Optical System for Matching Channels of Multi-Channel Transmitter and Channels of Rolling Shutter Type Receiver, and Three-Dimensional LiDAR Sensor including the Same

Abstract

The embodiments relate to an optical system for aligning the channels of a transmitting unit and a receiving unit in a 3D LiDAR sensor, and a 3D LiDAR sensor including the same, wherein the transmitting unit optical system through which a signal light emitted from a light source element of a multi-channel light source passes; and a receiving unit optical system through which the signal light passes to receive the signal light in a rolling shutter type image element, wherein the receiving unit optical system is configured such that the bending of the signal light for each channel is formed into a straight-line image on the image plane and aligned with the active channel area of ​​the rolling shutter type image element.

Description

Technology Field

[0001] Embodiments of the present application relate to an optical system for aligning the channel of a multi-channel transmitter with the channel of a rolling shutter type receiver, and a three-dimensional lidar sensor including the same. Background Technology

[0002] A LiDAR (Light Detection And Ranging) sensor is a sensor device that measures the distance to a target using light. Among the operating methods of LiDAR sensors, there is the Direct Time-of-Flight (dToF) method. A dToF LiDAR sensor generates a light pulse from a transmitter, measures the time it takes for this light pulse to be reflected back from a target object, and ultimately measures the distance between the target object and the LiDAR sensor by converting the measured time into a distance.

[0003] Recently, as major application fields of LiDAR, such as robotics, vehicles, and industrial sectors, have become more intelligent and advanced, the demand for 3D distance measurement is increasing. To meet this demand, there are various attempts to develop LiDAR sensors for 3D distance measurement.

[0004] FIG. 1 is a schematic diagram of a conventional rotary / fixed 3D dToF lidar sensor. FIG. 2 is a diagram explaining the operation of the transmitter in the global illumination method and the customized illumination method in a fixed 3D dToF lidar sensor.

[0005] The rotary 3D dToF LiDAR sensor measured 3D distance by rotating or vibrating a 2D LiDAR sensor, designed to measure distances corresponding to points or lines, using a drive such as a rotary motor. However, this non-fixed method caused problems such as vibration issues inside and outside the LiDAR sensor due to the drive, issues with the lifespan of the drive, and reduced durability and reliability.

[0006] To address the problems of such non-fixed methods, solid-state 3D dToF LiDARs without moving parts are being developed recently. As shown in Fig. 1, the solid-state 3D dToF LiDAR has a receiver element and a transmitter element. These elements are implemented in an array structure. The receiver element and the transmitter element are placed in the LiDAR sensor in a fixed state without moving with other parts such as actuators.

[0007] The receiver array of a fixed 3D dToF LiDAR is a device configured to operate by arranging high-sensitivity pixel elements, such as SPADs (Single Photon Avalanche Diodes), in a planar array and recording the time when light enters the corresponding pixel elements. Unlike general digital image devices that simply measure light intensity, this receiver array records the time when light enters, and thus possesses device characteristics that require additional circuit elements and massive internal data processing for this purpose.

[0008] For this reason, in fixed dToF lidar sensors, the receiver element is typically implemented using a rolling shutter method that sequentially reads parts of the pixel array (usually one line at a time) and then reconstructs the image, rather than a global shutter method that processes signals entering all areas of the pixel array at once.

[0009] If, as illustrated in FIG. 2, the signal light from the transmitter (Tx) is simply spread across the entire field of view like the global illumination method commonly used in fixed 3D dToF lidar sensors, most of the light is wasted outside the data acquisition area of ​​one line being read by the image element of the receiver (Rx).

[0010] Therefore, in order to fabricate an efficient fixed 3D dToF lidar sensor, it is required to implement a multi-channel transmitter in which each channel of the receiver element can irradiate light to the area viewed in 3D space.

[0011] Multi-channel transmitters can be broadly classified into mechanical, single-light source steering, or multi-light source electronic types.

[0012] Mechanical systems steer signal light using mechanically rotating or vibrating elements, primarily by directly rotating the LiDAR using motors or employing polygon mirrors or MEMS mirrors. Mechanical transmitters are vulnerable to vibration and failure due to the moving parts.

[0013] Single-source steering is a method of changing the direction of light emitted from one or a few light sources using special elements such as OPA (Optical Phase Array) or Metasurface. Because the difficulty of implementing these special elements is very high, most transmitters of the single-source steering method are not commercialized.

[0014] Finally, the multi-light source electronic type uses a light source element (e.g., Addressable VCSEL) capable of specifying a light emission area in one or two dimensions, and has a structure that combines an additional optical system thereon. Light output from different light emission areas in the multi-light source electronic transmitter propagates in different directions to realize the multi-channel light source required by a fixed 3D dToF LiDAR sensor. The multi-light source electronic type has the advantage of being relatively easy to implement and is therefore used in fixed 3D dToF LiDAR sensors.

[0015] As an example, Korean Patent Publication No. 10-2024-0001013 (published Jan. 3, 2024) implements an electronic transmitter by creating a special transmitter laser element having the same operating mode as a receiver element for multi-light source electronic scanning and arranging the same imaging optical system in the receiver element and the transmitter element.

[0016] However, in order to have the same operating mode as the receiver element, there is a condition that the characteristics of the transmitter element, such as channel selection and aspect ratio, must be identical to those of the receiver element. This condition leads to increased difficulty in designing and manufacturing the transmitter element, difficulties in driving due to shape fixation caused by aspect ratio restrictions, and consequently, increased manufacturing costs. Furthermore, the material cost of the transmitter is high because the transmitter uses an imaging optical system that is structurally complex and requires multiple lenses. In addition, there are significant difficulties in aligning the transmitter element with the imaging optical system. Finally, since both the transmitter element and the imaging optical system must be custom-manufactured according to the characteristics of the receiver element, the initial design and manufacturing costs are extremely high, and there is a problem of reduced flexibility when design changes are made. Prior art literature

[0017] Patent Publication No. 10-2024-0001013 (Published Jan. 3, 2024) The problem to be solved

[0018] Based on the discussion described above, embodiments of the present application aim to provide an optical system for aligning the channel of a multi-channel transmitter with the channel of a rolling shutter type receiver, and a three-dimensional lidar sensor including the same. means of solving the problem

[0019] An optical system according to one aspect of the present application may include a transmitting optical system through which signal light emitted from a light source element of a multi-channel light source passes, and a receiving optical system through which signal light passes to receive signal light from an image element of a rolling shutter type.

[0020] The transmitting optical system may include a first-1 optical element that focuses signal light emitted from each channel of a light source element into parallel light of a unique specific angle α corresponding to each channel, and a first-2 optical element that diffuses the parallel light in a specific axis direction so that the channel-specific signal light emitted from the transmitting unit is emitted in a curved state to have a curved shape in three-dimensional space.

[0021] The receiving optical system is a second optical element based on a mapping function in which r is proportional to a sine function when channel-specific signal light emitted from the transmitting unit is incident with respect to the optical axis and forms an image at a point on the image plane of the image element, and the bending of the channel-specific signal light is formed into a straight-line image on the image plane and can be configured to be aligned with the active channel area of ​​the rolling shutter type image element.

[0022] In one embodiment, the channel-specific signal light emitted from the transmitter can be defined as a direction vector v(α) in an orthogonal coordinate system in which the optical axis is the z-axis, the direction of the channel arrangement of the light source element is the y-axis, and a specific direction is the x-axis, and the y-axis component of the direction vector v(α) can be sin(α).

[0023] In one embodiment, the second optical element can satisfy the following mathematical equation for the y-axis component of the direction vector v(α) of the optical path formed by the signal light emitted from the transmitting optical system and the y-axis component of the direction viewed from the coordinates (u, v) of a point where an image is formed on the image element through the receiving optical system.

[0024] [Mathematical Formula]

[0025]

[0026] In one embodiment, the direction vector viewed from the coordinates (u, v) on the image element through the receiving optical system can satisfy the following mathematical equation.

[0027] [Mathematical Formula]

[0028]

[0029] In one embodiment, the first-1 optical element and the second optical element are an imaging optical system, and the first-2 optical element may be a non-imaging optical system.

[0030] In one embodiment, the first-1 optical element may include a pair of convex and concave lenses, the convex lens may be positioned closer to the light source element than the concave lens on the optical path of the signal light per channel, and the concave lens may be positioned closer to the first-2 optical element than the convex lens.

[0031] In one embodiment, the first-second optical element may include a lens having a shape that extends along a first direction in a three-dimensional structure and has curvature in a second direction perpendicular to the first direction.

[0032] In one embodiment, the light source element may be a one-dimensional multi-channel light source.

[0033] In one embodiment, the first-2 optical element may be positioned so that all channels of the light source element outputting in the direction of the exit port of the first-1 optical element can share a single diffusion optical system.

[0034] In one embodiment, the first and second optical elements can match the channels of the transmitting unit and the receiving unit when the number of channels of the light source element is equal to the number of channels of the image element or when the number of channels of the light source element is greater than the number of channels of the image element.

[0035] A three-dimensional lidar sensor according to another aspect of the present application may include an optical system according to the embodiments described above.

[0036] In one embodiment, the 3D LiDAR sensor may have a field of view of 90° or more in a specific direction. Effects of the invention

[0038] According to various embodiments of the present invention, a 3D dToF lidar sensor (10) can align the channels of a multi-channel transmitting element and the channels of a rolling shutter receiving element in 3D space through a mapping optical system within the receiving element configured to compensate for the bending of light from the transmitting element.

[0039] In addition, by configuring the transmitting optical system with a non-image optical system and providing a wide horizontal angle of view of 40° or more, especially 90° or more, it solves the disadvantages of complex and expensive image optical systems and the disadvantages of general non-image optical systems that have a narrow horizontal angle of view of about 40°.

[0040] In addition, the 3D dToF lidar sensor (10) has no moving parts such as a drive system, so it has strong durability and a long lifespan.

[0041] As a result, the above 3D dToF lidar sensor can overcome the high manufacturing cost and low flexibility of the optical system for matching the active areas of the existing transmitter and receiver. Brief explanation of the drawing

[0043] Figure 1 is a schematic diagram of a conventional rotary / fixed 3D dToF lidar sensor. Figure 2 is a diagram illustrating the operation of the transmitter in the global illumination method and the customized illumination method in a fixed 3D dToF lidar sensor. FIG. 3 is a schematic diagram of a three-dimensional dToF lidar sensor according to one aspect of the present application. Figure 4 is a diagram illustrating a non-image optical system compared to an image optical system. FIG. 5 is a diagram illustrating a transmitting channel that is activated when the number of channels of the receiving unit and the transmitting unit are the same, according to various embodiments of the present application. FIG. 6 is a diagram illustrating a transmitting channel that is activated when the number of channels of the transmitting unit is greater than the number of channels of the receiving unit, according to various embodiments of the present application. FIG. 7 is a diagram illustrating the arrangement relationship between a plurality of light source elements in a transmitting unit according to various embodiments of the present application. FIG. 8 is a schematic diagram of parallel light emitted from a first-1 optical element (121) according to various embodiments of the present application. FIG. 9 is a drawing illustrating a first-2 optical element close to a first-1 optical element according to various embodiments of the present application. FIG. 10 is a diagram illustrating channel-specific optical signals that pass through a transmitter in close proximity to an imaging optical system and a non-imaging optical system, according to various embodiments of the present application. FIG. 11 is a diagram illustrating a mapping function for a second optical element (220) according to various embodiments of the present application. FIG. 12 is a diagram comparing and analyzing the results of applying a mapping function for channel matching and existing mapping functions to a camera according to various embodiments of the present application. Specific details for implementing the invention

[0044] Hereinafter, embodiments of the present invention will be examined in detail with reference to the drawings.

[0045] However, this is not intended to limit the present disclosure to specific embodiments and should be understood to include various modifications, equivalents, and / or alternatives to the embodiments of the present disclosure. In connection with the description of the drawings, similar reference numerals may be used for similar components.

[0046] In this specification, expressions such as “have,” “may have,” “include,” or “may include” indicate the presence of such features (e.g., components such as numbers, functions, actions, steps, parts, elements, and / or parts), and do not exclude the presence or addition of additional features.

[0047] When it is stated that one component is "connected" or "connected" to another component, it should be understood that while it may be directly connected or connected to that other component, there may also be other components in between. On the other hand, when it is stated that one component is "directly connected" or "directly connected" to another component, it should be understood that there are no other components in between.

[0048] Expressions such as "first," "second," "first," or "second" used in various embodiments may modify various components regardless of order and / or importance and do not limit said components. Such expressions may be used to distinguish one component from another. For example, the first component and the second component may represent different components regardless of order or importance.

[0049] Examples of configurations of singular expressions used in this specification also include examples of configurations of plural expressions, unless the phrases associated with the singular expressions clearly indicate a meaning contrary to this.

[0050] As used herein, the expression “configured to” may be replaced, depending on the context, with, for example, “suitable for,” “having the capacity to,” “designed to,” “adapted to,” “made to,” or “capable of.” The term “configured to” may not necessarily mean only that which is “specifically designed to” in hardware. Instead, in some situations, the expression “device configured to” may mean that the device is “capable of” in conjunction with other devices or components. For example, the phrase “processor configured to perform A, B, and C” may mean a dedicated processor for performing the said operations (e.g., an embedded processor), or a generic-purpose processor (e.g., a CPU or an application processor) capable of performing said operations by executing one or more software programs stored in a memory device.

[0051] Terms used in this invention, including technical or scientific terms, may have the same meaning as generally understood by those skilled in the art as described in this invention. Terms used in this invention that are defined in general dictionaries may be interpreted as having the same or similar meaning as they have in the context of the relevant technology, and are not interpreted in an ideal or overly formal sense unless explicitly defined in this invention. In some cases, even terms defined in this invention may not be interpreted to exclude embodiments of this invention.

[0053] FIG. 3 is a schematic diagram of a three-dimensional dToF lidar sensor according to one aspect of the present application.

[0054] Referring to FIG. 3, the 3D dToF lidar sensor (10) includes a transmitter (100) that outputs a signal light of the lidar; and a receiver (200) that receives the signal light to measure a 3D distance.

[0055] The above 3D LiDAR sensor (10) is a dToF LiDAR sensor that receives signal light output from a transmitter (100) and reflected back from a target at a receiver (200), and measures the direct flight time of the signal light to measure the distance in 3D space from the sensor (10) to the target.

[0056] The above 3D dToF lidar sensor (10) may be a fixed 3D lidar sensor in which the transmitting optical system and the receiving optical system are fixed in the 3D lidar sensor. The 3D dToF lidar sensor (10) is positioned within the lidar sensor (10) in a fixed state so that the transmitting unit (100) and the receiving unit (200) are not moved by other parts within the sensor (10), such as a driving body.

[0057] The three-dimensional LiDAR sensor (10) according to the embodiments may be entirely hardware or have aspects that are partially hardware and partially software. For example, the system may collectively refer to hardware equipped with data processing capabilities and operating software for driving it. In this specification, terms such as “unit,” “system,” and “device” are intended to refer to a combination of hardware and software driven by said hardware. For example, the hardware may be a data processing device including a CPU (Central Processing Unit), a GPU (Graphic Processing Unit), or other processors. Additionally, the software may refer to a running process, object, executable, thread of execution, program, etc.

[0058] The transmitting unit (100) includes a light source element (110); and a transmitting unit optical system (120).

[0059] The light source element (110) is configured to emit signal light as a transmitting element. The light source element (110) can be implemented, for example, as an LED, VCSEL, laser, or various other elements that emit light signals.

[0060] Additionally, the light source element (110) may be a multi-channel light source. In various embodiments of the present application, the light source element (110) may be a one-dimensional multi-channel light source having a one-dimensional multi-channel structure (1D addressable).

[0061] The transmitting unit (100) may include one or more one-dimensional multi-channel light source elements (110). For example, the transmitting unit (100) may include one one-dimensional multi-channel light source element (110) as a transmitting unit element, or may include a plurality of one-dimensional multi-channel light source elements (110) as transmitting unit elements.

[0062] A multi-channel light source is configured to enable customized irradiation by dividing the light-emitting surface on a single light-emitting element into sub-regions to emit light only from specific light-emitting areas. In a multi-channel light source, a specific sub-region activated for light emission is referred to as a channel. Since channels can be selected, a multi-channel light source can be referred to as an addressable element. A multi-channel light source can be configured so that channel selection is performed in one dimension or in two dimensions.

[0063] Multi-channel light sources can effectively save space while achieving an effect similar to using multiple light source elements with only a single light-emitting element.

[0064] These multi-channel light sources (110) output signal light for each channel through an optical system (120).

[0065] The transmitting optical system (120) is an optical system that enables the transmitting unit (100), including a multi-channel light source (110), to emit signal light to a desired specific area by further refracting and / or reflecting the signal light emitted from the light source element 100 in order to irradiate signal light to a specific area in three-dimensional space. The channel of the transmitting unit (100) can be defined by the transmitting optical system (120).

[0066] The transmitting optical system (120) includes a first-1 optical system (121) that converts signal light emitted from a light source element (110) into parallel light, and a first-2 optical element (122) that diffuses the parallel light in a specific direction.

[0067] A multi-channel light source (110) emits signal light for each of the multiple channels and irradiates it onto a first-1 optical element (121). The first-1 optical element (121) is a focusing optical system that focuses the signal light for each channel of the light source element (110) into parallel light.

[0068] In various embodiments of the present application, the first-1 optical element (121) can convert signal light of each channel of the light source element (110) into parallel light of a specific angle α. The specific angle α is the propagation angle of the parallel light of each channel. Each channel of the light source element (110) can be distinguished (or identified) by the specific angle α of the parallel light of each channel. This specific angle α is described in more detail with reference to FIG. 8 below.

[0069] The first-2 optical element (122) is a diffusion optical system that diffuses channel-specific parallel light focused from the first-1 optical element (121) in a specific direction. In various embodiments of the present application, the specific direction may be a direction perpendicular to the channel direction of the light source element (110). As illustrated in FIG. 3, this specific direction may correspond to a horizontal direction on the pixel plane of the image element (210) of the receiver (200), and thus may be referred to as a horizontal direction.

[0070] In addition, the first-second optical element (122) may be a non-crystalline optical system.

[0071] Figure 4 is a diagram illustrating a non-image optical system compared to an image optical system.

[0072] Imaging optics are optical systems that collect light from a point of a light source to a point of a receiver. The most common example of an imaging optic is a camera lens. A camera lens collects light from a point on an object to a point on a film or image sensor. As illustrated on the left side of Fig. 4, under an imaging optics system, light output from a light source (A) is collected at a specific point (A') corresponding to it, and light output from a light source (B) is collected at another specific point (B') corresponding to it. Since a one-to-one correspondence is formed between the direction in which the camera views the object and the image sensor, an image of the object is reproduced at the location of the image sensor, and for this reason, it is called an imaging optics system.

[0073] On the other hand, non-imaging optics refer to all types of optical systems in which the aforementioned one-to-one correspondence between the light source and the receiver does not exist. A representative example of a non-imaging optical system is an optical system for lighting, such as an LED desk lamp. When considering the optical system of an LED desk lamp, it is designed not to gather light emitted from a circle (LED) to a single point on the desk to form an image, but rather to spread the light as evenly as possible within a designed angle range. As illustrated on the right side of Fig. 4, under a non-imaging optical system, light output from a light source (A) or a light source (B) reaches multiple points on the receiver. As such, since non-imaging optical systems are free from the constraints of imaging (i.e., one-to-one correspondence), they offer high design freedom and versatility, but they have the limitation of high design difficulty.

[0074] The second optical element 122, which operates as the above-mentioned non-destructive optical system, will be described in more detail with reference to Fig. 9 below.

[0075] Referring again to FIG. 3, the receiver (200) includes an image element (210); and a second optical element (220).

[0076] The receiver (200) receives the signal light output from the transmitter (100) and reflected back from the target. The reflected signal light is input to the image element (210) through the second optical system (220).

[0077] The image element (210) is a device that measures the time it takes for a light signal reflected from a target to return after being output from the transmitter (100). The image element (210) may be an image element for various lidar applications.

[0078] The image element (210) may be an array element with a planar structure. For example, the image element (210) may be an array element composed of pixels.

[0079] The image element (210) is configured to operate in a rolling shutter manner, which sequentially reads sub-regions on a pixel array to reconstruct an image of signal light. The image element (210) is configured to receive signal light in units of a single line or multiple lines on the pixel array of the image element (210) at a time. The pixel array of the image element (210) is divided into multiple channels, and each channel consists of one line or a few consecutive lines of pixels. In the rolling shutter method, only one channel is set as an active area at a specific time to receive signal light, while the remaining channels remain in an inactive state. The image element (210) reads information contained in the light signal through the channel set as the active area. The image element (210) can generate an image of the light signal irradiated over the entire pixel array by sequentially selecting active areas for the entire pixel array.

[0080] The channel direction of the image element (210) can be referred to as the horizontal direction.

[0081] The second optical element (220) focuses the signal light received by the receiver (200) and transmits it to the image element (210). The second optical element (220) is an imaging optical system for forming an image on the pixel array of the image element (210), similar to a conventional camera lens.

[0082] In various embodiments of the present application, the second optical element (220) is configured to accurately align the channel of the light source element (110) and the channel of the image element (210) in three-dimensional space, even though the second optical element (220) includes a non-fragmented optical system (122) in the transmitting unit (100). The second optical element (220) is an optical system that performs a mapping function to align the channels of the transmitting unit element 110 and the receiving unit element 210 with each other. The mapping function of the second optical element (220) can be expressed as a mapping function. The second optical element (220) will be described in more detail with reference to FIGS. 10, FIGS. 11, etc. below.

[0084] The above 3D LiDAR sensor (10) is configured to accurately align the channels of the light source element (110) and the channels of the image element (210) in 3D space when the transmitting unit (100) includes a single 1D multi-channel light source as a light source element (110).

[0085] As described above, the rolling shutter type image element (210) can acquire data in units of one line or in units of several lines. When acquiring data in units of one line, each channel activated on the pixel array of the image element (210) becomes a thin line shape, and in the case of the image element (210), each channel activated in the image element (210) becomes a thin band shape. Therefore, in order to match the channels of the transmitting unit (100) and the receiving unit (200) with each other, the light signal coming from each channel of the light source element (110) must also be in the form of a thin line or a thin band. Since each channel is in the form of a thin line or a band, by changing some or all channels activated for a short period of time and measuring the distance, a measurement of the three-dimensional distance can finally be performed.

[0086] A one-dimensional multi-channel light source (110) may have the same or more number of channels as an image element (210). The region that is activated in the light source element (110), i.e., the location of the channel, is selected based on the difference between the number of channels of the light source element (110) and the number of channels of the image element (210).

[0087] FIG. 5 is a drawing illustrating a transmitting channel that is activated when the number of channels of the receiving unit and the transmitting unit are the same, according to various embodiments of the present application. FIG. 6 is a drawing illustrating a transmitting channel that is activated when the number of channels of the transmitting unit is greater than the number of channels of the receiving unit, according to various embodiments of the present application.

[0088] Referring to FIG. 5, in order for the channels to be aligned with each other while the number of channels of the two elements (110, 210) is the same, a relationship is formed in which, when the channel of the image element (210) is activated to capture an optical signal, the channel region of the corresponding light source element (110) is activated to emit an optical signal. That is, the number of activated receiver channels and the number of activated transmitter channels can be the same.

[0089] Referring to FIG. 6, in order for the channels to be aligned with each other when the number of channels of the light source element (110) is greater than the number of channels of the image element (210), a relationship is formed in which two or more channels of the corresponding light source element (110) are simultaneously activated to emit a light signal when a channel of the image element (210) is activated to capture a light signal. The number of channels of the light source element (110) that are simultaneously activated is added by the difference between the number of one-dimensional channels of the light source element (110) and the number of channels corresponding to the channel direction of the light source element (110) in the image element (210), based on the state where the number of channels of the two elements (110, 210) is the same. The multiple channels of the light source element (110) that are activated are channels adjacent to each other in the light source element (110).

[0090] For example, as illustrated in FIG. 6, when the number of channels of the transmitting unit (100) is one (N+1) greater than the number of channels (N) of the receiving unit (200), the first and second channels of the transmitting unit (100) must be activated when the first channel of the receiving unit (200) is activated, and the second and third channels of the transmitting unit (100) must be activated when the second channel of the receiving unit (200) is activated. That is, the number of channels of the transmitting unit (100) that are activated when the number of channels of the light source element (110) is greater than the number of channels of the image element (210) can be expressed by the following mathematical formula.

[0091] [Mathematical Formula 1]

[0092]

[0093] Here, E represents the difference between the number of one-dimensional channels of the light source element (110) and the number of channels corresponding to the channel direction of the light source element (110) in the image element (210).

[0094] In order to increase resistance to channel alignment errors despite the difference in the number of channels between the receiver and the transmitter, the active area within the transmitter (100) where the transmitter channel emits light must be expanded.

[0095] In addition, the three-dimensional LiDAR sensor (10) is configured to accurately align the channels of the light source elements (110) and the channels of the image elements (210) in three-dimensional space even when the transmitting unit (100) includes a plurality of one-dimensional multi-channel light sources as light source elements (110).

[0096] FIG. 7 is a diagram illustrating the arrangement relationship between a plurality of light source elements in a transmitting unit according to various embodiments of the present application.

[0097] As described above, the transmitting unit (100) may include a plurality of light source elements (110) having multiple channels. In this case, as shown in FIG. 7, the plurality of light source elements (110) within the transmitting unit (100) are arranged in series in the one-dimensional channel direction of the light source elements (110). Then, the channel range of the transmitting unit (100) increases in proportion to the number of channels of the elements 110. Through this arrangement relationship, the case having only a single light source element (110) and the case having multiple light source elements (110) can be mathematically modeled simultaneously.

[0098] Meanwhile, the first-1 optical element (121) in the transmitting unit (100) may include a pair of convex lenses (121a) and concave lenses (121b). In the transmitting unit (100), a pair of convex lenses (121a) and concave lenses (121b) are arranged so that the centers of each lens align with each other. A pair of lenses (121a, 121b) may be fixed within the transmitting unit (100) through a fixing member (not shown).

[0099] A pair of lenses (121a, 121b) form a structure that focuses the channel-specific optical signals of the light source element (110) and converts them into parallel light.

[0100] FIG. 8 is a schematic diagram of parallel light emitted from a first-1 optical element (121) according to various embodiments of the present application.

[0101] Referring to FIG. 8, the convex lens (121a) is positioned closer to the light source element (110) in the optical path of the signal light for each channel, and the concave lens (121b) is positioned closer to the first-second optical element (122). Then, the first-first optical element (121) serves to convert the signal light emitted into each channel of the light source element into parallel light emitted at a specific angle α. This specific angle α of the parallel light is measured with the pair of lenses (121a, 121b) facing parallel to the one-dimensional channel direction of the light source element (110). The specific angle

[0102] When optical signals emitted from different channels pass through the first-1 optical element (121), they are emitted as parallel light at different angles α. As shown in FIG. 8 (a), when signal light from a light source element (110) emitted from a channel away from the center of the lens (e.g., channel 1) is incident on the first-1 optical element (121), it is output as parallel light refracted at an angle α1. On the other hand, as shown in FIG. 8 (b), when signal light emitted from a channel of the light source element (110) corresponding to the center of the lens (121a) (e.g., channel 3) is incident on the first-1 optical element (121), parallel light with α=0 is emitted. That is, the angle α of the parallel light can be measured based on when the signal light emitted from the channel corresponding to the center of the lens is incident on the focusing optical system.

[0103] Meanwhile, the optical signal passing through the first-1 optical element (121) is in a collimated state in the form of parallel light. The pattern of the optical signal emitted from each channel of the light source element (110) through the first-1 optical element (121) is concentrated in one direction.

[0104] In order to align the channel of the light source element (110) and the channel of the image element (210) in three-dimensional space, the channel emitted from the transmitter (100) must also be in the form of a thin line or a band in three-dimensional space. This is because, as mentioned above, one channel activated in the image element (210) has the form of a thin line or a band in three-dimensional space.

[0105] The first-2 optical element (122) may be a diffusion optical system that spreads light focused from the transmitter (100) horizontally. The first-2 optical element (122) is positioned in close proximity to the first-1 optical element (121) to operate as a diffusion optical system for the entire channel of the light source element (110) through the first-1 optical element (121).

[0106] In various embodiments of the present application, the first-2 optical element (122) may be positioned at a distance where all channel-specific optical signals of the light source element (110) that have passed through the first-1 optical element (121) can be incident. The first-2 optical element (122) linearly diffuses all channel-specific optical signals of the light source element (110).

[0107] Referring again to FIG. 8, it can be seen that when the central channel and the edge channel are activated, the distance required for the spatial separation of parallel light according to each channel is considerably long. This means that preparing a diffusion optical system separately for each channel of the light source element (110) is inefficient because it makes the volume of the entire optical system of the transmitter (100) very large. In particular, since the multi-channel light source is configured to partition the light-emitting region on a single light source element (110), the physical distance between channels on the element 110 is very close, and as a result, the difference in angle α regarding the direction of parallel light for adjacent channels is small, making it virtually impossible to apply a diffusion optical system (122) for each channel within a practical size.

[0108] On the other hand, the first-2 optical element (122) is positioned so that all channels of the light source element (110) output through the first-1 optical element (121) can share a single diffusion optical system. The first-2 optical element (122) is positioned close to the output port of the first-1 optical element (121). Then, the first-2 optical element (122) can operate as a single diffusion optical system for the entire light source element (110) through the first-1 optical element (121), rather than a set of individual diffusion optical systems for each channel.

[0109] FIG. 9 is a drawing illustrating the detailed structure of a first-2 optical element adjacent to a first-1 optical element according to various embodiments of the present application.

[0110] Referring to FIG. 9, the first-second optical element (122) may include a lens having a shape that extends along a first direction in a three-dimensional structure and has curvature in a second direction perpendicular to the first direction. The lens of the first-second optical element (122) may have a partial cylindrical shape, having a shape that has no bending along the vertical direction and can have an effective curvature that can collect or spread light in the horizontal direction.

[0111] Additionally, in various embodiments of the present application, the first-second optical element (122) may include one or more partially cylindrical lenses. The first-second optical element (122) may include one partially cylindrical lens, or a lenticular lens array in which a plurality of partially cylindrical lenses are arranged side by side on an array.

[0112] That is, in FIG. 9, the first-second optical element (122) is shown as a lenticular lens array consisting of a plurality of lenses in which the same partial cylinder shape is periodically repeated, but is not limited thereto and can actually be implemented as a single cylinder-shaped lens that can spread light only in the horizontal direction.

[0113] Meanwhile, as described above, since the first-2 optical element (122) is a non-crystalline optical system, it spreads light as evenly as possible within the designed angle range. The spreading angle in the horizontal direction and the intensity distribution of the spreading light in the first-2 optical element (122) may depend on the shape of the curvature of the lens of the first-2 optical element (122) or the degree of diffusion of the first-2 optical element (122).

[0114] FIG. 10 is a diagram illustrating channel-specific optical signals that pass through a transmitter in close proximity to an imaging optical system and a non-imaging optical system, according to various embodiments of the present application.

[0115] Referring to FIG. 10, a signal light output from one channel among the multiple channels of the light source element (110) is converted into a focused light form emitted at an angle α from the first-1 optical element (121) and then emitted in a diffused state from the first-2 optical element (122). Then, the signal light finally emitted from the transmitter (100) has a curved shape. When the light source element (110) emits a laser signal light, the emitted signal light of this curved shape represents a sheet of the curved shape, so it can be referred to as a laser sheet.

[0116] The laser sheet is composed of a curved optical path formed in three-dimensional space by light corresponding to each channel of the transmitting unit. In an orthogonal coordinate system where the optical axis is the z-axis, the channel arrangement direction of the transmitting unit element is the y-axis, and the horizontal direction is the x-axis, the laser sheet diffuses in the horizontal direction and has curvature according to the specific vertical angle (α) in the channel arrangement direction of the transmitting unit element 110. Therefore, the signal light emitted in the shape of a sheet is a direction vector for the shape of the sheet It can be defined as.

[0117] The above direction vector is a component representing the curved shape of the laser sheet, and under a structure in which the light source element (110) and the optical system (120) are arranged in the z-axis direction as shown in FIG. 10, it can be modeled by the following mathematical formula based on the y-axis direction component.

[0118] [Mathematical Formula 2]

[0119]

[0120] Equation 2 quantitatively describes the bending of the laser sheet. For reference, in Equation 2, the alignment error between the channel of the transmitting unit (100) and the channel of the receiving unit (200) and the thickness of the laser due to the first-1 optical element (121) are ignored.

[0121] Such bending of the laser sheet is inevitable under a structure in which the imaging optical system (121) and the non-imaging optical system (122) are arranged in close proximity in the transmitting unit (100) of FIG. 3.

[0122] As described below, the optical system (220) of the receiver (200) is configured to compensate for the bending of the signal light emitted by the transmitter (100) and to align the channel of the receiver (200) with the channel of the transmitter (100).

[0123] In various embodiments of the present application, the second optical element (220) in the receiver (200) may be configured such that an image of signal light emitted from the transmitter (100) appears as a straight line shape in a curved shape in three-dimensional space. Here, the image of the signal light may be an image that appears on the image element (210) by the corresponding signal light, i.e., the corresponding channel, when the emitted signal light is received by the receiver (200).

[0124] The second optical element (220) is an imaging optical system and can be configured based on a mapping function that makes the bending of the emitted signal light into a straight line shape. As a result, the second optical element (220) can cause the image of the laser sheet corresponding to each channel of the light source element (110) to be aligned side by side with the channel of the image element (210) on the image element (210).

[0125] When the second optical element (220) is implemented as a camera lens, the camera lens has a three-dimensional shape that satisfies the mapping function.

[0126] FIG. 11 is a diagram illustrating a mapping function for a second optical element (220) according to various embodiments of the present application.

[0127] In FIG. 11, channel-specific signal light emitted from the transmitting unit (100) is incident at an angle θ with respect to the optical axis and on the image element (210) of the receiving unit (200) at a distance r We can assume a situation where an image is formed at the point. In this case, θ and r The relationship can be defined in the form of the following mathematical expression through a mapping function (MF).

[0128] [Mathematical Formula 3]

[0129]

[0130] Meanwhile, if the point where an image is formed on the image element (210) of the receiver (200) is expressed in a coordinate system (u, v), the direction that the corresponding pixel is facing It can be summarized as follows through mathematical equation 3.

[0131] [Mathematical Formula 4]

[0132]

[0133] If the image of a laser sheet having a direction vector v(α) viewed through the second optical element (220) has a constant v value on the plane (u, v) of the image element (210), then the channel of the transmitting unit (100) and the channel of the receiving unit (200) can be matched with each other, as described above with reference to FIGS. 5 and 6.

[0134] Also, the direction vector of the laser sheet The y-axis direction component and the direction the receiver (200) is facing Assuming the y-axis component is the same, Equation 4 can be simplified as follows.

[0135] [Mathematical Formula 5]

[0136]

[0137] Meanwhile, the condition for the coordinate v of the received light to be constant according to a given channel angle α can be derived based on Equation 5. In the above Equation 5, the left side sin(α) is a value that depends only on the channel angle α. For the right side to have a constant value of v regardless of the u coordinate for the same α, sin(MF - ¹(r))·v / r must satisfy a specific relationship for r = √(u²+v²). The condition for satisfying this is that the mapping function MF takes the form proportional to the sine function as follows:

[0138] [Mathematical Formula 6]

[0139] MF = c*sin

[0140] Here, c is a constant. In one example, c may be the focal length f of a lens, but is not limited thereto, and accordingly, the second optical element (220) may be implemented as various optical systems (e.g., lenses) having f or other values.

[0141] Meanwhile, if this proportional relationship is applied briefly, Equation 5 can be simplified as follows.

[0142] [Mathematical Formula 7]

[0143]

[0144] A three-dimensional lidar sensor (10) including an optical system (120, 220) implemented to satisfy mathematical formula 7 can align the channels of a transmitter (100) and a receiver (200) including a non-image optical system without separate parts. In particular, even by utilizing an image optical system such as a camera lens and a transmitter including a non-image optical system, a three-dimensional lidar sensor (10) can be provided in which the channels of the transmitter and the receiver are aligned in three dimensions.

[0145] FIG. 12 is a diagram comparing and analyzing the results of applying a mapping function for channel matching and existing mapping functions to a camera according to various embodiments of the present application.

[0146] The graph of FIG. 12 is the result of simulating how an image appears on the image element (210) of the receiver (200) through each camera lens (i.e., the mapping function) when a laser from one channel of the transmitter is input to a camera with a second optical element (220) designed with a shape based on a mapping function according to mathematical formula 5, or a camera with a camera lens designed with a shape based on various mapping functions known at the time of filing of this patent.

[0147] Information regarding the various mapping functions (Rectilinear, Stereographic, Equidistant, Equisolid angle) shown in Fig. 12 can be obtained from web pages, such as Wikipedia (https: / / en.wikipedia.org / wiki / Fisheye_lens), so a detailed explanation is omitted.

[0148] The laser from one channel proceeds in the form of a line laser. The camera lenses designed with a shape different from the second optical element (220) and a different mapping function cause bending of the line laser. This is because each camera lens is not designed to compensate for the bending. As a result, the image of the line laser passing through the camera lenses designed with the different mapping function is found to be bent and not aligned in one channel area of ​​the image element (210).

[0149] On the other hand, when the second optical element (220) is used as a camera lens of the receiver (200), the image of the laser signal light corresponding to one channel passing through the second optical element (220) appears as a straight line shape without bending on the plane of the image element (210). That is, even though the laser signal light is emitted from the transmitter (100) in a bent sheet shape, it is confirmed that the image of the laser signal light is accurately aligned with one channel area of ​​the image element (210).

[0151] This three-dimensional LiDAR sensor (10) can solve the problem of matching the channels of the light source element (110) and the image element (210) so that the channels can be aligned with each other.

[0152] As a result, distortion in the high-angle viewing region caused by the bending of the signal light from the transmitter (100) in three-dimensional space can be compensated, and consequently, a three-dimensional lidar sensor with higher light reception efficiency compared to the existing one and a wide horizontal viewing angle between 40° and 180° can be realized. In particular, this three-dimensional lidar sensor (10) has a wide viewing angle of more than 90°. In addition, since moving parts used in rotary lidar sensors are unnecessary, the low flexibility that is a limitation of conventional three-dimensional lidar sensors can be overcome and manufacturing costs can also be saved.

[0154] The embodiments described above are combinations of the components and features of the present invention in a specific form. Each component or feature should be considered optional unless otherwise explicitly stated. Each component or feature may be implemented in a form not combined with other components or features. Additionally, it is possible to construct embodiments of the present invention by combining some components and / or features. The order of operations described in the embodiments of the invention may be changed. Some components or features of one embodiment may be included in another embodiment, or may be replaced with corresponding components or features of another embodiment. It is obvious that embodiments may be constructed by combining claims that do not have an explicit citation relationship in the claims, or that they may be included as new claims through amendments made after filing.

[0155] It will be apparent to those skilled in the art that the present invention may be embodied in other forms without departing from the technical spirit and essential features of the present invention. Accordingly, the above embodiments should be considered in all illustrative aspects rather than as a limiting one. The scope of the present invention shall be determined by a reasonable interpretation of the appended claims and all possible variations within the equivalent scope of the present invention. Explanation of the symbols

[0156] 10: 3D LiDAR sensor 100: Sender 110: Light source element 120: Transmitter optical system 121: 1-1 Optical Element 122: 1st-2nd Optical Element 200: Receiver 210: Image element 220: Second optical element

Claims

Claim 1 An optical system for aligning a channel of a transmitter and a channel of a receiver in a 3D LiDAR sensor comprises: a transmitter optical system through which signal light emitted from a light source element of a multi-channel light source passes; and a receiver optical system through which the signal light passes to receive the signal light in a rolling shutter type image element, wherein the transmitter optical system comprises a first-1 optical element that focuses the signal light emitted from each channel of the light source element into parallel light of a unique specific angle α corresponding to each channel; and a first-2 optical element that diffuses the parallel light in a specific direction so that the channel-specific signal light emitted from the transmitting unit is emitted in a bent state having a curved shape in three-dimensional space; wherein the receiving optical system is a second optical element based on a mapping function (MF) in which r is proportional to a sine function when the channel-specific signal light emitted from the transmitting unit is incident at an angle θ with respect to the optical axis and forms an image at a point of distance r on the image plane of the image element, and is configured such that the bending of the channel-specific signal light forms a straight-line image on the image plane and is aligned with the active channel region of the rolling shutter type image element, wherein the first-1 optical element and the second optical element are an image-forming optical system, and the first-2 optical element is a non-image-forming optical system, and the first-2 optical element is characterized by including a lens that extends along a first direction in a three-dimensional structure and has a shape with curvature in a second direction perpendicular to the first direction. Optical system. Claim 2 An optical system according to claim 1, wherein the channel-specific signal light emitted from the transmitting unit is defined as a direction vector v(α) in an orthogonal coordinate system in which the optical axis is the z-axis, the direction of the channel arrangement of the light source element is the y-axis, and the specific direction is the x-axis, and the y-axis component of the direction vector v(α) is sin(α). Claim 3 In claim 2, the optical system is characterized in that the second optical element satisfies the following mathematical formula, wherein the y-axis component of the direction vector v(α) of the optical path formed by the signal light emitted from the transmitting optical system and the y-axis component of the direction viewed from the coordinates (u, v) of a point where an image is formed on the image element through the receiving optical system satisfy the following mathematical formula: [Mathematical Formula] . Claim 4 In paragraph 3, the direction vector viewed at coordinates (u, v) on the image element through the receiving optical system An optical system characterized by satisfying the following mathematical formula: [Mathematical Formula] . Claim 5 delete Claim 6 An optical system according to claim 1, wherein the first-1 optical element comprises a pair of convex and concave lenses, wherein the convex lens is positioned closer to the light source element than the concave lens on the optical path of the signal light for each channel, and the concave lens is positioned closer to the first-2 optical element than the convex lens. Claim 7 delete Claim 8 An optical system according to claim 1, characterized in that the light source element is a one-dimensional multi-channel light source. Claim 9 An optical system according to claim 1, wherein the first-2 optical element is characterized in that all channels of the light source element outputting in the direction of the exit port of the first-1 optical element are positioned to share a single diffusion optical system. Claim 10 An optical system according to claim 1, wherein the first and second optical elements match the channel of the transmitting unit and the channel of the receiving unit when the number of channels of the light source element is equal to the number of channels of the image element or when the number of channels of the light source element is greater than the number of channels of the image element. Claim 11 A 3D lidar sensor characterized by comprising an optical system according to any one of claims 1 to 4, 6, and 8 to 10. Claim 12 In claim 11, the 3D lidar sensor is characterized by having a field of view of 90° or more in the specific direction.

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