Optical device and laser radar device having the same

Abstract

An optical device is disclosed, which is particularly used for a laser radar device, and has a lens and a lens for deflecting a beam away from a scanning area or into the scanning area, wherein the lens is configured as a lens array, and the lens is arranged in a beam path between the scanning area and the lens, wherein the optical device has at least one optical element arranged in front of the lens or connected to the lens in the radiation direction, and the at least one optical element is used to adjust the incident direction of the radiation to the lens array. In addition, a laser radar device is disclosed.

Description

Technical Field

[0001] The invention relates to an optical device, in particular for a laser radar device, comprising a lens and a lens for deflecting a beam away from a scanning area or into the scanning area, wherein the lens is configured as a lens array and the lens is arranged in the beam path between the scanning area and the lens. In addition, the invention relates to a laser radar device. Background Art

[0002] It is known that laser radar devices are implemented as laser scanner systems. Such systems usually produce beam expansion (Strahlaufweitung) when using micro-optical elements on the transmission side. This occurs without angular losses in the field of view or scanning area. On the one hand, the beam expansion is used to improve the system robustness with respect to local contamination of the transmission and / or reception lens, and on the other hand, the beam expansion is used to improve eye safety and increase the possibility of transmitting greater light power. As a result, the signal / noise ratio can be increased and thus the range of the laser radar device can also be increased. Such a laser radar device is known, for example, from DE 102015 217908A1.

[0003] However, a problem with such a lidar device is the fact that, in the case of scanning on the transmission side toward a μ-lens element not far from the optical axis, depending on the design of the extended transmission beam diameter and the spacing of the irradiated μ-lens element from the optical axis, regions of the transmission signal of different sizes are deflected directly into the aperture of the transmission / reception lens. Therefore, the "cut-off" part no longer reaches the scanning area, whereby gaps or shadows of different sizes can be generated between adjacent light spots at the target distance of the measurement area, depending on the scanning angle. Summary of the invention

[0004] The object on which the present invention is based can be seen as providing a LIDAR device and an optical arrangement which can use the full field of view of the lens without a light spot segment for scanning a scanning area.

[0005] This object is achieved by means of the technical solution of the present invention. Advantageous configurations of the present invention are various preferred embodiments.

[0006] According to one aspect of the present invention, an optical device, in particular for a laser radar device, is provided. The device comprises a lens and a lens for deflecting a beam away from a scanning area or into a scanning area. Preferably, the lens is configured as a lens array. The lens is arranged in a beam path between the scanning area and the lens, wherein the optical device comprises at least one optical element, the at least one optical element being used to adjust the incident direction of radiation onto the lens array, the at least one optical element being arranged before the lens in the radiation direction or connected to the lens.

[0007] According to another aspect of the present invention, a laser radar device for generating a beam and scanning a scanning area with the beam is provided. The laser radar device has a transmitting unit and a receiving unit, the transmitting unit is used to generate a beam and deflect the beam along the scanning area, and the receiving unit has at least one detector for receiving the reflected beam. The transmitting unit and / or the receiving unit have an optical device according to the present invention.

[0008] The lens may be composed of one or more lenses. In addition, the lens may be an aperture integrated or arranged on the lens for limiting the maximum emission surface. The lens array may be a μ lens array in particular.

[0009] By using optical elements, the beam can be influenced in such a way that a so-called spot section of the beam no longer impinges in the edge region of the lens.

[0010] This optical function can be realized, for example, by a wedge structure on the back side of the lens array used or in front of the back side. Alternatively or additionally, this optical function can be realized by a grating or a diffractive optical element or a holographic optical element.

[0011] When using a lens array with an additionally supported or integrated wedge array at the back, the edge area of ​​the transmitted light spot can be deflected by a matching wedge angle or grating, so that the aperture of the lens is no longer illuminated by the light spot. The light spot is deflected in such a way that it can also pass through the light-permeable area of ​​the lens. After passing through the lens, the light spot area affected by the optical element and the light spot area not affected by the optical element cannot be superimposed immediately. However, the light spot area just forms the desired beam diameter again at the target distance of the area to be detected or at the target distance of the scanning area. As a result, the full field of view of the light spot section of the lens without the transmission side can be used to scan the scanning area. In particular, more efficient and full use of the transmission power can be achieved. Alternatively or additionally, the transmission light spot can also be deflected away from the lens at an angle offset relative to the optical axis. As a result, the desired light spot position can be reached again at the set target distance, wherein the superposition of the beams is avoided at the same time.

[0012] Preferably, the optical device can be used in a lidar device on the transmitting side and / or the receiving side.

[0013] According to one embodiment, the optical element is designed as a diffractive optical element or a holographic optical element, which is applied to the lens at least on one side or arranged in the beam path of the beam at a distance from the lens. For the solution described below, both on the transmission side and on the reception side, the optical function can also be realized by means of a diffractive optical system. Instead of a wedge array, a grating array can be conceived, which deflects the transmission beam or the reception beam to the desired angle.

[0014] According to another embodiment, the optical element is configured as a wedge array having at least one surface mounted obliquely with respect to the radiation direction. The lens array having a wedge array can deflect the light portion incident on the lens axially parallel to the detector of the laser radar device at another angle in the area previously cut off by the aperture. Here, only a part of the signal radiated through the lens elements of the lens array or the entire light spot or beam is deflected in terms of angle so that it does not enter the lens aperture. As a result, common μ lenses can be used, so customization may not be necessary.

[0015] According to another embodiment, the optical element is spaced apart from the lens. Thus, in addition to the configuration of the wedge-shaped segments or surfaces, the influence of the optical element on the radiation can be adapted additionally by the distance to the lens. The separate optical element can be configured in particular as a retrofit solution and can be installed later in an already operating lidar device.

[0016] According to a further embodiment, the optical element is connected to the lens in one piece or in a material-locked manner. The wedge array can be mounted in particular on the back side of the lens array, so that the usually flat surface of the lens array is configured as a wedge array. Thus, a compact array equipped with optical functions on both sides can be provided, which can be optimally adapted to the field of view of the lens.

[0017] According to another embodiment, the at least one face of the wedge array is shaped rotationally symmetrically along the axis of symmetry. Preferably, the wedge array can have a shape that matches the shape of the lens or the opening shape of the aperture. The rotationally symmetrical shape of the wedge array can be produced particularly simply in terms of technology, for example.

[0018] According to another embodiment, the optical element configured as a wedge array has at least two faces which are mounted at an angle relative to the axis of symmetry. The mounting angle of the faces decreases as the distance from the axis of symmetry increases. The faces of the wedge array which are mounted at an angle can therefore have an adjustment which may be dependent on the radial distance and the arrangement of the lenses. The signal or the beam is deflected onto the lens on the transmission side by means of an angular difference, whereby it reaches the lens at a different position and therefore does not enter the aperture. The angular difference is selected such that the beam or the transmission signal illuminates the same object point at the target distance in the detection volume.

[0019] It is therefore also possible for the optical system to capture the light backscattered by the illuminated object point again completely and without spot sections at the same angle and to deflect it parallel to the wedge array axis in the direction of the detector. The wedge array can be designed as a μ-wedge array.

[0020] According to another embodiment, the radial spacing between the at least two faces increases with increasing spacing of the faces from the axis of symmetry. The height of the corresponding wedge structure or wedge surface can correspond to the pitch of the μ lens used. Depending on the embodiment of the optical device, the height can in particular be configured to be constant or variable. Due to the angle of incidence of the signal, which becomes steeper as a function of the spacing from the optical axis, the wedge angle must be adapted accordingly. As the spacing from the optical axis becomes greater, the spacing between the wedges or the faces themselves also increases. Advantageously, the entire structure can be constructed radially symmetrically to the optical axis or the axis of symmetry.

[0021] According to a further embodiment, the at least one face of the wedge array is oriented radially away from the axis of symmetry and the lens.

[0022] Thereby, the wedge array can be aligned directly with the incident beam.The arriving beam can be a beam generated by a transmitting unit or a beam reflected or backscattered in the scanning area.

[0023] Such optical devices can be used, for example, in automotive lidar systems, in the consumer sector, in the construction industry, in the technical sector, in trains, in drones or aircraft, in the industrial sector, such as in the field of automation technology, in the field of manufacturing, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The preferred embodiments of the present invention are further described below based on extremely simplified schematic diagrams.

[0025] Figure 1 A schematic diagram showing a laser radar device according to one embodiment;

[0026] Figure 2A-2B A schematic diagram showing a desired transmission spot arrangement and an actual transmission spot arrangement at a target distance in a scanning area;

[0027] Figure 3 A schematic partial view of a transmission unit with a corresponding light spot is shown;

[0028] Figures 4 to 7 An exemplary comparison diagram showing an optical device with and without an optical element;

[0029] Figure 8 Show Figure 7 Part B in the figure is used to illustrate the optical function of the optical device;

[0030] Fig. 9 A schematic diagram showing optical elements integrated into a lens;

[0031] Fig.10 showing a detailed view of the optical device;

[0032] Fig.11 A schematic diagram showing an array of wedges spaced apart from a lens. DETAILED DESCRIPTION

[0033] exist Figure 1 2 shows a schematic diagram of a lidar device 1 according to an exemplary embodiment. The lidar device 1 is used to generate a beam 2 and to scan a scanning area A with the beam 2. The device 1 has a transmission unit 4 having a laser 6 as a radiation source for generating the beam 2.

[0034] The generated beam 2 is continuously deflected by a movable mirror 8 of the transmission unit 4 . The movable mirror 8 can be designed as a pivotable μ-mirror and oscillates periodically, thereby scanning the scanning area A. The mirror 8 is used by the transmission unit 4 together with the reception unit 10 .

[0035] The beam 2 deflected by the mirror 8 is focused or shaped as parallel as possible by a collimator lens 12 and is deflected by a deflection mirror 14 transversely to the emission direction of the laser 6. The deflected beam 3 is emitted to a lens 16 along a first optical axis OA1.

[0036] The lens 16 is configured as a μ-lens array 16 and will be described in more detail below. The lens 16 acts on the beam 3 before it is deflected to a beam splitter 18 and a transmission optical system 20. The transmission optical system 20 serves to emit the beam 3 into a scanning region A.

[0037] According to this exemplary embodiment, the transmission optical system 20 is designed as a combined transmission / reception optical system 20 and is also used by the reception unit 10. The transmission / reception optical system 20 has a lens 22 and an aperture 24.

[0038] The beam 28 backscattered or reflected in the scanning area A, for example at the object 26, is received by the transmitting / receiving optical system 20 and directed via the beam splitter 18 to the lens 16 of the receiving unit 10. The lens 16 of the receiving unit 10 and the lens 16 of the transmitting unit 4 can be designed identically or differently.

[0039] After passing through the lens 16, the beam 28 is deflected onto a deflection mirror 30. The deflected beam is deflected onto the second optical axis OA2 by the deflection mirror 30, wherein the second optical axis OA2 can extend parallel to the first optical axis OA1. The deflected beam 29 is deflected back onto the detector 34 by the focusing lens 32 and by the pivotable mirror 8.

[0040] By the movement of the mirror 8 and the alternating movement of the mirror, the transmission beams 2 and 3 are scanned by the μ lens array 16 on the transmission side. The divergent transmission beam is then projected onto the transmission / reception optical system 20 by each μ lens element 17 before it can expand out of the laser radar device 1 and enter the scanning area A. After being reflected / scattered on the object 26 in the field A, the signal 28 reaches the transmission / reception optical system 20 again and is deflected to the detector 34 via the optical elements described above.

[0041] Figure 2A-2B The desired transmission light spot arrangement and the actual transmission light spot arrangement at the target distance in the scanning area A are illustrated with a schematic diagram to illustrate the problems in the prior art. Figure 2A Three different desired light spot arrangements are shown. Figure 2B Shown in Figure 2A The actual actual spot arrangement shown in . An inherent problem of conventional scanner systems is the fact that, in the case of scanning on the transmission side toward a μ lens element not far from the optical axis, different sized areas of the transmission signal are deflected directly into the aperture 24 of the transmission / reception lens, depending on the design of the expanded transmission beam diameter and the spacing of the irradiated μ lens element from the optical axis. This is Figure 3 As a result, these "truncated" parts 36 no longer enter the field or reach the lens 22 of the transmitting / receiving optical system 20, whereby gaps of different sizes are generated between adjacent light spots at the target distance of the measuring area, depending on the scanning angle of the mirror 8. Figure 2B The "cut-off" light spot on the left is shown in FIG.

[0042] This means that the full field of view of the lens 22 used can never be used without generating a light spot segment 36 which is approximately up to half the original diameter at most.

[0043] Depending on the diameter of the expanded transmission beam 3, the transmission beam 3 is cut off from a certain μ-lens height relative to the optical axis OA1 by the aperture 24 of the transmission / reception optical system 20. The distance of the μ-lens element 17 from the optical axis OA1 is converted into a deflection angle in the field (field of view angle, FoV). The larger the transmission beam diameter, the smaller the field of view angle at which the entire diameter of the transmission spot 3 is already cut off.

[0044] exist Figure 3 , two beams 3 . 1 , 3 . 2 and corresponding beam paths are shown by way of example, which can each be generated at different angles of the mirror 8 .

[0045] On the transmission side, the portion 36 of the beam 3 that impinges on the aperture 24 is not emitted into the scanning region A. On the reception side, these regions themselves cannot be received even with a possible previous illumination or are deflected parallel to the axis of the detector 34. The system is therefore insensitive in these regions.

[0046] exist Figure 4-7 An exemplary comparison of an optical device 38 with and without an optical element 40 is shown in FIG. Figure 4 and 5 Two scanning positions of the mirror 8 are shown when using a μ-lens array 16 without additional optical elements 40. The greater the distance between the illuminated μ-lens 16 and the optical axis OA1, the larger the area 36 of the light spot 3 that is cut off by the aperture 24, which is to represent the light spot segment. This has the following consequences: the larger the light spot segment 36, the smaller the remaining illuminated area in the scanning area A, or the larger the gap between adjacent light spots in the case of different positions of the mirror 8. Therefore, the height h of the light spot in the radial direction is s,Tr It can be reduced on one side by the light spot segment 36 .

[0047] exist Figure 6 and 7 The same as previously shown in Figure 4 and 5 , but using a μ-lens array 16 equipped with an additional optical element 40. According to this exemplary embodiment, the optical element 40 is designed as a wedge array and is integrated on the back side of the μ-lens array 16.

[0048] Here, it is explained how the light spot segment 36 is deflected by the corresponding wedge angle and no longer radiates directly into the aperture 24 of the lens 22. The light spot 3 is deflected in such a way that it still passes through the light-permeable area of ​​the lens 22. The two light spot areas 37 are superimposed directly after the lens 22, but the desired beam diameter is formed again exactly at the target distance of the area to be detected. As a result, the full field of view of the lens 22 can be used to scan the detection area A without the light spot segment 36 on the emission side.

[0049] On the receiving side, the regions 36 blocked by the aperture 24 are also not light-sensitive for the system shown by way of example. That is, if the signal from these regions returns to the lens 22, it cannot be deflected axially parallel in the direction of the detector 34. This signal portion is therefore lost in the system, which results in the object 26 not being detectable in these regions. Figure 6 and 8 With the μ-lens array 16 shown in FIG. 1 with the wedge array 40 , the region 36 previously cut off by the aperture 24 can be incident on the lens 22 at a different angle and deflected axially parallel in the direction of the detector 34 .

[0050] Figure 8 Show Figure 7 , for illustrating the optical function of the optical device 38 with and without the wedge array 40. The beam paths on the transmission side or on the reception side through the μ-lens element 17 and the lens 22 arranged downstream of the μ-lens element are shown. In particular, the beam paths are shown in comparison between the beam 3 ′ without the optical element 40 and the beam 3 with the optical element 40.

[0051] The beam focusing 3 by the upper half of the μ-lens element 17 is identical both on the transmission side and on the reception side, since it cannot be delimited by the lens aperture 24 .

[0052] Conversely, the transmission beam 3 ′ guided through the lower half of the μ-lens element 17 would be deflected directly into the aperture 24 on the transmission side without a corresponding wedge element or surface 42 of the optical element 40 .

[0053] If a matching wedge element 42 is now included in or placed upstream of the μ lens element 17, the beam bunching 3' can be deflected more strongly on the transmission side. As a result, this part also passes through the optical continuity of the lens 22. The two parts are superimposed shortly after the lens 22, thus forming a ring-shaped light spot with a previously defined diameter at the target distance of the measurement area.

[0054] Fig. 9The schematic diagram shows an optical device 38 having an optical element 40 integrated into the lens 16. In particular, the required geometry of the wedge elements or the geometry of the surfaces 42, 44 of the wedge array 40 is shown.

[0055] According to this embodiment, the optical element 40, which is configured as a wedge array 40, has two obliquely mounted faces 42, 44, which are formed rotationally symmetrically along a symmetry axis S. The faces 42, 44 are mounted on the face of the lens 16 that is opposite the μ lens element 17, thereby producing an integral unit consisting of the μ lens array and the wedge array 40. According to this embodiment, the symmetry axis S is also the symmetry axis of the lens 22 and coincides with the first optical axis OA1.

[0056] In particular, the following relationships arise here:

[0057] The greater the distance between the μ lens element 17 and the optical axis OA1, S, the greater the edge length or height h of the wedge elements 42, 44. k It must be larger because the beam segment 36 also increases with increasing distance from the optical axis.

[0058] The greater the distance between the μ lens element 17 and the optical axis OA1, S, the greater the angle β of the corresponding wedge element 42, 44. k The smaller it must be, the smaller it is, because the angle of the beam bundle 3 incident on the reception side relative to the entrance surface of the lens also decreases with increasing distance from the optical axis OA1, S.

[0059] Therefore, for each distance size of the μ lens element relative to the optical axis, the wedge element height h k and wedge angle β k To arrange the respective individual wedge elements 42 , 44 .

[0060] exist Fig.10 A detailed view of an optical device 38 according to a further exemplary embodiment is shown in . In this case, the optical element 40 embodied as a wedge array is not integrated into the lens 16 , but is spaced apart from the lens 16 .

[0061] Rather than only the part of the signal 3 that passes through the lens element 17 , the entire signal 3 is deflected in terms of angle in such a way that it does not impinge on the lens aperture 24 .

[0062] Signal 3' is deflected on the transmission side by wedge element 42 to lens 22 by means of an angular difference, whereby it reaches the lens at another location and does not enter lens aperture 24. The angular difference is selected such that the beam or the transmission signal illuminates the same object point at the target distance of detection space A.

[0063] It is therefore also possible for the lidar device 1 to capture the light 28 backscattered by the illuminated object point 26 again completely at the same angle without the spot section 36 and to deflect it axially parallel behind the μ-wedge array 40 in the direction of the detector 34 .

[0064] Fig.11 and Fig. 9 Similarly, a schematic diagram of a wedge array 40 is shown spaced apart from the lens. The height h of the wedge structures 42, 44 is k can correspond to the used pitch of the μ lens 17 and can be compared to Fig. 9 is constant. Since the incident angle of the signal 3 becomes steeper with increasing distance from the optical axis, the wedge angle must be matched. As the distance from the optical axis S becomes larger, the radial distance d between the wedges 42, 44 increases. k The entire structure is constructed radially symmetrically with respect to the optical axis S.

Claims

1. An optical device (38) comprising a lens (16) and a lens (22) for deflecting a beam (3) away from a scanning area (A) or into the scanning area (A), wherein: The lens (16) is configured as a lens array, and the lens (22) is arranged in the beam path between the scanning area (A) and the lens (16), wherein the lens (22) has an aperture integrated in or arranged on the lens (22) for limiting a maximum emission surface, characterized in that the optical device (38) has at least one optical element (40) arranged in front of the lens (16) in the radiation direction or connected to the lens (16), the at least one optical element being used to adjust the incident direction of the beam (3) onto the lens array, wherein the optical element (40) is configured as a wedge array, the wedge array having at least one surface (42, 44) mounted obliquely with respect to the radiation direction, so that at least a part of the beam (3) is deflected angularly in such a way that it does not enter the aperture of the lens (22).

2. The optical device according to claim 1, wherein: The optical element (40) is spaced apart from the lens (16).

3. The optical device according to claim 1, wherein: The optical element (40) is connected to the lens (16) in one piece or in a material-bonded manner.

4. The optical device according to any one of claims 1 to 3, wherein: The at least one face (42, 44) of the wedge array is shaped rotationally symmetrically along an axis of symmetry (S).

5. An optical device according to any one of the preceding claims 1 to 3, wherein: The optical element (40) configured as a wedge array has at least two faces (42, 44) arranged at an angle relative to a symmetry axis (S), wherein the arrangement angle of the faces (42, 44) decreases with increasing distance from the symmetry axis (S).

6. The optical device according to claim 5, wherein: The radial distance (d) between the at least two surfaces (42, 44) k ) increases as the distance between the surface and the axis of symmetry (S) increases.

7. The optical device according to any one of claims 1 to 3, wherein: The at least one face (42, 44) of the wedge array is oriented radially away from the axis of symmetry (S) and the lens (16).

8. The optical device according to claim 1, wherein: The optical device is used in a laser radar device (1).

9. The optical device according to claim 1, wherein: The optical element (40) is designed as a diffractive optical element or a holographic optical element which is applied to the lens (16) at least on one side or is arranged in the beam path of the beam (3) at a distance from the lens (16).

10. A laser radar device (1) for generating a beam (2) and scanning a scanning area (A) with the beam (3), the laser radar device comprising a transmitting unit (4) and a receiving unit (10), the transmitting unit being for generating the beam (2) and deflecting the beam (2) along the scanning area (A), the receiving unit having at least one detector (34) for receiving the reflected beam (28), characterized in that: The transmitting unit (4) and / or the receiving unit (10) comprises an optical device (38) according to any one of claims 1 to 9.

Images