Patent Description:
Automated guided vehicles (AGVs) used for transporting and returning goods in factories or warehouses generally travel along defined routes. However, in order to increase the work flexibility, there is an increasing need for autonomous driving based on path planning in the absence of a defined route, through simultaneous localization and mapping (SLAM). Also, technologies for avoiding obstacles using two-dimensional (2D) light detection and ranging (LiDAR) sensors have been needed. In addition, in recent years, attempts have been made to increase the work flexibility by mounting three-dimensional (3D) LiDAR sensors on various autonomous moving robots (AMRs) or forklifts in factories. Also, the demand for 3D LiDAR technology, which may be applied indoors and outdoors for transporting materials from warehouses outside the building, is increasing. The 3D LiDAR technology is advantageous not only in detecting obstacles for a wide horizontal viewing angle (about <NUM> degrees to about <NUM> degrees) and a vertical viewing angle (about <NUM> degrees to about <NUM> degrees), but also in detecting a specific viewing angle in detail in order to accurately measure a 3D state of a floor.

Document <CIT> discloses an optical scanning type object detection device comprising a mirror unit which rotates around a rotation axis and a plurality of light emitting/receiving units.

Document <CIT> discloses a scanning optical system including a mirror unit having a first mirror surface and a second mirror surface which incline to a rotation axis.

Example embodiments address at least the above problems and/or disadvantages and other disadvantages not described above. Also, the example embodiments are not required to overcome the disadvantages described above, and may not overcome any of the problems described above.

According to an aspect of an embodiment, there is provided a light detection and ranging (LiDAR) apparatus according to claim <NUM>.

By way of example, embodiments may provide a wide-viewing angle LiDAR using Pyramidal Mirror.

Embodiments may be mounted on an autonomous driving robot of automated guided vehicles (AGV), and autonomous moving robots (AMR) for factory automation.

Also, embodiments may provide a LiDAR device that obtains three dimensional (3D) distance images from autonomous vehicles.

Thus, embodiments may be used as a stationary sensor for security inside or outside a factory, or can be used in a device for obtaining a 3D distance image of an object passing by at a designated location on the side of an automobile road.

In particular, the proposed concept(s) may provide a 3D LiDAR sensor capable of securing wide viewing angles (e.g.<NUM> degrees or more in the horizontal direction, and <NUM> degrees or more in the vertical direction) required for the autonomous driving robot and providing multiple channels in the vertical direction.

According to an embodiment, there is provided a 3D LiDAR capable of improving resolution and high-speed measurement in a wide viewing angle LiDAR (horizontal: <NUM>° or more, vertical <NUM>° or more), and having a structure and means of a light transmitting unit characterized in that:.

There may be provided a means for securing a horizontal viewing angle (<NUM> degrees) by arranging the LD light horizontally in a <NUM>-degree angle section that is half of the <NUM>-degree M-polygon face.

There may be provided a means for precisely adjusting a tilt angle through multiple prisms, or a means for generating a tilt angle by controlling the angle of a single-axis MEMS mirror in order to implement the tilt angle in multiple LD output beams.

Some embodiments may have a structure in which a radial position of a reflective surface is varied according to the tilt angle of the C-polygon mirror in order to change the beam emitting from the C-polygon onto the M-polygon face according to the tilt angle to a converging beam that forms a focus.

Some embodiments may include a control means configured to drive the C-polygon stepwisely or the M-polygon continuously.

Embodiments may further comprise a coaxial optical system that simultaneously transmits and receives light beam through a same M-polygon face, and means for arranging Mode <NUM> and Mode <NUM> light sources according to the <NUM> degree rotation angle of the M-polygon.

Embodiment may comprise a means for controlling the driving of C-polygon stepwisely or continuously for one rotation of the M-polygon in driving modes divided into Mode1 and Mode2.

Some embodiments may comprise a means for transmitting light beam by dividing a horizontal rotation angle into <NUM>° intervals to minimize distortion of a vertical position of the light beam according to the LD tilt angle.

Embodiments may comprise a method of forming multiple vertical channels given by a combination of sizes of multiple LD tilt angles, C-polygon tilt angle, and M-polygon facets tilt angle.

According to another embodiment, there may be provided an optical structure of the light-receiving unit that forms images using a single 2D sensor for a wide horizontal angle of view. Such an embodiment may have a mirror shape in which an area of a light-receiving unit is separated from an area of a light-transmitting area in a M-polygon mirror, and a light-receiving area (EPD) of <NUM> or more in diameter is secured for <NUM> rotations.

Some embodiments may comprise a means for forming a coaxial optical system for each horizontal direction through a curved mirror and imaging the light beam, which is received in the light receiving area (EPD) in each direction, on a single 2D sensor.

Embodiments may comprise a means for improving the imaging resolution by adding a secondary concave mirror, a light receiving lens, etc. to displace the focus of a spherical mirror.

Some embodiments may comprise a means for arranging a point sensor or 1D Sensor in <NUM> directions to detect a position of an imaging spot according to a LD tilt angle, a position offset between the light-transmitting unit and the light-receiving unit.

Some embodiments may have a means for predicting a light-receiving position by 1D sensor in each direction according to the LD tilt angle to remove external noisy light.

The first rotatable mirror array and the second rotatable mirror array may be arranged to rotate about a same axis.

A number of the first plurality of inclined mirrors of the first rotatable mirror array may be a multiple of a number of the second plurality of inclined mirrors of the second rotatable mirror array.

The second plurality of inclined mirrors of the second rotatable mirror array may have different inclination angles.

At least a portion of the first plurality of inclined mirrors of the first rotatable mirror array may have different inclination angles.

At least two inclined mirrors of the first plurality of inclined mirrors of the first rotatable mirror array may have a same inclination angle.

The at least two inclined mirrors may having the same inclination angle to face each other, from among the first plurality of inclined mirrors of the first rotatable mirror array.

A number of scanning channels of the LiDAR apparatus in an elevation angle direction may be equal to a product of a number of inclination angles of the first plurality of inclined mirrors of the first rotatable mirror array and a number of inclination angles of the second plurality of inclined mirrors of the second rotatable mirror array.

An angle between two adjacent light sources from among the plurality of light sources may be half of an angle between two adjacent inclined mirrors from among the second plurality of inclined mirrors of the second rotatable mirror array, wherein the angle between two adjacent inclined mirrors is defined as an angle between a first line perpendicular to an inclined surface of a first inclined mirror and a second line, which intersects the first line, perpendicular to an inclined surface of a second inclined mirror adjacent the first include mirror.

The second plurality of inclined mirrors of the second rotatable mirror array may include a first inclined mirror having a first inclination angle, a second inclined mirror having a second inclination angle, a third inclination mirror having a third inclination angle, and a fourth inclined mirror having a fourth inclination angle, and the first, second, third, and fourth inclination angles may be different from each other.

The plurality of light sources may include a first light source, a second light source, a third light source, a fourth light source, and a fifth light source that are sequentially arranged at intervals of <NUM> degrees within an angle range of <NUM> degrees in the circumferential direction.

While the second rotatable mirror array is rotating, in a first mode in which the first light source, the third light source, and the fifth light source face any one of the first to fourth inclined mirrors of the second mirror array, the first light source, the third light source, and the fifth light source may sequentially emit the light, and in a second mode in which the second light source and the fourth light source face any one of the first to fourth inclined mirrors of the second rotatable mirror array, the second light source and the fourth light source may sequentially emit the light.

The first plurality of inclined mirrors of the first rotatable mirror array include a fifth inclined mirror having a fifth inclination angle, a sixth inclined mirror having a sixth inclination angle, a seventh inclined mirror having a seventh inclination angle, an eighth inclined mirror having a eighth inclination angle, a ninth inclined mirror having the fifth inclination angle, a tenth inclined mirror having the sixth inclination angle, an eleventh inclined mirror having the seventh inclination angle, and a twelfth inclined mirror having the eighth inclination angle, and the fifth, sixth, seventh, and eighth inclination angles are different from each other.

The second rotatable mirror array may be configured to continuously rotate, and the first rotatable mirror array is configured to rotate in a stepwise manner by <NUM> degrees.

While the first rotatable mirror array is stopped, the second rotatable mirror array may rotate by <NUM> degrees, and while the first rotatable mirror array rotates by one step, the second rotatable mirror array may rotate by <NUM> degrees.

The LiDAR apparatus may further include: a plurality of intermediate mirrors provided in the plurality of sections to reflect the light emitted from the plurality of light sources to the first rotatable mirror array.

Multiple light sources of the plurality of light sources may be arranged in a radial direction within each section of the plurality of sections.

The light sources arranged in the radial direction within each section may be tilted at different angles.

The LiDAR apparatus having multiple light sources of the plurality of light sources are arranged in a radial direction within each section of the plurality of sections may further include: a plurality of wedge prisms, each of the plurality of wedge prisms being configured to change a light traveling direction of the light, which is emitted from the multiple light sources arranged in the radial direction within each section, to be incident on a corresponding intermediate mirror at different angles.

A number of scanning channels of the LiDAR apparatus in an elevation angle direction may be equal to a product of a number of the multiple light sources arranged in the radial direction within each section of the plurality of sections, the number of inclination angles of the first plurality of inclined mirrors of the first rotatable mirror array, and the number of inclination angles of the second plurality of inclined mirrors of the second rotatable mirror array.

Each of the plurality of intermediate mirrors may include a reflective surface of which an inclination angle is adjusted by electrical control.

The first plurality of inclined mirrors of the first rotatable mirror array may have different radial positions of reflective surfaces such that the light emitted from a same light source, among the plurality of light sources, and the light reflected by the first plurality of inclined mirrors of the first rotatable mirror array may be incident at a same position on the second rotatable mirror array.

The first plurality of inclined mirrors of the first rotatable mirror array may be a plurality of right angle optical prisms having an inclined surface, and the plurality of right angle optical prisms may have a same height and different base lengths.

A viewing angle in an azimuth direction may be about <NUM> degrees to about <NUM> degrees, and a viewing angle in an elevation angle direction may be about <NUM> degrees to about <NUM> degrees.

The LiDAR apparatus may further include: a concave mirror reflecting the light reflected by the second rotatable mirror array after being incident onto the second rotatable mirror array from the outside of the LiDAR apparatus and converging the light on a focal point.

The photodetector may be on the focal point of the concave mirror.

The LiDAR apparatus may further include: a flat mirror that extends an optical path between the concave mirror and the photodetector by reflecting the light reflected by the concave mirror toward the photodetector; a band pass filter provided between the flat mirror and the photodetector, the band pass filter being configured to transmit only the light in an emission wavelength band of the plurality of light sources; and a lens that focuses the light on the photodetector.

The LiDAR apparatus may further include a plurality of photodetectors comprising the photodetector, the plurality of photodetectors being arranged in the circumferential direction.

A number of the plurality of photodetectors may be equal to a number of the plurality of light sources.

The LiDAR apparatus may further include: a mask provided on a light-receiving surface of the photodetector and having a plurality of openings corresponding to the plurality of photodetectors.

Each of the plurality of photodetectors may be a one-dimensional sensor array extending in a radial direction.

Hereinafter, a light detection and ranging (LiDAR) apparatus having a wide-viewing angle will be described in detail with reference to the accompanying drawings.

For example, when an element is referred to as being "on" or "above" another element, it may be directly on the other element, or intervening elements may also be present. In addition, it will be understood that when a unit is referred to as "comprising" another element, it may not exclude the other element but may further include the other element unless specifically oppositely indicates.

The use of the terms "a," "an," and "the" and similar referents is to be construed to cover both the singular and the plural. Unless explicitly stated or contradicted to the order of operations constituting the method, these operations may be performed in an appropriate order and are not necessarily limited to the order described.

In addition, terms such as ". module", or the like refer to units that perform at least one function or operation, and the units may be implemented as hardware or software or as a combination of hardware and software.

The connecting lines, or connectors shown in the various figures presented are intended to represent exemplary functional relationships and/or physical or logical couplings between the various elements. It should be noted that many alternative or additional functional relationships, physical connections or logical connections may be present in a practical device.

The use of any and all examples, or exemplary language (e.g., "such as") provided herein, is intended merely to better illuminate the inventive concept and does not pose a limitation on the scope of the inventive concept unless otherwise claimed.

<FIG> is a view of a light detection and ranging (LiDAR) apparatus <NUM> according to an example embodiment. Referring to <FIG>, the LiDAR apparatus <NUM> includes a first mirror array <NUM> and a second mirror array <NUM> arranged to face each other in a vertical direction of the LiDAR apparatus <NUM>, a plurality of light sources LD1 and LD5 emitting light toward the first mirror array <NUM>, and a light-receiving unit that includes elements <NUM>, <NUM> and <NUM> to detect light coming from outside by being reflected by an external object.

The first mirror array <NUM> may have a shape of a polygonal frustum (e.g., a square frustum, a pentagon frustum, a hexagon frustum, an octagon frustum, etc.) or a truncated pyramid (e.g., a truncated square pyramid, a truncated pentagon pyramid, a truncated hexagon pyramid, a truncated octagon pyramid, etc.). The first mirror array <NUM> includes a plurality of inclined mirrors arranged in a circumferential direction of a horizontal plane that is perpendicular to the vertical direction of the LiDAR apparatus <NUM>. For example, the first mirror array <NUM> may be a polygon mirror when viewed from the top of the first mirror array <NUM>, and the base of the first mirror array <NUM> may has a polygon shape. The first mirror array <NUM> is rotatable about a rotation axis. To this end, the LiDAR apparatus <NUM> may further include a first motor <NUM> that rotates the first mirror array <NUM>.

The second mirror array <NUM> is arranged to face the first mirror array <NUM> to reflect light reflected by the first mirror array <NUM> to the outside of the LiDAR apparatus <NUM>. Like the first mirror array <NUM>, the second mirror array <NUM> also includes a plurality of inclined mirrors arranged in the circumferential direction. For example, the second mirror array <NUM> may also be a polygon mirror. In addition, the second mirror array <NUM> is rotatable about the rotation axis. To this end, the LiDAR apparatus <NUM> may further include a second motor <NUM> that rotates the second mirror array <NUM>. The first mirror array <NUM> and the second mirror array <NUM> may be arranged to rotate about the same axis.

Although only two light sources LD1 and LD5 are shown in the cross-sectional view of <FIG>, additional light sources may be arranged at regular intervals in the circumferential direction. Each of the light sources LD1 and LD5 may be configured to emit pulsed light at regular time intervals under the control of a processor. In addition, the light sources LD1 and LD5 may be configured to emit light in an infrared band that is not visible to the human eye. For example, the light sources LD1 and LD5 may be configured to emit light having a wavelength band in a range selected from about <NUM> to about <NUM>,<NUM>. The light sources LD1 and LD5 may be, for example, pulsed laser diodes, but are not limited thereto. When an emission wavelength is controlled within a tolerance range, a light-emitting diode LED may be used as the light sources LD1 and LD5.

The LiDAR apparatus <NUM> may further include a plurality of collimating lenses C1 and C5 that make the light emitted from the light sources LD1 and LD5 into parallel beams. The LiDAR apparatus <NUM> may further include a plurality of intermediate mirrors M1 and M5 that reflect the light emitted from the light sources LD1 and LD5 to the first mirror array <NUM>. The intermediate mirrors M1 and M5 may be arranged in an optical path between the light sources LD1 and LD5 and the first mirror array <NUM>. The optical path between the light sources LD1 and LD5 and the first mirror array <NUM> may be bent by <NUM> degrees by the intermediate mirrors M1 and M5. However, the intermediate mirrors M1 and M5 are be omitted, and the light sources LD1 and LD5 may be arranged to directly face the first mirror array <NUM> without the intermediate mirrors M1 and M5.

The light emitted from the light sources LD1 and LD5 is reflected by the first mirror array <NUM> and incident on the second mirror array <NUM>. Then, the light may be scanned to the outside of the LiDAR apparatus <NUM> as transmission light by rotation of the second mirror array <NUM>. A portion of the transmitted light may be reflected by an external object and returned to the LiDAR apparatus <NUM> as received light. The received light returned from the outside to the LiDAR apparatus <NUM> may be reflected back by the second mirror array <NUM> and transmitted to the light-receiving unit.

The light-receiving unit of the LiDAR apparatus <NUM> may include a concave mirror <NUM> that reflects received light returned from the outside reflected by the second mirror array <NUM> and converges the received light onto a focal point, and a photodetector <NUM> on the focal point of the concave mirror <NUM>. The received light reflected by the second mirror array <NUM> is directly incident on the concave mirror <NUM> without passing through the first mirror array <NUM>. To this end, the diameter of the second mirror array <NUM> may be greater than the diameter of the first mirror array <NUM>, and the diameter of the concave mirror <NUM> may be similar to or greater than the diameter of the second mirror array <NUM>. In addition, a reflective surface of the concave mirror <NUM> may be arranged facing the second mirror array <NUM>, and the first mirror array <NUM> may be between the concave mirror <NUM> and the second mirror array <NUM>. By using the concave mirror <NUM>, received light incident on the second mirror array <NUM> from various external directions may be transmitted to one photodetector <NUM>.

The LiDAR apparatus <NUM> may further include a flat mirror <NUM> that folds an optical path of the received light reflected by the concave mirror <NUM> by about <NUM> degrees. When a focal length of the concave mirror <NUM> is long, the flat mirror <NUM> may reduce the volume of the LiDAR apparatus <NUM> by folding the optical path of the received light by about <NUM> degrees. To this end, the flat mirror <NUM> may be arranged in a position that extends an optical path between the concave mirror <NUM> and the photodetector <NUM> by reflecting light reflected by the concave mirror <NUM> toward the photodetector <NUM>. In more detail, the flat mirror <NUM> may be between the concave mirror <NUM> and the first mirror array <NUM>, and in particular, may be on an upper surface of the first mirror array <NUM>. The diameter of the flat mirror <NUM> is less than the diameter of the concave mirror <NUM>. The received light sequentially reflected by the second mirror array <NUM> and the concave mirror <NUM> may be reflected by the flat mirror <NUM> and then focused on the photodetector <NUM>.

<FIG> shows only the photodetector <NUM> between the focal point of the concave mirror <NUM> and the flat mirror <NUM> for convenience, but the LiDAR apparatus <NUM> may further include an additional component other than the photodetector <NUM>. For example, <FIG> is a cross-sectional view illustrating an additional configuration of the light-receiving unit of the LiDAR apparatus <NUM> shown in <FIG>. Referring to <FIG>, the light-receiving unit of the LiDAR apparatus <NUM> may further include a band pass filter <NUM> and a lens <NUM> arranged between the flat mirror <NUM> and the photodetector <NUM>. The band pass filter <NUM> removes noise by transmitting only light in the same wavelength band as that of light emitted from light sources LD1 and LD5. The lens <NUM> further focuses light on the photodetector <NUM>. When the lens <NUM> is further arranged, the photodetector <NUM> may be on a focal point formed by the concave mirror <NUM> and the lens <NUM>.

<FIG> is a plan view of a configuration of the second mirror array <NUM> of the LiDAR apparatus <NUM> illustrated in <FIG>. Referring to <FIG>, the second mirror array <NUM> may have a truncated square pyramid shape in which a vertex is cut in a direction parallel to the base. Accordingly, the second mirror array <NUM> may have four inclined surfaces, and may include four inclined mirrors F1, F2, F3, and F4 respectively formed on the four inclined surfaces. In addition, in order to reduce the volume and weight of the second mirror array <NUM>, four corner portions of the base that are not optically used may be further cut.

<FIG> is a cross-sectional view of the first inclined mirror F1 and the third inclined mirror F3 of the second mirror array <NUM> cut in a vertical direction, and <FIG> is a cross-sectional view of the second inclined mirror F2 and the fourth inclined mirror F4 of the second mirror array <NUM> cut in a vertical direction. As illustrated in <FIG>, the four inclined mirrors F1, F2, F3, and F4 of the second mirror array <NUM> may have different inclination angles. The first inclined mirror F1 may have a first inclination angle α1, the second inclined mirror F2 may have a second inclination angle α2 different from the first inclination angle α1, the third inclined mirror F3 may have a third inclination angle α3 different from the first and second inclination angles α1 and α2, and the fourth inclined mirror F4 may have a fourth inclination angle α4 different from the first to third inclination angles α1, α2, and α3.

<FIG> shows that the second mirror array <NUM> has a truncated quadrangular pyramid shape having four inclined mirrors in the sides of the second mirror array <NUM>, but this is only exemplary, and the shape of the second mirror array <NUM> is not limited thereto. For example, the second mirror array <NUM> may have a truncated pentagonal pyramid shape having five inclined mirrors, or may have a truncated hexagonal pyramid shape having six inclined mirrors. <FIG> illustrates that a bottom base and a top base of the second mirror array <NUM> have an octagon shape and a square shape, respectively, but different shapes may be used for the bottom base and the top base of the second mirror array <NUM>.

<FIG> is a plan view of a configuration of the first mirror array <NUM> according to an example embodiment. Referring to <FIG>, the first mirror array <NUM> may have a truncated polygonal pyramid shape in which a vertex is cut in a direction parallel to the base. In particular, the number of sides of the first mirror array <NUM> may be a multiple of the number of sides of the second mirror array <NUM>. For example, when the second mirror array <NUM> is a truncated square pyramid, the first mirror array <NUM> may have a truncated octagonal pyramid shape or a truncated dodecagonal pyramid shape. <FIG> illustrates an example in which the first mirror array <NUM> has a truncated octagonal pyramid shape. In this case, the first mirror array <NUM> may have <NUM> inclined surfaces, and may include <NUM> inclined mirrors A1, A2, A3, and A4 respectively formed on the <NUM> inclined surfaces. Accordingly, the number of the inclined mirrors A1, A2, A3, and A4 of the first mirror array <NUM> is a multiple of the number of the inclined mirrors F1, F2, F3, and F4 of the second mirror array <NUM>.

In addition, the inclined mirrors A1, A2, A3, and A4 of the first mirror array <NUM> may have different inclination angles. For example, the first mirror array <NUM> may include two first inclined mirrors A1 having a fifth inclination angle, two second inclined mirrors A2 having a sixth inclination angle different from the fifth inclination angle, two third inclined mirrors A3 having a seventh inclination angle different from the fifth and sixth inclination angles, and two fourth inclined mirrors A4 having a eighth inclination angle different from the fifth to seventh inclination angles. Accordingly, the first mirror array <NUM> may include at least two inclined mirrors having the same inclination angle. When the first mirror array <NUM> has a truncated octagonal pyramid shape, among the plurality of inclined mirrors A1, A2, A3, and A4 of the first mirror array <NUM>, two inclined mirrors having the same inclination angle may be arranged to face each other.

<FIG> is a plan view of a configuration of the first mirror array <NUM> according to another example embodiment. Referring to <FIG>, the first mirror array <NUM> may have a truncated dodecagonal pyramid shape. In this case, the first mirror array <NUM> may have <NUM> inclined surfaces, and may include <NUM> inclined mirrors A1, A2, and A3 respectively formed on the <NUM> inclined surfaces. The inclined mirrors A1, A2, and A3 of the first mirror array <NUM> may have different inclination angles. For example, the first mirror array <NUM> may include four first inclined mirrors A1 having a fifth inclination angle, four second inclined mirrors A2 having a sixth inclination angle different from the fifth inclination angle, and four third inclined mirrors A3 having a seventh inclination angle different from the fifth and sixth inclination angles.

<FIG> are only some examples of various first mirror arrays <NUM>, and the first mirror array <NUM> may be configured differently from <FIG>. For example, when the first mirror array <NUM> has a truncated dodecagonal pyramid shape, the first mirror array <NUM> may include four types of inclined mirrors having different inclination angles, and three inclined mirrors having the same inclination angle may be arranged in each of them. Alternatively, when the first mirror array <NUM> has a truncated dodecagonal pyramid shape, the first mirror array <NUM> may include six types of inclined mirrors having different inclination angles, and two inclined mirrors having the same inclination angle may be arranged in each of them. In addition, when the second mirror array <NUM> has a pentagonal shape, the first mirror array <NUM> may have a truncated decagonal pyramid shape.

Each of the circles indicated in <FIG> exemplarily shows a beam diameter of transmission light incident on the first mirror array <NUM>. When configuring the first mirror array <NUM>, the beam diameter of the transmission light may be considered. For example, the first mirror array <NUM> may be configured such that the width of each of the inclined mirrors of the first mirror array <NUM> is not less than the beam diameter of the transmission light at a position on the inclined mirror where the transmission light is incident.

<FIG> is a view illustrating an arrangement relationship between the second mirror array <NUM> and a plurality of light sources. Referring to <FIG>, a plurality of light sources LD1, LD2, LD3, LD4, and LD5 may be arranged in a plurality of sections in which an angle range of <NUM> degrees or more in a circumferential direction is divided in equal intervals, respectively. For example, when the second mirror array <NUM> has a truncated square pyramid shape, the five light sources LD1, LD2, LD3, LD4, and LD5 may be sequentially arranged in the circumferential direction at intervals of <NUM> degrees within an angle range of <NUM> degrees. In addition, five intermediate mirrors M1, M2, M3, M4, and M5 may be sequentially arranged at intervals of <NUM> degrees in the circumferential direction to reflect light emitted from the five light sources LD1, LD2, LD3, LD4, and LD5 to the first mirror array <NUM>. When the second mirror array <NUM> has a truncated hexagonal pyramid shape, nine light sources may be sequentially arranged in the circumferential direction at intervals of <NUM> degrees within an angle range of <NUM> degrees.

Accordingly, an angle between two adjacent light sources from among the plurality of light sources may be half of an angle between two adjacent inclined mirrors among the plurality of inclined mirrors of the second mirror array <NUM>. For example, when the second mirror array <NUM> has a truncated square pyramid shape, the angle between two adjacent inclined mirrors is <NUM> degrees and the plurality of light sources are arranged at intervals of <NUM> degrees. When the second mirror array <NUM> has a truncated hexagonal pyramid shape, the angle between two adjacent inclined mirrors is <NUM> degrees and the plurality of light sources are arranged at intervals of <NUM> degrees.

By arranging a plurality of light sources in this manner, it is possible to secure a horizontal viewing angle in a wide angle range of <NUM> degrees or more in an azimuth direction. While the second mirror array <NUM> is rotating, light emitted from each light source is not scanned over the entire viewing angle range in the azimuth direction, but is scanned only within an angle section in which each light source is arranged. For example, when five light sources are arranged at an angle of <NUM> degrees, light emitted from each light source is scanned within a range of -<NUM> to +<NUM> degrees around the light source. Further, when nine light sources are arranged at an angle of <NUM> degrees, light emitted from each light source is scanned within a range of -<NUM> to +<NUM> degrees around the light source.

However, because the number of light sources is greater than the number of inclined mirrors of the second mirror array <NUM> within a horizontal viewing angle range, light emitted from all light sources is not simultaneously scanned by the inclined mirrors of the second mirror array <NUM>. Therefore, a scanning operation in the azimuth direction may be performed by being divided into two modes. For example, <FIG> and <FIG> exemplarily show changes in a scanning mode according to rotation of the second mirror array <NUM>.

Referring to <FIG>, in a first mode, the first light source LD1, the third light source LD3, and the fifth light source LD5 face the first inclined mirror F1, the fourth inclined mirror F4, and the third inclined mirror F3 of the second mirror array <NUM> respectively, and the second light source LD2 and the fourth light source LD4 face the boundary between two adjacent inclined mirrors. In this case, the second light source LD2 and the fourth light source LD4 are in an off state, and the first light source LD1, the third light source LD3, and the fifth light source LD5 alternately and sequentially emit light. Then, the light emitted from the first light source LD1, the third light source LD3, and the fifth light source LD5 is scanned in an azimuth direction.

In an example shown in <FIG>, light L1 emitted from the first light source LD1 may be scanned by the first inclined mirror F1. In addition, light L3 emitted from the third light source LD3 may be scanned by the fourth inclined mirror F4, and light L5 emitted from the fifth light source LD5 may be scanned by the third inclined mirror F3. However, this is only an example, an inclined mirror for scanning the lights L1, L3, and L5 emitted from the first light source LD1, the third light source LD3, and the fifth light source LD5 may change as the second mirror array <NUM> rotates.

The first light source LD1, the third light source LD3, and the fifth light source LD5 alternately and repeatedly start to emit light when an angle between a mirror surface of an inclined mirror facing each of the light sources and each of the light sources reaches within -<NUM> degrees. For example, while the second mirror array <NUM> is rotating, after the first light source LD1 instantaneously emits pulsed light, the third light source LD3 instantaneously emits pulsed light, and then the fifth light source LD5 instantaneously emits pulsed light. Then, the first light source LD1 instantaneously emits pulsed light again. In the meantime, when the second mirror array <NUM> rotates and an angle between a mirror surface of an inclined mirror facing each of the light sources and each of the light sources exceeds +<NUM> degrees, the first mode is terminated. The first light source LD1, the third light source LD3, and the fifth light source LD5 are turned off. Accordingly, the light emitted from each of the first light source LD1, the third light source LD3, and the fifth light source LD5 is scanned in an azimuth direction within a section of an angle range of <NUM> degrees in which each light source is arranged.

Referring to <FIG>, in a second mode, the second light source LD2 and the fourth light source LD4 face the first inclined mirror F1 and the fourth inclined mirror F4 of the second mirror array <NUM>, and the first light source LD1, the third light source LD3, and the fifth light source LD5 face the boundary between two adjacent inclined mirrors. In this case, the first light source LD1, the third light source LD3, and the fifth light source LD5 are in an off state, and the second light source LD2 and the fourth light source LD4 alternately and sequentially emit light. The light emitted from each of the second light source LD2 and the fourth light source LD4 is scanned in an azimuth direction within a section of an angle range of <NUM> degrees in which each light source is arranged. In this way, the LiDAR apparatus <NUM> may overall have a horizontal viewing angle of <NUM> degrees.

<FIG> and <FIG> illustrate a case in which the second mirror array <NUM> has a truncated quadrangular pyramid shape, but even when the second mirror array <NUM> has a different shape, scanning in the azimuth direction may be performed using the same principle. For example, when the second mirror array <NUM> has a truncated hexagonal pyramid shape and nine light sources are arranged, five odd-numbered light sources alternately and sequentially emit light in the first mode, and in the second mode, four even-numbered light sources may alternately and sequentially emit light.

On the other hand, in <FIG> and <FIG>, dashed circles represent received lights R1, R2, R3, R4, and R5 reflected back from an external object. Light transmission and reception are performed coaxially through the same inclined mirror of the second mirror array <NUM>. For example, when the light L1 emitted from the first light source LD1 is scanned by the first inclined mirror F1, the received light R1 reflected back from an external object may be incident on the first inclined mirror F1. The position at which the lights L1, L2, L3, L4, and L5 transmitted to the outside are incident on the inclined mirror and the position at which the received lights R1, R2, R3, R4, and R5 are incident on the same inclined mirror may be different. For example, the lights L1, L2, L3, L4, and L5 transmitted to the outside may be incident on an upper portion of the inclined mirror instead of the center. This may be adjusted by the size of the first mirror array <NUM>. In this case, the received light R1, R2, R3, R4, and R5 may be incident on a lower portion of the inclined mirror.

<FIG> is a view of a transmission light and a received light incident on one inclined mirror of the second mirror array <NUM>. As described above, transmission light Tx is incident on an upper portion of the inclined mirror of the second mirror array <NUM>, and received light Rx is incident on a lower portion of the same inclined mirror. A beam diameter of the received light Rx may be greater than a beam diameter of the transmission light Tx. For example, the beam diameter of the transmission light Tx may be about <NUM>, and the received light Rx may have an entrance pupil diameter (EPD) of about <NUM> or more. An incident position of the received light Rx having a large diameter may be offset with respect to an incident position of the transmission light Tx by making the transmission light Tx incident on an almost upper edge of the inclined mirror. By offsetting the transmission light Tx and the received light Rx with respect to each other, optical interference between the transmission light Tx and the received light Rx may be minimized.

<FIG> exemplarily shows a relative positional relationship between pieces of received light caused by pieces of transmission light scanned in different directions within one angle section while the second mirror array <NUM> is rotating and an inclined mirror. According to the rotation of the second mirror array <NUM>, the transmission light may be projected in a left, center, or right direction. When transmission light Txc is projected toward the center of the inclined mirror, received light Rxc is incident on the center of the inclined mirror. When transmission light Txl is projected in the left direction of the inclined mirror when viewed from above the second mirror array <NUM>, received light Rxl may be incident on the right edge of the inclined mirror. In addition, when transmission light Txr is projected in the right direction of the inclined mirror when viewed from above the second mirror array <NUM>, received light Rxr may be incident on the left edge of the inclined mirror. Because a lower portion of the inclined mirror has a larger area than an upper portion of the inclined mirror, the received lights Rxl, Rxc, and Rxr having an increased EPD may be sufficiently incident on an area Rx' of the inclined mirror.

By rotating the second mirror array <NUM>, scanning may be performed in the azimuth direction in the above-described manner. Scanning in an elevation angle direction may be performed by a combination of the first mirror array <NUM> and the second mirror array <NUM>. Because the inclined mirrors of the first mirror array <NUM> have a plurality of different inclination angles and the inclined mirrors of the second mirror array <NUM> have a plurality of different inclination angles, light may travel in different elevation angle directions according to a combination of the inclined mirror of the first mirror array <NUM> and the inclined mirror of the second mirror array <NUM> to which light is incident. The number of scanning channels in the elevation angle direction is given by a product of the number of inclination angles of the plurality of inclined mirrors of the first mirror array <NUM> and the number of inclination angles of the plurality of inclined mirrors of the second mirror array <NUM>. For example, when the first mirror array <NUM> has four different inclination angles and the second mirror array <NUM> has four different inclination angles, <NUM> scanning channels may be formed in the elevation angle direction. The vertical viewing angle is given by (the number of scanning channels in the elevation direction-<NUM>) × (vertical angular resolution).

The first mirror array <NUM> and the second mirror array <NUM> continuously rotate at different rotation speeds such that the plurality of inclination angles of the first mirror array <NUM> and the plurality of inclination angles of the second mirror array <NUM> may be evenly combined. Alternatively, the first mirror array <NUM> is stepwise driven and the second mirror array <NUM> is continuously rotated. For example, after the second mirror array <NUM> rotates by <NUM> degrees while the first mirror array <NUM> is stopped, the first mirror array <NUM> may rotate by an angle between two adjacent inclined mirrors of the first mirror array <NUM>. In this case, the first motor <NUM> that rotates the first mirror array <NUM> may be a step motor.

<FIG> exemplarily shows a sequential step drive of the first mirror array <NUM>. <FIG> exemplarily shows that the first mirror array <NUM> has a truncated octagonal pyramid shape having eight inclined mirrors. In this case, the first mirror array <NUM> may rotate stepwise or discretely by <NUM> degrees in a clockwise direction. For example, the first mirror array <NUM> may rotate by <NUM> degrees during eight steps. Because two inclined mirrors having the same inclination angle are symmetrically arranged in the first mirror array <NUM>, when the first mirror array <NUM> rotates half a turn during four steps, scanning in the elevation angle direction of one frame may be completed. Although <FIG> illustrates that the first mirror array <NUM> rotates clockwise, it is also possible to rotate counterclockwise.

<FIG> exemplarily shows a plurality of regions of the second mirror array <NUM> continuously rotating. Referring to <FIG>, when the second mirror array <NUM> rotates clockwise, areas from ① to ⑧ face the inclined mirrors of the first mirror array <NUM> in sequence. Alternatively, when the second mirror array <NUM> rotates counterclockwise, areas from ① to ② face the inclined mirrors of the first mirror array <NUM> in sequence.

However, because the second mirror array <NUM> continues to rotate while the first mirror array <NUM> is stepped to a next position after one rotation of the second mirror array <NUM>, the position of the inclined mirror of the first mirror array <NUM> and the position of the inclined mirror of the second mirror array <NUM> may not be exactly the same. Therefore, an appropriate time delay may be applied to the step drive and stopping operations of the first mirror array <NUM> such that the second mirror array <NUM> rotates by <NUM> degrees relative to the first mirror array <NUM> while the first mirror array <NUM> performs one step drive. For example, the second mirror array <NUM> rotates by <NUM> degrees while the first mirror array <NUM> is stopped, the second mirror array <NUM> may rotate by <NUM> degrees while the first mirror array <NUM> is stepped to a next position, and the second mirror array <NUM> may rotate by <NUM> degrees while the first mirror array <NUM> is stopped again. Then, while elevation angle direction scanning of one frame is performed, the first mirror array <NUM> may rotate half a turn and the second mirror array <NUM> may rotate <NUM> rotations.

<FIG> exemplarily shows a change in relative position according to the rotation of the first mirror array <NUM> and the second mirror array <NUM>. First, areas from ① to ⑧ of the second mirror array <NUM> face the first inclined mirror A1 of the first mirror array <NUM> in sequence while the second mirror array <NUM> rotates by <NUM> degrees. Thereafter, while the first mirror array <NUM> is stepped to a next position, the second mirror array <NUM> rotates from area ① to area ②. In addition, areas ③ to ② of the second mirror array <NUM> face the second inclined mirror A2 of the first mirror array <NUM> in sequence while the second mirror array <NUM> rotates by <NUM> degrees. While the first mirror array <NUM> is stepped to a next position, the second mirror array <NUM> rotates from areas ③ to ④. Then, areas ⑤ to ④ of the second mirror array <NUM> face the third inclined mirror A3 of the first mirror array <NUM> in sequence while the second mirror array <NUM> rotates by <NUM> degrees. While the first mirror array <NUM> is stepped to a next position, the second mirror array <NUM> rotates from areas ⑤ to ⑥. Then, areas ⑦ to ⑥ of the second mirror array <NUM> face the fourth inclined mirror A4 of the first mirror array <NUM> in sequence while the second mirror array <NUM> rotates by <NUM> degrees. Finally, while the first mirror array <NUM> is stepped to a next position, the second mirror array <NUM> is rotated from areas ⑦ to ⑧ to complete one frame.

<FIG> exemplarily shows a plurality of vertical channels in an elevation angle direction formed according to a change in a relative position between the first mirror array <NUM> and the second mirror array <NUM>. In the case illustrated in <FIG>, <FIG> scanning channels may be formed in the elevation angle direction. Assuming that inclined mirrors of the first mirror array <NUM> optically have inclination angles of -<NUM> degrees, -<NUM> degrees, +<NUM> degrees, and +<NUM> degrees, and the inclined mirrors of the second mirror array <NUM> optically have inclination angles of -<NUM> degrees, -<NUM> degrees, +<NUM> degrees, and +<NUM> degrees, scanning in each elevation direction is possible at intervals of <NUM> degrees from -<NUM> degrees to +<NUM> degrees. Thus, a vertical viewing angle may be <NUM> degrees. Here, the inclination angles represent angles increased or decreased based on <NUM> degrees.

The configurations of the first mirror array <NUM> and the second mirror array <NUM> described with reference to <FIG> are illustrated for convenience of description. When the configurations of the first mirror array <NUM> and the second mirror array <NUM> are selected differently, the number of scanning channels in the elevation angle direction, the range of the vertical viewing angle, the number of rotations of the second mirror array <NUM> during one frame, etc. Further, in <FIG>, it is exemplified that inclination angles of the inclined mirrors of the second mirror array <NUM> are greater than inclination angles of the inclined mirrors of the first mirror array <NUM>, but are not limited thereto.

<FIG> exemplarily shows an example embodiment including a plurality of light sources emitting light at different inclination angles. In order to further increase the number of scanning channels in an elevation angle direction, an incident angle of light incident on the first mirror array <NUM> from a light source may be multiplexed. In other words, light may be incident on the first mirror array <NUM> at a number of different inclination angles. To this end, as shown in <FIG>, a plurality of light sources LD11, LD12, and LD13 may be arranged in a radial direction within one angle section in an azimuth direction. The plurality of light sources LD11, LD12, and LD13 arranged in the radial direction within one angle section may be tilted at different angles. Light emitted from the plurality of light sources LD11, LD12, and LD13 passes through corresponding collimating lenses C11, C12, and C13, and is incident on one intermediate mirror M1 at different angles. Then, light reflected by the intermediate mirror M1 is incident on the first mirror array <NUM> at different angles. As a result, light emitted from the plurality of light sources LD11, LD12, and LD13 may be scanned at different angles in the elevation direction by the second mirror array <NUM>.

<FIG> exemplarily shows an arrangement relationship between the second mirror array <NUM> and the plurality of light sources in the example embodiment shown in <FIG>. Referring to <FIG>, when the second mirror array <NUM> has a truncated square pyramid shape, a plurality of light sources may be arranged in the radial direction within five angle ranges arranged in the circumferential direction at intervals of <NUM> degrees, respectively. For example, the plurality of light sources LD11, LD12, LD13 are arranged in the radial direction in a first angle section, and the plurality of light sources LD11, LD12, and LD13 are tilted at different angles. Further, a plurality of light sources LD21, LD22, and LD23 are arranged in the radial direction in a second angle section, and the plurality of light sources LD21, LD22, LD23 are tilted at different angles. Similarly, within the third to fifth angle sections, a plurality of light sources LD31, LD32, and LD33, a plurality of light sources LD41, LD42, and LD43, and a plurality of light sources LD51, LD52, and LD53 that are tilted at different angles may be arranged in the radial direction. <FIG> illustrate that three light sources are arranged within one angle section, this is only an example, and the disclosure is not limited thereto.

When a plurality of light sources are tilted at different angles within one angle section, the number of scanning channels in the elevation angle direction is given by a product of the number of light sources tilted at different angles, the number of inclination angles of a plurality of inclined mirrors of the first mirror array <NUM>, and the number of inclination angles of a plurality of inclined mirrors of the second mirror array <NUM>. For example, <FIG> exemplarily shows a plurality of vertical channels in an elevation angle direction formed according to a change in a relative position between the first mirror array <NUM> and the second mirror array <NUM> in the example embodiment shown in <FIG>. In <FIG>, it is assumed that the number of light sources tilted at different angles is three, the first mirror array <NUM> has <NUM> inclination angles, and the second mirror array <NUM> has <NUM> inclination angles. In addition, it is assumed that tilting angles of the three light sources are optically -<NUM> degrees, <NUM> degrees, and +<NUM> degrees, inclined mirrors of the first mirror array <NUM> optically have inclination angles of -<NUM> degrees, <NUM> degrees, and +<NUM> degrees, and inclined mirrors of the second mirror array <NUM> optically have inclination angles of -<NUM> degrees, -<NUM> degrees, +<NUM> degrees, and +<NUM> degrees. Here, the tilting angles represent angles increased or decreased relative to a vertical direction. In this case, the number of scanning channels in an elevation angular direction is <NUM>, and scanning in the elevation angular direction is possible at intervals of <NUM> degree from -<NUM> degrees to +<NUM> degrees. Therefore, a vertical viewing angle is <NUM> degrees.

In <FIG>, the plurality of light sources LD11, LD12, and LD13 are shown to be inclined, but in this case, assembly and maintenance may be difficult. <FIG> are views illustrating various example embodiments for multiplexing an inclination angle of light emitted from a light source without obliquely arranging a light source.

Referring to <FIG>, the plurality of light sources LD11, LD12, and LD13 in one angle section are arranged parallel to each other. In order to multiplex inclination angles of light emitted from the plurality of light sources LD11, LD12, and LD13 arranged in parallel, among the plurality of light sources LD11, LD12, and LD13, wedge prisms P11 and P13 may be arranged in an optical path between some of the light sources LD11 and LD13 and the intermediate mirror M1. The two wedge prisms P11 and P13 may change a light traveling direction to different angles. The wedge prisms P11 and P13 may in particular be arranged in an optical path between the collimating lenses C11 and C13 and the intermediate mirror M1. Further, among the plurality of light sources LD11, LD12, and LD13, no wedge prism may be arranged in an optical path between some of the light sources LD12 and the intermediate mirror M1. The above-described configuration may be applied to the light sources LD21, LD22, LD23; LD31, LD32, LD33; LD41, LD42, LD43; LD51, LD52, and LD53 arranged in all other angle sections shown in <FIG>.

Referring to <FIG>, the intermediate mirror M1 may include a reflective surface S1 where the inclination angle is adjusted by electrical control. For example, the reflective surface S1 of the intermediate mirror M1 may be composed of micro electro mechanical systems (MEMS). In this case, only one light source LD1 may be arranged within one angle section. Light emitted from the light source LD1 may be incident on the first mirror array <NUM> at various angles according to a change in the inclination angle of the reflective surface S1 of the intermediate mirror M1.

Referring to <FIG>, a LiDAR apparatus may not include the rotating first mirror array <NUM>. Instead, the LiDAR apparatus may include a plurality of light source arrays LA1 and LA5 each including a plurality of light sources arranged in a vertical direction. Although only two light source arrays LA1 and LA5 are illustrated in <FIG>, light source arrays may be arranged within a plurality of angle sections obtained by dividing an angle range of <NUM> degrees or more in the circumferential direction at equal intervals, respectively. For example, when the second mirror array <NUM> has a truncated square pyramid shape, five light source arrays may be sequentially arranged in the circumferential direction at intervals of <NUM> degrees within an angle range of <NUM> degrees.

The first light source array LA1 may include a support SP1 extending in a vertical direction and the plurality of light sources LD11, LD12, and LD13 fixed to the support SP1 and arranged in the vertical direction. Likewise, the fifth light source array LA5 may also include a support SP5 extending in a vertical direction and the plurality of light sources LD51, LD52, and LD53 fixed to the support SP5 and arranged in the vertical direction. The plurality of light sources LD11, LD12, and LD13 and LD51, LD52, and LD53 may be, for example, vertical cavity surface emitting laser (VCSEL), and may be arranged to emit light in a horizontal direction. Light emitted from the plurality of light sources LD11, LD12, and LD13 and LD51, LD52, and LD53 becomes a parallel beam by a plurality of collimating lenses C11, C12, and C13 and C51, C52, and C53.

The LiDAR apparatus may also include a plurality of mirror arrays MA1 and MA5 each including a plurality of mirrors arranged in a parabolic shape in a vertical direction to face each of a plurality of light sources. Although only two mirror arrays MA1 and MA5 are illustrated in <FIG>, each light source array may be arranged within a plurality of angle sections obtained by dividing an angle range of <NUM> degrees or more in the circumferential direction at equal intervals. For example, when the second mirror array <NUM> has a truncated square pyramid shape, five mirror arrays may be sequentially arranged in the circumferential direction at intervals of <NUM> degrees within an angle range of <NUM> degrees.

The first mirror array MA1 corresponds to the first light source array LA1. The first mirror array MA1 may include a plurality of mirrors M11, M12, and M13 respectively reflecting light emitted from the plurality of light sources LD11, LD12, and LD13 of the first light source array LA1 to the second mirror array <NUM>. The plurality of mirrors M11, M12, and M13 may be arranged in a parabolic shape in a vertical direction. For example, a mirror arranged lower among the plurality of mirrors M11, M12, and M13 may be further away from a corresponding light source from among the plurality of light sources LD11, LD12, and LD13. In addition, the fifth mirror array MA5 corresponds to the fifth light source array LA5. The fifth mirror array MA5 may also include a plurality of mirrors M51, M52, and M53 respectively reflecting light emitted from the plurality of light sources LD51, LD52, and LD53 of the fifth light source array LA5 to the second mirror array <NUM>. An incident angle of light incident on the second mirror array <NUM> may be multiplexed by the plurality of mirrors M11, M12, and M13 and M51, M52, and M53.

When a plurality of inclined mirrors of the first mirror array <NUM> have different inclination angles, light reflected by different inclined mirrors of the first mirror array <NUM> maybe incident on different positions of the second mirror array <NUM>. <FIG> exemplarily shows a configuration in which light reflected by a plurality of inclined mirrors of the first mirror array <NUM> is incident on different positions on the second mirror array <NUM>. Referring to <FIG>, as the first mirror array <NUM> or the second mirror array <NUM> rotates, light reflected by different inclined mirrors of the first mirror array <NUM> is sequentially incident on the second mirror array <NUM>. However, when inclination angles of the inclined mirrors are different from each other, light is incident on different positions on the second mirror array <NUM>. In this case, an area where transmission light is incident and an area where received light is incident may overlap on an inclined mirror of the second mirror array <NUM>. This phenomenon, as shown in <FIG>, may occur when positions of light incident points on the plurality of inclined mirrors of the first mirror array <NUM> in a radial direction are kept constant while the first mirror array <NUM> rotates.

Therefore, positions of reflective surfaces of the plurality of inclined mirrors of the first mirror array <NUM> in the radial direction may be different from each other such that light emitted from the same light source and light reflected by the plurality of inclined mirrors of the first mirror array <NUM> is incident at the same position on the second mirror array <NUM>. <FIG> exemplarily shows a configuration in which light reflected by a plurality of inclined mirrors of the first mirror array <NUM> is incident at the same position on the second mirror array <NUM>. Referring to <FIG>, positions of light incident points on the plurality of inclined mirrors A1, A2, and A3 of the first mirror array <NUM> in a radial direction may be different from each other. In addition, inclination angles of the plurality of inclined mirrors A1, A2, and A3 may be set such that light is incident at the same position on the second mirror array <NUM>. Then, while the first mirror array <NUM> or the second mirror array <NUM> is rotating, positions where light is incident on the plurality of inclined mirrors of the second mirror array <NUM> may be kept constant.

<FIG> is a view of a configuration of a first mirror array <NUM>' according to another example embodiment. Referring to <FIG>, a plurality of inclined mirrors of the first mirror array <NUM>' may include a plurality of right angle prisms 113a, 113b, and 113c. The first mirror array <NUM>' may further include a support plate <NUM> supporting the plurality of right angle prisms 113a, 113b, and 113c. In this case, the first mirror array <NUM>' may not be a polygon mirror. The plurality of right angle prisms 113a, 113b, and 113c may have the same height and different lengths of the bases. Accordingly, the plurality of right angle prisms 113a, 113b, and 113c may have different inclination angles. In addition, positions of light incident points on the plurality of right angle prisms 113a, 113b, and 113c in a radial direction may be different from each other. As described with reference to <FIG>, the inclination angles of the plurality of prisms 113a, 113b, and 113c may be set such that light is incident at the same position on the second mirror array <NUM>.

<FIG> is a cross-sectional view of a configuration of a light-receiving unit according to another example embodiment. In a case of the light-receiving unit shown in <FIG>, it has been described that the photodetector <NUM> is on a focal point formed by the concave mirror <NUM> and the lens <NUM>. In this case, because light is incident on the photodetector <NUM> from all directions, noise may increase. The light-receiving unit illustrated in <FIG> may sequentially include the concave mirror <NUM> (see <FIG>), the flat mirror <NUM>, the band pass filter <NUM>, two lenses <NUM> and <NUM>, a mask <NUM>, and a photodetector array <NUM> in a light traveling direction of light. The lens <NUM> may be on a focal point formed by the concave mirror <NUM> and the lens <NUM>, and the photodetector array <NUM> may be on a focal point of the lens <NUM>. In this case, light incident on the second mirror array <NUM> from different directions may reach different positions on the photodetector array <NUM>.

<FIG> illustrates that the flat mirror <NUM> is used as a mirror that reflects light from the concave mirror <NUM> to the photodetector <NUM>, but is not limited thereto. For example, in order to increase or decrease an effective focus of the concave mirror <NUM>, a convex mirror or a concave mirror may be arranged at the position of the flat mirror <NUM> instead of the flat mirror <NUM>.

<FIG> shows an exemplary structure of the mask <NUM> of the light-receiving unit illustrated in <FIG>. The mask <NUM> suppresses noise by limiting light incident on the photodetector array <NUM>. To this end, the mask <NUM> may include a plurality of openings through which light passes. For example, when the second mirror array <NUM> has a truncated square pyramid shape and five light sources are sequentially arranged in the circumferential direction at intervals of <NUM> degrees, the mask <NUM> may include five openings H1, H2, H3, H4, and H5 sequentially arranged in the circumferential direction at intervals of <NUM> degrees. The number and positions of a plurality of openings arranged in the mask <NUM> are not limited thereto, and may vary according to the number and positions of light sources.

In addition, <FIG> shows an exemplary configuration of the photodetector array <NUM> shown in <FIG>. Referring to <FIG>, the photodetector array <NUM> may include a plurality of photodetectors arranged at regular intervals in a circumferential direction around a central optical axis. For example, when the second mirror array <NUM> has a truncated square pyramid shape and five light sources are sequentially arranged in the circumferential direction at intervals of <NUM> degrees, the photodetector array <NUM> may include five photodetectors D1, D2, D3, D4, and D5 that are sequentially arranged in the circumferential direction at intervals of <NUM> degrees. The number and positions of a plurality of photodetectors arranged in the photodetector array <NUM> are not limited thereto, and may vary according to the number and positions of light sources. The number of photodetectors of the photodetector array <NUM> may be the same as the number of light sources, and the arrangement of the photodetectors may be similar to the arrangement of light.

The mask <NUM> is disposed on a light-receiving surface of the photodetector array <NUM>, and the openings H1, H2, H3, H4, and H5 of the mask <NUM> may correspond to the plurality of photodetectors D1, D2, D3, D4, and D5 of the photodetector array <NUM>, respectively. Accordingly, light passing through the openings H1, H2, H3, H4, and H5 of the mask <NUM> may be incident on the corresponding photodetectors D1, D2, D3, D4, and D5 of the photodetector array <NUM>.

Further, light emitted from a plurality of light sources through the second mirror array <NUM>, after being reflected by an external object, may pass through the corresponding openings H1, H2, H3, H4, and H5 of the mask <NUM> and may be incident on the corresponding photodetectors D1, D2, D3, D4, and D5 of the photodetector array <NUM>. Accordingly, it is possible to reduce noise and improve a signal-to-noise ratio by limiting ambient light.

<FIG> is a view of a configuration of a photodetector array <NUM>' of a light-receiving unit according to another example embodiment. Referring to <FIG>, the photodetector array <NUM>' may include a plurality of one-dimensional sensor arrays DA1, DA2, DA3, DA4, and DA5 arranged at regular intervals in a circumferential direction around a central optical axis and extending in a radial direction. As shown in <FIG> and the like, when the plurality of light sources LD11, LD12, and LD13 are arranged in the radial direction within one angle section in an azimuth direction, each of the one-dimensional sensor arrays DA1, DA2, DA3, DA4, and DA5 may detect light emitted by incident on the second mirror array <NUM> at a plurality of different inclination angles from the plurality of light sources LD11, LD12, and LD13 arranged within a corresponding angle section.

According to the above-described example embodiments, in the azimuth direction, transmitters are configured within a plurality of angle sections in which an angle range of <NUM> degrees or more is divided in equal intervals, and light emitted from each transmitter is scanned by the first mirror array <NUM> and the second mirror array <NUM> within a corresponding angle section. Therefore, a horizontal viewing angle of <NUM> degrees or more may be secured. For example, a viewing angle in the azimuth direction may be about <NUM> degrees to about <NUM> degrees. In addition, because scanning is performed individually within a relatively narrow angle section, the influence of tilting of a beam passing through the first mirror array <NUM> and geometric distortion of a beam due to rotation of the second mirror array <NUM> may be minimized.

In addition, according to the disclosed example embodiment, in an elevation angle direction, the number of vertical channels may be greatly increased because a plurality of vertical channels are formed by multiplexing an inclination angle of a light source within each angle section and a combination of a plurality of inclined mirrors of the first mirror array <NUM> and a plurality of inclined mirrors of the second mirror array <NUM>. Accordingly, a vertical viewing angle of <NUM> degrees or more may be secured. For example, a viewing angle in the elevation angle direction may be about <NUM> degrees to about <NUM> degrees.

According to the above-described example embodiments, while increasing a viewing angle in an azimuth direction and an elevation angle direction, a high frame rate of about <NUM> or more may be achieved only by controlling rotation speeds of the first mirror array <NUM> and the second mirror array <NUM>.

Because the LiDAR apparatus according to the example embodiments has a horizontal viewing angle and a vertical viewing angle that are wide, the LiDAR apparatus may accurately detect objects not only in front but also on the side, and may detect a three-dimensional state of the ceiling or floor in detail.

Such a LiDAR apparatus, for example, may be mounted on a vehicle and configured to extract distance and relative speed information with vehicles in front. However, the LiDAR apparatuses according to the above-described example embodiments are not necessarily applicable only to a vehicle. For example, in addition to vehicles, the LiDAR apparatuses may be mounted on ships, aircraft, or drones, and used to search for and avoid obstacles in front of the ships, aircraft, and drones. Furthermore, the above-described LiDAR apparatus may be used as an autonomous driving robot for factory automation, a stationary sensor for security, or a purpose for obtaining 3D information about an object that is installed on the side of a road and passes through the road.

Claim 1:
A light detection and ranging, LiDAR, apparatus (<NUM>) comprising:
a first rotatable mirror array (<NUM>) including a first plurality of inclined mirrors (A1..<NUM>) arranged in a circumferential direction;
a plurality of light sources (LD1..<NUM>) configured to emit light toward the first rotatable mirror array;
a second rotatable mirror array (<NUM>) including a second plurality of inclined mirrors (F1..<NUM>) arranged in the circumferential direction, the second rotatable mirror array (<NUM>) facing the first rotatable mirror array (<NUM>) to reflect the light reflected by the first rotatable mirror array to an outside of the LiDAR apparatus; and
a photodetector (<NUM>) configured to detect the light reflected by the second rotatable mirror array after being incident onto the second rotatable mirror array from the outside of the LiDAR apparatus,
wherein the plurality of light sources are provided in a plurality of sections into which an angle range of <NUM> degrees or more is divided in equal intervals in the circumferential direction,
characterized in that the second rotatable mirror is adapted to rotate in a continuous manner and the first rotatable mirror is adapted to rotate in a stepwise manner or in a continuous manner at a different rotation speed to the second rotatable mirror.