Vcsel array lidar transmitter with small angular divergence

Abstract

The present disclosure relates to a VCSEL array LIDAR transmitter with small angular divergence. A light detection and ranging (LIDAR) transmitter includes a plurality of light emitters that generate a plurality of light beams. A first lens is positioned in an optical path of the plurality of light beams at a distance from at least one of the plurality of light emitters that is less than a focal length of the first lens. The first lens converges the plurality of light beams into a converged light beam having a beam waist. A second lens is positioned in an optical path of the converged light beam. The second lens projects the converged light beam to a target range. A position of the second lens and an emission width of the at least one of the plurality of light emitters are configured to provide a desired field of view of the LIDAR transmitter at the target range.

Description

[0001] This application is a divisional application of the invention patent application filed on July 6, 2018, with application number 201880047615.6 and invention title "VCSEL array LIDAR transmitter with small angular divergence".

[0002] The chapter headings used herein are for organizational purposes only and should not be construed in any way as limiting the subject matter described in this application.

[0003] Related application chapters

[0004] This application is a non-provisional application of co-pending U.S. Provisional Patent Application Serial No. 62 / 538,149, filed July 28, 2017, entitled “VCSEL Array LIDAR Transmitter with Small Angular Divergence”. The entire contents of U.S. Patent Application Serial No. 62 / 538,149 are incorporated herein by reference. Summary of the Invention

[0005] Autonomous, self-driving, and semi-autonomous vehicles use a combination of different sensors and technologies, such as radar, image recognition cameras, and sonar, to detect and locate surrounding objects. These sensors enable significant improvements in driver safety, including collision warning, automatic emergency braking, lane departure warning, lane keeping assist, adaptive cruise control, and autonomous driving. Among these sensor technologies, Light Detection and Ranging (LIDAR) systems play a crucial role in enabling real-time, high-resolution 3D mapping of the surrounding environment. Attached Figure Description

[0006] In the following detailed description, the present teachings and their additional advantages are described in more particular, in conjunction with the accompanying drawings, according to preferred and exemplary embodiments. It will be understood by those skilled in the art that the drawings described below are for illustrative purposes only. The drawings are not necessarily drawn to scale, but generally focus on illustrating the principles of the teachings. The drawings are not intended to limit the scope of the applicant's teachings in any way.

[0007] Figure 1 The diagram illustrates the operation of the LIDAR system according to this teaching.

[0008] Figure 2 An example of a LIDAR system using two lasers according to this teaching is illustrated.

[0009] Figure 3 An embodiment of a multi-emitter laser source for a LIDAR transmitter, according to this teaching, is illustrated.

[0010] Figure 4A cross-sectional view of an embodiment of the illuminator for a LIDAR transmitter according to this teaching is shown.

[0011] Figure 5A The illustration shows a measurement point cloud of an embodiment of the single-wavelength 2D multi-emitter LIDAR transmitter of this teaching.

[0012] Figure 5B The illustration shows a measurement point cloud of an embodiment of a dual-wavelength 2D multi-emitter LIDAR transmitter according to this teaching.

[0013] Figure 6 The illustration shows a perspective view of a schematic diagram of the structure of a prior art bottom-emitting VCSEL laser used in some embodiments of the LIDAR transmitters described in this teaching.

[0014] Figure 7 The illustration shows a schematic diagram of an embodiment of a 2D monolithic VCSEL array with twenty-five individual laser emitters according to the present teachings.

[0015] Figure 8 The illustration shows a schematic diagram of an embodiment of a 2D monolithic VCSEL array having twenty-five individual laser emitters including sub-apertures, in accordance with the present teachings.

[0016] Figure 9 The illustration shows a schematic diagram of light projected by a single transmitter in a single-lens LIDAR transmitter system, according to this teaching.

[0017] Figure 10 The illustration shows a schematic diagram of light projected by multiple transmitters in a single-lens LIDAR transmitter system according to this teaching.

[0018] Figure 11A The illustration is a schematic diagram showing an extended view of light projected by multiple transmitters in a single-lens LIDAR system with high-angle divergence transmitters.

[0019] Figure 11B The diagram illustrates the far field... Figure 11A A schematic diagram of a condensed view of the light projected by the system.

[0020] Figure 12 The illustration shows a schematic diagram of an embodiment of a dual-lens illuminator projecting light in a small-angle divergence LIDAR transmitter according to the present teaching.

[0021] Figure 13 The illustration shows a schematic diagram of an embodiment of a multi-transmitter array small-angle divergence LIDAR transmitter according to the present teachings.

[0022] Figure 14AThe illustration shows a schematic diagram of an extended view of a small-angle divergence LIDAR transmitter illuminator utilizing multiple transmitter arrays on a single substrate, in accordance with this teaching.

[0023] Figure 14B The diagram shows Figure 14A A schematic diagram of a condensed view of a small-angle divergence LIDAR transmitter.

[0024] Figure 15 The illustration shows a scaled, condensed view of an embodiment of the small-angle divergence LIDAR transmitter of this teaching, indicating the relative independence of the transmitter arrays.

[0025] Figure 16 An embodiment of an illuminator for a multi-wavelength LIDAR system using multiple transmitter arrays, according to this teaching, is illustrated.

[0026] Figure 17 The diagram illustrates how to combine them. Figure 16 The described illuminator generates a measurement point cloud. Detailed Implementation

[0027] The teachings will now be described in more detail with reference to exemplary embodiments of the teachings as illustrated in the accompanying drawings. While the teachings have been described in conjunction with various embodiments and examples, this does not mean that the teachings are limited to these embodiments. Rather, as those skilled in the art will recognize, the teachings encompass various alternatives, modifications, and equivalents. Those of ordinary skill in the art who will have access to the teachings herein will recognize additional implementations, modifications, and embodiments, as well as other areas of use, all within the scope of this disclosure set forth herein.

[0028] The reference to "an embodiment" or "embodiment" in this specification means that a particular feature, structure, or characteristic described in connection with that embodiment is included in at least one embodiment of this teaching. The phrase "in an embodiment" appearing throughout this specification does not necessarily refer to the same embodiment.

[0029] It should be understood that the steps of the method described herein can be performed in any order and / or simultaneously, provided that the teaching remains operational. Furthermore, it should be understood that the apparatus and method described herein may include any number or all of the described embodiments, provided that the teaching remains operational.

[0030] This teaching relates to Light Detection and Ranging (LIDAR) systems that measure the distance to various objects or targets reflected and / or scattered light. LIDAR systems are expected to have a small footprint, high measurement resolution, and high detection sensitivity. VCSEL array-based transmitters promise to provide these benefits. These VCSEL array-based LIDAR transmitters require improvements in optical design to enhance performance and reduce the size, weight, power, cost, and complexity of the LIDAR system. As an example, a LIDAR transmitter design is needed to produce small angular divergence in a compact package.

[0031] Figure 1 The illustration depicts the operation of a LIDAR system 100 implemented in a vehicle according to this teaching. The LIDAR system 100 includes a laser projector (also called an illuminator) that projects a beam 102 generated by a light source onto a target scene, and a receiver that receives light 104 reflected from an object (shown as person 106) in the target scene. The LIDAR system typically also includes a controller that calculates distance information about the object 106 based on the reflected light, and elements that can scan or provide a specific pattern of light, which may be a static pattern across a desired range and field of view (FOV). The receiver and controller are used to convert the received signal light into measurements representing a point-by-point 3D map of the surrounding environment falling within the range and FOV of the LIDAR system. In various embodiments, depending on the specific application, the controller may be a simple circuit or a more complex processor.

[0032] The laser source and beam projection device forming the illuminator, along with the receiver, can be located at the front of vehicle 108. A person 106 and / or another object, such as a car or lamppost, will provide light reflected from the source back to the receiver, and the range or distance to that object is determined. As is known in the art, a LIDAR receiver calculates range information based on time-of-flight measurements of light pulses emitted from the light source. Furthermore, location information about the reflecting surfaces is determined using the beam profile of the scene in the target plane associated with the illumination and a specific range, and known information based on the specific design of the source and projector systems, thereby generating a complete x, y, z, or 3D picture of the scene. In other words, a point-by-point 3D map of the surrounding environment represents a set of measurement data indicating the location information of all surfaces from which illumination is reflected from the source to the receiver within the field of view of the LIDAR system. In this way, a 3D representation of objects in the field of view of the LIDAR system is obtained. The point-by-point 3D data map can also be referred to as a measurement point cloud.

[0033] A feature of this teaching is that the illuminator may include a laser that emits beams of light having independent, different wavelengths. Typically, LIDAR systems do not utilize different laser wavelengths to improve the angular resolution of the LIDAR system. In particular, a feature of some embodiments of the LIDAR systems of this teaching is that they use multiple laser wavelengths to achieve finer angular resolution and performance in a low-cost, compact optical design. Furthermore, the multi-wavelength LIDAR systems of this teaching can provide a simple path to improved security and parallelization. See, for example, U.S. Patent Application Serial No. 15 / 456,789, filed March 3, 2017, entitled “Multi-Wavelength LIDAR System,” and U.S. Patent Application Serial No. 62 / 396,295, filed September 19, 2016, entitled “WDMLidar System.” Both U.S. Patent Application Serial Nos. 15 / 456,789 and 62 / 396,295 are assigned to the assignee and are incorporated herein by reference.

[0034] Figure 2 An embodiment of a multi-wavelength LIDAR system 200 using two lasers according to this teaching is illustrated. A first laser 202 operates at a first wavelength, and a second laser 204 operates at a second wavelength. The lasers may include integrated or separate collimating optics forming part of an optical projection element for forming a beam profile at various target planes across the FOV and range of the LIDAR system. Illuminator 206 may also include optics 208 that further shapes and projects the beam to form a specific beam profile at target plane 210. In various embodiments, different types of optics may be used to form the optical projection element, including, for example, one or more of lenses, diffractive optics, prisms, thin-film wavelength-sensitive devices, and partial mirrors. Single-lens or multi-lens optics may be used.

[0035] Receiver 212 receives light reflected from the surface of objects at various target planes 210 within the FOV and range of the LIDAR system. If different wavelengths are used, receiver 212 may be able to distinguish between two wavelengths of light emitted from sources 202 and 204. In this case, reflected illumination from each wavelength is processed individually. Controller 214 processes the received light. Controller 214 provides LIDAR data at output 216. The complexity of controller 214 depends on the specific configuration of the LIDAR system. Controller 214 may be used to control laser sources 202 and 204. In various embodiments, controller 214 may include various circuits, integrated circuits, microprocessors, or computers. Adding N lasers of the same or different wavelengths... Figure 2The LIDAR system shown is relatively simple. In some embodiments, additional optical elements are present to collimate the light and provide the desired field of view (FOV).

[0036] As described herein, a projection element is an element that collimates or otherwise shapes and projects a laser beam or multiple laser beams in a specific direction. The projection element may include one or more optics located in the beam path. These optics and their positions, together with the initial shape and path of one or more beams emitted from the laser source, produce a desired beam profile, which is a combination of beam shape and / or beam position at a specific point in space. After receiving light reflected from an object at a receiver in a LIDAR system, the system generates a measured point cloud or point-by-point data map based on the pattern of the light projected by the illuminator and its performance parameters, including angular resolution and field of view.

[0037] A key feature of this teaching is the ability to generate different LIDAR FOV, range, and / or resolution in a compact system using different wavelengths. Beams of two or more wavelengths can share at least some of the same optics forming the projection element and still achieve different beam profiles that produce measurement point clouds representing different ranges and / or FOVs and / or resolutions at each wavelength. For example, one problem with prior art LIDAR systems using signal wavelengths is that the transmit power required to reach a 100-meter range is too high, causing the receiver to saturate for near-field reflections (e.g., a few meters). Consequently, these prior art LIDAR systems cannot see nearby objects. This problem can be addressed with a dual-wavelength system, where the first wavelength is used for the 100-meter range, while the second wavelength, with low power, is used only for near-field measurements. Multi-wavelength measurements can be performed simultaneously using a controller with parallel computing capabilities. Extending this configuration to more than two wavelengths is relatively straightforward.

[0038] Another feature of this teaching is the ability to add lasers with additional wavelengths to perform functions other than LIDAR ranging. For example, additional lasers can be added to provide measurements of the orientation of optics within a LIDAR system. Light from these sources at additional wavelengths can be used for the single purpose of providing angle measurements of elements that project and / or replicate or scan the beam. In some embodiments, MEM devices are used to project the beam, and direct feedback of the mirror position is important. Another laser, combined with a suitable receiver measurement system, can provide direct angle measurements of the mirror position. A natural extension of the above embodiments would be to use multiple lasers of the same wavelength in each case, i.e., a 1D or 2D array of lasers for each wavelength, rather than a single laser for each wavelength.

[0039] In some systems, a single large lens is used for collimation and to set the projection angle of each VCSEL device. It should be noted that instead of a single lens, two or more lenses can be used as part of a shared lens configuration. One aspect of using shared optics for collimation and projection angle is the direct mapping between the lateral position of the VCSEL device relative to the central axis of the lens and the pointing angle of the projected laser beam. The lateral distance between two VCSEL lasers of the same or similar wavelengths will correspond to the difference in projection angle created by the shared lens system.

[0040] Furthermore, since VCSEL devices are not ideal point sources but have finite lateral dimensions, there will be additional divergence that cannot be reduced by the optics without reducing the overall FOV of the optical system. Moreover, depending on the finite size of the VCSEL, the divergence of the collimated beam, the number of VCSEL devices, and the FOV and other parameters, using shared optics with lasers of the same or similar wavelengths may result in beam overlap or gaps across the 3D measurement span.

[0041] A key feature of the LIDAR system described in this teaching is the use of VCSEL chips with clusters of emission apertures to take advantage of the higher optical power and larger diameter clusters offered by these devices. As described herein, VCSEL devices are not ideal point sources but have finite lateral dimensions. Furthermore, high-power top-emitting VCSEL lasers used for LIDAR illumination typically employ multiple emission sub-apertures to achieve the desired high power output. These multiple sub-apertures form clusters or groups and are ideally as physically close as possible while still maintaining the required electro-optical efficiency.

[0042] In some embodiments, the VCSEL array is a two-dimensional array. In some embodiments, the VCSEL array is monolithic, and all lasers share a common substrate. Various types of common substrates can be used. For example, the common substrate can be a semiconductor material. The common substrate can also include a ceramic material.

[0043] In some embodiments, the VCSEL is a top-emitting VCSEL. In other embodiments, the VCSEL is a bottom-emitting VCSEL. Each VCSEL may have a single large emission aperture, or each VCSEL may be formed by two or more sub-apertures within a larger effective emission diameter. A group of sub-apertures forming a larger effective emission region is sometimes referred to as a cluster.

[0044] Figure 3 The illustration shows a multi-element emitter laser source 300 with two different VCSEL wavelengths uniformly interlaced in the vertical direction. Figure 3The embodiment shown illustrates a single common substrate 304, but it will be apparent to those skilled in the art that multiple substrates can also be used. There are six VCSEL strips 306, 308. The cluster VCSEL devices 302 of strip 306 emit at a common wavelength. These are the strips 306 labeled "VCSELλ1" in the figure. The cluster VCSEL devices 302 of dark strip 308 emit at different wavelengths. Strip 308 is labeled "VCSELλ2" in the figure. A total of thirty cluster VCSEL devices 302 are shown.

[0045] Combination Figure 3 The illuminator used in the multi-element emitter laser source 300 can utilize a shared lens system for collimating and projecting the beam within the desired field of view (FOV). Figure 4 The figure shows a cross-sectional view of an embodiment of an illuminator 400 for a multi-wavelength LIDAR system according to the present teachings, which uses... Figure 3 The multi-wavelength laser source is shown in the figure. Illuminator 400 includes a multi-emitter laser source 402 and a projection element 404 including a wavelength multiplexer 406 and a first lens 408. Projection element 404 is used to project laser beams 410, 412 emitted from laser source 402. The emitters for multi-emitter laser source 402 are located on VCSEL substrate 414.

[0046] Figure 4 The projection element 404 includes two optical devices 406 and 408. The first optical device is a wavelength multiplexer 406, which is a wavelength-sensitive optics device used to combine a laser beam 410, originating from one optical path and traveling at one of two wavelengths, with a laser beam 412, originating from another optical path and traveling at the other of two wavelengths, into a common optical path. In some embodiments, the wavelength multiplexer includes a diffractive optics device configured to substantially shift the path of one wavelength while allowing the second wavelength to pass unobstructed. Diffractive optics are well known in the art and can be used to provide precise beam manipulation and beam shaping of lasers. In some embodiments, wavelength-sensitive diffractive optics are used. In other embodiments, an array of refractive optics, such as prisms, is used. The second device is a lens 408, which is used to further project and shape the laser beams 410 and 412 to form a desired beam shape pattern and beam position at the target plane of the LIDAR system.

[0047] Figure 4 The illustration shows how light from two VCSEL strips of different wavelengths passes through the optical system. For clarity, only laser beams 410 and 412 from the two VCSEL emitters are shown being tracked by the light. Figure 4 Only a single lens 408 is illustrated; however, those skilled in the art will understand how to use it. Figure 4 The multi-wavelength system illustrated in the diagram can be implemented, for example, in combination with the following... Figure 12 The described dual-lens or multi-lens system.

[0048] In operation, light from the beam profile formed by the illuminator at the target plane is reflected from the surface of an object in that target plane. The target plane in a LIDAR system is a virtual reference point operating within the full range and field of view. Many different target planes exist at various distances from the LIDAR module, allowing the system to generate a three-dimensional representation of objects within the field of view and range detected by the LIDAR system. A portion of the light reflected from the surface of an object illuminated by the beam profile in the target plane is directed to a receiver. The receiver detects the light and then converts the received light signal into an electrical signal. A controller electrically connected to the light source and receiver converts the received signal into a measurement point cloud. The angular resolution of the points in the measurement point cloud depends on the relative position of the beam profile at the target plane, as further described below. It will be apparent to those skilled in the art that… Figure 4 Many other variations of the embodiment of the illuminator 400 shown are within the scope of this teaching. For example, the VCSEL laser can be located on either a flat or curved common surface. It will also be apparent to those skilled in the art that some deviation from a curved or flat central surface may be permitted.

[0049] Figure 5A The illustration shows a measurement point cloud 500 based on an embodiment of single-wavelength 2D laser source illumination according to this teaching. The distance between the vertical spacing 502 of the measurement points 504 determines the vertical angular resolution. The horizontal spacing 506 of the points on the point cloud determines the horizontal angular resolution of the point cloud.

[0050] Figure 5B The illustration shows a measurement point cloud 550 of an embodiment of dual-wavelength 2D laser source illumination according to this teaching. Measurement points corresponding to VCSELs with λ1 are shown as circles 552, and measurement points corresponding to VCSELs with λ2 are shown as triangles 554. The composite point cloud includes a point cloud derived from reflections received at λ1 and a point cloud derived from reflections received at λ2.

[0051] For example, Figure 5B The measurement point cloud 550 shown can be used with... Figure 3 The patterns of VCSEL emitters at different wavelengths shown are multi-emitter laser sources and Figure 4 This is achieved through an illuminator configuration. A portion of the light from the beam generated by the illuminator at the target plane is reflected by the surface of the object and incident on one or more light receivers capable of detecting light of a specific wavelength. The resulting measurement point cloud 550 includes points representing light from different beam profiles at different wavelengths.

[0052] refer to Figure 3 -5, VCSEL strips 306 and 308 of different wavelengths occupy different rows of the laser source in the vertical direction, and the centers of the individual VCSEL devices 302 in different rows are offset in the horizontal direction. The beams from the emitters of the different wavelength strips are projected by the projection element 404, causing the beam position to be slightly offset in the vertical direction at the target plane. This results in an offset 556 in the measurement point cloud. The offset of the center positions of the VCSELs in adjacent strips, together with the design of the projection element, causes the measurement points representing each wavelength to be horizontally staggered along the offset vertical line. The angular resolution of the measurement in a given dimension is directly related to the offset of the points in that dimension, which is directly related to the position of the beam in that dimension at the target plane.

[0053] refer to Figure 5A -B Both, and the performance trade-offs associated with using dual-wavelength resolution are clear. In Figure 5B In one embodiment, a beam of one wavelength travels substantially uninterruptedly, but a beam of a second wavelength is intentionally shifted in position to substantially overlap with the beam of the first wavelength in one direction. This can be adjusted based on the design of the wavelength multiplexer. Figure 5B The diagram indicates an offset of 556 for the beam position at each wavelength. For example, in some embodiments, Figure 4 The wavelength multiplexer 406 is specifically designed to provide a specific offset 556 for the beam position at each wavelength. In various embodiments, various devices in the projection element are used to position the laser beam at both wavelengths. These same or other devices can alter the beam shape and their position on the target plane.

[0054] and Figure 5A Compared to the single-wavelength embodiment, combined with Figure 5B The described embodiments double the angular resolution in the preferred direction (in this case, the horizontal) at the cost of halving the angular resolution in the vertical direction. This is done while keeping the overall physical dimensions of the system relatively constant. In some applications, a finer resolution in one direction may be preferred or necessary, for example, if the system needs to distinguish between a pole or tree with a cross-section of only 100 mm and a pedestrian. At 30 m, we would need an angular resolution of less than 0.15 degrees. For automotive LiDAR systems, since the identification of public objects such as people, poles, and trees is required because they are tall and narrow, a very small angular resolution in the horizontal direction is highly desirable, at the cost of a wider angular resolution in the vertical direction. In some embodiments, the angular resolution of the measured point cloud is less than 0.4 degrees at a predetermined distance from the target plane to the optical projection element.

[0055] One feature of this teaching is that the light sources of a single-element emitter and a multi-element emitter operating at different wavelengths do not need to be located on the same surface. Another feature of this teaching is that the surfaces can be oriented along different spatial planes in three-dimensional space. For example, the planes can be on two orthogonal planes. In some embodiments, we use multiple surface-emitting lasers consisting of at least two sets of lasers with different wavelengths. We also utilize three-dimensional space, with each set of lasers oriented in two or more flat or curved surfaces, which are not necessarily orthogonal. In these embodiments, compared to embodiments where the lasers are co-located on a common surface, the packaging and optical alignment complexity increases, but we are able to increase the resolution angle across the entire field of view in two orthogonal directions without any compromise. This provides both higher accuracy and full access to all capabilities associated with more than one wavelength. That is, simultaneous operation of multiple wavelengths, redundancy, security, and other features can be achieved.

[0056] One feature of this teaching is that its small-angle divergence LiDAR transmitter provides a compact LiDAR module, which is particularly suitable for LiDARs operating at required ranges of approximately 100 meters. Another feature of this teaching's small-angle divergence LiDAR transmitter is its ability to utilize solid-state light emitters. Therefore, the LiDAR transmitter of this teaching can be constructed using non-moving parts. Furthermore, multiple lasers that can emit at the same or different wavelengths can be used to establish a one-to-one mapping between each laser and the 3D measurement point cloud.

[0057] Figure 6The illustration shows a schematic perspective view of the structure of a known bottom-emitting VCSEL laser 600 that can be used in a small-angle divergence LIDAR transmitter according to this teaching. Note that the emitting area of ​​the VCSEL laser 600 typically ranges from a few micrometers in diameter for mW power operation to 100 micrometers or larger for 100mW and higher CW power operation. Various embodiments of this teaching utilize a variety of known VCSEL laser devices, including top-emitting VCSELs, bottom-emitting VCSELs, and various types of high-power VCSELs. The VCSEL is fabricated on a substrate 602, which may be GaAs or other semiconductor materials. An n-type distributed Bragg reflector (DBR) 604 is positioned on the substrate. An active region 606 is formed on the n-type DBR 604, followed by an aperture 608, which may be made of an oxide material. A p-type distributed Bragg grating DBR 610 is then grown on the active region 606. Typically, p-type DBRs are highly reflective, while n-type DBRs are partially reflective, resulting in light output 612 from the bottom substrate side of the layered structure. An active region 606, an oxide aperture 608, and a p-type DBR 610 are formed in a mesa structure 614. Top contacts 616 and bottom contacts 618 are used to supply current to the active region 606 to generate the output light 612. The oxide aperture 608 limits the current supplied to the active region 606. The top contact 616 is p-type, while the bottom contact 618 is n-type. An emission aperture 620 is formed in the bottom contact 618 to allow the output light 612 to exit from the bottom substrate side of the bottom-emitting VCSEL 600. This type of VCSEL can be a single element, or multiple VCSELs can be fabricated as a one-dimensional or two-dimensional array on a substrate 602.

[0058] Figure 7 A schematic diagram of an embodiment of a 2D monolithic VCSEL array 700 having twenty-five individual laser emitters 702 of the present teachings is illustrated. Each laser emitter 702 has an emission aperture 704 with a diameter a, and the emission from each individual laser emitter 702 substantially fills the entire emission aperture 704. Thus, each laser emitter 702 generates a laser beam with a diameter a equal to the diameter of the emission aperture 704. The laser emitters 702 are uniformly spaced in the horizontal direction at a spacing dx 706. The laser emitters 702 are uniformly spaced in the vertical direction at a spacing dy 708. The overall size of the array, measured from the center of the outermost laser, is a distance Dx 710 in the horizontal direction and a distance Dy 712 in the vertical direction. The actual chip size will be slightly larger than distances Dx 710 and Dy 712.

[0059] Figure 8A schematic diagram of an embodiment of a 2D monolithic VCSEL array 800 having twenty-five individual laser emitters 802 of the present teaching is illustrated. Each laser emitter 802 has an emission aperture 804 of diameter a. Each laser emitter 802 is electrically connected to act as a sub-aperture, and their combined emission is formed by a plurality of sub-apertures 803 contained within the emission aperture 804 of dimension a. Thus, each laser emitter 802 generates a laser beam with a diameter a equal to the diameter of the emission aperture 804. The laser emitters 802 are uniformly spaced at a distance of 806dx in the horizontal direction. The laser emitters 802 are uniformly spaced at a distance of 808dy in the vertical direction. The overall size of the array, measured from the center of the outermost laser, is a distance of 810Dx in the horizontal direction and a distance of 812Dy in the vertical direction. The actual chip size will be slightly larger than distances of 810Dx and 812Dy. Figure 8 The illustration shows a laser emitter with a circular emission shape. In various embodiments, the emitter can produce beams of various shapes. For example, elliptical, square, rectangular, and various unusual shapes can be achieved. The emission width is the width of the shape in a particular direction and will determine the angular divergence of the LIDAR transmitter in that particular direction, as further described below.

[0060] Some embodiments of this teaching utilize bottom-emitting high-power arrays, such as VCSELs where each laser has a single large aperture, for example... Figure 7 The configuration shown. Other embodiments of this teaching utilize configurations including, Figure 8 The diagram shows a top-emitting high-power array of large-aperture VCSELs with sub-apertures. However, those skilled in the art will recognize that this teaching is not limited to these configurations of top- and bottom-emitting VCSELs and their associated emission apertures.

[0061] Existing systems use a single shared lens for all emitting elements to generate a one-to-one mapping between each laser and a specific measurement point and / or projection angle. See, for example, U.S. Patent No. 7,544,945, which describes using five lasers and a single projection lens together to form five separate projected beams with different angular spacing. The single projection lens provides two functions. The first function is to collimate the laser beams to determine the spot size of the beam in the far field. The spot size is set at the desired range according to the requirements of the LiDAR system. For example, a typical requirement for a LiDAR system is that the laser spot diameter at 100 m should be less than 0.5 m. This is equivalent to a full-angle divergence of 5 mrad. The second function of the optical lens is to determine the full field of view of the projected laser beams, which is determined by the positions of the two outermost beams in the far field within the range of the LiDAR system. The angular resolution between each measurement beam is then determined by dividing the full field of view by the number of lasers N-1 in each direction.

[0062] One drawback of existing single-projection-lens LIDAR systems is that they do not take into account the finite size of the laser emitter's aperture. In systems utilizing a single projection lens, the laser is positioned at the focal point of the single projection lens to collimate the laser beam.

[0063] Figure 9 The diagram illustrates the projection of light from a single-lens LiDAR transmitter system 900. A lens 902 is positioned at a focal length 904f relative to the plane 906 of the laser emitter. The distance 908y1 represents half the emission width, i.e., the radius of the emitted laser beam. The angle 910θ1 is the divergence of the emitted laser beam. According to classical optics, the optical invariance rule tells us that the product of the beam radius and the beam divergence will be a constant. Therefore, the laser beam radius 912 behind the lens is now y2, and the divergence 914 is θ2, where: 01*y1=02*y2. Geometrically, we can see that the focal length 904f is related to y2 by the following equation: y2=f*θ1. Combining these two equations, we obtain the relationship θ2=y1 / f. This relationship shows that in a single-lens LiDAR transmitter, the angular divergence of the collimated beam is directly related to the focal length of the lens. This relationship also shows how the angular divergence depends on the width of the emitter size and the associated radius of the circular aperture. This relationship sets a minimum size constraint on the lens focal length required for a specific size of the emitted laser beam. For example, a typical high-power VCSEL has a circular shape with an effective emission diameter of 100 micrometers. Therefore, y1 equals 50 micrometers. To meet the criteria for the 100m LIDAR system described herein, the divergence (overall angle) should be less than 5-mrd. The minimum focal length of the projection lens system is then 20mm.

[0064] The examples described herein generally assume a circularly symmetrical system with a circular emission shape and a spherical lens. However, it will be apparent to those skilled in the art that this teaching applies to emission shapes and lens shapes with other shapes and geometries. The described width and focal length relationships are then applied to a specific orientation. For example, a rectangular emitter and / or lens system comprising cylindrical and / or spherical lenses can be used. These choices will depend on the desired beam pattern for the target area. For example, the system can be configured to have different fields of view and angular resolution in the horizontal and vertical directions.

[0065] In the above analysis, we used classical optical formulas assuming small angles and thin lenses. If the dimensions or angles are large (which is common in compact transmitter designs), then classical optical formulas may not provide sufficient angular divergence and accuracy of the obtained field of view. In these cases, a full three-dimensional electromagnetic model would be preferred.

[0066] Figure 10The diagram 1000 illustrates light projected by multiple transmitters in a single-lens LIDAR transmitter system. A single projection lens 1002 is located on a substrate 1006 at a distance from the array of VCSEL laser transmitters 1004. Figure 10 The illustration shows light projected by an array of laser emitter systems, which completely represent the VCSEL laser emitter 1004 as a finite light source with an emission aperture of width a. Figure 10 In the image, the center-to-center distance 1008D of the outermost laser is mapped to an angular field of view 1010β, which is the center-to-center angular offset between the two outermost projected beams 1012 and 1014. Each vertical position of the laser in the focal plane of the lens is mapped to a unique angular projection angle. Thus, for a source with a finite emission aperture of dimension a, the resulting beam divergence will be approximately equal to a*(β / D).

[0067] refer to Figure 10 The typical spacing d of a VCSEL array is 250 micrometers, therefore the center-to-center distance 1008D of the outermost emitter is 1.25 mm. Assuming the emission aperture diameter a is 100 micrometers and the maximum divergence over the full angle is 5 mrad, we can calculate that the full field of view 1010 of the lens β cannot exceed 62.5 mrad (3.58 degrees). If the field of view generated by the lens is greater than 3.58 degrees, then due to the finite size of the laser emission area, the divergence of the laser beam will exceed 5 mrad over the full angle.

[0068] Figure 10 The inherent divergence of the VCSEL laser emitter is approximately 2 degrees. This low divergence allows the laser beam to remain largely separated as it exits the plane of the array substrate 1006 and travels through the lens toward the far field, except at point 1016 on the right side of the lens, where the laser beams intersect to form a beam waist.

[0069] Figure 11A -B shows a more typical configuration with greater beam divergence. Figure 11A A schematic diagram 1100 illustrates an extended view of light projected by multiple transmitters in a single-lens LIDAR system with high-angle divergence transmitters. Figure 11B The diagram illustrates the process of... Figure 11A A schematic diagram 1150 illustrates a condensed view of the far-field light projected by the system. In both diagrams, emitter arrays 1102 and 1152 illuminate corresponding lenses 1104 and 1154. Figure 10 Compared to the example shown, each emitter 1106, 1156 generates a laser beam 1108, 1158 with a relatively wide divergence. Lenses 1104, 1154 converge the respective emitted beams 1108, 1158 to produce beam waists 1110, 1162. Figure 11A -B illustrates how the laser beam will seek a more typical ~20-degree VCSEL divergence. In this configuration, as shown, beams 1108 and 1158 significantly overlap at lenses 1104 and 1154. And as... Figure 11B As shown, with Figure 10 Compared to the previous example, the position 1160 where the beam is completely separated is much farther from lens 1154. We can see that the inherent divergence of the VCSEL and the size of the array will determine the minimum lens aperture of this single lens system. The greater the divergence and the larger the array size, the larger the minimum aperture required to truncate the laser beam emitted by the VCSEL array will be.

[0070] Therefore, for LIDAR transmitters, there are two main reasons for the divergence of the transmitted beam at the target range in the far field, which includes a series of laser beams emitted by the aperture and / or sub-apertures of the VCSEL array. One source of the final beam divergence is a function of the size of the laser emission area and the focal length of the lens system. The second source of the final beam divergence is a function of the laser emission size and the projected field of view of the lens. A feature of this teaching is the recognition that different lens systems with the same focal length but different projected fields of view can be designed.

[0071] The optical detection and ranging method according to this teaching includes generating multiple beams, which may be multi-wavelength beams. A first lens is positioned in the optical path of the multiple beams at a distance less than the focal length of the first lens from at least one of the multiple light emitters. The first lens converges the multiple beams into a converged beam having a beam waist. A second lens is positioned in the optical path of the converged beam such that it projects the converged beam onto a target area. The position of the second lens can be further selected to reduce the angular resolution of the LIDAR transmitter at the target area. Also in some methods, the aperture size of the second lens is selected to be equal to the size of the beam waist of the converged beam. The position of the second lens and the emission width of at least one of the multiple light emitters are selected to provide a desired field of view for the LIDAR transmitter at the target area.

[0072] Figure 12 The illustration shows a schematic diagram of an embodiment of the lens system for projecting light in a small-angle divergence LIDAR transmitter 1200 according to this teaching. A first lens 1202 is positioned very close to a VCSEL laser array 1204, which includes multiple individual laser emitters 1206. The first lens 1202 can be positioned closer to the emitters than a distance equal to the focal length of the first lens. The figure illustrates laser beams 1202, 1210 emitted by the individual laser emitters 1206. Only the central laser beam 1208 and the outer laser beams 1210 are shown. However, all laser emitters 1206 in the array can generate laser beams as desired.

[0073] The second lens 1212 is positioned after the first lens 1202 and projects laser beams 1208 and 1210 to a far-field position 1214, where the laser beams from the respective transmitters are nominally separated. The first lens 1202 is placed at a specific distance 1216 from the array, at which the desired convergence of laser beams 1208 and 1210 is generated at the second lens 1212. The second lens 1212 is placed at a specific distance 1218 from the first lens 1202 to generate a desired field of view at the desired far-field position 1214 (target range).

[0074] like Figure 12 As shown, the first lens 1202 acts as a beam convergent, causing the laser beam 1210 to be redirected inward from the outermost VCSEL transmitter 1220, resulting in a smaller minimum lens aperture for the second lens 1212 compared to a single lens system. This means the physical transmitter can be smaller because the minimum lens aperture of the second lens 1212 determines the size of the largest lens in the system. In this example, the beam waist generated by the converging first lens 1202 is formed at the location of the second lens 1212, and the aperture of the second lens is equal to the size of the beam waist. Each beam generated by the transmitter fills the aperture of the second lens.

[0075] Compared to a single-lens system with the same focal length, this dual-lens configuration offers significantly improved performance while maintaining the desired low divergence of the output beam. This dual-lens configuration also advantageously minimizes the size of the LIDAR transmitter. Furthermore, the projection angle of the dual-lens system can be varied without changing the overall focal length of the lens system. The curvature of the lens surfaces in this dual-lens system can be adjusted to provide an additional degree of freedom in maintaining the focal length while enabling different fields of view. This additional degree of freedom also allows adjustment of the field of view to minimize the divergence of the individual emitted laser beams when necessary, while maintaining the overall compact size of the transmitter.

[0076] As described in this article, the divergence of the transmitted laser beam from the individual laser emitters is a key factor in determining the field of view obtained from the lens system. Once the maximum field of view is determined based on the maximum divergence, the angular resolution of the system is determined by the spacing between the individual lasers in the array, which must not be less than their respective emission widths.

[0077] The small-angle divergence LIDAR transmitters of this teaching can be configured in various designs to achieve the specific field of view and angular resolution required to address the needs of particular sensor applications. For example, some automotive applications require a maximum divergence of five milliradians at a half-angle. Field of view, divergence, and aperture size are all related. Furthermore, the transmitter emission width, transmitter spacing, and array size are critical. In one particular embodiment, a 16x16 element two-dimensional array is configured for an 18.3-degree field of view using a dual-lens system with the first lens positioned at a position smaller than the focal length of the first lens in the array, where the emission width is 125 micrometers, the laser spacing is 250 micrometers, and the maximum half-angle divergence is 5 mrad. Larger fields of view using this teaching are possible, for example, by using smaller emission widths.

[0078] Angular resolution is determined by dividing the field of view by the array size. Using a transmitter with the minimum possible emission width means more elements in the array, and therefore the minimum possible angular resolution. One particular embodiment, with an array of sixteen elements in one dimension, an emission width of 50 micrometers, a laser spacing of 250 micrometers, and a maximum half-angular divergence of 5 mrad, is configured for a 45.8-degree field of view. The angular resolution of this configuration is 2.8 degrees. Lower resolutions are possible, for example, by using more array elements with smaller spacing.

[0079] In various embodiments, the field of view and angular resolution can differ in different directions; for example, in some systems, the horizontal field of view and angular resolution differ from the vertical field of view and angular resolution.

[0080] One feature of this teaching is that the compact size of the dual-lens projection system, along with other design features, allows multiple transmitter arrays to be combined into a single transmitter system. Figure 13 The illustration shows a schematic diagram of an embodiment of a lens system according to this teaching, which projects light into a small-angle divergence LIDAR transmitter 1300 using multiple transmitter arrays 1302, 1304, and 1306. Figure 13 In this configuration, several transmitter arrays 1302, 1304, and 1306 are used to cover a wider combined field of view 1308. Each VCSEL transmitter uses its own transmitter array 1302, 1304, and 1306, and the placement of the transmitter arrays 1302, 1304, and 1306 in three-dimensional space (x, y, z) allows the beams to be combined into desired patterns, such as a uniform pattern in the far field or a pattern with desired overlap or gaps.

[0081] For example, the positions of transmitter arrays 1302, 1304, and 1306 can be selected such that the beam pattern at the target area is arranged such that the beams from the first transmitter array 1302 and the beams from the second transmitter array 1304 form a gap at the target plane. Alternatively, the positions of transmitter arrays 1302, 1304, and 1306 can be selected such that the beam pattern at the target area is arranged such that the beams from the first transmitter array 1302 and the beams from the second transmitter array 1304 overlap at the target plane. Furthermore, the positions of transmitter arrays 1302, 1304, and 1306 can be selected such that the beam pattern at the target area is arranged such that the beams from the first transmitter array 1302 and the beams from the second transmitter array 1304 form a uniform light pattern at the target plane. It will be apparent to those skilled in the art that the relative positions of the transmitter arrays and the associated optical lenses that converge and project the multiple beams emitted from the transmitter arrays allow for the projection of various patterns at the target plane.

[0082] In some embodiments, a plurality of transmitter arrays are used to cover a wider or narrower field of view by physically adjusting the position (x, y, z) and pointing angle of the individual transmitters, thereby generating a desired laser beam pattern at the target range using all six dimensions. When used in a LIDAR system, the pattern of the various laser beams at the target range produces an associated desired measurement point cloud.

[0083] In one embodiment, at least two transmitter arrays are positioned such that the beams substantially overlap at the target range. In this embodiment, the field of view of the dual transmitter system is the same as that of each transmitter array and lens system. Systems with more than two arrays can also be configured with patterns that substantially completely overlap at the target range. Such an arrangement results in improved angular resolution. Embodiments of this teaching using multiple transmitter arrays can achieve angular resolution of less than 0.25 degrees using state-of-the-art transmitter array technology.

[0084] One feature of this teaching is that multiple transmitter arrays can be placed on a single substrate. Each transmitter array can have a different shape and spacing, and the spacing between each transmitter array can also be varied on the substrate. Figure 14A The illustration shows a schematic diagram of an extended view of an embodiment of a lens system that utilizes a plurality of transmitter arrays on a single substrate of the present teaching to project light into a small-angle divergence LIDAR transmitter.

[0085] Figure 14B The illustration shows that Figure 14AThis is a schematic diagram of a condensed view of an embodiment of a lens system for projecting light in a small-angle divergence LIDAR transmitter. Multiple transmitter arrays 1402, 1404, 1406, and 1408 are positioned on a common substrate 1410. Each transmitter array 1402, 1404, 1406, and 1408 has associated first lenses 1412, 1414, 1416, and 1418 and second lenses 1422, 1424, 1426, and 1428. For clarity, Figure 14A -B Instead of showing the fully divergent laser beam emitted by each VCSEL transmitter, a single beam from the center of the three VCSEL transmitters is shown to illustrate the concept of this teaching. For each transmitter array 1402, 1404, 1406, 1408, a single beam from the top outer transmitters 1432, 1434, 1436, 1438 is shown. Furthermore, for each transmitter array 1402, 1404, 1406, 1408, a single beam from the bottom outer transmitters 1442, 1444, 1446, 1448 is shown. For each transmitter array 1402, 1404, 1406, 1408, a single beam from the center outer transmitters 1452, 1454, 1456, 1458 is shown. Figure 14A The embodiment of -B uses multiple array transmitters 1402, 1404, 1406 to increase angular resolution. For a single transmitter array using a single VCSEL array on a substrate, the angular resolution is set by the field of view and the number of individual laser emitters in the array. If a denser angular resolution is desired, multiple transmitters can be combined by overlapping the output beams in the far field within the desired range.

[0086] Figure 14A The illustration shows four transmitter arrays 1402, 1404, 1406, and 1408 attached to a common substrate 1410. While a common substrate is not strictly necessary, it may be desirable from an ease of assembly perspective. Various known common substrates can be used, including substrates formed of semiconductor or ceramic materials. The common substrate can be a printed circuit board (PCB). In some embodiments, several transmitter arrays share a single common substrate, such as a single semiconductor or ceramic carrier substrate. In other embodiments, the transmitter arrays are located on different common substrates, and then these two common substrates with arrays are placed on a third common substrate, such as a PC board.

[0087] Each of the four transmitter arrays 1402, 1404, 1406, and 1408 has its own corresponding lens system, which includes first lenses 1412, 1414, 1416, and 1418 and second lenses 1422, 1424, 1426, and 1428 corresponding to each transmitter array 1402, 1404, 1406, and 1408, as shown in the figure. The laser beams emitted from the four transmitter arrays 1402, 1404, 1406, and 1408 are overlapped and combined by adjusting the positions of each of the four lens systems, including the first lenses 1412, 1414, 1416, and 1418 and the second lenses 1422, 1424, 1426, and 1428, relative to their corresponding transmitter arrays 1402, 1404, 1406, and 1408. The positions of the second lenses 1422, 1424, 1426, and 1428 in each transmitter are shown as different radial offsets 1452, 1454, 1456, and 1458 from the centers P1, P2, P3, and P4 of each corresponding transmitter array 1402, 1404, 1406, and 1408. The first lenses 1412, 1414, 1416, and 1418 of each transmitter array 1402, 1404, 1406, and 1408 can also be radially offset from the centers of their associated transmitter arrays 1402, 1404, 1406, and 1408. These offsets will allow each transmitter array 1402, 1404, 1406, and 1408 to achieve the desired beam pattern within the target range. Specific radial offset values ​​are selected as needed to create the specific angular field pattern required by the LIDAR system at the range. These radial offset values ​​are typically not equal, but may be equal in certain embodiments.

[0088] A feature of this teaching is that the lateral offset between individual VCSEL arrays is not critical for determining the combined beam pattern within the target range. Figure 14A The diagram illustrates lateral offsets 1460, 1462, and 1464 with values ​​of S1, S2, and S3. For a typical LiDAR system with a range of 100m, the exact values ​​of S1, S2, and S3 are not important because the offsets do not increase with distance. In many embodiments, after only a few meters, the initial offsets between arrays, represented by lateral offsets 1460, 1462, and 1464 in the diagram, are no longer significant compared to the offsets caused by differences in the projection angles set by the lens systems of each array. Figure 14B The condensed view shows a representation of how beams combine in the far field.

[0089] pass Figure 15 The configuration shown illustrates the relative independence of the projection field pattern of the lens system of this teaching in the lateral offset of the array. Figure 15The illustration shows a schematic diagram of scaled convergent and extended views of an embodiment of the small-angle divergence LIDAR transmitter of this teaching, to illustrate the relative independence of the separation between the transmitter arrays. Figure 15 The illustration shows an example of scaling the combined laser beams. Extended and condensed views are shown. In one configuration, the initial lateral offset is 10 mm in extended view 1502 and in condensed view 1504. In another configuration 1506, the initial lateral offset is 20 mm in extended view 1506 and in condensed view 1508.

[0090] In one particular embodiment, the laser beam of each VCSEL array is offset by 2 degrees, and there is a 1-degree offset between the transmitters, such that the laser beam in the final beam pattern is uniformly offset by 1 degree in the far field. It can be seen that at ~5m, there is no substantial difference in the far-field pattern.

[0091] A key feature of this teaching is that the lens system is capable of controlling the beam divergence and step size or position in the far field. Known LIDAR projection systems typically only control the step size and lack the ability to independently control the beam divergence and step size or position in the far field. Furthermore, the LIDAR system of this teaching can introduce additional beam control of the far-field pattern by using additional optical elements. Specifically, by positioning the first lens close to the transmitter array, the lens system of this teaching provides different step sizes for the focal point, independent of the optical system.

[0092] One feature of the LIDAR system described in this teaching is the ability to use wavelengths to provide control over the laser beam pattern generated in the far field at the target range, as well as the associated measurement point cloud of the LIDAR system. Figure 16 An embodiment of an illuminator 1600 for a multi-wavelength LIDAR system using multiple transmitter arrays of the present teaching is illustrated. In this embodiment, multiple surface-emitting laser arrays are used, including at least two sets of lasers with different wavelengths, VCSELλ1 1602 and VCSELλ2 1604.

[0093] Another feature of the LIDAR system of this teaching is the use of three-dimensional space. VCSELλ1 1602 and VCSELλ2 1604 are oriented in two surfaces orthogonal to each other. Those skilled in the art will recognize that various three-dimensional (X, Y, and Z) degrees of freedom and / or six-dimensional degrees of freedom (X, Y, Z, pitch, yaw, and roll) including the angles of VCSELs 1602 and 1604 can be used in the LIDAR system of this teaching. The beams are combined by using a wavelength multiplexer 1806, which allows one wavelength to pass through while reflecting a second wavelength.

[0094] The wavelength multiplexer 1606 can be implemented, for example, by using a thin-film filter that allows the first wavelength to pass through without deflection, while the second wavelength is deflected at 45 degrees, and the output beams are combined. For simplicity, we show a cubic multiplexer 1606 formed by two prisms with equal triangular cross-sections, wherein the thin-film filter for reflecting or passing wavelengths is located at the central plane of the cube where the two triangular prisms meet.

[0095] The positions of the two substrates of VCSELλ1 1602 and VCSELλ2 1604, relative to wavelength multiplexer 1606, can be laterally shifted to create the desired overlap or interleaving of the two beams. Figure 17 The diagram shows how to use it. Figure 16 The illuminator embodiment generates a measurement point cloud 1700. It will be apparent to those skilled in the art that the use of laser emitters with different wavelengths is not limited to the configuration shown herein. Different wavelengths can be associated with each array, or different wavelengths can be emitted from a single array in various patterns. Furthermore, the arrays can be configured with various 3D spatial patterns including different emission angles for each array.

[0096] A feature of this teaching is that the optical projection system takes into account the finite emission area of ​​the VCSEL lasers forming the emitter array. Known LIDAR projection optics model the laser source as a point source. In some embodiments of the LIDAR system of this teaching, each adjacent VCSEL within the array has a separation distance greater than the individual diameter of the emission area of ​​each laser. The VCSEL laser array all share a common optical lens system with a net aperture smaller than the combined projection diameter of the VCSEL laser array in free space. This is accomplished by a first lens that at least converges the outermost beam. In some embodiments, the first lens, acting as a converging lens, is positioned adjacent to the VCSEL array at a distance smaller than the focal length of the first lens. The maximum field of view of the lens system is defined by the emission width of the laser, the optical system defining the divergence of the laser beam, and the separation distance of the lasers in the array.

[0097] In some embodiments, multiple transmitter arrays are overlapped in free space to create a denser angular resolution than that could be created using a single transmitter with the same VCSEL array dimensions. Each transmitter array has an associated first lens. The first lens of each individual transmitter array is radially offset to produce a different angular pattern. The radial offset of each lens system does not need to be the same. The transmitter arrays are located on a common substrate, and the distances between the various transmitter arrays do not need to be the same. In embodiments with multiple transmitters, the wavelengths of the transmitter arrays and / or the individual VCSELs of each transmitter array may be the same or different. In embodiments of LIDAR systems using different wavelengths as taught in this invention, wavelength-sensitive elements can be used to further converge or diverge the beam in the far field based on the wavelength of the beam.

[0098] The optical detection and ranging method according to this teaching includes providing a first transmitter array comprising a first plurality of light emitters, the first plurality of light emitters generating a first plurality of light beams, which may be multi-wavelength beams. A first lens is positioned in the optical path of the first plurality of light beams at a distance less than the focal length of at least one of the plurality of light emitters, such that the first lens converges the first plurality of light beams to form a first converged beam having a beam waist. A second lens is positioned in the optical path of the first converged beam, such that the second lens projects the first converged beam onto a target range. The position of the second lens and the emission width of at least one of the first plurality of light emitters are selected to provide a desired field of view of the projected first converged beam within the target range.

[0099] The method further includes providing a second transmitter array comprising a second plurality of light emitters that generate a plurality of second beams, which may be multi-wavelength beams. A third lens is positioned in the optical path of the second plurality of beams at a distance less than the focal length of at least one of the second plurality of light emitters, such that the third lens converges the second plurality of beams to form a second converged beam having a beam waist. A fourth lens is positioned in the optical path of the second converged beam, such that the fourth lens projects the second converged beam onto a target range. The position of the fourth lens and the emission width of at least one of the second plurality of light emitters are selected to provide a desired field of view of the projected second converged beam within the target range. The positions of the first transmitter array and the second transmitter array are selected to provide a desired field of view of the LIDAR transmitter within the target range.

[0100] Equivalent

[0101] While the applicant's teachings have been described in conjunction with various embodiments, it is not intended to limit the applicant's teachings to such embodiments. Rather, as those skilled in the art will recognize, the applicant's teachings encompass a variety of alternatives, modifications, and equivalents, which can be made without departing from the spirit and scope of these teachings.

Claims

1. A light detection and ranging LIDAR transmitter, comprising: a) A first plurality of light emitters, the first plurality of light emitters generating a first plurality of light beams at a first wavelength; b) A second plurality of light emitters, the second plurality of light emitters generating a second plurality of light beams at a second wavelength; c) A first lens positioned in the optical path of the first plurality of light beams, wherein the distance between the first lens and the first plurality of light emitters is less than the focal length of the first lens, and the first lens converges the first plurality of light beams; as well as d) A third lens positioned in the optical path of the second plurality of light beams, wherein the distance between the third lens and the second plurality of light emitters is less than the focal length of the third lens, and the third lens converges the second plurality of light beams. The relative positions of the first plurality of light emitters and the second plurality of light emitters cause the first plurality of light beams and the second plurality of light beams to overlap at the target range.

2. The LIDAR transmitter as claimed in claim 1, wherein, The first plurality of light emitters and the second plurality of light emitters are positioned on the same substrate.

3. The LIDAR transmitter as described in claim 2, wherein, The substrate includes a ceramic substrate.

4. The LIDAR transmitter as described in claim 2, wherein, The substrate includes a semiconductor substrate.

5. The LIDAR transmitter as claimed in claim 2, wherein, The substrate includes a printed circuit board substrate.

6. The LIDAR transmitter as claimed in claim 1, wherein, At least one of the first plurality of optical emitters and the second plurality of optical emitters includes a VCSEL device.

7. The LIDAR transmitter as claimed in claim 1, wherein, At least some of the first plurality of optical emitters and the second plurality of optical emitters comprise a one-dimensional VCSEL array.

8. The LIDAR transmitter as claimed in claim 1, wherein, At least some of the first plurality of optical emitters and the second plurality of optical emitters comprise a two-dimensional VCSEL array.

9. The LIDAR transmitter as claimed in claim 1, wherein, The relative positions of the first plurality of light emitters and the second plurality of light emitters cause the first plurality of light beams and the second plurality of light beams to overlap in one dimension within the target range.

10. The LIDAR transmitter as claimed in claim 1, wherein, The relative positions of the first plurality of light emitters and the second plurality of light emitters cause the first plurality of light beams and the second plurality of light beams to completely overlap within the target range.

11. The LIDAR transmitter as claimed in claim 1, wherein, At least one of the first lens and the third lens is positioned radially offset from the center of a corresponding one of the first plurality of light emitters and the second plurality of light emitters.

12. The LIDAR transmitter as claimed in claim 1, wherein, Both the first lens and the third lens are positioned radially offset from the center of a corresponding one of the first plurality of light emitters and the second plurality of light emitters.

13. The LIDAR transmitter as claimed in claim 12, wherein, The radial offset of the first lens relative to the center of the first plurality of light emitters is the same as the radial offset of the third lens relative to the center of the second plurality of light emitters.

14. The LIDAR transmitter of claim 12, wherein, The radial offset of the first lens relative to the center of the first plurality of light emitters is different from the radial offset of the third lens relative to the center of the second plurality of light emitters.

15. The LIDAR transmitter as claimed in claim 1, wherein, The positions of the first plurality of light emitters and the second plurality of light emitters are configured to provide a desired field of view at the target range.

16. The LIDAR transmitter of claim 15, wherein, The LIDAR transmitter has an angular resolution of less than 2.8 degrees at the target range.

17. A light detection and ranging LIDAR transmitter, comprising: a) A first array of light emitters, the first array of light emitters generating a light beam at a first wavelength; b) A second array of light emitters that generates a second array of light beams at a second wavelength; c) A first lens positioned in the optical path of the first array of the beam, the distance between the first lens and the first array of the light emitter is less than the focal length of the first lens, and the first lens converges the first array of the beam; as well as d) A third lens positioned in the optical path of the second array of the light beam, wherein the distance between the third lens and the second array of the light emitter is less than the focal length of the third lens, and the third lens converges the second array of the light beam. The relative positions of the first array and the second array of the light emitter cause the first array and the second array of the light beam to be staggered at the target range.

18. The LIDAR transmitter of claim 17, wherein, At least one of the first array of optical emitters and the second array of optical emitters includes a VCSEL device.

19. The LIDAR transmitter of claim 17, wherein, At least one of the first array of optical emitters and the second array of optical emitters includes a one-dimensional VCSEL array.

20. The LIDAR transmitter of claim 17, wherein, At least one of the first array of optical emitters and the second array of optical emitters includes a two-dimensional VCSEL array.

21. A light detection and ranging LIDAR transmitter system, comprising: a) Substrate; b) A first transmitter array, positioned on a substrate and comprising a plurality of light emitters that generate a plurality of light beams; c) A first lens is positioned in the optical path of the plurality of beams generated by the first transmitter array, the distance between the first lens and the first transmitter array is less than the focal length of the first lens, and the first lens converges the plurality of beams into a converged beam with a beam waist. d) A second lens, positioned in the optical path of the converging beam of the plurality of beams generated by the first transmitter array, the second lens having a first radial offset relative to the center of the first transmitter array; e) A second transmitter array, positioned on a substrate and comprising multiple light emitters that generate multiple beams; f) A third lens, positioned in the optical path of the plurality of beams generated by the second transmitter array, wherein the distance between the third lens and the second transmitter array is less than the focal length of the third lens, and the third lens converges the plurality of beams into a converging beam having a beam waist; and g) A fourth lens, positioned in the optical path of the converging beam of the plurality of beams generated by the second transmitter array, the fourth lens having a second radial offset relative to the center of the second transmitter array. The first radial offset and the second radial offset are selected to achieve the desired beam pattern at the target range.

22. The LiDAR transmitter system of claim 21, wherein, The desired beam pattern at the target range includes non-overlapping beam patterns.

23. The LiDAR transmitter system of claim 21, wherein, The desired beam pattern at the target range includes overlapping beam patterns.

24. The LiDAR transmitter system of claim 21, wherein, The desired beam pattern at the target range includes interlaced beam patterns.

25. The LiDAR transmitter system of claim 21, wherein, The first radial offset and the second radial offset are different radial offsets.

26. The LiDAR transmitter system of claim 21, wherein, The substrate includes a printed circuit board.

27. The LiDAR transmitter system of claim 21, wherein, The substrate includes a ceramic carrier.

28. The LiDAR transmitter system of claim 21, wherein, The substrate comprises a single semiconductor.

29. The LIDAR transmitter system of claim 21, further comprising a third transmitter array located on the substrate.

30. The LiDAR transmitter system of claim 29, wherein, The distance between the first transmitter array and the second transmitter array and the distance between the second transmitter array and the third transmitter array are different distances.

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