Optical expander for lidar system and lidar system

Abstract

The present disclosure relates to an optical expander (10) for a receive path of a lidar system (50), configured to expand at least one light beam (12) for reception by at least one pixel (22) of an optical sensor (20) of the lidar system (50), the expander (10) including at least one of a concave and / or convex cylindrical lens (13), a one-sided microcylinder lens array structure, or a two-sided microcylinder lens array structure. The present disclosure further relates to the lidar system (50).

Description

[Technical Field]

[0001] The present disclosure relates to the field of lidar systems comprising an optical transmitter, an optical receiver, and a control unit. [Background technology]

[0002] Modern vehicles (cars, vans, trucks, motorcycles, etc.) have numerous sensors whose data is used for driver information and / or made available to driver assistance systems. The sensors can detect the vehicle's environment and other road users. Based on the collected data, a model of the vehicle's environment can be generated, and the system can respond to changes in this vehicle environment.

[0003] An important sensor principle for detecting the environment of a vehicle, for example, is LIDAR technology (LIDAR engl. Light Detection and Ranging). LIDAR systems have an optical transmitter and an optical receiver. The transmitter can emit a transmitted light. In LIDAR systems, the light used can be laser light in the ultraviolet, visible, or infrared range. The receiver can receive the emitted light as received light after reflection from objects in the field of view of the LIDAR system.

[0004] Lidar systems are constantly being further improved for various functions, such as obtaining environmental information in the near and far ranges of vehicles, such as passenger cars or commercial vehicles. Lidar systems can also function as sensor systems for driver assistance systems, especially assistance systems for autonomous or semi-autonomous vehicle control. In particular, they can be used to detect obstacles and / or other road users in front of, behind, or in blind spots of the vehicle.

[0005] The received light can be evaluated by the control unit of the lidar system using the transmitted light. The spatial position and distance of the object from which the reflection occurred can be determined. Also, the relative velocity can be measured. Reflected light or reflected light is understood to mean any light that is reflected back, and in particular includes light that is reflected back by scattering or absorption emission.

[0006] Scanning lidar systems emit a light beam whose direction moves continuously in a scanning direction. One-dimensional (1D) scanning lidar systems perform one-dimensional scanning, for example, horizontally in front of a vehicle. In a 1D scanning lidar system, the optical receiver's optical sensor can have pixels, each with an active area having a first dimension along a first axis and a second dimension smaller than the first dimension. An example of such a sensor is the Sony IMX 449 / 459. The advantage of this larger dimension is that, on the one hand, the smaller axis size allows the sensor to maintain high angular resolution. On the other hand, the larger axis size allows the active area of ​​the pixel to be increased to increase the sensor's dynamic range.

[0007] U.S. Patent Application Publication No. 2020 / 0096615 describes an anamorphic camera lens that collects and focuses a light beam onto such pixels having an active area with a first dimension that is greater than a second dimension perpendicular to the first dimension.

[0008] A cylindrical lens array for an optical system is described in U.S. Patent Application Publication No. 2016 / 0170287. The cylindrical lens array is used to collimate a laser beam in the transmit optical path of a data communication system. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] US Patent Application Publication No. 2020 / 0096615 [Patent Document 2] US Patent Application Publication No. 2016 / 0170287 Summary of the Invention

[0010] An optical expander for the receive path of the lidar system is configured to expand at least one optical beam for reception by at least one pixel of the optical sensor of the lidar system. The optical sensor converts the optical information into electrical information, which can then be processed. The expander includes at least an optical expansion element, which includes at least one of a concave and / or convex cylindrical lens, a single-sided microcylinder lens array structure, or a double-sided microcylinder lens array structure. The expansion spreads the energy of the optical beam over a wider area of ​​the pixel. The area illuminated by the optical beam on the pixel may form an elliptical outline. The beam expansion in the receive path can reduce the blooming effect and increase the dynamic range of the optical sensor. As a result, the detection range of the receiver and the entire lidar system can be increased.

[0011] The concave and / or convex cylindrical lens, also referred to as a concave / convex cylindrical lens, may be a concave cylindrical lens having two concave surfaces, and the convex cylindrical lens may be a convex cylindrical lens having two convex surfaces or a concave / convex cylindrical lens having a concave cylindrical lens and a convex cylindrical lens. The concave / convex cylindrical lens is configured to expand at least one optical beam in the receive path of the lidar system, as described above. The optical expander may include two or more convex / concave cylindrical lenses, for example in the form of a cylindrical lens array.

[0012] In one embodiment, the optical expander is configured to expand at least one optical beam in one predetermined direction. The one predetermined direction can be adapted for reception by at least one pixel. For example, if the at least one pixel has a larger surface area in a first dimension than in a second dimension, the expansion of the at least one optical beam in one predetermined direction can be in the first dimension. This means that the optical beam is expanded in a dimension that is larger than the pixel. This allows more energy of the optical beam to be absorbed by the pixel because the illumination area of ​​the pixel, i.e., the area that is hit by the expanded optical beam, is larger. The high angular resolution of the lidar can be maintained in other dimensions of the at least one optical beam.

[0013] The single-sided microcylinder lens array structure comprises a substrate having microcylinder lenses on one surface of the substrate. The double-sided microcylinder lens array structure comprises a substrate having microcylinder lenses on two surfaces of the substrate, for example, on opposite surfaces of the substrate. The substrate preferably comprises an optically transparent material, for example, glass and / or plastic. The substrate functions as a carrier for the microlenses and may further have optical properties that affect at least one light beam.

[0014] In one embodiment of the light expander, expanding the at least one light beam comprises increasing the diameter of the at least one light beam in at least one direction and / or increasing the direction of the at least one light beam in at least one direction. Depending on the type of light expanding element, expanding the light beam can mean increasing the diameter of the at least one light beam and / or increasing the size of the at least one light beam.

[0015] When the aspect ratio of the beam expansion is not too large, a regular convex / concave lens can be used. However, as the aspect ratio becomes larger, for example, greater than 1:5, 1:7, or 1:9, the curvature of the lens becomes larger. As a result, the overall size of the receiver of the lidar system becomes larger. To keep the design of the lidar system compact, a microlens array can be introduced.

[0016] A microlens array includes a plurality of microlenses formed in a one- or two-dimensional array on a support substrate. A single-sided microlens array includes an array of microlenses on one surface of the support substrate. A double-sided microlens array includes microlens arrays on both surfaces of the support substrate. Preferably, the two microlens arrays of a double-sided microlens array are disposed on opposing surfaces of the support substrate. The microlenses are small lenses, e.g., less than a few millimeters in diameter, and in some cases even smaller, such as 10 μm. The small size of the microlenses allows for large beam expansion without increasing the size of the optical system. A cylindrical microlens includes at least a partial cylindrical shape. If the microlenses are made of glass, the substrate should not be thicker than the microlenses. A microcylinder lens array may include convex and / or concave microcylinder lenses. By appropriately arranging the convex and / or concave microcylinder lenses on one or both sides of the substrate, the desired light expansion can be achieved.

[0017] One microcylinder lens in the array of microcylinder lenses may be configured to expand at least one optical beam for reception by one pixel in the pixel array of the optical sensor. When coupled with beam steering optics in the receiver of the lidar system, the optical beam from a particular angle of incidence in the field of view of the radar system can be directed toward individual pixels in the receiver's optical sensor. The optical expander specifically expands the incident beam to illuminate a larger area of ​​the optical pixel at the optical center. This allows for a high optical resolution relative to the angle of incidence while simultaneously increasing the area received by the pixel from the optical beam.

[0018] The associated pair of opposing micro-cylinder lenses of the double-sided micro-cylinder lens array is configured to expand at least one light beam for reception by one pixel of the pixel array of the optical sensor. The micro-cylinder lenses on each side of the substrate can be taken into consideration when designing the optical properties of the double-sided micro-cylinder lens array, and the thickness of the substrate, along with its optical refractive index, can be taken into consideration for the overall design of the double-sided micro-cylinder lens array. At the same time, when the double-sided micro-cylinder lens array is used in combination with beam steering optics, the two micro-cylinder lenses on each side of the substrate can work together to produce a desired optical effect on a single light beam passing through the two micro-cylinder lenses working together. The beam can be expanded to simultaneously impinge on a larger area of ​​the associated pixel of the optical sensor. In the other dimension of the unexpanded beam, the angular resolution relative to the field of view of the lidar system can be maintained.

[0019] In an embodiment, the support substrate comprises glass. In an embodiment, the microcylinder lenses are manufactured by a molding method. In particular, it is possible to mold glass microcylinder lenses onto the support substrate.

[0020] In other embodiments, the microcylinder lenses comprise a polymer material. Polymer microcylinder lenses can be fabricated by a polymer-on-glass (PoG) method, which allows for the fabrication of polymer microcylinder lenses on a supporting substrate comprising glass.

[0021] In another embodiment, the microcylinder lenses may be fabricated by a chip-on-glass method, which can be used to fabricate and integrate the microcylinder lenses directly onto a glass substrate.

[0022] The thickness of the glass substrate may vary over its spatial extent or may be constant over its spatial extent. The thickness of the glass substrate can then be taken into consideration when designing the optical properties of the microlens cylinder array. In particular, the refractive index of the microlens cylinder can depend on the thickness of the glass substrate. The desired optical properties may be designed taking into account the combination of the microlens cylinder and the substrate.

[0023] The lidar system includes an optical expander in its receive path. The receiver of the lidar system includes an expander that can be disposed between a collecting lens and the receiver's optical sensor. Alternatively, a collecting lens may be disposed between the expander and the receiver's optical sensor. Both optical configurations are possible and may have advantages for achieving desired optical characteristics in the receive path of the lidar system and / or may have cost advantages. The lidar system further includes a transmitter for emitting a transmitted light beam and a control unit for controlling the emission and reception of the light beam for object detection, distance determination, and / or velocity determination within the field of view of the lidar system. The emitted light and received light are used to perform object detection, distance detection, and relative velocity detection.

[0024] In embodiments of the lidar system, the expander is configured to more uniformly expand at least one light beam received by at least one pixel of the optical sensor. This can increase the effective area of ​​reception of the received light beam, particularly on pixels that have unequal dimensions in one direction of the pixel's reception area compared to another direction. When the optical sensor comprises a pixel array, it can be advantageous to use an optical expander comprising a microlens array to expand different light beams for different pixels of the pixel array. The different light beams passing through the microlens cylinder array are received from different angles of incidence in the field of view of the lidar system.

[0025] The pixel array of the optical sensor may be one-dimensional, i.e. formed by a column of pixels, or it may be two-dimensional, i.e. formed by a two-dimensional area.

[0026] In one embodiment of a lidar system, the pixel array is a one-dimensional row of pixels, and the surface area of ​​the pixels is greater in a first dimension perpendicular to the row than in a second dimension parallel to the row. The expander is configured to expand at least one light beam in a predetermined direction, the predetermined direction being the direction of the first dimension of the pixel, i.e., the direction in which the pixel has a greater extent. In particular, the expander can include a microlens cylinder array configured to simultaneously expand several light beams. Each light beam can then be associated with one pixel of the optical sensor. Each pitch of the microlens cylinder array can then correspond to a microlens cylinder configured to expand one light beam directed at one pixel.

[0027] In one embodiment, the lidar system is a scanning lidar system in which the scan direction is parallel to one predetermined expansion direction of the at least one light beam, thereby maintaining high optical resolution for angles of incidence perpendicular to the scan direction, where the light beam is not expanded to maintain this high angular resolution. [Brief explanation of the drawings]

[0028] Embodiments will now be described, by way of example only, with reference to the accompanying drawings, in which like reference numerals are used to refer to like elements throughout and in which structures and devices shown are not necessarily drawn to scale.

[0029] [Figure 1] 1 illustrates a schematic of an optical expander in the receive path of a lidar system. [Figure 2] 10 illustrates the effect of an optical expander. [Figure 3] 10A and 10B show the effect of a one-sided microcylinder lens array. [Figure 4] 10A and 10B show the effect of a one-sided microcylinder lens array. [Figure 5] 1 illustrates the effect of a diverging lens. [Figure 6] 1 shows a schematic diagram of a Galilean telescope. [Figure 7] 1 shows a schematic diagram of a Keplerian telescope. [Figure 8] 10A and 10B show schematic diagrams of simulation results of an optical expander. [Figure 9] 10A and 10B show schematic diagrams of the effect of single-sided and double-sided microcylinder lens arrays. [Figure 10] 1 shows the results of the detection rate versus detection range of the lidar system. [Figure 11] 1 shows a schematic diagram of a vehicle with a lidar system and its field of view. DETAILED DESCRIPTION OF THE INVENTION

[0030] 1 shows an optical receiver 30 of a lidar system 50. An incident light beam 12 passes through a beam steering system 14. The beam steering system 14 is configured to direct light beams 12 coming from different angles of incidence in different directions to be received by different pixels 22 of an optical sensor 20 of the optical receiver 30.

[0031] The light expander 10 is positioned after the beam steering system 14. The condenser lens 16 is positioned after the light expander 10. The series of elements 14, 10, and 16 is described in the direction of travel of the incident light 12. In some embodiments, the light expander 10 may be positioned after the condenser lens 16. The condenser lens 16 focuses the incident light 12 onto pixels 22 of the optical sensor 20. The pixels 22 have surfaces for receiving the incident light beam 12. The dimensions of the surface of the pixel 22 are larger in a first direction than in a second direction. The first direction is perpendicular to the second direction. Each pixel 22 includes several single-photon avalanche diodes (SPADs) 18. The single-photon avalanche diodes 18 are semiconductor photodetectors. The SPADs 18 respond with a current when a photon is absorbed. The current increases with the number of received photons. The SPADs 18 can detect single photons by a current avalanche that can be caused by a received photon. Pixel 22 has three SPADs 18 in the second direction and nine SPADs 18 in the first direction. Thus, pixel 22 is three times as elongated in the first direction as it is in the second direction. Light expander 10 is constructed and arranged to expand incident light beam 12 in the direction of the first dimension of pixel 22.

[0032] The beam steering system 14 may include, for example, an optical phased array OPA. An optical phased array allows for the phase and amplitude of light waves to be controlled through a two-dimensional surface using adjustable surface elements. The beam steering system 14, e.g., an optical phased array, can be used to transmit, reflect, or capture, i.e., receive, the optical beam 12. The optical phased array dynamically controls the optical properties of its surface. This allows for the direction of the optical beam 12 to be steered, thereby changing the field of view of the optical sensor 20 of the optical receiver 30. The beam steering system 14 may also be a rotating mirror / MEMS that reflects the incident optical beam 12 in different directions depending on the rotational position of the rotating mirror.

[0033] The light beam 12 is received by a collecting lens 16, which may be, for example, a camera lens. The pixels 22 are arranged in a one-dimensional pixel array 21.

[0034] The optical receiver 30 can be positioned to receive light within a scanning lidar system 50, with the larger dimension of the pixel 22 then, for example, positioned toward the scanning lidar system 50. In the scanning lidar system 50, the optical transmitter 40 transmits a scanning optical beam 62 that incrementally changes the direction of the beam 62 within a field of view 64 of the lidar system 50, thereby scanning the field of view 64. The scan direction 66 then is the direction in which the position of the transmitted optical beam 62 increases.

[0035] The dynamic range increases in a first direction of the pixel 22 where the pixel 22 contains more SPADs 18. This may correspond to, for example, the scan direction 66. The high angular resolution of the lidar system 50 is maintained in a second dimension where the number of SPADs 18 is fewer, for example, three. This corresponds to a direction perpendicular to the scan direction 66. The dynamic range of the lidar system 50 increases in the first direction where the number of SPADs 18 is increased, for example, to nine SPADs 18.

[0036] FIG. 2 shows a receive path, facing right, with such a pixel 22 having a larger first dimension with nine SPADs 18 and a smaller second dimension with three SPADs 18. The top of FIG. 2 shows an incident light beam 12 being focused onto the pixel 22 by a focusing lens 16. In the top of FIG. 2, the focusing lens 16 focuses the light beam 12 onto a focal plane 24 located at the receive surface of the pixel 22. The bottom of FIG. 2 shows another receive path with the pixel 22 and the focusing lens 16. The receive path includes an optical expander 10 in combination with the focusing lens 16. The optical expander 10 expands the incident light beam 12, thereby moving the focal plane 24 to a position behind the pixel 22. This results in the expansion of the light beam 12 on the pixel 22.

[0037] One dimension of the light beam 12 is subjected to the expanding effect of the light expander 10. This one dimension corresponds to a first dimension of the pixel 22 that is larger than a second dimension of the pixel 22. No expanding effect is applied to the other dimension of the light beam 12. This can be seen in the lower part of Figure 2, where an elliptical illumination area 23 illuminated by the incident beam 12 is shown.

[0038] In the lower portion of Figure 2, light 12 illuminates a larger area 23 on pixel 22 than in the upper portion of Figure 2. A light expander 10 inserted between beam steering system 14 and collector 16 expands the illuminated area 23. In a system with a pixel array 21, each pixel 22 corresponds to a particular angle of incidence. The light expander 10 can expand the light 12 from each angle of incidence by increasing the size and / or divergence of the light beam 12 in the direction of the larger dimension of the pixel 22.

[0039] In the scanning lidar system 50, this larger dimension can correspond to the scan direction 66. The angular resolution perpendicular to this scan direction remains the same as before. The use of a micro-cylinder lens array in the expander 10 makes it possible to achieve a high aspect ratio for the pixels 22. This would otherwise require optical lenses with very large curvatures. This can be achieved with a micro-lens array without significantly increasing the size of the individual micro-lenses 26 of the array. This allows for a compact implementation. The micro-lens array also improves the uniformity of the beam 12, further increasing the dynamic range of the receiver 30.

[0040] FIG. 3 shows a one-sided microlens array 10 with individual microlenses 26. The individual lenses 26 are sometimes referred to as pitches. Incident light 12 travels through the light expander 10 and the condenser lens 16 and is received by the pixel 22. The embodiment shown in FIG. 3 shows a one-sided microlens array 10. A single microlens 26 can have a one-sided concave and one-sided convex, double-concave, or double-convex profile. Proper design of these characteristics can achieve the desired optical effect. An advantage of such a light expander 10 is that it can be very low cost. Only one side of the light expander 10 needs to be configured to expand the beam 12 as desired. Such an expander 10 can increase the dynamic range of the receiver 30.

[0041] 3 also illustrates that pixels 22 may receive beams 12 with different angular resolutions, e.g., adjacent pitches, which may result in pixels 22 receiving more noise, which may reduce the detection range of the lidar system 50.

[0042] 4 shows an embodiment having a double-sided microcylinder lens array 10. The double-sided microcylinder lens array 10 includes microlenses 26 on two opposing surfaces of a substrate 11. The two opposing microlenses 26 are sometimes referred to as a pitch.

[0043] In the embodiment shown in FIG. 4, the double-sided microcylinder lens array 10 exhibits microlenses 26 with convex surfaces on one side. These convex microlenses 26 face toward the incoming received light beam 12. On the other side of the microcylinder lens array 10, the microlenses 26 are concave. They face toward the focusing lenses 16. Two microlenses 26 arranged at a pitch, i.e., directly opposite each other on the substrate 11, function together to achieve a desired optical effect for at least one light beam 12. Using such a double-sided microcylinder lens array 10, not only can the expansion of the light beam 12 be achieved, but the so-called blooming effect, which is the reception of light from adjacent light beams 12, can also be significantly reduced. This is illustrated in FIG. 4. The optical effect achieved by the pitch of two microlenses 26 arranged directly opposite each other on the substrate 11, is further illustrated below with reference to FIG. 6 or 7.

[0044] 5 shows an embodiment of a diverging lens 13 that can be included in the light expander 10. The diverging lens 13 is an embodiment of a concave lens having two concave surfaces. A parallel light beam 12 directed toward the diverging lens 13 is expanded into a diverging light beam 12 by the diverging lens 13. Such a diverging lens 13 may be used as the light expander 10. The diverging rays of the output light beam 12 have a virtual focal point 15.

[0045] FIG. 6 shows a Galilean telescope optical system GT. The Galilean telescope GT is an optical device having a biconvex objective lens 27 and a biconcave eyepiece lens 28, also known as a camera lens or eyepiece lens. The biconvex objective lens 27 forms an image. The eyepiece lens 28, also known as a camera lens or eyepiece lens, is biconcave and therefore a diverging lens. The camera lens is located in front of the focal point. The optical principle of the Galilean telescope GT, which has an objective lens 27 and a camera lens 28, includes two elements. By properly designing the double-sided microcylinder lens array 10, these two elements 27 and 28 can be replaced by a single pitch of the double-sided microcylinder lens array 10. One of the microlenses 26 in the pitch functions as the objective lens 27, and the other microlens 26 in the pitch, located opposite the first microcylinder lens 26 on the substrate 11, functions as the camera lens 28. If this is properly designed, each pitch of the microcylinder lens array 10 can function to perform the optical effect of a Galilean telescope GT. The necessary distance between the objective lens 27 and the eyepiece lens 28 can be ensured by the substrate 11.

[0046] Another embodiment for designing the optical characteristics of a single pitch of the double-sided microcylinder lens array 10 is shown in Figure 7. Figure 7 illustrates the optical principle of the Keplerian telescope KT. The Keplerian telescope KT includes a positive objective lens 32 and a positive eyepiece lens or camera lens 34. The eyepiece lens, eyepiece lens, or camera lens 34 is a positive convex lens and therefore a converging lens. It is positioned behind the focal point of the other converging objective lens 32. If the two elements 32 and 34 are properly designed, they can be realized with a single pitch of the double-sided microcylinder lens array 10. In this case, such a pitch can have the optical characteristics of the Keplerian telescope KT. The required distance between the objective lens 32 and the eyepiece lens 34 can be ensured by the substrate 11.

[0047] The principle of application of either the Galilean telescope GT or the Keplerian telescope KT is to decrease the diameter of the beam 12 and increase the divergence of the beam 12. This can be shown in the following equation:

[0048]

number

[0049] The advantage of using a double-sided microcylinder lens array 10 is that it maintains the angular resolution of the system and increases the dynamic range of the pixels 22. It also reduces the blooming effect caused by crosstalk between adjacent light beams 12.

[0050] Preferably, the microlens cylinder array 10 is a glass microcylinder array. Glass is not temperature-sensitive, and anti-reflection (AR) coatings on glass are very stable. To reduce costs, the expander 10 may be placed behind the camera lens 16 between the camera lens and the pixels 22. In such an embodiment, the light expander 10 can be designed more cost-effectively due to its smaller size. The material of the microcylinder lens array 10 may be a plastic, such as PMMA, or a hybrid material, such as a polymer combined with a chip-on-glass material. Using such a plastic material can reduce costs. On the other hand, plastics and / or polymers are more temperature-sensitive than glass because they exhibit a strong thermal expansion coefficient. Also, anti-reflection coatings have lower adhesion on polymers compared to glass. Therefore, depending on the actual use case, either glass and / or plastic can be selected as the material included in the substrate 11 and / or the microlenses 26.

[0051] Figure 8 shows the simulation results for the beam expander 10. The left part of Figure 8 shows how the light beam 12 propagates through the light expander 10. For the light beam 12, the diameter after the one-pitch light expander 10 is reduced by a factor of three. However, the divergence angle increases by a factor of three. This is shown in the right half of Figure 8, where the results for two example incident angles are shown. The y-axis in the right diagram of Figure 8 shows the distribution of the output angle of the light beam 12 for two different input incident angle distributions. The top right diagram shows the distribution of the output angle for incident angles from -0.025° to +0.025°. The bottom right diagram of Figure 8 shows the distribution of the output angle for incident angles from -0.075° to -0.025°. It can be seen that for incident angles from -0.025° to 0.025°, the output angle is from -0.075° to +0.075° (top diagram). 8, an exit angle of +0.075° to +0.225° is obtained for an incident angle of −0.075° to −0.025°. In this way, the effect of the optical expander 10 in increasing the divergence of the light beam 12 can be shown by simulation.

[0052] FIG. 9 shows pixels 22 with signal photons 36 and noise photons 38. Each pixel 22 shown includes a SPAD 18. The top pixel 22 shown in FIG. 9 does not use a light expander 10. The middle pixel 22 shown uses a single-sided microcylinder lens array 10. The bottom pixel in FIG. 9 uses a double-sided microcylinder lens array 10. It can be seen that the double-sided microcylinder lens array 10 significantly reduces blooming, as can be seen from the reduced number of photons 38. It can be seen that the double-sided microcylinder lens array 10 can significantly reduce crosstalk from adjacent light beams 12.

[0053] In FIG. 10, the two left-hand diagrams a) and d) show the results for a lidar system 50 without an optical expander 10. By comparison, the center column shows the results b) and e) for a lidar system 50 with a single-sided microcylinder lens array 10, and the right-hand column shows the results c) and f) for a lidar system 50 with a double-sided optical microcylinder lens array 10. The graphs show a curve of detection rate (y-axis) versus detection range in meters (x-axis). Plotted on the x-axis is the detection range between 0 and 300 m. Plotted on the y-axis is the detection rate between 0 and 1.0. It can be seen that using the currently important optical expander 10 improves the detection rate as well as the detection range.

[0054] The dashed lines in each graph represent single-emission measurements, i.e., measurements after one short transmission of the light 62. The solid lines in the graphs in FIG. 10 represent seven-emission measurements. The seven-emission measurements represent measurements after seven emissions of the transmitted light 62. Graphs a), b), and c) show the detection rate versus detection range for a low-reflectivity target with a reflectivity of approximately 10%. Graphs d), e), and f) show the detection rate versus detection range for a high-reflectivity target with a reflectivity of approximately 90%. This graph shows that a single-sided or double-sided microcylinder lens array 10 increases the detection rate compared to a system without an optical expander 10 in the receiving path. A single-sided microcylinder lens array 10 can expand the dynamic range. A double-sided microcylinder lens array 10, as shown in the right column, does not reduce the detection range for low-reflectivity targets, while at the same time exhibiting a significantly larger detection range for both high-reflectivity and low-reflectivity targets.

[0055] 11 schematically shows a vehicle 60, for example a passenger car. A lidar system 50 is arranged in the front region of the vehicle 60. The lidar system 50 comprises an optical transmitter 40 and an optical receiver 30. In a control unit 52, the transmitted and received optical beams 62, 12 can be evaluated, for example as time-of-flight measurements, for example for object detection and / or distance detection within a monitored region of a field of view 64. The transmission process in the transmitter 40, the reception process in the receiver 30, and also the beam steering of the transmitted and received optical beams can be monitored and controlled by the control unit 52.

[0056] The field of view 64 is located in front of the front region of the vehicle 60. In the illustrated example, the region ahead of the vehicle 60 in the direction of travel can therefore be monitored. It is also possible to arrange the lidar system 50 in other regions of the vehicle 60, for example in the rear region and / or in the side regions. It is also possible to arrange several lidar systems 50 on the vehicle 60, in particular also in the corner regions of the vehicle 60.

[0057] The lidar system 50 can be used to detect stationary or moving objects within the field of view 64, particularly vehicles, people, animals, plants, obstacles, road irregularities, particularly potholes or stones, road boundaries, traffic signs, vacant lots, bridges in particular parking spaces, precipitation, etc.

[0058] The transmitted light beam 62 can be directed, for example, by a mirror element or an optical phased array, to move smoothly across the field of view 64 and scan in a scan direction 66, i.e., to illuminate gradually in steps in the scan direction 66. The transmitted light beam 62 is then reflected back by objects within the field of view 64 as a reflected light beam 12 and received by the receiver 30. In the embodiment shown in Figure 11, the scan direction 66 extends horizontally in front of the vehicle.

Claims

1. An optical expander (10) for a receive path of a lidar system (50), configured to expand at least one light beam (12) for reception by at least one pixel (22) of an optical sensor (20) of the lidar system (50), the expander (10) including at least one of a concave and / or convex cylindrical lens (13), a one-sided microcylinder lens array structure, or a two-sided microcylinder lens array structure.

2. 2. The optical expander of claim 1, configured to expand the at least one optical beam (12) in one predetermined direction, particularly for reception by the at least one pixel (22), wherein a surface area of ​​the at least one pixel (22) is greater in a first dimension than in a second dimension.

3. 3. The optical expander of claim 1, wherein the expanding of the at least one light beam (12) comprises increasing a diameter of the at least one light beam (12) in the at least one direction and / or increasing a divergence of the at least one light beam (12) in the at least one direction.

4. 4. The optical expander according to any one of claims 1 to 3, wherein the microcylinder lens array comprises convex and / or concave microcylinder lenses (26).

5. 4. The optical expander of claim 3, wherein one microcylinder lens (26) of the one-sided microcylinder lens array is configured to expand the at least one light beam (12) for reception by one pixel (22) of a pixel array (21) of the optical sensor (20).

6. 4. The optical expander of claim 3, wherein one microcylinder lens (26) on each side of the double-sided microcylinder lens array is configured to expand the at least one light beam (12) for reception by one pixel (22) of a pixel array (21) of the optical sensor (20).

7. 6. The light expander according to any one of claims 3 to 5, wherein the microcylinder lens array comprises a supporting substrate (11), for example a glass substrate.

8. 7. The optical expander according to claim 6, wherein the microcylinder lens (26) is manufactured by a casting method.

9. 7. The optical expander of claim 6, wherein the microcylinder lens (26) comprises a polymer material and is fabricated by a polymer-on-glass method.

10. 10. An optical expander according to any one of claims 6 to 9, wherein the thickness of the glass substrate (11) varies or is constant over its spatial extent.

11. 11. The optical expander of claim 10, wherein the refractive index of the microcylinder lens (26) depends on the thickness of the glass substrate (11).

12. A lidar system (50) including the optical expander (10) according to any one of claims 1 to 11 in its receiving path, wherein the expander (10) is disposed between a collecting lens (16) and the optical sensor (20), or the collecting lens (16) is disposed between the expander (10) and the optical sensor (20).

13. 13. The lidar system of claim 12, wherein the expander is configured to more uniformly expand the at least one light beam for reception by the at least one pixel of the optical sensor.

14. 14. The lidar system of claim 12 or 13, wherein the optical sensor (20) includes a pixel array (21) having a column of pixels (22), the surface area of ​​the pixels being greater in the first dimension perpendicular to the column than in the second dimension parallel to the column, and the expander (10) is configured to expand the at least one light beam (12) in one predetermined direction, the one predetermined direction being the direction of the first dimension of the pixels (22).

15. 15. The lidar system of claim 12, wherein the lidar system is a scanning lidar system in which the scanning direction is parallel to the one predetermined direction of expansion of the at least one light beam.

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