Optical expander of 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) to be received by at least one pixel (22) of an optical sensor (20) of the lidar system (50), the expander (10) comprises at least one of a concave and / or convex cylindrical lens (13), a structure of a single-sided microcylindrical lens array, and a structure of a double-sided microcylindrical lens array. The disclosure also relates to a lidar system (50).

Description

Technical Field

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

[0002] Modern vehicles (cars, vans, trucks, motorcycles, etc.) have a large number of sensors whose data is used for driver information and / or can be used for driver assistance systems. 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 react to changes in this vehicle's environment.

[0003] An important sensor principle for detecting the environment (e.g. vehicles) is lidar technology (Light Detection and Ranging). A lidar system has an optical transmitter and an optical receiver. The transmitter can emit transmitted light. In a lidar system, the light used can be a laser in the ultraviolet, visible or infrared range. The receiving device can receive the transmitted light as received light after being reflected by an object in the field of view of the lidar system.

[0004] LiDAR systems are continually being further developed for a variety of different functions, for example for obtaining information about the environment in the near and far range of a vehicle, such as a passenger car or commercial vehicle. LiDAR systems can also be used as sensor systems for driver assistance systems, in particular 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 the blind spot area of ​​the vehicle.

[0005] The received light can be evaluated by the control unit of the lidar system using the emitted light. The spatial position and distance of the object from which the reflection occurred can be determined. Furthermore, the relative speed can also be determined. Reflection or reflected light is understood to mean any light that is reflected back and should in particular also include light that is reflected back by scattered or absorbed emission.

[0006] A scanning LiDAR system emits a light beam, sequentially moving the direction of the light beam in a scanning direction. A 1D scanning LiDAR system performs scanning in one direction, such as the horizontal direction in front of the vehicle. In a 1D scanning LiDAR system, the optical sensor of the optical receiver may have pixels, wherein the active area has a first dimension along a first axis and a second dimension that is smaller than the first dimension. An example of such a sensor is the Sony IMX 449 / 459. The advantages of this one-dimensional magnification are: on the one hand, the smaller size of the axis can maintain a high angular resolution of the entire sensor. On the other hand, the large size of the axis can increase the effective area of ​​the pixel to increase the dynamic range of the sensor.

[0007] In US 2020 / 0096615 A1, a deformable camera lens is described that collects and focuses a light beam onto a pixel having an active area having a first dimension that is greater than a second dimension that is perpendicular to the first dimension.

[0008] US 2016 / 0170287 A1 describes a cylindrical lens array for an optical system, which is used to parallelize laser beams in a transmission optical path of a data communication system. Summary of the invention

[0009] An optical expander for a receiving path of a laser radar system is configured to expand at least one light beam to be received by at least one pixel of an optical sensor of the laser radar system. The optical sensor converts optical information into electrical information, which can then be processed. The expander includes at least one optical expansion element, which includes at least one of a concave and / or convex cylindrical lens, a structure of a single-sided micro-cylindrical lens array, and a structure of a double-sided micro-cylindrical lens array. Due to the expansion, the energy of the light beam is spread over a larger area of ​​the pixel. The area on the pixel illuminated by the light beam can form an elliptical profile. The beam expansion in the receiving path can reduce the halo effect and increase the dynamic range of the optical sensor. Therefore, the detection range of the receiver and the laser radar system as a whole can be increased.

[0010] A 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, a 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. As described above, the concave / convex cylindrical lens is configured to extend at least one light beam in a receiving path of a lidar system. The optical expander may include more than one convex / concave cylindrical lens, for example in the form of a cylindrical lens array.

[0011] In one embodiment, the optical expander is configured to expand at least one light beam in a predetermined direction. The predetermined direction may be suitable for being received by at least one pixel. For example, if at least one pixel has a larger surface area in a first dimension than in a second dimension, the expansion of at least one light beam in a predetermined direction may be in the first dimension. This means that the light beam is expanded in a dimension where the pixel is also larger. This allows more of the light beam energy to be absorbed by the pixel because the illuminated area of ​​the pixel is larger, i.e., the area reached by the expanded light beam is larger. In the other dimensions of the at least one light beam, the high angular resolution of the lidar can be maintained.

[0012] The structure of the single-sided micro-cylindrical lens array comprises a substrate with micro-cylindrical lenses on one surface of the substrate. The structure of the double-sided micro-cylindrical lens array comprises a substrate with micro-cylindrical lenses on both 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 serves as a carrier for the micro-lenses and may additionally have optical properties that have an influence on the at least one light beam.

[0013] In an embodiment of the optical expander, the expansion of 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 optical expansion element, expanding the light beam may mean increasing the diameter of the at least one light beam and / or increasing the dimension of the at least one light beam.

[0014] When the aspect ratio of the beam expansion is not very large, ordinary convex / concave lenses can be applied. However, when the aspect ratio becomes larger, such as 1:5, 1:7 or 1:9 or even larger, the curvature of the lens becomes larger. Therefore, the overall dimensions of the receiver of the lidar system become larger. In order to keep the lidar system design compact, a microlens array can be introduced.

[0015] The microlens array includes a plurality of microlenses forming a one-dimensional or two-dimensional array on a supporting substrate. A single-sided microlens array includes a microlens array on one surface of a supporting substrate. A double-sided microlens array includes a microlens array on two surfaces of a supporting substrate. Preferably, the two microlens arrays of the double-sided microlens array are located on opposite surfaces of the supporting substrate. The microlenses are small lenses, for example, with a diameter less than a few millimeters, and may even be as small as 10 μm. Small-sized microlenses provide large beam expansion without increasing the size of the optical system. The cylindrical microlens at least partially includes a cylindrical shape. When the microlens is made of glass, the substrate should not be thicker than the microlens. The microcylindrical lens array may include convex and / or concave microcylindrical lenses. By appropriately arranging convex and / or concave microcylindrical lenses on one side of the substrate or on both sides of the substrate, the desired optical expansion can be achieved.

[0016] One of the micro cylindrical lenses in the micro cylindrical lens array can be configured to expand at least one light beam to be received by one of the pixels in the pixel array of the optical sensor. In combination with the beam steering optics of the receiver of the lidar system, a light beam of a specific angle of incidence from the field of view of the lidar system can be steered to the individual pixels of the optical sensor of the receiver. The optical expander can specifically expand the incident light beam to reach, i.e. illuminate, a larger area of ​​the optical pixel of the optical center. This allows to achieve a high optical resolution relative to the angle of incidence while increasing the area of ​​the pixel receiving the light beam.

[0017] The associated pairs of micro-cylindrical lenses on opposite sides of the double-sided micro-cylindrical lens array are configured to expand at least one light beam to be received by a pixel of the pixel array of the optical sensor. When designing the optical properties of the double-sided micro-cylindrical lens array, the micro-cylindrical lenses on each side of the substrate can be considered, and the thickness of the substrate and its optical refractive index can also be considered for the overall design of the double-sided micro-cylindrical lens array. At the same time, when the double-sided micro-cylindrical lens array is used in conjunction with a beam steering optical element, the two micro-cylindrical lenses on each side of the substrate can work together to achieve the desired optical properties of a light beam passing through the two micro-cylindrical lenses working together. The light beam can be expanded to simultaneously reach a larger area of ​​the associated pixels of the optical sensor. In other dimensions where the light beam is not expanded, the angular resolution relative to the field of view of the lidar system can be maintained.

[0018] In various embodiments, the support substrate comprises glass. In various embodiments, the micro cylindrical lenses are produced by a casting method. In particular, glass micro cylindrical lenses can be cast on the support substrate.

[0019] In other embodiments, the micro cylindrical lenses comprise a polymer material. The polymer micro cylindrical lenses can be produced by a polymer on glass process (PoG). This allows the polymer micro cylindrical lenses to be produced on a supporting substrate comprising glass.

[0020] In other embodiments, the micro cylindrical lens can be produced by a chip-on-glass packaging method. Using this method, the micro cylindrical lens can be manufactured and directly integrated on a glass substrate.

[0021] The thickness of the glass substrate may vary within its spatial extent, or may remain constant within its spatial extent. The thickness of the glass substrate may be considered when designing the optical properties of the micro cylindrical lens array. In particular, the refractive index of the micro cylindrical lens may depend on the thickness of the glass substrate. The combination of the micro cylindrical lens and the substrate may be considered to design the desired optical properties.

[0022] The laser radar system includes an optical expander in its receiving path. The receiver of the laser radar system includes the expander, which can be placed between the focusing lens of the receiver and the optical sensor. Alternatively, the focusing lens can be placed between the expander and the optical sensor of the receiver. Both optical settings are possible and can have the advantage of achieving the desired optical characteristics in the receiving path of the laser radar system and / or can have cost advantages. The laser radar system also includes a transmitter for emitting a transmission light beam, and a control unit for controlling the emission and reception of the light beam, for target detection, for distance determination and / or for speed determination within the field of view of the laser radar system. Target detection, distance detection and relative speed detection are performed using the transmitted light and the received light.

[0023] In various embodiments of the lidar system, the expander is arranged to more uniformly expand at least one light beam to be received by at least one pixel of the optical sensor. This may allow increasing the effective reception area of ​​the received light beam, in particular at pixels where the size in one direction is different from the size of the reception area of ​​the pixel in another direction. For cases where the optical sensor comprises an array of pixels, it may be advantageous to use an optical expander comprising an array of microlenses to expand different light beams for different pixels of the pixel array. Different light beams passing through the array of microcylindrical lenses are received from different angles of incidence in the field of view of the lidar system.

[0024] The pixel array of the optical sensor may be one-dimensional, ie, forming rows of pixels. The pixel array of the optical sensor may also be two-dimensional, ie, forming a two-dimensional area.

[0025] In one embodiment of a lidar system. The pixel array is one-dimensional, having rows of pixels, wherein the surface area of ​​the pixels is larger in a first dimension perpendicular to the row than in a second dimension parallel to the row. The expander is arranged to expand at least one light beam in a predetermined direction, wherein the one predetermined direction is in the direction of the first dimension of the pixels, i.e., in the direction in which the pixels have a larger extension. In particular, the expander may include an array of micro cylindrical lenses configured to expand multiple light beams simultaneously. Each light beam may be associated with a pixel of the optical sensor. Each pitch of the micro cylindrical lens array may correspond to a micro cylindrical lens, which may be configured to expand a light beam directed to a pixel.

[0026] In one embodiment, the laser radar system is a scanning laser radar system, wherein the scanning direction is parallel to a predetermined expansion direction of at least one light beam. This allows a high optical resolution of the incident angle to be maintained in a direction perpendicular to the scanning direction. In the direction perpendicular to the scanning direction, the light beam is not expanded to maintain this high angular resolution. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Embodiments will now be described by way of example only with reference to the accompanying drawings. The same reference numerals are used throughout to refer to the same elements. The structures and devices shown are not necessarily drawn to scale.

[0028] Figure 1 An optical expander in the receive path of a lidar system is schematically shown.

[0029] Figure 2 The effect of an optical expander is schematically shown.

[0030] Figure 3 The effect of a single-sided micro cylindrical lens array is schematically shown.

[0031] Figure 4The effect of a single-sided micro cylindrical lens array is schematically shown.

[0032] Figure 5 The effect of a diverging lens is schematically shown.

[0033] Figure 6 A Galilean telescope is shown schematically.

[0034] Figure 7 The Kepler telescope is shown schematically.

[0035] Figure 8 The simulation results of the optical expander are schematically shown.

[0036] Fig. 9 The effect of single-sided and double-sided micro-cylindrical lens arrays is schematically shown.

[0037] Fig.10 The results of the relationship between the detection rate and the detection range of the lidar system are shown.

[0038] Fig.11 A schematic diagram of a vehicle with a lidar system and its field of view is shown. DETAILED DESCRIPTION

[0039] Figure 1 An optical receiver 30 of a LiDAR system 50 is shown. An incident light beam 12 passes through a beam steering system 14. The beam steering system 14 is configured to steer the light beam 12 from different incident angles to different directions to be received by different pixels 22 of an optical sensor 20 of the optical receiver 30.

[0040] The optical expander 10 is arranged after the beam steering system 14. The focusing lens 16 is arranged after the optical expander 10. The elements 14, 10, and 16 are arranged in sequence in the propagation direction of the incident light 12. In some embodiments, the optical expander 10 can be arranged after the focusing lens 16. The focusing lens 16 focuses the incident light 12 on the pixel 22 of the optical sensor 20. The pixel 22 includes a surface for receiving the incident light beam 12. The surface dimension of the pixel 22 is larger in the first direction than in the second direction. The first direction is perpendicular to the second direction. Each pixel 22 includes a plurality of single photon avalanche diodes (SPADs) 18. The single photon avalanche diode 18 is a solid-state photodetector. When a photon is absorbed, the SPAD 18 reacts with an electric current. The electric current increases as the number of received photons increases. The SPAD 18 can detect a single photon because the received photon may generate an avalanche current. The pixel 22 includes three SPADs 18 in the second direction and nine SPADs 18 in the first direction. Thus, the pixel 22 extends three times in the first direction than in the second direction. The optical expander 10 is configured and arranged such that the incident light beam 12 is expanded in the first dimension of the pixel 22 .

[0041] The beam steering system 14 may, for example, comprise an optical phased array OPA. With an optical phased array, the phase and amplitude of a light wave can be controlled by using a two-dimensional surface of adjustable surface elements. The beam steering system 14, such as an optical phased array, may be used to transmit, reflect or capture, i.e. receive, the light beam 12. The optical phased array dynamically controls the optical properties of its surface. The direction of the light beam 12 may be steered, thereby changing the viewing direction of the optical sensor 20 of the optical receiver 30. The beam steering system 14 may also be a rotating mirror / MEMS, which reflects the incident light beam 12 in different directions depending on the rotational position of the rotating mirror.

[0042] The light beam 12 is received by a condenser lens 16 , which may be, for example, a camera lens. The pixels 22 are arranged in a one-dimensional pixel array 21 .

[0043] The optical receiver 30 may be arranged to receive light in a scanning LiDAR system 50. The larger dimension of the pixel 22 is then arranged, for example, in the direction of the scanning LiDAR system 50. In the scanning LiDAR system 50, the optical transmitter 40 transmits a scanning light beam 62, gradually changing the direction of the light beam 62 within the field of view 64 of the LiDAR system 50, thereby scanning the field of view 64. The scanning direction 66 is the direction in which the position of the transmitted light beam 62 increases.

[0044] In a first direction of the pixel 22, in which the pixel 22 includes more SPADs 18, the dynamic range increases. This may correspond, for example, to the scanning direction 66. In a second dimension, in which the number of SPADs 18 is smaller (e.g., three), the high angular resolution of the lidar system 50 is maintained. This would correspond to a direction perpendicular to the scanning direction 66. In the first direction, the number of SPADs 18 increases to, for example, nine SPADs 18, and the dynamic range of the lidar system 50 increases.

[0045] exist Figure 2 In FIG. 1 , the right side shows a receiving path with such a pixel 22 having a larger first dimension including nine SPADs 18 and a smaller second dimension including three SPADs 18. Figure 2 In the upper part of FIG. 1 , an incident light beam 12 is shown, which is focused by a focusing lens 16 onto a pixel 22. Figure 2 In the upper part, the condenser lens 16 focuses the light beam 12 on the focal plane 24, which is located on the receiving surface of the pixel 22. Figure 2 , another receiving path with a pixel 22 and a condenser lens 16 is shown. The receiving path includes an optical expander 10 in combination with the condenser 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 an expansion of the light beam 12 on the pixel 22.

[0046] The expansion effect of the optical expander 10 is applied to one dimension of the light beam 12. This one direction corresponds to the first dimension of the pixel 22, which is larger than the second dimension of the pixel 22. With respect to the other dimensions of the light beam 12, no expansion effect is applied thereto. This can be seen in Figure 2 In the lower part of FIG. 1 , an elliptical illumination area 23 illuminated by the incident light beam 12 is shown.

[0047] exist Figure 2 The lower part of the light 12 illuminates the pixel 22. Figure 2 The optical expander 10 inserted between the beam steering system 14 and the condenser lens 16 expands the illuminated area 23. In a system with a pixel array 21, each pixel 22 corresponds to a certain incident angle. The optical expander 10 can expand the light 12 from each incident angle by increasing the dimension and / or divergence of the beam 12 in the direction of the larger dimension of the pixel 22.

[0048] In a scanning lidar system 50, the larger dimension can correspond to the scanning direction 66. The angular resolution perpendicular to this scanning direction remains the same as before. The use of a micro cylindrical lens array for the expander 10 allows a high aspect ratio of the pixel 22 to be achieved. Otherwise this would require the optical lens to have a very large curvature. This can be achieved with a micro lens array without increasing the size of each individual micro lens 26 in the array too much. This allows a compact implementation. In addition, the micro lens array will increase the uniformity of the light beam 12, which can further increase the dynamic range of the receiver 30.

[0049] Figure 3 A single-sided microlens array 10 is shown with individual microlenses 26. The individual lenses 26 may also be referred to as pitches. An incident light beam 12 passes through the optical expander 10 and the condenser lens 16 and is received by a pixel 22. Figure 3 The illustrated embodiment shows a single-sided micro cylindrical lens array 10. One micro lens 26 can have a profile that is concave on one side and convex on one side, a profile that is concave on both sides, or a profile that is convex on both sides. Appropriate design of these characteristics can achieve the desired optical effect. The advantage of such an optical expander 10 is that the cost is very low. Only one side of the optical expander 10 needs to be configured to expand the light beam 12 as required. Such an expander 10 can increase the dynamic range of the receiver 30.

[0050] Figure 3 It is also shown in FIG. 5 that the pixel 22 may also receive the light beam 12 at another angular resolution, such as adjacent pitches. Therefore, the pixel 22 may receive more noise, and therefore, the detection range of the laser radar system 50 may be reduced.

[0051] Figure 4 An embodiment is shown having a double-sided micro-cylindrical lens array 10. The double-sided micro-cylindrical lens array 10 includes micro-lenses 26 on two opposite surfaces of a substrate 11. Two micro-lenses 26 opposite to each other may be referred to as a pitch.

[0052] exist Figure 4 In the illustrated embodiment, the double-sided micro-cylindrical lens array 10 shows micro-lenses 26 that are convex on one side. These convex micro-lenses 26 face the incident received light beam 12. On the opposite side of the micro-cylindrical lens array 10, the micro-lenses 26 are concave. They face the focusing lens 16. One pitch, i.e. two micro-lenses 26 directly opposite each other on the substrate 11, work together to achieve the desired optical effect on at least one light beam 12. With such a double-sided micro-cylindrical lens array 10, not only can the expansion of the light beam 12 be achieved, but also the so-called blurring effect of the light received from adjacent light beams 12 can be significantly reduced. This is like Figure 4 As shown below. Figure 6 or Figure 7The optical effect achieved by the pitch of two microlenses 26 directly facing each other on the substrate 11 is further described.

[0053] Figure 5 An embodiment of a diverging lens 13 is shown, which can be included in the optical expander 10. The diverging lens 13 is an embodiment of a concave lens having two concave surfaces. The light beam 12 parallel to the diverging lens 13 is expanded by the diverging lens 13 into a diverging light beam 12. Such a diverging lens 13 can be used as an optical expander 10. The diverging rays of the outgoing light beam 12 have a virtual focus 15.

[0054] Figure 6 The Galilean telescope optical system GT is shown. The Galilean telescope GT is an optical device having a biconvex objective lens 27 and a biconcave eyepiece (also called camera lens or eyepiece lens) 28. The biconvex objective lens 27 forms an image. The eyepiece 28, also called camera lens or eyepiece lens, is a biconcave lens and is therefore a diverging lens. The camera lens is placed in front of the focus. The optical principle of the Galilean telescope GT having the objective lens 27 and the camera lens 28 includes two elements. Through the appropriate design of the double-sided micro-cylindrical lens array 10, these two elements 27, 28 can be replaced by a single pitch of the double-sided micro-cylindrical lens array 10. One of the micro-lenses 26 of this pitch will perform the function of the objective lens 27, and the other micro-lens 26 of this pitch placed opposite to the first micro-cylindrical lens 26 on the substrate 11 will perform the function of the camera lens 28. If designed properly, each pitch of the micro-cylindrical lens array 10 can function and perform the optical effect of the Galilean telescope GT. The required distance between the objective lens 27 and the eyepiece 28 can be achieved by the substrate 11.

[0055] Figure 7 Another embodiment for designing the optical characteristics of one pitch of the double-sided micro cylindrical lens array 10 is shown. Figure 7 The optical principle of the Keplerian telescope KT is shown. The Keplerian telescope KT includes a positive objective lens 32 and a positive eyepiece or camera lens 34. The eyepiece or eyepiece lens or camera lens 34 is a positive convex lens and is therefore a condensing lens. It is placed behind the focus of another condensing objective lens 32. If properly designed, the two elements 32 and 34 can be realized by a pitch of a double-sided micro cylindrical lens array 10. Such a pitch can have the optical characteristics of the Keplerian telescope KT. The required distance between the objective lens 32 and the eyepiece 34 can be realized by the substrate 11.

[0056] The principle of applying the Galilean telescope GT or the Keplerian telescope KT is to reduce the diameter of the light beam 12 and increase the divergence of the light beam 12. This can be expressed by the following formula:

[0057] .

[0058] The advantage of using a double-sided micro-cylindrical lens array 10 is that the angular resolution of the system is maintained and the dynamic range of the pixels 22 is increased. Furthermore, blurring effects due to crosstalk of adjacent light beams 12 can be reduced.

[0059] Preferably, the micro cylindrical lens array 10 is a glass micro cylindrical array. Glass is not sensitive to temperature, and the anti-reflection (AR) coating on glass is very stable. To reduce costs, the expander 10 can be placed behind the camera lens 16, between the camera lens and the pixel 22. In such an embodiment, the optical expander 10 can be designed to be more cost-effective due to the smaller size. The material of the micro cylindrical lens array 10 can be a plastic, such as PMMA, or a hybrid material, such as a polymer combined with a glass chip-on-chip material. Using such a plastic material can reduce costs. On the other hand, plastic and / or polymer is more sensitive to temperature than glass because it exhibits a strong thermal expansion coefficient. In addition, compared with glass, the adhesion of the anti-reflection coating to the polymer is lower. Therefore, according to actual use, glass and / or plastic can be selected as the material included in the substrate 11 and / or the micro lens 26.

[0060] Figure 8 Simulation results of the beam expander 10 are shown. Figure 8 The left part of FIG. 1 shows how the beam 12 propagates through the optical expander 10. For the beam 12, the diameter in one pitch after the optical expander 10 is reduced by a factor of three. However, the divergence angle is increased by a factor of three. This is shown in FIG. Figure 8 The right half of the figure shows the results for two examples of incident angles. Figure 8 The y-axis of the right graph shows the output angular distribution of the light beam 12 for two different input incident angle distributions. The upper right graph shows the output angular distribution when the incident angle is -0.025° to +0.025°. Figure 8 The lower right figure of shows the output angle distribution when the incident angle ranges from -0.075° to -0.025°. It can be seen that for input angles of -0.025° to 0.025°, the output angle is -0.075° to +0.075° (top figure). For incident angles of -0.075° to -0.025°, output angles of +0.075° to +0.225° are achieved, as shown in Figure 8 Thus, the effect of the optical expander 10 in increasing the divergence of the light beam 12 can be shown in the simulation.

[0061] exist Fig. 9 , a pixel 22 is shown with a signal photon 36 and a noise photon 38. Each pixel 22 shown includes a SPAD 18. Fig. 9 In the top pixel 22 shown, no optical expander 10 is applied. In the middle pixel 22 shown, a single-sided micro cylindrical lens array 10 is applied. Fig. 9In the lower part of the double-sided micro-cylindrical lens array 10, a double-sided micro-cylindrical lens array 10 is applied. It can be seen that the double-sided micro-cylindrical lens array 10 significantly reduces blur, which can be seen from the reduction in the number of photons 38. It can be seen that the double-sided micro-cylindrical lens array 10 can significantly reduce crosstalk from adjacent light beams 12.

[0062] exist Fig.10 In the figure, the two figures on the left (a) and (d) show the results of the laser radar system 50 without the optical extender 10. In contrast, the middle column shows the results (b) and (e) of the laser radar system 50 with a single-sided micro-cylindrical lens array 10, while the right column shows the results (c) and (f) of the laser radar system 50 with a double-sided optical micro-cylindrical lens array 10. These figures show the curves of the detection rate (y-axis) relative to the detection range in meters (x-axis). The detection range between 0 and 300 m is plotted on the x-axis. The detection rate between 0 and 1.0 is plotted on the y-axis. It can be seen that the application of the optical extender 10 currently significantly improves the detection rate as well as the detection range.

[0063] The dashed line in each graph shows the measured value of a single measurement, ie the measured value after emitting light 62 once. Fig.10 The solid line shown in the graph gives 7 measurement values. The 7 measurement values ​​show the measurement values ​​after emitting light 62 7 times. a), b), c) show the variation of the detection rate of a low-reflection target with a reflectivity of about 10% with the detection range. Graphs d), e) and f) show the variation of the detection rate of a high-reflection target with a reflectivity of about 90% with the detection range. The graph shows that the single-sided or double-sided micro-cylindrical lens array 10 increases the detection rate compared to a system without an optical expander 10 in the receiving path. The single-sided micro-cylindrical lens array 10 can increase the dynamic range. The double-sided micro-cylindrical lens array 10 shown in the right column does not reduce the detection range of low-reflection targets, and shows extremely high detection rates and detection ranges for both high-reflection targets and low-reflection targets.

[0064] Fig.11 A vehicle 60, such as a passenger car, is schematically shown. A lidar system 50 is arranged in the front area of ​​the vehicle 60. The lidar system 50 comprises an optical transmitter 40 and an optical receiver 30. In a control unit 52, the emission and reception light beams 62, 12 can be evaluated, for example, by time-of-flight measurement, for example for object detection and / or distance detection in a monitoring area such as a field of view 64. The emission process in the transmitter 40, the reception process in the receiver 30 and the beam steering of the emission and reception light beams can also be monitored and controlled by the control unit 52.

[0065] The field of view 64 is located in front of the front area of ​​the vehicle 60. Thus, in the example shown, the area in front of the vehicle 60 in the direction of travel can be monitored. The lidar system 50 can also be arranged in other areas of the vehicle 60, for example in the rear area and / or in the side areas. It is also possible to arrange a plurality of lidar systems 50 on the vehicle 60, in particular in the corner areas of the vehicle 60.

[0066] The lidar system 50 can be used to detect stationary or moving targets in the field of view 64, in particular vehicles, people, animals, plants, obstacles, road irregularities (in particular potholes or stones), road boundaries, traffic signs, open spaces, bridges (in particular parking spaces), accumulated water, etc.

[0067] The emission light beam 62 can be steered, for example, by means of a reflector element or an optical phased array in the emission light path, so that it slides across the field of view 64 and is scanned in the scanning direction 66, i.e., the emission light beam 62 is irradiated step by step in the scanning direction 66. The emission light beam 62 is then reflected back by the target in the field of view 64 as a reflected light beam 12 and received by the receiver 30. Fig.11 In the exemplary embodiment shown, scanning direction 66 extends in a horizontal direction in front of the vehicle.

Claims

1. An optical expander (10) for a receiving path of a laser radar system (50), the expander (10) being configured to expand at least one light beam (12) for reception by at least one pixel (22) of an optical sensor (20) of the laser radar system (50), the expander (10) comprising at least one of a concave and / or convex cylindrical lens (13), a structure of a single-sided micro-cylindrical lens array, and a structure of a double-sided micro-cylindrical lens array.

2. The optical expander according to claim 1, the expander being configured to expand the at least one light beam (12) in a predetermined direction so as to be received in particular by the at least one pixel (22), wherein: The surface area of ​​the at least one pixel (22) is greater in the first dimension than in the second dimension.

3. The optical extender according to claim 1 or 2, wherein: The expansion of the at least one light beam (12) comprises increasing the diameter of the at least one light beam (12) in at least one direction and / or increasing the divergence of the at least one light beam (12) in at least one direction.

4. An optical extender according to any one of the preceding claims, wherein: The micro cylindrical lens array comprises convex and / or concave micro cylindrical lenses (26).

5. The optical extender according to claim 3, wherein: A micro-cylindrical lens (26) of the single-sided micro-cylindrical lens array is configured to expand the at least one light beam (12) so as to be received by a pixel (22) of the pixel array (21) of the optical sensor (20).

6. The optical extender according to claim 3, wherein: One micro-cylindrical lens (26) on each side of the double-sided micro-cylindrical lens array is configured to expand the at least one light beam (12) to be received by a pixel (22) of a pixel array (21) of the optical sensor (20).

7. The optical extender according to any one of claims 3 to 5, wherein: The micro cylindrical lens array comprises a supporting substrate (11), such as a glass substrate.

8. The optical extender according to claim 6, wherein: The micro cylindrical lens (26) is produced by a casting method.

9. The optical extender according to claim 6, wherein: The micro cylindrical lens (26) comprises a polymer material and is produced by a polymer-on-glass method.

10. The optical extender according to any one of claims 6 to 9, wherein: The thickness of the glass substrate (11) varies or remains constant within the spatial range of the glass substrate (11).

11. The optical extender according to claim 10, wherein: The refractive index of the micro cylindrical lens (26) depends on the thickness of the glass substrate (11).

12. A laser radar system (50) comprising an optical extender (10) according to any one of the preceding claims in a receiving path of the laser radar system (50), wherein: The expander (10) is placed between a condenser lens (16) and the optical sensor (20), or wherein the condenser lens (16) is placed between the expander (10) and the optical sensor (20).

13. The laser radar system according to claim 12, wherein: The expander (10) is arranged to more uniformly expand at least one light beam (12) received by at least one pixel (22) of the optical sensor (20).

14. The laser radar system according to claim 12 or 13, wherein: The optical sensor (20) comprises a pixel array (21) having rows of pixels (22), wherein the surface area of ​​the pixels is larger in a first dimension perpendicular to the rows than in a second dimension parallel to the rows, and wherein the expander (10) is arranged to expand the at least one light beam (12) in a predetermined direction, wherein the predetermined direction is in the direction of the first dimension of the pixels (22).

15. The laser radar system according to any one of claims 12 to 14, wherein: The laser radar system (50) is a scanning laser radar system (50), wherein the scanning direction (66) is parallel to a predetermined expansion direction of the at least one light beam (12).

Images