Detection and ranging system employing optical waveguide

Abstract

An optical waveguide has at least two main outer surfaces and is configured to guide light via internal reflection, and is arranged with one of the two main outer surfaces facing the scene. An optical coupling structure is associated with the optical waveguide and is configured to couple a portion of the light guided by the optical waveguide toward the scene. An illumination device is arranged to emit light for coupling into the optical waveguide, the light being collimated before coupling into the optical waveguide. A detector is configured to sense light reflected from an object located in the scene in response to illumination of an object by light coupled from the optical waveguide via the optical coupling structure. A processing subsystem is configured to process the signal from the detector to derive information associated with the object.

Description

[0001] Cross-references to related applications

[0002] This application claims priority to U.S. Provisional Patent Application No. 62 / 954,739, filed December 30, 2019, the entire disclosure of which is incorporated herein by reference. Technical Field

[0003] This invention relates to optical waveguides, and more particularly to optical waveguides for detection and ranging systems. Background Technology

[0004] Light detection and ranging (LIDAR) systems are used in a variety of applications, including, for example, three-dimensional (3D) sensors for autonomous vehicles. A LIDAR system employs a light emitter unit, a scanning device, and a light receiver unit. The light emitter unit emits laser pulses, the scanning device guides the emitted laser pulses toward the scene to scan a large field of interest, and the light receiver unit collects light reflected from objects in the scene and processes the collected reflected light to derive information about the scanned objects.

[0005] Optical emitter units typically emit laser pulses at relatively high intensities that can be harmful to the human eye. Therefore, many LiDAR systems are subject to eye safety regulations, especially when deployed in vehicles such as autonomous vehicles. The intensity of the laser is determined by several parameters, including, for example, the emission power of the laser source, the duration of the laser pulse, the angular divergence of the laser beam, and the size of the exit pupil at the output of the optical emitter unit. To achieve a longer operating range, it is preferable to emit lasers with relatively high intensity and low beam divergence, resulting in relatively short pulse durations.

[0006] To achieve high intensity for each spot of light in the illuminated scene, the beam is scanned across the scene (typically vertically and horizontally, i.e., laterally) by a scanning device to emit light pulses in all directions. The scanning device can be implemented in various ways, but is typically achieved using a relatively large, rapidly moving mirror that provides scanning of the laser emitter aperture in both vertical and horizontal directions.

[0007] Optimal or near-optimal results can be achieved using light emitters and receivers operating in the near-infrared (NIR) region of the electromagnetic spectrum. However, light in the NIR region is invisible to the human eye, and therefore NIR light can cause substantial damage to the viewer's eyes without the viewer being aware of the damage. To reduce the possibility of eye damage, many LIDAR systems operating in the NIR range employ power limiting at the emitter to reduce the intensity of the received reflected beam. Summary of the Invention

[0008] This invention relates to a detection and ranging system employing an optical waveguide. In a preferred embodiment, beams from multiple laser sources operating at different wavelengths (preferably in the NIR region) are combined into a combined beam to illuminate a scanning device (e.g., a scanning mirror). The scanning beam is collimated by collimating optics (e.g., a collimating lens or a mirror) and coupled into an optical waveguide made of a transparent material (e.g., glass). The light is coupled into the optical waveguide via an optical coupling configuration, typically implemented as a coupling prism or coupling reflector. Through internal reflection, the coupled light is trapped within the optical waveguide between the main outer surfaces of the waveguide for guidance through the waveguide (i.e., propagation within the waveguide). The propagating light is gradually coupled out of the waveguide via an optical coupling configuration, preferably implemented as a set of mutually parallel partially reflecting surfaces arranged within the waveguide and tilted relative to the parallel main surfaces of the waveguide. As a result, the input beam of the waveguide is multiplied into several parallel output beams, thereby multiplying the output aperture of the system while maintaining parallel propagation. The output beams consist of all the component laser beams that propagate together. In some embodiments, the scanning device scans the emission field while maintaining a large output aperture to achieve a large scan output field. In some preferred but non-limiting embodiments, one of the laser sources operates at a wavelength in the visible region of the electromagnetic spectrum to improve eye safety.

[0009] According to the teachings of embodiments of the present invention, a system is provided. The system includes: an optical waveguide having at least two main outer surfaces for guiding light via internal reflection, a first of the two main outer surfaces being arranged facing a scene; an optical coupling structure associated with the optical waveguide, configured to couple a portion of the light guided by the optical waveguide toward the scene out of the optical waveguide; an illumination device arranged to emit light for coupling into the optical waveguide, the light being collimated before coupling into the optical waveguide; a detector for sensing light reflected from an object located in the scene in response to illumination of an object by light coupled from the optical waveguide via the optical coupling structure; and a processing subsystem including at least one processor, the processing subsystem being electrically associated with the detector and configured to process signals from the detector to derive information associated with the object.

[0010] Optionally, the system also includes a focusing optics for focusing the reflected light onto the detector.

[0011] Optionally, the focusing optics are associated with the second of the two main outer surfaces.

[0012] Alternatively, the reflected light is transmitted through the two main outer surfaces before being received by the focusing optics.

[0013] Optionally, the output aperture of the system is at least partially defined by the coupling configuration, and the input aperture of the system is at least partially defined by the focusing optics.

[0014] Optionally, the input aperture and the output aperture overlap at least partially.

[0015] Optionally, the input aperture and the output aperture are non-overlapping.

[0016] Optionally, the system also includes a diffractive optical element associated with a first of the two main outer surfaces.

[0017] Optionally, the system further includes a first scanning device arranged to scan the scene using light coupled from an optical waveguide via an optical coupling structure.

[0018] Optionally, a first scanning device is arranged between the irradiation device and the optical waveguide, and the first scanning device is configured to deflect the light emitted by the irradiation device to cover an angular range, such that the light coupled out from the optical waveguide covers the corresponding angular range.

[0019] Optionally, the first scanning device is associated with the first of the two main outer surfaces.

[0020] Optionally, the system further includes a collimating optics arranged in the optical path between the irradiation device and the optical waveguide for collimating the light before it is coupled into the optical waveguide by the light emitted by the irradiation device.

[0021] Optionally, the system further includes: an optical component arranged in the optical path between the irradiation device and the optical waveguide, and configured to perform aperture expansion of the light emitted by the irradiation device in at least a first dimension.

[0022] Optionally, the system further includes a second scanning device associated with the first of the two primary outer surfaces and configured to scan a second dimension orthogonal to the first dimension.

[0023] Optionally, the optical components are configured to perform the expansion of light emitted by the irradiation device in a first dimension and a second dimension orthogonal to the first dimension.

[0024] Optionally, the optical component includes: a light-transmitting substrate for guiding light emitted by the irradiation device via internal reflection, and a second light coupling structure associated with the substrate for coupling a portion of the light guided by the substrate toward the light waveguide and out of the substrate.

[0025] Optionally, the optical coupling structure includes multiple partially reflective surfaces arranged obliquely within the optical waveguide relative to the two main outer surfaces.

[0026] Optionally, the optical coupling configuration includes a diffractive optical element associated with at least one of the two main outer surfaces.

[0027] Optionally, the system further includes an optical coupling structure associated with and configured to couple light into the optical waveguide for propagation within the waveguide via internal reflection.

[0028] Optionally, the irradiation device includes multiple light beam sources configured to produce light of different corresponding wavelengths.

[0029] Optionally, the illumination device also includes a beam combiner for combining the light generated by the beam source into a combined beam.

[0030] Optionally, the wavelength is in the near-infrared region of the electromagnetic spectrum.

[0031] Alternatively, the beam source is implemented as a laser source.

[0032] Optionally, the laser source is a pulsed laser source, and the processing subsystem is electrically associated with the irradiation device and is also configured to control the pulse timing of the laser source.

[0033] Optionally, one of the light sources is configured to generate light in the visible region of the electromagnetic spectrum, and the remaining light sources are configured to generate light of different corresponding wavelengths in the near-infrared region of the electromagnetic spectrum.

[0034] Optionally, the processing subsystem is electrically associated with the irradiation device and is also configured to control the irradiation timing of the irradiation device.

[0035] Optionally, the information associated with the object derived by the processing subsystem includes time-of-flight information.

[0036] Optionally, the information associated with the object derived by the processing subsystem includes the distance from the detector to the object.

[0037] Optionally, the processing subsystem is also configured to construct a three-dimensional representation of the object based on information associated with the object.

[0038] Alternatively, the system is deployed in a ground-based vehicle.

[0039] Optionally, the system is installed on the aircraft.

[0040] Optionally, the optical waveguide has a trapezoidal shape in its cross-section so that lateral scanning of the scene can be achieved using light coupled from the optical waveguide.

[0041] Optionally, the system further includes: a light-transmitting substrate having two pairs of parallel main outer surfaces forming a rectangular cross-section; and an optical coupling structure associated with the substrate, wherein light coupled to the substrate travels through the substrate via quadruple internal reflection, and a portion of the intensity of the light traveling through the substrate is coupled out of the substrate and coupled into an optical waveguide via the optical coupling structure.

[0042] Optionally, the optical waveguide includes two pairs of parallel main outer surfaces forming a rectangular cross-section, and light coupled into the optical waveguide travels through the optical waveguide via quadruple internal reflection.

[0043] Optionally, the system further includes: an optical coupling structure, and an optical waveguide including a first waveguide segment associated with the optical coupling structure and a second optical waveguide segment associated with the optical decoupling structure, wherein light coupled into the optical waveguide travels through the first waveguide segment by internal reflection, and a portion of the intensity of the light traveling through the first waveguide segment is deflected by the optical coupling structure in a first direction to be decoupled from the first waveguide segment and coupled into the second optical waveguide segment to travel through the second optical waveguide segment by internal reflection, and the light traveling through the second optical waveguide segment is deflected by the optical decoupling structure in a second direction to be decoupled from the optical waveguide toward the scene.

[0044] Optionally, the optical coupling structure realizes light scanning in the first dimension, and the optical decoupling structure realizes light scanning in the second dimension which is substantially orthogonal to the first dimension.

[0045] According to an embodiment of the teachings of the present invention, a Light Detection and Ranging (LIDAR) system is also provided. The LIDAR system includes: a transmitter comprising: an optical waveguide having at least two primary outer surfaces for guiding light via internal reflection, one of which is arranged in a facing relationship with a scene; an optical coupling structure associated with the optical waveguide, configured to couple a portion of the light guided by the optical waveguide toward the scene out of the optical waveguide; at least one beam source configured to emit a coherent beam for coupling into the optical waveguide, the coherent beam being collimated before being coupled into the optical waveguide; and a first scanning device arranged to scan the scene using light coupled from the optical waveguide via the optical coupling structure; and a receiver comprising: a detector for sensing light reflected from an object located in the scene in response to illumination of an object by light coupled from the optical waveguide via the optical coupling structure; and a processing subsystem including at least one processor electrically associated with the detector and configured to process signals from the detector to construct a three-dimensional representation of the object.

[0046] Optionally, the processing subsystem is electrically associated with the irradiation device and is also configured to control the irradiation timing of the irradiation device.

[0047] Optionally, the transmitter has an output aperture at least partially defined by an optical coupling structure, and the receiver has an input aperture at least partially defined by a focusing optics, and the input aperture and the output aperture at least partially overlap.

[0048] Optionally, the transmitter has an output aperture at least partially defined by an optical coupling structure, and the receiver has an input aperture at least partially defined by a focusing optics, and the input aperture and the output aperture are non-overlapping.

[0049] The term “optical waveguide” as used in the specification and claims refers to any light-transmitting body formed of a transparent material, preferably a light-transmitting solid, which may be used interchangeably herein as a “light-transmitting substrate,” “light guide,” or “light-guide optical element.”

[0050] Unless otherwise defined herein, all technical and / or scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. Exemplary methods and / or materials are described below, but similar or equivalent methods and materials may be used in the practice or testing of embodiments of the invention. In case of conflict, the patent specification and its definitions shall prevail. Furthermore, materials, methods, and embodiments are illustrative only and not restrictive. Attached Figure Description

[0051] Some embodiments of the invention are described herein by way of example only, with reference to the accompanying drawings. Detailed reference is made to the drawings, emphasizing that the details shown are illustrative and for the purpose of discussing embodiments of the invention in an illustrative manner. In this regard, the description in conjunction with the drawings will make it clear to those skilled in the art how to practice embodiments of the invention.

[0052] Now turn your attention to the accompanying drawings, where the same reference numerals or characters indicate corresponding or identical parts. In the drawings:

[0053] Figure 1 This is a schematic representation of a light detection and ranging (LIDAR) system having a transmitter, a receiver, and a processing system according to a non-limiting embodiment of the present invention, which is arranged in a vehicle for illuminating objects located in a scene;

[0054] Figure 2 It is according to an embodiment of the present invention. Figure 1A schematic representation of the architecture of a LiDAR system, wherein the transmitter has an optical waveguide having a set of partially reflective surfaces arranged within the waveguide for performing aperture expansion, and wherein the transmitter and receiver are arranged in a common aperture configuration.

[0055] Figure 3 It is similar to an embodiment of the present invention. Figure 2 This is a schematic representation, but the transmitter and receiver are arranged in a non-overlapping aperture configuration.

[0056] Figure 4 It is similar to an embodiment of the present invention. Figure 2 This is a schematic representation, but it also includes diffractive optical elements arranged at the output of the optical waveguide;

[0057] Figure 5 This is a schematic front view showing a front view of an optical waveguide of a transmitter according to an embodiment of the present invention, the optical waveguide having an embedded set of partially reflective surfaces for performing aperture expansion;

[0058] Figure 6A and Figure 6B The images show a side view and a bottom view, respectively, schematic representations of an optical waveguide of a transmitter according to an embodiment of the present invention, the optical waveguide having an embedded set of partially reflective surfaces for performing two-dimensional aperture expansion;

[0059] Figure 7 This is a schematic front view showing two optical waveguides of a transmitter according to an embodiment of the present invention, wherein the first optical waveguide has a first set of partially reflective surfaces for performing two-dimensional aperture expansion, and the second optical waveguide has a second set of partially reflective surfaces for performing one-dimensional aperture expansion;

[0060] Figure 8 This is a schematic front view showing an optical waveguide of a transmitter according to an embodiment of the present invention, the optical waveguide having a first set of partially reflective surfaces for performing aperture expansion in a first dimension and a second set of partially reflective surfaces for performing aperture expansion in a second dimension;

[0061] Figure 9 It is similar to an embodiment of the present invention. Figure 2 A schematic representation, but with a scanning device arranged at the output of the optical waveguide; and

[0062] Figure 10 This is a block diagram of the processing subsystem of a LIDAR system, which is configured to process signals from the detectors of the receiver to derive information associated with objects located in the scene. Detailed Implementation

[0063] This invention is a detection and ranging system using optical waveguides.

[0064] The principles and operation of the system according to the present invention can be better understood by referring to the accompanying drawings.

[0065] Before explaining at least one embodiment of the present invention in detail, it should be understood that the invention is not necessarily limited to the details of the construction and arrangement of the components and / or methods set forth in the following description and / or shown in the drawings and / or examples. The invention can be implemented or practiced in various ways and with other embodiments.

[0066] Now refer to the attached diagram, Figure 1 A light detection and ranging (LIDAR) system (interchangeably referred to as the "system") according to a non-limiting embodiment of the invention is shown, generally indicated by reference numeral 10. In the illustrated embodiment, system 10 is arranged in a ground-based motor vehicle 12, which may be an autonomous vehicle (i.e., a "self-driving car"), a driver-operated vehicle, or a computer-assisted driver-operated vehicle (i.e., a "semi-autonomous vehicle"). Although vehicle 12 is schematically shown as a car, vehicle 12 can be implemented as any type of vehicle in which the LIDAR system can be arranged, including but not limited to motorcycles, motorized bicycles, electric bicycles, electric scooters, etc., and ground-based military vehicles (e.g., armored personnel carriers, trucks, armored fighting vehicles, etc.). Furthermore, in some embodiments, all or some components of system 10 of the invention may be arranged separately from the vehicle, for example as part of a helmet or other headgear, which can be particularly useful when system 10 is arranged for vehicles such as motorcycles, in which the driver / operator wears a helmet or headgear while operating the vehicle.

[0067] Generally, system 10 includes a light emitter subsystem 100 (which may be interchangeably referred to herein as the “emitter subsystem” or “emitter”) for generating collimated light and directing it toward scene 30 (also referred to herein as the “region of interest”, “field of interest”, or “field of view”), the collimated light being schematically represented herein by an illumination beam 14; a light receiver subsystem 200 (which may be interchangeably referred to herein as the “receiver subsystem” or “receiver”) for receiving light reflected or backscattered from object 18 in scene 30 in response to illumination from emitter 100; and a processing subsystem 300 associated with emitter subsystem 100 and receiver subsystem 200 for controlling some components of emitter subsystem 100 and for processing signals from receiver subsystem 200 to derive information associated with object 18.

[0068] A scene is generally considered to be any scene in front of transmitter 100 that can be illuminated by transmitter 100. When system 10 is deployed for use with a vehicle, scene 30 is generally considered to be any scene in front of the vehicle that can be illuminated by transmitter 100. In the context of vehicle deployment, objects in the scene that can be detected and imaged by system 100 include, for example, other vehicles in the vehicle path, pedestrians, cyclists, trees, rocks, street signs, streetlights, or any other solid or obstructive objects.

[0069] The scanning device of the transmitter subsystem 100 scans the beam 14 vertically and horizontally (laterally) in the field of interest. The scanning beam 14 is... Figure 1 The double-headed arrow 16 indicates this. Note that the transverse scan is along both the inside and outside of the paper plane, and therefore the transverse scan is... Figure 1 The beam 14 is indistinguishable from the object 18. Upon impact with the object 18, the beam 14 is reflected or backscattered by the object 18 as reflected light, schematically represented here by multiple rays 20. Some of the reflected light 20, schematically represented here by ray 22, reaches the receiver subsystem 200 for detection by the receiver subsystem 200 (specifically, a photodetector, as will be discussed in further detail below). The processing subsystem 300 processes the signal from the receiver subsystem 200 to derive information associated with the object 18, such as time-of-flight (TOF) information, range (i.e., distance) information (based on TOF), and direction of arrival information. In some embodiments, this information may be used by the processing subsystem 300 to construct a three-dimensional (3D) representation (i.e., point cloud) of the object 18, which can then be used to render a 3D image of the object 18.

[0070] Now refer to Figure 2 The diagram illustrates a schematic representation of a system 10 according to a non-limiting embodiment of the invention. The transmitter 100 includes an illumination and beam combining unit 102, an optical waveguide 120, and an optical coupling configuration 118 for coupling light from the illumination and beam combining unit 102 into the optical waveguide 120. The optical waveguide 120 is a light-transmitting substrate formed of a transparent material (e.g., glass) having multiple surfaces, including at least a pair of preferably parallel surfaces (also referred to herein as "primary outer surfaces") 122 and 124 for guiding light via internal reflection. At one of the surfaces 122, the light is coupled to a scene (e.g., Figure 1 The optical waveguide 120 is arranged in a facing relationship in the scene 30 (shown including object 18). The receiver 200 preferably includes: a focusing optics 202 for receiving light 22 reflected from an object (e.g., object 18) in the scene and converting the received light into a converging beam of captured light; and a photodetector (which may be interchangeably referred to as a "detector" or "optical sensor") 204 for sensing the captured light and generating a signal indicating at least one parameter (intensity) of the captured light.

[0071] The illumination and beam combining unit 102 includes an illumination device 104 arranged to emit a beam for coupling into the optical waveguide 120. The illumination device 104 includes at least one beam source, preferably at least two beam sources, and more preferably at least three beam sources. For example, the beam sources (which may be interchangeably referred to herein as “light source,” “illumination source,” or “source”) are preferably implemented as a group (i.e., multiple) of laser sources, such as laser diodes, fiber lasers, or microchip lasers, each configured to generate (i.e., produce) a coherent beam of corresponding laser illumination. In some non-limiting implementations, the laser sources are arranged side-by-side to emit separate laser beams in a common direction to form a combined beam. In other non-limiting embodiments, the illumination device 104 also includes a beam combiner (not shown), and the laser sources are arranged at various positions relative to the beam combiner to combine the beams from the individual beam sources into a combined beam. Beam combiners are well known in the art and can be implemented in various ways, such as using beam splitter devices, dichroic mirrors, prisms, etc.

[0072] In some non-limiting embodiments, one of the beam sources is implemented as a visible light laser source configured to generate laser light in the visible region of the electromagnetic spectrum, and the remaining beam sources are implemented as NIR laser sources configured to generate laser light of different corresponding wavelengths in the NIR region of the electromagnetic spectrum. In a set of preferred but non-limiting implementations, the beam sources are implemented as a set of two or three modulated NIR laser sources and visible light laser sources placed side by side or combined via a beam combiner. The visible light laser sources can be modulated for distance detection or modulated to not transmit simultaneously during NIR laser transmission. Alternatively, the visible light laser can be configured to operate in continuous wave (CW) mode. The visible light laser sources are preferably configured to generate light with wavelengths (e.g., wavelengths in the range of 420 nm to 680 nm) corresponding to colors easily distinguishable by the human eye. In embodiments where NIR laser sources generate light of different corresponding wavelengths, three NIR laser sources combined with visible light laser sources emitting light at approximately 940 nm (e.g., 935 nm, 940 nm, and 935 nm respectively) have been found to be particularly suitable for LiDAR applications. It should be noted that a significantly high proportion of solar radiation intensity at wavelengths near 940 nm is typically absorbed by the atmosphere, and therefore sunlight near 940 nm tends not to strike the photosensor, or strikes it at a relatively low intensity compared to the light to be detected by the photosensor. It should also be noted that all beam sources can emit beams of the same wavelength (e.g., all at 940 nm). Furthermore, while visible light lasers can be used in conjunction with NIR lasers for eye-safe purposes, eye-safe lasers outside the NIR and visible regions can also be used. For example, lasers at the lower end of the short-wavelength infrared (SWIR) region, particularly those near 1550 nm, are safer for the eyes than lasers in the NIR region.

[0073] Using a light source that emits light at different corresponding wavelengths allows the receiver 200 to detect a wide variety of materials, as some types of materials may have a greater spectral response to certain wavelengths than to others. For example, plants typically exhibit higher light reflectance at wavelengths around 700 nm. Variations in spectral response also allow the processing subsystem 300 to map a scene by identifying wavelength-dependent changes in the signal intensity generated by the detector 204.

[0074] In addition to having beam sources and, in some cases, beam combiners, the illumination apparatus 104 may also include various components that can be used to modify the parameters of the beam generated by the beam sources. Such components include, but are not limited to, modulators for modulating the beam intensity and / or phase and / or frequency, and amplifiers for amplifying the intensity signal of the generated beam. In some non-limiting implementations, each beam source is associated with both a modulator and an amplifier. In other implementations, only some beam sources are associated with both a modulator and / or an amplifier.

[0075] The emission timing of the beam source and the modulation and / or amplification of the beam generated by the beam source are preferably controlled by the processing subsystem 300. In some embodiments, the beams generated by the beam sources are coherently combined, and each beam source has an associated phase modulator that allows adjustment of the relative phase shift between the beams to maintain the phase coherence of the beams. In such an embodiment, the processing subsystem 300 measures the relative phase shift between the beams and actuates the phase modulator to adjust the phase shift.

[0076] The light emitted by the irradiation device 104 can be unpolarized or polarized. To generate polarized light, the irradiation device 104 may include a linear polarizer disposed at the output of the beam source or the output of the beam combiner, such that the combined beam passes through the linear polarizer. If the beam source itself is a polarized light source, such a linear polarizer is not required.

[0077] A combined beam of light from a beam source, schematically indicated by a thick arrow and generally labeled as reference numeral 108, is scanned by scanning device 106. Scanning device 106 preferably includes: optical components for redirecting (i.e., deflecting) the incident beam; and electromechanical components (e.g., electromechanical actuators) for adjusting the position and / or orientation of the optical components to achieve beam divergence in a desired direction. Scanning device 106 can be implemented as any suitable beam divergence or beam redirection mechanism, including, for example, a single scanning or tilting mirror performing scanning in two orthogonal dimensions (e.g., vertical and horizontal / lateral), a pair of orthogonal single-axis scanning or tilting mirrors, and a set of prisms, wherein one or more of the prisms can rotate / tilt about one or more rotational / tilting axes. Preferably, scanning device 106 is electrically associated with processing subsystem 300, which controls the scanning operation of scanning device 106.

[0078] A collimating optics device 110 is arranged in the optical path between the scanning device 106 and the optical waveguide 120. The collimating optics device 110 includes at least one optical component that collimates the scanning beam 108 onto the output aperture (i.e., exit pupil) of the illumination and beam combining unit 102. In the illustrated embodiment, the collimating optics device 110 includes a pair of collimating optical elements, schematically shown as lenses 112 and 114, forming an intermediate image plane 116 between lenses 112 and 114. In some non-limiting implementations, a micro-lens array (MLA) or diffuser is arranged at the image plane 116 to match the exit pupil of the illumination and beam combining unit 102 to the entrance pupil (i.e., input aperture) of the optical waveguide 120. This aperture matching by the MLA or diffuser disperses the intensity of the beam 108 across the input aperture of the optical waveguide 120, thereby reducing the overall intensity of the beam 108 to be coupled into the optical waveguide 120. The reduced intensity of beam 108 further enhances eye safety and is therefore preferably implemented using an MLA or diffuser for aperture matching. Collimating optics 110 also generates a pupil image between the plane of scanning device 106 and the exit pupil plane of illumination and beam combining unit 102 (adjacent to optical coupling structure 118), such that all scanned beams are transmitted through the exit pupil of illumination and beam combining unit 102 and into optical waveguide 120. It should be noted that illumination device 104 itself may have a small exit pupil, and therefore the use of an MLA may not be necessary unless uniform beam output is required. It should also be noted that in some embodiments, illumination device 104 may include collimating optics such that the combined beam 108 from the beam source is a collimated beam. For example, some beam combiners employ embedded collimating optics such that the individual beams are collimated by the beam combiner in addition to being combined by it. In such an implementation, the collimating optics 110 may not be necessary, or the collimating optics 110 may be used to re-collimate the beam 108 if the beam becomes decollimated due to scanning by the scanning device 106.

[0079] The scanning and collimating beam from the illumination and beam combining unit 102 is coupled into the optical waveguide 120 via an optical coupling configuration 118, schematically represented herein as a coupling prism at an appropriate angle. Other suitable optical coupling configurations for coupling illumination into the optical waveguide 120, for example, by using a coupling reflector or diffractive optics, are well known in the art. The coupled beam propagates (i.e., is guided) through the optical waveguide 120 by repeated internal reflections at surfaces 122 and 124. The propagating beam 128 (generally designated) is schematically represented by a thick arrow. In some preferred but non-limiting implementations, the propagation through the optical waveguide 120 by internal reflection is in the form of total internal reflection (TIR), whereby illumination (beam 128) incident at surfaces 122 and 124 at an angle greater than a critical angle results in reflection of the illumination at surfaces 122 and 124. As is well known in the art, the critical angle is defined by the refractive index of the material constituting the optical waveguide 120 and the refractive index of the medium (e.g., air) in which the optical waveguide 120 is disposed. In other non-limiting implementations, propagation through the optical waveguide 120 via internal reflection is achieved by a reflective coating (e.g., an angle-selective reflective coating) applied to surfaces 122 and 124.

[0080] The light beam 128 propagates within the optical waveguide 120 and strikes an optical coupling structure associated with the waveguide 120. In the illustrated embodiment, this structure is implemented as a series of parallel partially reflective surfaces 126 arranged at an angle to surfaces 122 and 124 within the waveguide 120, wherein a portion of the intensity of the light beam 128 is reflected toward the scene (e.g., Figure 1 In scenario 30), the optical waveguide 120 is coupled out. The partially reflective surface 126 can extend along the elongation direction of the optical waveguide 120 (in...). Figure 1 The reflective surfaces 126 are spaced evenly (vertically) or may be non-uniformly spaced. The partially reflective surfaces 126 are typically formed from a transparent plate coated with a suitable coating that provides the desired reflective pattern. In some non-limiting embodiments, the coating is a dielectric coating, while in other embodiments, the coating comprises portions of a metallic material (e.g., silver) arranged in a predetermined pattern on the transparent plate. The portions of the metallic material can take various shapes, including, for example, dots, elongated elliptical dots, and lines, depending on the desired reflective pattern.

[0081] It should be noted that the partially reflective surface 126 illustrates only one non-limiting optical coupling configuration suitable for use with the optical waveguide 120, and other optical coupling configurations may be used to couple illumination out of the optical waveguide 120. The optical coupling configuration can be any optical coupling device that deflects the portion of illumination propagating within the optical waveguide 120 by an angle through internal reflection, such that the deflected portion of illumination leaves the optical waveguide 120. Other examples of such suitable optical coupling devices include, but are not limited to, one or more diffractive optical elements arranged on either surface 122 or surface 124.

[0082] exist Figure 2 In the non-limiting implementation shown, each of the partial reflective surfaces 126 reflects (couples out) a certain proportion of the guided beam 128 from the optical waveguide 120 toward the scene, wherein the reflected beam is schematically represented by beams 130A, 130B, and 130C (which correspond to the beams guided to the scene). Figure 1 (Scanning beam 14 in scene 30). In some non-limiting implementations, the reflectivity of the partially reflective surface increases along the elongation direction of the optical waveguide 120 from the near end of the optical waveguide 120 (which is adjacent to the optical coupling structure 118) to the far end, which is generally opposite to the near end. In a particularly preferred but non-limiting implementation, the last partially reflective surface (e.g., the partially reflective surface of the reflective illumination 128 to generate the coupled beam 130C) is totally reflective (i.e., 100% reflectivity).

[0083] The effect of the optical waveguide 120 and the optical coupling configuration on the beam 108 from the illumination and beam combining unit 102 is that, as the beam 128 propagates within and couples out of the optical waveguide 120, the output aperture (exit pupil) of the illumination and beam combining unit 102 is multiplied (i.e., expanded). This aperture expansion (aperture multiplication) can be in one dimension (e.g., in...). Figure 2 (The case of the non-limiting implementation of the optical waveguide 120 in the middle), or it can be in two dimensions.

[0084] Details of optical waveguides used in near-eye displays can be found in various commonly owned patents that perform a one-dimensional aperture expansion on image illumination generated by an image projector with a small output aperture for coupling to the viewer's eye. These patents include the following patents, the entire contents of which are incorporated herein by reference: U.S. Patent Nos. 6,829,095, 7,577,326, 7,724,444, 7,751,122, 9,551,880, and 9,025,253. Details of optical waveguides used in near-eye displays can also be found in various commonly owned patents that perform a two-dimensional aperture expansion on image illumination generated by an image projector with a small output aperture for coupling to the viewer's eye. These patents include the following patents, the entire contents of which are incorporated herein by reference: U.S. Patent Nos. 10,133,070 and 10,551,544.

[0085] It should be noted that while surfaces 122 and 124 are preferably parallel to each other, the parallelism requirement is less stringent for optical waveguides used in non-display applications, such as optical waveguide 120 in this embodiment, where the waveguide is used to illuminate a scene using laser illumination covering a desired angular range. This contrasts with the optical waveguides in the aforementioned common patents, where any deviation in the parallelism between the main outer surfaces would result in the formation of a non-conjugate image set through the waveguide, leading to a degraded image quality from the waveguide to the viewer's eye.

[0086] It should be noted that in many LiDAR system configurations (referred to as "common aperture" configurations), the receiver unit is located at the same aperture as the transmitter unit. The benefits of using a common aperture configuration include the absence of parallax effects that interfere with the LiDAR system and a more compact system. Figure 2A non-limiting embodiment of the system 10 shown utilizes a common aperture configuration. Here, the receiver 200 is associated with surface 124 of the optical waveguide 120 so as to be located behind the optical waveguide 120. The input aperture of the system 10 (which is the input aperture of the receiver 200 and is generally defined by the focusing optics 202) is contained within (i.e., completely overlapped with) the output aperture of the system 10 (which is the output aperture of the transmitter 100 and is generally defined by a combination of the optical waveguide 120 and the optical coupling configuration (e.g., the distribution of partially reflective surfaces within the optical waveguide 120). Reflected light 22 from the scene (i.e., light reflected by objects in the scene), here represented as rays 22A, 22B, and 22C, passes through the optical waveguide 120 so as to be received by the focusing optics 202 associated with surface 124. In particular, light 22 is transmitted through surface 122, through partially reflective surface 126, and through surface 124 to the focusing optics 202. In a configuration where the partial reflective surfaces 126 are arranged in a spaced-apart relationship so as not to overlap and to be discontinuous (i.e., there is a space between the end of one partial reflective surface and the beginning of the next), some or all of light 22A, light 22B, and light 22C can pass directly through the optical waveguide 120 through the empty space between adjacent pairs of partial reflective surfaces. In other configurations, a portion of the intensity of light 22A, 22B, and 22C can be transmitted through the partial reflective surfaces 126 to reach the focusing optics 202.

[0087] A focusing optics device 202, schematically represented as a lens (but may include a set of lenses), is arranged in the optical path between the scene and the photodetector 204. The focusing optics device 202 receives light 22A, light 22B, and light 22C from the scene (i.e., light reflected by an illuminated object in the scene) and converts the received light 22A, light 22B, and light 22C into a converging beam (schematically represented as ray 23A, ray 23B, and ray 23C) that strikes the detector 204. In some implementations, the focusing optics device 202 forms an image of the object on the detector 204. The focusing optics device 202 is preferably arranged to define a field of view corresponding to an area or portion of the scene illuminated by the emitter 100, so as to capture light reflected from objects in the illuminated scene. In some embodiments, a passband spectral filter may be arranged in the optical path from the scene to the detector 204 to block light of wavelengths outside the given wavelength range generated by the illumination device 104 from reaching the detector 204. The spectral filter can ideally be positioned between the focusing optics 202 and the detector 204, but can alternatively be arranged between the surface 124 and the focusing optics 202.

[0088] The outer surface of the optical waveguide 120 (i.e., surface 122, surface 124) is preferably coated with an anti-reflective coating to prevent the optical waveguide 124 from scattering the light emitted by the transmitter 100 back to the receiver 200.

[0089] In embodiments where the irradiation device 104 emits polarized light, the partially reflective surface is preferably polarization-sensitive, such that the proportion of the intensity of the polarized light reflected by the partially reflective surface depends on the polarization direction of the propagating beam. In embodiments where the transmitted beams 130A, 130B, and 130C are polarized, a polarizer (not shown) is preferably arranged in the optical path between the receiver 200 and the optical waveguide 120 (e.g., associated with surface 124) to substantially suppress saturation of the receiver 200. Note that such suppression may come at the cost of 50% transmittance of the light 22 from the scene.

[0090] Continue to refer to Figure 1 and Figure 2 In this case, now refer to Figure 3 It shows a schematic representation of a system 10 according to another non-limiting embodiment of the present invention, which is consistent with the reference. Figure 2 The described implementation is essentially similar, but features a "non-overlapping aperture" configuration. Here, the receiver 200 is positioned adjacent to the transmitter 100 such that the system's input aperture (i.e., the input aperture of the receiver 200) is separated from the system's output aperture (i.e., the output aperture of the transmitter 100). While this configuration results in a less compact system, it can be particularly valuable in situations where residual reflections from the illumination and beam combining unit 102 are expected to saturate the receiver 200.

[0091] In addition to having non-overlapping apertures, Figure 3The illustrated embodiment features a simplified illumination and beam combining unit 102. Here, the collimating optics have only a single collimating optical element 112, eliminating the need for an intermediate image plane. As a result, the collimating optics do not perform pupil imaging, and the exit pupil of the illumination and beam combining unit 102 does not overlap with the entrance pupil of the optical waveguide 120. The simplified structure of the illumination and beam combining unit 102 in the illustrated embodiment can be used, especially if the exit pupil of the illumination and beam combining unit 102 is much smaller than the entrance pupil of the optical waveguide 120, so that the beam 108 at the output of the illumination and beam combining unit 102 travels through the entrance pupil into the optical waveguide 120 but remains within the optical waveguide 120, minimizing energy loss. The necessary size difference between the exit pupil of the illumination and beam combining unit 102 and the entrance pupil of the optical waveguide 120 can be achieved, for example, by generating a narrow beam 108 to reduce the size of the exit pupil of the illumination and beam combining unit 102 and / or increasing the thickness of the optical waveguide 120 (i.e., the distance between surfaces 122 and 124) to increase the size of the entrance pupil of the optical waveguide 120.

[0092] It should be noted that the receiver 200 can be arranged relative to the transmitter 100 such that a portion of the focusing optics 202 is associated with the surface 124 (i.e., a portion of the focusing optics 202 is located behind the optical waveguide 120), and the remaining portion of the focusing optics 202 is positioned adjacent to the optical waveguide 120. In such an arrangement, the input aperture of the receiver 200 defined by the focusing optics 202 overlaps with a portion of the output aperture of the transmitter 100.

[0093] exist Figure 2 and Figure 3 In the non-limiting embodiment shown, the scanning device 106 scans the transmission field by deflecting the light from the irradiation device 104, causing the scanning beam 108 to strike the optical coupling structure 118 at a varying incident angle, thereby coupling the irradiation from the irradiation device 104 into the optical waveguide 120 within a corresponding coupling angle range. The angular scanning expansion of the beam 108 at the optical coupling structure 118 causes a corresponding angular expansion of the propagating beam 128, resulting in output beams 130A, 130B, and 130C coupling out of the optical waveguide 120 within corresponding angular ranges for irradiating and scanning the scene.

[0094] Figure 4 The diagram illustrates a method for increasing the angular range of the output beam, showing a schematic representation of a system 10 according to yet another non-limiting embodiment of the invention. Figure 4 The implementation methods shown are generally similar to Figure 2The embodiments shown are similar, except that diffractive optical elements 140, such as one or more diffraction gratings, are arranged in front of the output aperture of the emitter 100 (i.e., associated with surface 122 and between surface 122 and the scene). In some non-limiting implementations, the diffractive optical elements 140 are mechanically positioned adjacent to surface 122 so as to be associated with surface 122 and span the entire coupling region of surface 122, which is defined as the portion of surface 122 spanned by the projection of the partially reflecting surface 126 in a projection plane parallel to the plane of surface 122. Preferably, the diffractive optical elements 140 span a large portion of the length of surface 122 (this length is within...). Figure 4 (in the vertical direction) so as to cover at least 80% of the length of the surface 122, and more preferably at least 90% of the length of the surface 122.

[0095] In the illustrated embodiment, the beam sources operate at different corresponding wavelengths (i.e., the light emitted by each beam source has a different corresponding wavelength), and the combined beam 128 is not dispersed as it propagates through the optical waveguide 120. When the coupled beams 130A, 130B, and 130C pass through the diffractive optical element 140, they are dispersed by the diffractive optical element 140 to generate corresponding dispersed beams, schematically represented by thick dashed arrows and generally designated as dispersed beams 136A, 136B, and 136C, thereby increasing the angular range covered by beams 130A, 130B, 130C, 136A, 136B, and 136C. When using a common aperture configuration, as... Figure 4 As shown, the diffractive optical element 140 also directs additional reflected light from the scene (here indicated by rays 32A, 32B, and 32C) toward the receiver 200 for capture by the detector 204. It should be noted that, although... Figure 4 A common aperture configuration is shown, but the diffractive optical element 140 can be used for similar purposes. Figure 3 In the non-overlapping aperture configuration shown, the diffractive optical element 140 is not arranged in front of the receiver 200. In this embodiment, the diffractive optical element 140 only deflects the output beams 130A, 130B, and 130C (in order to generate corresponding beams 136A, 136B, and 136C), and does not deflect any incident light from the scene toward the receiver 200.

[0096] As described above, the optical waveguide 120 can be implemented in various ways to achieve expansion of the input aperture in one or two dimensions. The following paragraphs describe various implementation options of the optical waveguide 120 to enable scanning of the scene and aperture expansion via the coupled beam.

[0097] Continue to refer to Figure 2 and Figure 4 In the case of, also refer to Figure 5 This shows a front view of an optical waveguide 120 according to a non-limiting embodiment of the present invention. Although the optical waveguide 120 is in the first plane ( Figures 2 to 4 The optical waveguide 120 has a rectangular cross-section in the plane of the paper (assuming surfaces 122 and 124 are parallel), but surface 122 itself is trapezoidal, so that the optical waveguide 120 has a trapezoidal cross-section in the coupling plane (orthogonal to the first plane). Here, the parallel top surface 132 and the parallel bottom surface 134 have different lengths, causing the left side surface 142 and the right side surface 144 to taper inward. The coupled beam 128 propagates through internal reflection between surfaces 122 and 124, but also... Figure 2 Coupled in the vertical direction within a certain angular range, which corresponds to Figure 5 Lateral scan of beam 128 (in) Figure 2 and Figure 4 (within and outside the page), where the horizontal scan 150 of beam 128 is composed of... Figure 5 The double-headed arrow in the diagram indicates this. Vertical scanning of the beam also exists, as described above, achieved through the angular scanning extension of beam 108 at the optical coupling structure 118, but... Figure 5 It is not discernible in the front view shown.

[0098] Figure 6A and Figure 6B Schematic side and bottom views of an implementation of an optical waveguide 120 according to another non-limiting embodiment of the invention are shown. Here, the optical waveguide 120 has an elongation direction corresponding to the vertical direction as shown arbitrarily, and includes two pairs of parallel surfaces forming a rectangular cross-section, namely surfaces 122, 124, 142, and 144. A partially reflective surface 126 at least partially traverses the optical waveguide 120 at an angle to the elongation direction. An optical coupling configuration (not shown here) and an illumination and beam combining unit 102 are arranged relative to the optical waveguide 120 to direct the input beam (e.g., Figures 2 to 4 The light beam 108 is coupled into the optical waveguide 120, wherein the initial propagation direction is at an inclined coupling angle relative to the first pair of parallel surfaces, namely surfaces 122, 124, 142, and 144. The light beam 128 travels along the optical waveguide 120 through quadruple internal reflection (i.e., in a spiral manner to propagate in two dimensions), wherein a portion of the intensity of the light beam 128 reflected at the partially reflecting surface 126 is directed toward the scene and coupled out of the optical waveguide 120. The spiral propagation of the light beam 128 couples out light beams 130A, 130B, and 130C (in... Figure 6B The effect (usually represented as 130) is that the coupled beam is both perpendicular (e.g., Figure 6A(As indicated by the double-headed arrow in the image) and horizontally (as shown in the image) Figure 6B The double-headed arrows in the image indicate that the scene is being scanned effectively.

[0099] Figure 7 A construction according to another non-limiting embodiment of the invention is shown, wherein a pair of optical waveguides 220 and 320 are used to perform vertical and lateral scanning. Here, the first optical waveguide 220 is similar to the reference designation. Figure 6A and Figure 6B The optical waveguide described, and the second optical waveguide 320 is similar to the reference. Figure 5 The optical waveguide described. The first optical waveguide 220 has an extension direction corresponding to the horizontal direction as shown arbitrarily, and two pairs of parallel planes form a rectangular cross section. Figure 7 Only a pair of parallel faces 222 and 224 are shown, but there are also faces that are parallel to each other. Figure 6B A second pair of parallel surfaces, similar to surfaces 142 and 144, are included. Multiple partially reflective surfaces 226 traverse at least partially across the first optical waveguide 220 at an angle to the direction of extension. The second optical waveguide 320 is optically coupled to the first optical waveguide 220 and has a pair of parallel surfaces. Figure 7 Only one of the surfaces 332 is shown in the diagram, and a second optical waveguide 320 is arranged with surface 332 facing the scene to be illuminated. The second optical waveguide 320 also includes a parallel top surface 332 and bottom surface 334, as well as a left side surface 342 and a right side surface 344. Figure 5 Similarly, surfaces 332 and 334 have different lengths, causing side surfaces 342 and 344 to taper inwards. Here, multiple partially reflective surfaces 326 also traverse the second optical waveguide 320 at least partially at an angle to surface 332. Partially reflective surfaces 226 and 326 are arranged such that partially reflective surface 226 is located in a first set of mutually parallel planes, and partially reflective surface 326 is located in a second set of mutually parallel planes inclined relative to the first set of planes.

[0100] The optical coupling between optical waveguides 220 and 320, the arrangement and configuration of partially reflective surfaces 226 and 326, and the coupling structure (not shown here) are arranged with the illumination and beam combining unit 102 such that when the output beam from the illumination and beam combining unit 102 (e.g., Figures 2 to 4When beam 108 is coupled into the first optical waveguide 220 with an initial propagation direction inclined at coupling angles relative to two pairs of parallel planes of the first optical waveguide 220, the coupled beam 228 travels along the optical waveguide 220 via quadruple internal reflection, wherein a portion of the intensity of beam 228 is reflected at the partially reflecting surface 226 to couple into the second optical waveguide 320 as illumination (schematically represented by beams 230A, 230B, 320C), and then propagates within the second optical waveguide 320 (i.e., between the surface 230A and the other surface parallel to surface 332) via double internal reflection, wherein a portion of the intensity of illuminations 230A, 230B, 320C is reflected at the partially reflecting surface 326 to couple out of the second optical waveguide toward the scene (via surface 332). The beam coupled out of the second optical waveguide 320 via the partially reflecting surface 326 (from...) Figure 7 (The page appears) Beams 330A-1, 330A-2, 330A-3, 330B-1, 330B-2, 330B-3, 330C-1, 330C-2, and 330C-3 are represented by solid black circles. Here, the scanning achieved by the first optical waveguide 220 is given a lateral ( Figure 7 The horizontal scan indicated by the double-headed arrow in the image is enhanced.

[0101] Clearly, compared to optical waveguides that perform one-dimensional aperture expansion, the reference... Figures 6A to 7 The described optical waveguide performs two-dimensional aperture expansion to generate a greater number of pupil images and reduces the concentration of illumination intensity.

[0102] Structurally similar to a reference Figures 6A to 7 Further details regarding the structure and operation of the described optical waveguide can be found in the aforementioned U.S. Patent No. 10,133,070.

[0103] Figure 8 A schematic front view of an optical waveguide 420 according to another non-limiting embodiment of the present invention is shown. Here, the optical waveguide 420 consists of two substrate sub-sections, namely a first waveguide segment 421 and a second waveguide segment 423. The dashed line represents the plane 425 separating the two segments, namely 421 and 423. As can be seen from the figure, the two segments, namely 421 and 423, have a trapezoidal shape in the coupling plane of the optical waveguide 420, wherein the coupling plane is represented by plane 432.

[0104] A first set of partially reflective surfaces 426a is arranged in a first segment 421 of the optical waveguide 420, inclined relative to planes 424 and 425, while a second set of partially reflective surfaces 426b is arranged in a second segment 423 of the optical waveguide 420, inclined relative to plane 432. Furthermore, the plane containing the partially reflective surfaces 426a is inclined or perpendicular to the plane containing the partially reflective surfaces 426b.

[0105] The arrangement and configuration of the partial reflective surfaces 426a, 426b, and the coupling structure (not shown here) with the arrangement of the illumination and beam combining unit 102, such that when the output beam from the illumination and beam combining unit 102 (e.g., Figures 2 to 4 When beam 108 is coupled into the first segment 421 of the optical waveguide 420, the coupled beam 428 propagates in the first guiding direction through double internal reflection between planes 424 and 425 within the first segment 421, wherein a portion of the intensity of beam 428 is reflected at a partially reflecting surface 426A to be coupled as illumination (schematically represented by beams 430A, 430B, and 420C) into the second segment 423 of the optical waveguide 420, and then through a surface 432 and another surface parallel to surface 432 ( Figure 8 The double reflection within the second segment 423 of the optical waveguide (indistinguishable from the first guiding direction) propagates in the second guiding direction (inclined from the first guiding direction), wherein a portion of the intensity of illuminations 430A, 430B, and 423C is reflected at the partially reflective surface 426b to couple out the second segment 423 of the optical waveguide 420 toward the scene (via surface 432). The light beam coupled from the second segment 423 of the optical waveguide 420 through the partially reflective surface 426B (from...) Figure 8 (The following appears to be a list of beams:) 530A-1, beam 530A-2, beam 530A-3, beam 530B-1, beam 530B-2, beam 530B-3, beam 530C-1, beam 530C-2, and beam 530C-3 are represented by solid black circles. In the structure shown, the first segment 421 and the first set of partial reflective surfaces 426A achieve aperture expansion in the first dimension, i.e., lateral aperture expansion and beam scanning (represented by the double-headed arrows in the first segment 421), and the second segment 423 and the second set of partial reflective surfaces 426B achieve aperture expansion in the second dimension (orthogonal to the first dimension), i.e., vertical aperture expansion and beam scanning (represented by the double-headed arrow group in the second segment 423).

[0106] Further details of the structure and operation of optical waveguides employing partially reflective surface groups with different orientations can be found in the aforementioned U.S. Patent No. 10,551,544, which uses partially reflective surface groups to redirect propagating illumination from one guiding direction to another and to couple illumination out of the optical waveguide.

[0107] Although the LIDAR system implementation described so far relates to a transmitter subsystem employing a scanning device as part of the illumination and beam combining unit, other implementations are possible, such as arranging an external scanning device at the output of the optical waveguide. Now refer to... Figure 9 The illustration shows a schematic representation of a system according to a non-limiting embodiment of the invention, which is generally similar to the reference. Figure 2 The described embodiment, however, has an external scanning device 160 associated with surface 122 and arranged at the output of optical waveguide 120, instead of a scanning device 106 arranged as part of illumination and beam combining unit 102.

[0108] In some embodiments, the scanning device 160 is configured to perform a two-dimensional scan, while in other embodiments, it is configured to perform a one-dimensional scan. In embodiments where the scanning device 160 performs a two-dimensional scan, the collimating optics 110 collimates the beam 108 transmitted by the illumination device 104 (optionally using pupil imaging, as indicated by the image plane 116), and the collimated beam 108 is coupled into the optical waveguide 120 for aperture multiplication via propagation through internal reflection and coupling out through the partially reflective surface 126. Here, the coupled beams 130A, 130B, and 130C illuminate a single direction, and the scanning device 160 vertically and laterally deflects beams 130A, 130B, and 130C to perform vertical and lateral scans, thereby scanning the entire region of interest two-dimensionally. The deflected beams generated by the scanning device 160 from beams 130A, 130B, and 130C... Figure 9 The image is schematically represented by beams 136A, 136B, and 136C. Note that the lateral scan occurs both within and outside the plane of the paper, and is therefore achieved by the deflected beams 136A, 136B, and 136C. Figure 9 It is indistinguishable from the middle.

[0109] In an embodiment where the scanning device 160 performs a one-dimensional scan (e.g., a vertical scan), the illumination and beam combining unit 102 further includes an optical component 170 disposed at the output of the illumination device 104 and upstream of the collimating optics 110, configured as a one-dimensional beam expander to generate illumination lines in the far field and on the image plane 116. In a non-limiting implementation of such an embodiment, the optical component 170 is implemented as a one-dimensional scanning device (similar to) that generates illumination lines at high speed. Figure 2 (106 in the image), thereby generating a high-resolution scene when imaged by detector 204. In another non-limiting implementation, optical component 170 is implemented as a diffuser (i.e., a light-scattering optical element) or a cylindrical lens.

[0110] According to a non-limiting implementation based on other embodiments, the optical component 170 is implemented as a two-dimensional beam expander illuminating a rectangular field. An example of such a two-dimensional beam expander is shown in reference [reference]. Figure 6A and Figure 6B The described optical waveguide has an embedded partially reflective surface. In such an implementation, detector 204 is preferably implemented as a rectangular pixel array to enable simultaneous distance detection from an array of illumination points in the field of interest. Such an implementation may not necessarily require an external scanning device 160; however, a scanning device 160 may be included to further expand the size of the scanned field in the vertical and / or lateral dimensions.

[0111] The scanning device 160 can be implemented as any suitable beam divergence or beam steering mechanism, including but not limited to a single scanning or tilting mirror performing scanning in two orthogonal dimensions, a pair of orthogonal single-axis scanning or tilting mirrors, or a set of prisms having one or more prisms that can rotate / tilt about one or more rotation / tilt axes. Preferably, the scanning device 160 is electrically associated with the processing subsystem 300, which controls the scanning operation of the scanning device 160.

[0112] The following paragraphs describe the processing subsystem 300, and specifically, describe the components of the processing subsystem 300 and the processing and control functions provided by the processing subsystem 300. Generally, the processing subsystem 300 is electrically associated with components of the transmitter 100 and the receiver 200 to provide processing and control functions to the subsystems of the LIDAR system 10. Specifically, the processing subsystem 300 is electrically associated with the detector 204 and is configured to process signals from the detector 204 to determine the relationship with illuminated objects in the scene (e.g., Figure 1 Information associated with object 18 in the image. In some embodiments, the processing subsystem 300 may use the derived information to construct a 3D representation of object 18 and / or a scene mapping based on the identification of wavelength-related variations in the signal generated by detector 204. The processing subsystem 300 is also electrically associated with illumination device 104 and is configured to control various illumination parameters of illumination device 104, including but not limited to the illumination timing of the beam source (e.g., the start and stop times of laser source emission and pulse duration), the modulation of the beam generated by the beam source, and the output power of the beam source (controlled via amplifier). The output power of each beam source may be dedicated.

[0113] The processing subsystem 300 is preferably further configured to synchronize the detector 204 with the illumination timing of the light source, so as to integrate the light during the integration period corresponding to the illumination period of the illumination device 104. Furthermore, the processing subsystem 300 is compatible with scanning devices of various embodiments, such as scanning device 106 (…). Figures 2 to 4) and external scanning device 160 ( Figure 9 ) and / or optical components 170 when implemented as a scanning device Figure 9 Electrical connection is used to control the scanning action of the scanning device.

[0114] The processing system 300 can be implemented using any suitable type of processing hardware and / or software known in the art—including, but not limited to, any combination of various dedicated computerized processors that operate under any suitable operating system and implement suitable software and / or firmware modules. The processing system 300 may also include various communication components for allowing wired or wireless communication with LAN and / or WAN devices for bidirectional information transmission. Figure 10 A simplified block diagram of a processing subsystem 300 according to a non-limiting example implementation is shown. Here, the processing subsystem 300 includes at least one computerized processor 302 coupled to a storage medium 304. The storage medium 304 may be one or more computerized memory devices, such as volatile data storage devices. The processor 302 (which may be more than one processor) may be implemented as any number of computerized processors, including but not limited to microprocessors, microcontrollers, application-specific integrated circuits (ASICs), digital signal processors (DSPs), image processors, field-programmable gate arrays (FPGAs), field-programmable logic arrays (FPLAs), etc. Such computerized processors include computer-readable media storing program code or instruction sets, or being able to communicate electronically with computer-readable media, the program code or instruction sets causing the computerized processor to perform actions when executed by the computerized processor. Types of computer-readable media include, but are not limited to, electronic, optical, magnetic, or other storage or transmission devices capable of providing computer-readable instructions to the computerized processor.

[0115] It should be noted that, in addition to the processor 302 and storage medium 304, the processing subsystem 300 may also include additional electronic circuitry for receiving and / or processing analog and / or digital signals, such as demodulation circuitry, frequency synthesizers, mixers, bandpass filters, low-pass filters, amplifiers (e.g., low-noise amplifiers), analog-to-digital converters (e.g., in the form of sampling and quantization circuitry), digital-to-analog converters, local oscillators, etc. It should also be noted that, in some embodiments, the processing subsystem 300 itself may be integrated as part of the receiver 200. In other embodiments, sub-components of the processing subsystem 300 may be integrated as part of the receiver 200, while other components of the processing subsystem 300 may be independent components separate from the receiver 200.

[0116] Reference above Figures 2 to 9 The described implementation of the LIDAR system, with its optical waveguide construction and scanning apparatus, provides various solutions for scanning a field of interest (i.e., a scene of interest), whereby the output beam from the LIDAR system sweeps across a wide number of angular positions within the field of interest to illuminate objects within it. As discussed, the illuminated objects in the field of interest, with varying corresponding directions of arrival, reflect or backscatter some of the illumination from the LIDAR system back to the LIDAR system's receiver. The detector 204 of the LIDAR system's receiver provides photon sensing capability, enabling the capture of the reflected illumination and the processing subsystem 300 to derive information associated with the light-reflecting object. As discussed, the derived information is preferably used to generate a 3D representation of the illuminated object in the field of interest.

[0117] As is known to those skilled in the art, the measurement principle used to generate a 3D representation of an object in a LiDAR system is Time-of-Flight (TOF), in which a beam of light generated by the transmitter of the LiDAR system (e.g., transmitter 100) is projected (via beam scanning) onto an object in the scene, and the reflected illumination is detected (e.g., by detector 204) and processed (e.g., by processing subsystem 300) to determine the distance to the object (i.e., range), thereby allowing the creation of a 3D point cloud. The distance to the object is measured based on the round-trip delay of the light wave traveling to the object, typically the distance from the object to detector 204. Distance measurement can be achieved by modulating the intensity, phase, and / or frequency of the emitted laser illumination and measuring the time required for the modulation pattern to appear at the receiver.

[0118] One method for Time-of-Flight (TOF) measurement is based on intensity modulation of short pulses of laser illumination. Here, the short pulses of laser illumination are directed into the scene, and the distance to an object in the scene is determined by multiplying the speed of light by the time it takes for the pulse to travel to the object. As described above, the processing subsystem 300 preferably provides synchronization between the illumination device 104 and the detector 204, thereby providing synchronization between the pulse timing of the beam source and the integrated period of the detector 204. For TOF measurement, the processing subsystem 300 actuates a timer circuit (which may be part of the processing subsystem 300) to initialize the timer when each laser pulse is emitted, and actuates the timer circuit to terminate the timer when an output signal is received from the detector 204. The detector 204 generates an output signal in response to capturing illumination reflected from the object, wherein the output signal indicates the intensity of the light captured by the detector 204. TOF is measured as the time elapsed between timer initialization and timer termination. Since TOF explicitly represents twice the distance to the object (i.e., the distance from the emitter to the object plus the distance from the object to the detector), TOF should be halved to provide the actual distance to the object. Therefore, using a simple intensity modulation method, the distance D to the object can be expressed as:

[0119]

[0120] Where c is the speed of light (approximately 3 × 10⁻⁶). 8 m / s).

[0121] Another method for TOF measurement is based on amplitude modulation of a continuous wave (called AMCW), which compares the phase of the emitted illumination with the phase of the detected reflected illumination. Here, the optical power of the emitted CW laser signal is expressed using a constant frequency f. M Modulation is typically done at frequencies of several hundred kHz, therefore the intensity signal of the emitted beam is at frequency f. M The emitted light is either a sine wave or a square wave. Detector 204 captures reflected illumination from the object and generates an output signal indicating the intensity of the captured illumination. The distance measurement D is based on the phase shift ΔΦ that occurs between the emitted and reflected intensity signals and the modulation frequency f. M Therefore, it can be derived and expressed as follows:

[0122]

[0123] Here, c represents the speed of light.

[0124] Techniques for demodulating the generated intensity signal and extracting phase information are well known in the art, but several brief examples are provided herein. In a non-limiting example, a mixer and low-pass filter arrangement can be used, or phase measurement can be obtained by sampling the generated intensity signal and cross-correlating the sampled signal with a transmitted phase signal shifted by multiple fixed phase offsets. Another method involves sampling the generated intensity signal, mixing it with a transmitted phase signal shifted by multiple fixed phase offsets, and then sampling the mixed signal at the resulting multiple phases. The various techniques mentioned herein utilize various electronic components, including, for example, mixers, filters, local oscillators, analog-to-digital converters, digital-to-analog converters, etc., and can be implemented as an integral part of receiver 200, an integral part of processing subsystem 300, or electronic circuitry shared between processing subsystem 300 and receiver 200.

[0125] Another method for TOF measurement is based on continuous wave frequency modulation (called FMCW), whereby the instantaneous photofrequency of the emitted intensity signal is periodically shifted, typically by changing the output power of the beam source. As in the AMCW method, detector 204 captures reflected illumination from the object and generates an output signal indicating the intensity of the captured illumination. However, here, the signal generated by detector 204 is mixed with the emitted source signal to create a beat frequency that can be used to measure the object distance. For a static object, the time delay between the emission of the laser illumination and the collection of illumination by detector 204 results in a constant frequency difference (i.e., beat frequency) f from the signal mixing. B By linearly changing the instantaneous optical frequency of the emitted laser irradiation within a period T, the beat frequency f is... B It varies proportionally to TOF, and therefore, through equivalence, is proportional to the distance D to the object. B The proportional relationship between the time of flight (TOF) and the time of time (TOF) can be expressed as follows:

[0126]

[0127] Therefore, D can be represented as:

[0128]

[0129] Where B is the sweep bandwidth.

[0130] The frequency difference between the transmitted and received signals is represented as a periodic phase difference, which is expressed as a beat frequency f. B This results in alternating patterns of constructive and destructive interference, thereby generating a frequency f. B The beat frequency signal. The beat frequency signal is analyzed in the frequency domain using Fourier analysis; the beat frequency f... BThe peak value can be easily converted into distance. A particularly preferred technique for performing frequency domain analysis is the Fast Fourier Transform (FFT). The FFT algorithm is well known in the art and can be implemented using the processing subsystem 300.

[0131] In the example above, the instantaneous frequency changes linearly and increases monotonically to generate the ramp modulation frequency. However, in many practical applications of FMCW, a triangular modulation frequency is used instead of the ramp. Here, the rate of frequency change is expressed as 2f. M B, where f M It is the modulation frequency. Therefore, the beat frequency f B It can be represented as follows:

[0132]

[0133] Here, the beat frequency f can also be obtained by applying the FFT algorithm. B The peak value is converted into distance to analyze the beat frequency signal. When used to detect moving objects, this triangulation has specific values ​​where the object's velocity (i.e., speed and direction) can be determined by calculating the Doppler frequency.

[0134] It should be noted that all the techniques described above for determining TOF and distance to an object are described in the context of point-by-point measurement, wherein a single pulse or a single modulated laser beam is emitted by transmitter 100 to illuminate a point on an object in the scene, and thereby receiver 200 (in particular detector 204) captures the light reflected from the object in response to the illumination, and processing subsystem 300 derives TOF and distance information based on the signal generated by detector 204 in response to the captured light. However, as is known in the art, one of the key outputs generated by a LIDAR system is a 3D representation of the illuminated object, which is typically in the form of a 3D point cloud or a 3D image of it. Such a point cloud is typically generated by scanning the field of view to illuminate a large number of points of the object and, for each illuminated point, responsively calculating the TOF and distance based on the captured backscattered (reflected) light. According to a preferred embodiment of the invention, processing subsystem 300 is configured to scan the field of view (using a reference) Figures 2 to 9The described optical waveguide and scanning arrangement configuration enables the generation of a 3D representation, such as a point cloud, by illuminating multiple points on an object in a scene with a beam of light. Via the aforementioned emitter 100, the aperture-multiplied emitted beam is repeatedly repositioned (or simultaneously illuminates a large area of ​​the scene) via the aforementioned scanning device, and the corresponding reflected light from the object is captured by detector 204 to generate a corresponding signal. This signal is processed by processing subsystem 300 according to the various techniques described above for determining TOF and distance, in order to construct the point cloud. Preferably, processing subsystem 300 provides synchronization between illumination device 104 and various scanning devices (e.g., scanning device 106, scanning device 160, and optical components 170 in some non-limiting implementations) to enable scanning illumination of the entire field of interest.

[0135] Generally, the density of a point cloud is limited by the scanning rate (i.e., how quickly different areas within the scene are illuminated) and the capture rate of the detector 204. When the detector 204 is implemented as a sensor matrix or a rectangular pixel array, it can simultaneously capture reflected light from multiple areas, thus providing a higher overall capture rate. Preferably, the transmitter 100 and receiver 200 are configured such that the processing subsystem 300 can generate a “high-density” point cloud resembling a 3D image. The processing subsystem 300 can also be configured to convert the 3D point cloud into a two-dimensional (2D) depth image using techniques known in the art.

[0136] Although the embodiments of the invention described herein involve the use of an irradiation device having a beam source configured to produce light having wavelengths in the NIR region of the electromagnetic spectrum and / or the visible region of the electromagnetic spectrum, other embodiments in which the irradiation device includes one or more beam sources configured to produce light outside the NIR and visible regions are also possible, including, for example, beam sources configured to produce light in the ultraviolet region of the electromagnetic spectrum.

[0137] The achievable operating range of a system according to the embodiments described herein is typically a function of several parameters, including, for example, beam wavelength, beam intensity, pulse duration, and beam divergence. Some of these parameters can be adjusted by controlled inputs from the processing subsystem 300 to the illumination device 104, while others can be adjusted by modifying various optical and scanning components of the illumination and beam combining unit 102, and still others can be adjusted by changing the type of beam source arranged in the illumination device 104. Those skilled in the art will understand how to adjust the various parameters to achieve the desired operating range. By adjusting some of these parameters, the system according to the embodiments described herein can achieve an operating range superior to that of conventional LIDAR systems. Ignoring atmospheric attenuation, beam divergence, or other degrading factors, a conventional LIDAR system using an NIR laser operating at approximately 900 nm has a maximum operating range of approximately 100 meters. In a non-limiting example, assuming a predetermined intensity at the input aperture of the optical waveguide 120 (for eye safety), and assuming that the optical waveguide 120 provides a three-fold expansion of the aperture (in two dimensions), the total output power at the output aperture of the transmitter 100 increases ninefold, and therefore the operating range of the system 10 increases threefold compared to a conventional LIDAR system (according to the inverse square law). Therefore, it is contemplated that the LIDAR system of the present invention can achieve an operating range of at least 300 meters.

[0138] It should be noted that when the LIDAR system according to embodiments of the invention is arranged in a driver-operated ground-based vehicle or arranged for use with a driver-operated ground-based vehicle, the optical waveguide of the disclosed embodiments can be advantageously mounted in front of the driver of the vehicle, for example, integrated into the vehicle's dashboard or windshield. When the LIDAR system is arranged as part of a helmet, the optical waveguide of the disclosed embodiments can be advantageously mounted as part of the helmet in the front region of the helmet.

[0139] Although embodiments of the disclosed LiDAR system have been described so far in the context of LiDAR applications for ground-based vehicles such as autonomous or semi-autonomous vehicles, embodiments of the present invention can also be advantageously used for fixed-ground LiDAR applications and airborne LiDAR applications such as remote sensing applications. For ground applications, embodiments in which the system is arranged on a fixed platform (e.g., a support or tower) to collect data associated with objects in a scene are contemplated. For aerospace applications, embodiments in which the system is arranged on or mounted to an aircraft, such as a manned (i.e., manually piloted) aircraft (e.g., airplane, helicopter, etc.) or an unmanned aircraft (e.g., unmanned aerial vehicle, drone, etc.). In such embodiments, the system is preferably arranged on the underside or belly of the aircraft, thereby enabling the system to collect data associated with objects in a remote scene monitored by the aircraft on the ground (typically at altitudes in the range of 10 to 100 meters, or up to 1 kilometer, when using a high-intensity laser source arranged on a small UAV or drone).

[0140] It should be noted that although the transmitters and receivers of the embodiments disclosed herein have been described in the specific context of use in LIDAR applications, particularly for use with ground-based or airborne LIDAR systems, the transmitter and receiver configurations based on the above embodiments can be adapted to non-LIDAR applications that do not require scene scanning, such as laser rangefinder applications. For example, a transmitter configuration without the scanning device of the above embodiments can be advantageously used as part of a ground-mounted or handheld laser rangefinder system, wherein a single point or small group of points in a scene is illuminated without scanning in order to measure the distance to that point or group of points.

[0141] Various embodiments of this disclosure have been described for illustrative purposes, but are not intended to be exhaustive or limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terminology used herein has been chosen to best explain the principles, practical applications, or technical improvements of the embodiments relative to existing technologies in the market, or to enable others skilled in the art to understand the embodiments disclosed herein.

[0142] As used in this article, unless the context clearly indicates otherwise, the singular forms (“a”, “an”) and “the” include plural references.

[0143] The word "exemplary" is used here to mean "serving as an example, instance, or illustration." Any implementation described as "exemplary" is not necessarily to be construed as preferred or advantageous over other implementations and / or to exclude combinations of features from other implementations.

[0144] It should be understood that certain features of the invention described in the context of a single embodiment for clarity may also be provided in combination in a single embodiment. Conversely, various features of the invention described in the context of a single embodiment for brevity may also be provided individually or in any suitable sub-combination or as suitably as in any other described embodiment of the invention. Certain features described in the context of various embodiments are not considered essential features of those embodiments unless the embodiment would be inoperable without those elements.

[0145] As with the drafting of appended claims without multiple claims, this is done merely to accommodate formal requirements in jurisdictions where such multiple claims are not permitted. It should be noted that all possible combinations of features implied by making the claims multiple are explicitly contemplated and should be considered part of the invention.

[0146] Although the invention has been described in conjunction with specific embodiments thereof, it will be apparent to those skilled in the art that many alternatives, modifications, and variations will be apparent. Therefore, the invention is intended to include all such alternatives, modifications, and variations falling within the spirit and broad scope of the appended claims.

Claims

1. A light detection and ranging system, comprising: a light waveguide having at least two major external surfaces for guiding light by internal reflection, a first one of the two major external surfaces being arranged in a facing relationship with a scene; a light incoupling arrangement associated with the light waveguide, the light incoupling arrangement being configured for coupling light into the light waveguide for propagation within the light waveguide by internal reflection; a light outcoupling arrangement associated with the light waveguide, comprising a series of partially reflective surfaces arranged within the light waveguide at an oblique angle to the major external surfaces, the light outcoupling arrangement being configured for outcoupling a portion of light guided by the light waveguide from the light waveguide towards the scene to provide one or two dimensional aperture expansion; an illumination device arranged to emit light for coupling into the light waveguide, the light being collimated prior to incoupling into the light waveguide; an illumination and beam combining unit having collimating optics arranged in an optical path between the illumination device and the light waveguide for collimating the light emitted by the illumination device prior to coupling of the light into the light waveguide; a detector for sensing light reflected from an object located in the scene in response to illumination of the object by light outcoupled from the light waveguide by the light outcoupling arrangement; and a processing subsystem comprising at least one processor, the processing subsystem being electrically associated with the detector and configured to process signals from the detector to derive information associated with the object, characterized in that: the illumination and beam combining unit is configured to direct light towards the light incoupling arrangement to spread an intensity of the light over an input aperture of the light incoupling arrangement, wherein an exit pupil of the illumination and beam combining unit is adapted to an entrance pupil of the light waveguide; the partially reflective surfaces are parallel and configured to outcouple a portion of the guided light beam as a parallel light beam towards the scene; the light detection and ranging system further comprises a light coupling arrangement, and wherein the light waveguide comprises a first waveguide section associated with the light coupling arrangement and a second light waveguide section associated with the light outcoupling arrangement, and wherein light coupled into the light waveguide travels through the first waveguide section by internal reflection, and a portion of an intensity of the light travelling through the first waveguide section is deflected in a first direction by the light coupling arrangement to be outcoupled from the first waveguide section and coupled into the second light waveguide section to travel through the second light waveguide section by internal reflection, and wherein light travelling through the second light waveguide section is deflected in a second direction by the light outcoupling arrangement to be outcoupled from the light waveguide towards the scene, wherein the light coupling arrangement enables scanning of light in a first dimension, and wherein the light outcoupling arrangement enables scanning of light in a second dimension substantially orthogonal to the first dimension. focusing optics for focusing the reflected light onto the detector.

2. The light detection and ranging system of claim 1, further comprising: ​ 3. The light detection and ranging system of claim 2, wherein, The focusing optics are associated with a second one of the two major outer surfaces that is arranged away from the scene.

4. The light detection and ranging system of claim 2, wherein, The reflected light is transmitted by the two major outer surfaces before being received by the focusing optics.

5. The light detection and ranging system of claim 2, wherein, An output aperture of the system is at least partially defined by the out-coupling configuration, and wherein an input aperture of the system is at least partially defined by the focusing optics.

6. The light detection and ranging system of claim 5, wherein, The input aperture at least partially overlaps the output aperture.

7. The light detection and ranging system of claim 5, wherein, The input aperture and the output aperture are non-overlapping.

8. The light detection and ranging system of claim 1, further comprising: A diffractive optical element associated with the first one of the two major outer surfaces.

9. The light detection and ranging system of claim 1, further comprising: A first scanning device arranged to scan the scene with light that is out-coupled from the optical waveguide by the light out-coupling configuration.

10. The light detection and ranging system of claim 9, wherein, The first scanning device is arranged between the illumination device and the optical waveguide, and wherein the first scanning device is configured to deflect light emitted by the illumination device to cover an angular range such that the light out-coupled from the optical waveguide covers a corresponding angular range.

11. The light detection and ranging system of claim 9, wherein, The first scanning device is associated with the first one of the two major outer surfaces.

12. The light detection and ranging system of claim 1, further comprising: An optical component arranged in an optical path between the illumination device and the optical waveguide, and the optical component is configured to perform aperture expansion of light emitted by the illumination device in at least a first dimension.

13. The light detection and ranging system of claim 12, further comprising: A second scanning device associated with the first one of the two major outer surfaces, and the second scanning device is configured to scan a second dimension that is orthogonal to the first dimension.

14. The light detection and ranging system of claim 12, wherein, The optical component is configured to perform expansion of light emitted by the illumination device in the first dimension and a second dimension that is orthogonal to the first dimension.

15. The light detection and ranging system of claim 12, wherein, The optical component comprises a light-transmissive substrate for guiding light emitted by the illumination device by internal reflection, and a second light out-coupling configuration associated with the substrate for out-coupling a portion of the light guided by the substrate from the substrate towards the optical waveguide.

16. The light detection and ranging system of claim 1, wherein, The light out-coupling configuration comprises a diffractive optical element associated with at least one of the two major outer surfaces.

17. The light detection and ranging system of claim 1, wherein, The illumination device comprises a plurality of beam sources configured to generate light of different respective wavelengths.

18. The light detection and ranging system of claim 17, wherein, The illumination device further comprises a beam combiner for combining the light generated by the beam sources into a combined beam.

19. The light detection and ranging system of claim 17, wherein, The wavelengths are in the near-infrared region of the electromagnetic spectrum.

20. The light detection and ranging system of claim 17, wherein, The beam sources are implemented as laser sources.

21. The light detection and ranging system of claim 20, wherein, The laser sources are pulsed laser sources, and wherein the processing subsystem is electrically associated with the illumination device and is further configured to control pulse timing of the laser sources.

22. The light detection and ranging system of claim 17, wherein, One of the beam sources is configured to generate light in the visible region of the electromagnetic spectrum, and wherein the remaining beam sources are configured to generate light of different respective wavelengths in the near-infrared region of the electromagnetic spectrum.

23. The light detection and ranging system of claim 1, wherein, The processing subsystem is electrically associated with the illumination device, and the processing subsystem is further configured to control illumination timing of the illumination device.

24. The light detection and ranging system of claim 1, wherein, The information associated with the object derived by the processing subsystem comprises time-of-flight information.

25. The light detection and ranging system of claim 1, wherein, The information associated with the object derived by the processing subsystem comprises a distance from the detector to the object.

26. The light detection and ranging system of claim 1, wherein, The processing subsystem is further configured to construct a three-dimensional representation of the object based on the information associated with the object.

27. The light detection and ranging system of claim 1, wherein, The system is arranged in a ground-based vehicle.

28. The light detection and ranging system of claim 1, wherein, The system is mounted to an aircraft.

29. The light detection and ranging system of claim 1, wherein, The optical waveguide has a trapezoidal shape in cross-section so as to enable lateral scanning of the scene with light coupled out of the optical waveguide.

30. The lidar system of claim 29, further comprising: a light-transmissive substrate having two pairs of parallel major external surfaces forming a rectangular cross-section; and a light-coupling configuration associated with the substrate, wherein light coupled into the substrate travels through the substrate by four-fold internal reflection, and a portion of the intensity of the light traveling through the substrate is coupled out of the substrate by the light-coupling configuration and into the optical waveguide.

31. The light detection and ranging system of claim 1, wherein, The optical waveguide comprises two pairs of parallel major external surfaces forming a rectangular cross-section, and wherein light coupled into the optical waveguide travels through the optical waveguide by four-fold internal reflection.

32. A lidar system, comprising: a transmitter, the transmitter comprising: an optical waveguide having at least two major external surfaces for guiding light by internal reflection, one of the major external surfaces being arranged in facing relationship with a scene, a light-in-coupling configuration associated with the optical waveguide, the light-in-coupling configuration being configured for coupling light into the optical waveguide for propagation within the optical waveguide by internal reflection; a light-out-coupling configuration associated with the optical waveguide, the light-out-coupling configuration comprising a series of partially-reflecting surfaces arranged within the optical waveguide at an oblique angle to the major external surfaces, the light-out-coupling configuration being configured for coupling a portion of light guided by the optical waveguide out of the optical waveguide towards the scene to provide one- or two-dimensional aperture expansion, at least one beam source configured to emit a coherent light beam for coupling into the optical waveguide, the coherent light beam being collimated prior to being coupled into the optical waveguide, an illumination and beam-combining unit having collimating optics arranged in an optical path between the illumination device and the optical waveguide for collimating light emitted by the illumination device prior to coupling of the light into the optical waveguide; and a first scanning device arranged to scan the scene with light coupled out of the optical waveguide by the light-out-coupling configuration; a receiver, the receiver comprising: a detector for sensing light reflected from an object located in the scene in response to illumination of the object by light coupled out of the optical waveguide by the light-out-coupling configuration; and a processing subsystem comprising at least one processor, the processing subsystem being in electrical association with the detector and the processing subsystem being configured to process signals from the detector to construct a three-dimensional representation of the object, characterized in that: the illumination and beam combining unit is configured to direct light toward the light incoupling configuration to have an intensity of the light spread over an input aperture of the light incoupling configuration, wherein an exit pupil of the illumination and beam combining unit is adapted to an entrance pupil of the optical waveguide; the partially reflective surface is parallel and configured to couple out a portion of the directed light beam as a parallel light beam toward the scene from the optical waveguide; the light detection and ranging system further comprises a light coupling configuration, and wherein the optical waveguide comprises a first waveguide section associated with the light coupling configuration and a second optical waveguide section associated with the light outcoupling configuration, and wherein light coupled into the optical waveguide travels through the first waveguide section by internal reflection, and a portion of an intensity of the light traveling through the first waveguide section is deflected in a first direction by the light coupling configuration to be coupled out of the first waveguide section and into the second optical waveguide section to travel through the second optical waveguide section by internal reflection, and wherein light traveling through the second optical waveguide section is deflected in a second direction by the light outcoupling configuration to be coupled out of the optical waveguide toward the scene, wherein the light coupling configuration implements a scan of light in a first dimension, and wherein the light outcoupling configuration implements a scan of light in a second dimension substantially orthogonal to the first dimension.

33. The light detection and ranging system of claim 32, wherein, the processing subsystem is electrically associated with the illumination device, and the processing subsystem is further configured to control illumination timing of the illumination device.

34. The light detection and ranging system of claim 32, wherein, the emitter has an output aperture defined at least in part by the light outcoupling configuration, and wherein the receiver has an input aperture defined at least in part by focusing optics, and wherein the input aperture at least partially overlaps the output aperture.

35. The light detection and ranging system of claim 32, wherein, the emitter has an output aperture defined at least in part by the light outcoupling configuration, and wherein the receiver has an input aperture defined at least in part by focusing optics, and wherein the input aperture is non-overlapping with the output aperture.

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