DE102020208785A1 - LiDAR system - Google Patents

Abstract

The invention relates to a LiDAR system, comprising: an optical waveguide, a laser radiation source which is set up to generate laser radiation and to couple the generated laser radiation at least partially into the optical waveguide, a decoupling element which has at least one luminous surface and is set up to couple the laser radiation into the optical waveguide To decouple laser radiation at least partially from the optical waveguide and to emit it via the at least one luminous surface, the at least one luminous surface being set up to deflect the laser radiation that is coupled out. The invention relates to a motor vehicle.

Description

The invention relates to a LiDAR system and a motor vehicle.

State of the art

The disclosure document DE 10 2017 213 706 A1 discloses a LiDAR system.

Disclosure of Invention

The object on which the invention is based is to be seen as providing a LiDAR system.

The object on which the invention is based can also be seen in the provision of a motor vehicle.

These respective objects are solved by means of the corresponding subject matter of the independent claims. Advantageous configurations of the invention are the subject matter of the dependent subclaims.

According to a first aspect, there is provided a LiDAR system, comprising: an optical fiber,
a laser radiation source which is set up to generate laser radiation and to at least partially couple the generated laser radiation into the optical waveguide,
a decoupling element having at least one luminous surface, which is set up to transmit at least the laser radiation coupled into the optical waveguide
to be partially decoupled from the optical waveguide and to emit via the at least one luminous surface,
wherein the at least one luminous surface is set up to deflect the coupled-out laser radiation.

According to a second aspect, a motor vehicle is provided which includes the LiDAR system according to the first aspect.

The invention is based on and includes the knowledge that the above object can be achieved in that the luminous surface of the decoupling element, via which the laser radiation decoupled from the optical waveguide is emitted, deflects the decoupled laser radiation.

This brings about the technical advantage, for example, that the direction of propagation of the emitted laser radiation can be efficiently influenced.

As a rule, it is the case that decoupling elements, which decouple laser radiation from an optical waveguide, have a preferred direction in which decoupling is particularly efficient, in particular maximally efficient.

However, this preferred direction does not necessarily have to match the direction in which the emitted laser radiation is intended to propagate.

However, since lateral displacement of the decoupled laser radiation is possible by means of the luminous surface, the decoupled laser radiation can advantageously be emitted in a desired direction.

Thus, in particular, the technical advantage is brought about that an efficient LiDAR system is provided.

The abbreviation "LiDAR" stands for "Light Detection and Ranging".

According to one embodiment, the LiDAR system according to the first aspect is a LiDAR system for a motor vehicle.

According to one embodiment, the LiDAR system is set up to emit laser radiation, in particular laser pulses and/or continuous-wave radiation, in particular frequency-modulated (FMCW) continuous-wave radiation, for scanning the environment in different spatial directions (deflection directions) and via a transit time measurement to determine a distance from the scattering, in particular reflective, surface of the radiation reflected back in each case, ie to carry out a transit time measurement.

According to a first embodiment, it is provided that the at least one luminous surface is set up to deflect the decoupled laser radiation in such a way that the deflected laser radiation propagates parallel to the normal to the surface of the decoupling element, in particular parallel to the normal to the surface of the luminous surface.

This brings about the technical advantage, for example, that a particularly suitable propagation direction can be used for the coupled-out laser radiation.

As a result, the laser radiation deflected in this way can advantageously be coupled efficiently into optical elements or optical elements can efficiently image or, for example, diffract the laser radiation deflected in this way.

For example, the laser radiation deflected in this way can be efficiently aligned along an optical axis of an optical element.

In one embodiment it is provided that the LiDAR system comprises an optical element which is set up to image the laser radiation emitted by means of the at least one luminous surface, the at least one luminous surface being arranged in a focal plane of the optical element.

This brings about the technical advantage, for example, that the emitted laser radiation can be efficiently imaged by the optical element.

The optical element is, for example, a lens or is, for example, an objective.

In one embodiment it is provided that a wedge and/or a prism and/or a grating, in particular a blazed grating, in particular a multilevel grating, is arranged on the at least one luminous surface.

This brings about the technical advantage, for example, that the laser radiation that is coupled out can be efficiently deflected.

In one embodiment it is provided that the at least one luminous area has a surface structure which has at least one element selected from the following group of surface structures: wedge structure, prism structure, blazed grating structure and multi-level grating structure.

This brings about the technical advantage, for example, that the laser radiation that is coupled out can be efficiently deflected.

According to one embodiment, it is provided that the decoupling element is designed as a switchable decoupling element, so that the at least partial decoupling of the laser radiation coupled into the optical waveguide can be switched on and off.

This brings about the technical advantage, for example, that the coupled-in laser radiation can be coupled out efficiently.

According to one embodiment it is provided that the decoupling element is an element selected from the following group of decoupling elements: grating coupler, liquid crystal, MEMS grating, volume hologram.

This brings about the technical advantage, for example, that particularly suitable decoupling elements can be used.

According to one embodiment, it is provided that the light waveguide has a main light waveguide branch and several secondary light waveguide branches connected to the main light waveguide branch, the laser radiation source being set up to couple the generated laser radiation at least partially into the main light waveguide branch, so that the laser radiation coupled into the main light waveguide branch can be further coupled into the secondary light waveguide branches, wherein the decoupling element is set up to decouple the laser radiation coupled into the secondary light waveguide branches and to emit it via the at least one luminous surface.

This brings about the technical advantage, for example, that the laser radiation generated can be guided efficiently.

In one embodiment it is provided that the LiDAR system is connected to a control system of the motor vehicle according to the third aspect.

This brings about the technical advantage, for example, that the motor vehicle can be operated efficiently by means of the control system.

The abbreviation "bzw." stands for "respectively".

The term “or” stands for “respective”, which stands for “and/or” in particular.

The terms multilevel lattice and multilevel lattice can be used interchangeably. In English, the term "multilevel grating" is used.

The phrase "at least one" means "one or more".

In one embodiment, the LiDAR system is part of a, in particular semi-autonomous, driver assistance system or an autonomous system.

According to one embodiment, the LiDAR system comprises a transmission path, which preferably comprises the optical waveguide, the laser radiation source and the decoupling element.

In one embodiment, the LiDAR system includes a reception path for detection of the scattered light. For example, the receive path partially overlaps the transmit path. For example, the receiving pad includes a or multiple beam splitters. In particular, the reception path and the transmission path are designed separately, so they do not overlap, so they are free of overlap.

• 1 ein LiDAR-System,
• 2 bis 11 jeweils einen Lichtwellenleiter, welcher in einem LiDAR-System nach dem ersten Aspekt verwendet werden kann, und
• 12 ein Kraftfahrzeug.

Embodiments of the invention are shown in the drawings and explained in more detail in the following description. Show it:

• 1 a LiDAR system,
• 2 until 11 in each case an optical waveguide which can be used in a LiDAR system according to the first aspect, and
• 12 a motor vehicle.

The same reference symbols can be used below for the same features.

1 shows a LiDAR system 101.

The LiDAR system 101 includes a laser radiation source 103 which is set up to generate laser radiation, represented symbolically by an arrow with the reference number 105 .

The LiDAR system 101 also includes an optical waveguide 107. The laser radiation source 103 is set up to at least partially couple the generated laser radiation 105 into the optical waveguide 107.

The optical waveguide 107 comprises a main optical waveguide branch 109 and a plurality of secondary optical waveguide branches 111 which are connected to the main optical waveguide branch 109 and which run at a distance from one another and perpendicular to the main optical waveguide branch 109 . The auxiliary light waveguide branches 111 form a lattice arrangement.

The laser radiation source 103 is set up to at least partially couple the generated laser radiation 105 into the main optical waveguide branch 109 . The coupled-in laser radiation will then propagate in the main optical waveguide branch 109 and will be coupled further into the secondary optical waveguide branches 111 .

The LiDAR system 101 also includes a decoupling element 113 which is set up to at least partially decouple the laser radiation coupled into the optical waveguide 107 from the optical waveguide 107 .

The decoupling element 113 comprises a plurality of luminous surfaces 115 via which the decoupled laser radiation is emitted.

The decoupling element 113 comprises, for example, a plurality of gratings (not shown) which are located below the luminous surfaces 115, it being possible for the coupled-in laser radiation to be decoupled via the gratings (not shown) based on the principle of diffraction.

The decoupling element 113 has a structure or shape corresponding to the secondary optical waveguide branches 111 .

This therefore means that the laser radiation coupled into the secondary light waveguide branches 111 is coupled out via the decoupling element 113 and is emitted via the luminous surfaces 115 .

In this case, the emitted laser radiation has a specific spatial direction, which is different from a surface normal of the decoupling element 113, for example.

In order, for example, to deflect the laser radiation that is coupled out so that the emitted laser radiation propagates parallel to the normal to the surface of the coupling-out element 113, provision is made for the luminous surfaces 115 to be designed in such a way that they correspondingly deflect the laser radiation that is coupled out.

The LiDAR system 101 further comprises an optical element 117, the luminous surfaces 115 being arranged in a focal plane 119 of the optical element 117.

The optical element 117 images the emitted laser radiation.

The optical element 117 is, for example, a lens or is, for example, an objective.

1 FIG. 12 thus shows schematically the structure of a transmitting and/or receiving unit for a so-called focal plane array. i.e. Light emitters or light receivers are placed in the back focal plane of a lens. As a result, light can be emitted or received in dedicated solid angles.

Through the grid arrangement, formed by means of the secondary optical waveguide branches 111, preferably switchable emitter or receiver can thus z. B. a scanning sensor can be realized, preferably with parallel (especially in the sense of temporally parallel use) transmission or receiving channels.

2 shows an optical waveguide 201 in which coupled-in laser radiation 203 propagates.

A decoupling element 205 is also provided, which is embodied as a MEMS grid switch. MEMS stands for microelectromechanical system.

The MEMS grating switch 205 has a plurality of regions 207 which have a lower refractive index than the optical waveguide 201.

The MEMS grid switch 205 can be removed from the optical waveguide 201 so that the coupled-in laser radiation 203 cannot be coupled out.

3 shows the MEMS grating switch 205 in contact with the optical waveguide 201. The plurality of regions 207 with the lower refractive index form a grating for the coupled-in laser radiation 203, via which the coupled-in laser radiation 203 can be coupled out of the optical waveguide 201.

The laser radiation that is coupled out is identified by an arrow with the reference number 301 .

An arrow with the reference number 303 is also drawn in, which is intended to represent a surface normal of a surface 209 of the MEMS grid switch 205 .

The MEMS grid switch 205 is thus a switchable decoupling element, so that the at least partial decoupling of the laser radiation 203 coupled into the optical waveguide 201 can be switched on and off.

As the 3 shows symbolically, the direction of propagation of the decoupled laser radiation 301 does not correspond to the surface normal 303.

This is due, for example, to the fact that a diffraction efficiency is at a maximum when decoupling in a specific spatial direction and if there are deviations from this direction, the diffraction efficiency decreases rapidly. This specific spatial direction does not necessarily correspond to the surface normal 303.

However, it can be advantageous for optical applications if the propagation direction of the emitted laser radiation runs parallel to the surface normal 303 .

For this reason, according to the concept described here, it is provided that the surface 209 of the MEMS grid switch 205, this surface forming a luminous surface via which the decoupled laser radiation 301 is emitted, is designed in such a way that it deflects the decoupled laser radiation 301.

4 shows a first way to do this.

According to 4 the luminous surface 209 is formed as an inclined plane.

The reference number 401 points to auxiliary lines shown in broken lines, which are intended to symbolize the surface 209 originally running horizontally.

Correspondingly, the surface 209 is provided with a wedge structure 403, a second side of the wedge 403 being symbolically marked with the reference number 405 with an auxiliary line shown in dashed lines.

This wedge structure is created, for example, by applying a wedge angle. For example, a wedge tool can remove the surface 209 accordingly.

In one embodiment it can be provided that this wedge structure is applied as a separate element, for example by combining two components or an entire wafer.

This wedge structure acts as a prism, in particular as a wedge prism, and thus deflects the laser radiation 301 that is coupled out in the direction of the surface normal 303 in such a way that the emitted laser radiation runs parallel to the surface normal 303 . The correspondingly deflected laser radiation is identified by reference number 407 .

Furthermore, the arrow with the reference number 301 is shown as a dashed line in order to illustrate the direction in which the coupled-out laser radiation would have been emitted if the luminous surface 209 had not been formed accordingly.

5 shows a second possibility to bring about the deflection of the emitted laser radiation.

According to 5 the luminous surface 209 has a blazed grating structure 501 .

This means that the surface 209 is provided with a blazed grating.

Here, too, the reference number 401 designates auxiliary lines, represented by dashed lines, which represent the luminous surface 209 without the blazed grating structure 501 .

6 FIG. 12 shows a third possibility for bringing about the deflection of the decoupled laser radiation, so that it runs parallel to the surface normal 303 after deflection.

According to 6 the luminous surface 209 is provided with a multi-level grid 601, whereby the multilevel grid 601 has a first level 603, a second level 605 and a third level 607.

This multilevel grating 601 discretely approximates the blazed grating structure 501 of FIG 5 .

7 shows a carrier substrate 701 on which an optical waveguide 703 is arranged. Within the optical waveguide 703, coupled-in laser radiation propagates, represented symbolically by an arrow with the reference number 705.

A top side 707 of the optical waveguide 703 facing away from the carrier substrate 701 has a surface structure which has a geometry which corresponds to a profile of a square-wave voltage or square-wave oscillation. The surface structure thus has a square wave geometry.

A liquid crystal layer 709 is arranged on the upper side 707, which has a shape complementary to the surface structure of the upper side 707, so that the gaps between the individual rectangles of the square-wave oscillation geometry are filled by means of the liquid crystal layer 709.

The liquid crystal layer 709 is arranged on a covering substrate 711 which faces away from the upper side 707 .

An upper side of the cover substrate 711, which faces away from the liquid crystal layer 709, is identified by reference number 715.

This upper side 715 forms a luminous surface through which laser radiation coupled out of the optical waveguide 703 can emit.

A voltage source 713 is also provided, which can apply an electrical voltage to the liquid crystal layer 709 .

The carrier substrate 701 has a first refractive index n1. The optical waveguide 703 has a second refractive index n2. The liquid crystal layer 709 has a third refractive index n3 which depends on the applied voltage. The cover substrate 711 has a fourth refractive index n4. A region surrounding the arrangement of cover substrate 711, liquid crystal layer 709, optical waveguide 703 and carrier substrate 701 has a fifth refractive index n5.

The following correlations or relations apply to the refractive indices: n2<n1; n1 = n4; n4 > n5.

The liquid crystal layer 709 is set up in such a way that when a first voltage U1 is applied, the third refractive index n3 is equal to the second refractive index n2. Then the coupled-in laser radiation 705 is not coupled out.

8th shows the case in which a second voltage U2, which is different from the first voltage U1, is applied to the liquid crystal layer 709. When the voltage U2 is applied, the liquid crystal layer 709 is set up to have a third refractive index n3, which is smaller than the second refractive index n2.

In this case, the coupled-in laser radiation 705 is coupled out.

The surface structure of the upper side 707 forms a grid for the laser radiation 705, so that when the second voltage U2 is applied, the coupled-in laser radiation 705 is diffracted via this grid and is thus coupled out of the optical waveguide 703.

As already explained above, the diffraction efficiency when decoupling does not have to be maximum in precisely the spatial direction which runs parallel to the surface normal 303 .

The first voltage U1 can be 0 volts.

To now analogous to the embodiments according to 4 until 6 to achieve a deflection of the decoupled laser radiation 301 in such a way that it is emitted in the direction of the surface normal 303, the same options can be provided as in FIGS 4 until 6 described.

9 shows analogous to 4 a wedge structure 403.

10 shows analogous to 5 a blazed grating structure 501.

11 shows analogous to 6 a multilevel lattice structure 601.

12 shows a motor vehicle 1201.

The motor vehicle 1201 has the LiDAR system 101 of 1 on, with the sake of clarity symbolic for the individual elements 1 only a rectangle with the reference number 101 is drawn.

In summary, the concept described here is based in particular on correcting the propagation direction of the emitted laser radiation by impressing a linear phase, which corresponds to a lateral displacement in spatial frequency space (k-space), on the at least one luminous surface of the decoupling element.

• Aufbringen eines Keilwinkels / Prismas (auf Englisch: Wedge angle / prism). Dies kann z.B. mittels eine Keilwerkzeuges oder mittels eines oberflächlichen Abtragens von Material oder durch Aufbringen einer Keilstruktur, z.B. durch Kombination zweier Bauteile oder ganzer Wafer, erfolgen.

This can be done, for example, as follows:

• Application of a wedge angle / prism (in English: Wedge angle / prism). This can be done, for example, by means of a wedge tool or by removing material from the surface or by applying a wedge structure, for example by combining two components or entire wafers.

Imprinting, pressing or lithographic incorporation of a blazed grating either as a continuous (greyscale) profile or as a discrete / quantized multilevel structure (multilevel grating).

This brings about the technical advantage in particular that, regardless of the direction in which the laser radiation is coupled out, a specific propagation direction can be brought about in which the coupled out laser radiation emits via the luminous surface. Thus, for example, the decoupled laser radiation can be emitted via the luminous area in a direction that corresponds to a propagation direction specified by an overall system architecture.

QUOTES INCLUDED IN DESCRIPTION

This list of documents cited by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent Literature Cited

• DE 102017213706 A1 [0002]

Claims (9)

LiDAR system (101), comprising: an optical fiber (107, 201, 703), a laser radiation source (103) which is set up to generate laser radiation and to couple the generated laser radiation (105) at least partially into the optical waveguide (107, 201, 703), a decoupling element which has at least one luminous surface (115, 209, 715) and is set up to decouple the laser radiation (203) coupled into the optical waveguide (107, 201, 703) at least partially from the optical waveguide (107, 201, 703) and via the to emit at least one luminous area (115, 209, 715), wherein the at least one luminous surface (115, 209, 715) is set up to deflect the coupled-out laser radiation (301, 303). LiDAR system (101) after claim 1 , wherein the at least one luminous surface (115, 209, 715) is set up to deflect the decoupled laser radiation (301, 303) in such a way that the deflected laser radiation propagates parallel to the surface normal of the decoupling element. LiDAR system (101) after claim 1 or 2 , comprising an optical element which is set up to image the laser radiation emitted by means of the at least one luminous surface (115, 209, 715), the at least one luminous surface (115, 209, 715) being arranged in a focal plane of the optical element. LiDAR system (101) according to one of the preceding claims, wherein a wedge and/or a prism and/or a grating, in particular a blazed grating, in particular a multi-level grating, is arranged on the at least one luminous surface (115, 209, 715). LiDAR system (101) according to one of the preceding claims, wherein the at least one luminous surface (115, 209, 715) has a surface structure which has at least one element selected from the following group of surface structures: wedge structure (403), prism structure, blaze grating structure ( 501) and multilevel lattice structure. LiDAR system (101) according to one of the preceding claims, wherein the decoupling element is designed as a switchable decoupling element (205, 709), so that the at least partial decoupling of the optical waveguide (107, 201, 703) coupled laser radiation (203) and can be turned off. LiDAR system (101) according to one of the preceding claims, wherein the decoupling element (113, 203, 709) is an element selected from the following group of decoupling elements (113, 203, 709): grating coupler, liquid crystal (709), MEMS grating (203), volume hologram. LiDAR system (101) according to one of the preceding claims, wherein the optical waveguide (107, 201, 703) has a main optical waveguide branch (109) and a plurality of secondary optical waveguide branches (111) connected to the main optical waveguide branch (109), the laser radiation source (103) being set up to couple the generated laser radiation (105) at least partially into the main fiber optic branch (109), so that the laser radiation (203) coupled into the main fiber optic branch (109) can be further coupled into the secondary fiber optic branches (111), the decoupling element being set up to enter the secondary fiber optic branches (111) to decouple coupled-in laser radiation (203) and to emit it via the at least one luminous surface (115, 209, 715). Motor vehicle (1201), comprising the LiDAR system (101) according to any one of the preceding claims.

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