the phases of the transmitting scanner and the receiving scanner are linked and rotated. 4. The method of claim 3,
A laser optical system for lidar, characterized in that a wing linkage electrode is shared between a wing formed in each mirror of the two scanners and a neighboring driving electrode so that the phases of the transmitting scanner and the receiving scanner are linked and rotated. 4. The method of claim 3,
A laser optical system for lidar, characterized in that a spring-linked lever and a hinge are shared between the springs of the two scanners so that the phases of the transmitting scanner and the receiving scanner are linked and rotated. 4. The method of claim 3,
A laser optical system for lidar, characterized in that a mirror linkage lever and a hinge are shared between the mirrors of the two scanners so that the phases of the transmitting scanner and the receiving scanner are linked and rotated. 5. The method of claim 4,
Laser optical system for lidar, characterized in that a comb structure having a step difference is formed on both sides of the spring-connected electrode between the springs of the transmitting scanner and the receiving scanner. 10. The method of claim 9,
A ground electrode formed on each spring of the transmitting scanner and the receiving scanner is adjacent to the spring-connected electrode, and comb electrodes having no step difference are formed on both sides of the ground electrode, and the driving electrode adjacent to the ground electrode and the A laser optical system for lidar, characterized in that a step is formed between the ground electrodes. 10. The method of claim 9,
A ground electrode formed on each spring of the transmitting scanner and the receiving scanner is adjacent to the spring-connected electrode, and a comb electrode having a step difference is formed on both sides of the ground electrode, and a driving electrode adjacent to the ground electrode and A laser optical system for lidar, characterized in that there is also a step difference between the ground electrodes. 7. The method of claim 6,
A comb electrode having no step difference is formed on both of the wing linkage electrodes of the transmitting scanner and the receiving scanner, and a step is formed between the driving electrode adjacent to the wing linkage electrode and the wing linkage electrode. laser optics. 7. The method of claim 6,
A comb electrode having a step difference is formed on both of the wing linkage electrodes of the transmitting scanner and the receiving scanner, and a step is formed between the driving electrode adjacent to the wing linkage electrode and the wing linkage electrode. laser optics. According to claim 1,
A laser optical system for lidar, characterized in that the transmitting scanner and the receiving scanner are driven in the middle of their respective resonance frequencies, and the phase difference is compensated for by the input voltage for driving. 6. The method according to claim 4 or 5,
A laser optical system for lidar, characterized in that a variable focus lens is used in the transmission optical system according to the measurement direction and distance of interest. According to claim 1,
The laser optical system for LiDAR, characterized in that the receiving scanner is driven by compensating for a phase difference in the time domain due to the optical transmission/reception distance with respect to the transmitting scanner. According to claim 1,
The laser optical system for lidar, characterized in that the receiving scanner is driven by compensating for a phase difference in a spatial region due to a gaze error with respect to the transmitting scanner. According to claim 1,
A laser optical system for lidar, characterized in that it compensates for the phase difference occurring in the temporal and spatial domains to the rotation angle of the receiving scanner according to the measurement direction and distance of interest. According to claim 1,
A laser optical system for lidar, characterized in that the laser light source and the detector are arranged to face each other, and the transmitting scanner and the receiving scanner are driven with a phase difference of 90 degrees. According to claim 1,
A laser optical system for lidar, characterized in that, according to the measurement distance of interest, the laser power is adjusted in inverse proportion to the square of the distance or the pulse rate is increased linearly.

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