EP3622317A1

EP3622317A1 - Transmitter optics for a lidar system, optical arrangement for a lidar system, lidar system and working device

Info

Publication number: EP3622317A1
Application number: EP18723800.1A
Authority: EP
Inventors: Hans-Jochen Schwarz; Joern Ostrinsky
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2017-05-12
Filing date: 2018-05-08
Publication date: 2020-03-18
Also published as: KR20200004873A; DE102017208052A1; JP2020519891A; CN110622030A; US11500105B2; WO2018206517A1; US20210157008A1

Abstract

The present invention relates to transmitter optics (60) for a LiDAR system (1) for illuminating a field of view (50) with light, comprising a line light source (65-1) for generating and emitting primary light (57) in line form, and comprising deflection optics (62), which have a lens arrangement (68) in an intermediate image plane (69) of the deflection optics (62) for outputting received primary light (52) into the field of view (50) and a deflection mirror (64), which can pivot one-dimensionally about an axis (64-1), for collecting primary light (57) from the line light source (65-1) and for directing the primary light (57) onto the lens arrangement (68) and, in doing so, imaging the light line source (65-1) onto the lens arrangement (68) such that the image of the light line source (65-1) sweeps over the lens arrangement (68) or part thereof when the deflection mirror (63) pivots.

Description

Description title

Transmitter optics for a LiDAR system, optical arrangement for a LiDAR system, LiDAR system and working device

State of the art

The present invention relates to a transmitter optics for a LiDAR system for illuminating a field of view with light, an optical arrangement for a LiDAR system for optically detecting a field of view, a LiDAR system as such and a working device and in particular a vehicle.

With the use of working devices, of vehicles and other machines and plants are increasingly operating assistance systems or

Sensor arrays used to detect the operating environment. In addition to radar-based systems or systems based on ultrasound, light-based detection systems are also used, e.g. so-called LiDAR systems (English: LiDAR: light detection and ranging).

In scanning or scanning LiDAR systems, the primary light is passed through the field of view after being generated by rotating or tilted optical elements to scan it in a scanning or scanning manner with primary light. On the one hand, the oscillating or rotating components in such systems have comparatively high inertial forces which must be overcome. Furthermore, optical elements used in the form of microlenses or the like must be made as accurately as possible, even when other optical components are moving, in order to obtain a high imaging quality. This requires a considerable apparatus and control engineering effort.

Disclosure of the invention The transmitter optics according to the invention for a LiDAR system with the features of claim 1 has the advantage that with a comparatively simple structure and reduced inertial forces in a scanning LiDAR system a particularly lossless and

faithful coverage of the field of view is achieved. this will

according to the invention with the features of claim 1, characterized in that a transmitter optics for a LiDAR system for illuminating a field of view with light is specified, which is formed (i) with a line light source for generating and outputting primary light in line form and (ii) with a

Ablenkoptik having a lens arrangement in an intermediate image plane of the deflection optics for outputting received primary light in the field of view and a one-dimensional pivotable about an axis deflection mirror for receiving primary light from the line light source and for directing the primary light on the lens assembly and thereby optically imaging the

Line light source on the lens assembly such that the image of the

Line light source at a pivoting movement of the deflection mirror the

Lens arrangement or a part thereof sweeps.

The dependent claims show preferred developments of the invention.

There are various embodiments for the lens arrangement.

Thus, according to a preferred embodiment of the transmitter optics according to the invention, the lens arrangement for outputting the received primary light in the field of view (a) a segmented lens arrangement, a lens array, a lens matrix, a microlens array, a rod lens array with a plurality of rod lenses with parallel rod axes, in particular with rod axes parallel aligned to a pivot axis of the pivoting mirror, (b) a diffractive optical element, in particular a DOE, and / or (c) have a hologram.

Also with regard to the line light source, different embodiments with one or more underlying light sources are advantageous.

It can be the transmitter optics (A) according to the invention a laser, a

Edge emitter laser, a surface laser, a vertical cavity surface (VCSEL) A laser (vertical external cavity surface emitting laser) and / or (B) have an arrangement with an illuminable or illuminated gap. Alternatively, a respective laser may also be designed as a gas laser or as a solid-state laser, which is expanded to a line using a corresponding beam-shaping optical system.

There are also various embodiments with regard to

Deflection mirror, which can also be generally referred to as a deflection, conceivable.

The deflection mirror according to preferred embodiments of the transmitter optics can be designed

to carry out a pivoting movement and / or a rotational movement, in particular about a fixed axis of rotation, in a continuous manner and / or in the manner of a torsional vibration,

with at least one prism mirror or a polyhedral mirror with a polygonal cross-sectional area or base area,

with at least one planar, convex and / or concave mirror surface,

- with at least one micromirror, - silicon-based,

to be operated statically and / or resonantly or to be operable.

Other advantageous developments in the transmitter optics according to the invention for a LiDAR system have an intermediate image optics. This intermediate image optics can be formed

to image the line light source onto the lens array, as optics between the deflection mirror and the line light source, as optics between the line light source and the deflection mirror, - As beam-shaping optics for generating a line illumination on the lens assembly, in particular in the manner of a laser line, and / or - as a telecentric and / or f-theta optics to produce a planar

Image field in the intermediate image plane.

Furthermore, the present invention also relates to an optical arrangement for a LiDAR system as a whole, namely for the optical detection of a field of view, in particular for a working device and / or a vehicle, with a transmitter optics for illuminating a field of view with primary light, which is formed according to the present invention , and with a receiver optics for receiving secondary light from the field of view. In an advantageous embodiment of the optical according to the invention

Arrangement for a LiDAR system, the transmitter optics and the receiver optics are formed, for example, with at least partially or partially mutually coaxial beam paths, in particular in the region of the beam exit side and the beam entrance side of the LiDAR system.

Under these circumstances, a beam splitter may be formed to accommodate the

Beam paths of a coaxial shape on the beam exit side and the beam entrance side of the optical arrangement of the LiDAR system in a path from the line light source of the transmitter optics and in a path to a

Transfer detector array of the receiver optics.

Alternatively, optical arrangements according to the invention for a LiDAR system are conceivable, which despite the partial or sectional coaxial design of the beam paths of transmitter optics on the beam exit side and receiver optics on the beam entrance side are designed without beam splitter, in which case an intended detector arrangement of the receiver optics in the immediate vicinity of the line light source and / or next to

Line light source is arranged.

In an alternative embodiment of the optical arrangement according to the invention for a LiDAR system, the transmitter optics and the receiver optics are substantially or largely separate from each other and / or formed to each other biaxial beam paths, in particular on the

Beam exit side of the transmitter optics and on the beam entrance side of the

Receiver optics. According to another aspect of the present invention, a LiDAR

System created as such, which for the optical detection of a

Field of view and in particular for a working device and / or for a vehicle is formed and has an optical arrangement according to the invention.

Finally, the subject of the present invention is also a

Working device and in particular a vehicle, which are formed with a LiDAR system according to the present invention for the optical detection of a field of view.

Brief description of the figures

Embodiments of the invention will be described in detail with reference to the accompanying drawings.

FIG. 1 shows the manner of a schematic block diagram

Structure of an embodiment of the LiDAR system according to the invention. FIG. 2 shows a first plan view in the manner of a schematic plan view

Embodiment of the transmitter optics invention.

Figures 3 and 4 show the manner of schematic plan views

Embodiments of the LiDAR system according to the invention using embodiments of the transmitter optics according to the invention

Figure 5 shows a kind of schematic plan view of a

Embodiment of the transmitter optics invention with two transmission paths.

Preferred embodiments of the invention Hereinafter, embodiments of the invention and the technical background will be described in detail with reference to Figs. Identical and equivalent as well as equivalent or equivalent elements and components are designated by the same reference numerals. Not in every case of their occurrence, the detailed description of the designated elements and components is reproduced.

The illustrated features and other properties can be isolated in any form from each other and combined with each other, without departing from the gist of the invention.

Figure 1 shows in the form of a schematic block diagram a

Embodiment of the LiDAR system 1 according to the invention using an embodiment of the optical arrangement 10 according to the invention.

The LiDAR system 1 according to FIG. 1 has an embodiment of the transmitter optics 60 according to the invention, which is provided by a light source unit 65 with a line light source 65-1, e.g. in the form of a laser, and primary light 57 - possibly after passing through a beam shaping optics 66 - in a field of view 50 for the investigation of an object 52 located there emits.

Furthermore, the LiDAR system 1 according to FIG. 1 has a receiver optics 30, which receives secondary light 58 reflected by the object 52 in the field of view 50 via a lens 34 as a primary optic and, if appropriate, via a

Secondary optics 35 - transmits to a detector array 20 for detection.

The control of the light source unit 65 with the line light source 65-1 and the detector arrangement 20 via control lines 42 and 41 by means of a control and evaluation unit 40th

Core aspects of the present invention are concentrated in the area of the deflecting optics 62 and manifest themselves in the provision of a rotating mirror 63, which rotates about a rotation axis or pivot axis 64-1 by means of a rotation axis 63

Pivoting movement 64 or rotational movement 64 is pivotable or rotatable, thereby illuminating the lens assembly 68 scanning with an image of the line light source 65-1 of the light source unit 65 imaging. The Lens assembly 68 having a plurality of individual lenses is configured to direct primary light 57 into field of view 50 having object 52 therein. Preferably, part of the deflection optics 62 is also a projection optics 90, which is set up to emit the primary light 57 at different angles into the field of view 50 and, if appropriate, to receive secondary light 58 from the various angles of the field of view 50 in the manner of an objective.

Figure 2 shows, in the manner of a schematic plan view, an embodiment of the transmitter optics 60 according to the invention as part of an optical arrangement 10 for a LiDAR system 1 and concentrates on core aspects of the present invention.

These consist in the use of a line light source 65-1 as part of the light source unit 65 and the use of a lens assembly 68, which defines an intermediate image plane 69, on which by a third

Measure provided rotating mirror 63 which is rotatable about a rotational movement 64 about a rotation axis 64-1, an image of the line light source 65-1 the

Intermediate image plane 69 and thus the lens assembly 68 is shown sweeping.

The lens assembly 68 itself serves to direct the primary light 57 into the field of view 50, thereby monitoring the field of view 50 in the manner of an environment.

In the embodiment according to FIG. 2, the rotating mirror 63 is designed in the manner of a prism mirror with a base surface in the form of a uniform hexagon and square or rectangular mirror surfaces. The

Lens assembly 68 consists of a plurality of parallel to each other

aligned rod lenses, whose axis of symmetry is aligned parallel to the axis of rotation 64-1 of the rotating mirror 63. The individual lens segments are designed here by way of example biconcave.

FIGS. 3 and 4 show, in the manner of schematic plan views, embodiments of the LiDAR system 1 according to the invention using FIG

Embodiments of the transmitter optics 60 according to the invention. In the embodiment according to FIG. 3, the beam paths 31 and 61 of the receiver optics 30 and the transmitter optics 60 according to the invention are partially coaxial with each other and are separated only in the region and by the action of the beam splitter 80.

The transmitter optics 60 according to FIG. 3 correspond to the core according to FIG

Embodiment according to Figure 2. In addition, however, here is a

Intermediate image optics 70 with partial optics 71, 72 and 73 - the latter optional - between the line light source 64-1 of the light source unit 65 and the beam splitter 80 and the line light source 65-1, the beam splitter 80 and the rotating mirror 63 or between the rotating mirror 63 and the intermediate image plane 69 of the

Lens assembly 68 is formed.

In addition, an objective optics 90 is also provided between the rotating mirror 63 and the lens arrangement 68, which serves for the projection of the primary light 57 into the field of view 50 and the rear projection of the secondary light 58 coming from the field of view 50. After separation of the beam paths 61 and 31 of the transmitter optics 60 and the

Receiver optics 30 is located on the receiver side, a detector assembly 20 having a plurality of sensor elements 22. Between the

Detector assembly 20 and the beam splitter 80 is a secondary optics 35 of the receiver optics 30 is formed to image the secondary light 58 in a suitable manner to the detector array 20 and the sensor elements 22.

The embodiment according to Figure 4 is the core with

Coaxially guided beam paths 31 and 61 for the receiver optics 30 and for the transmitter optics 60, but here no beam splitter 80 is used. Rather, here the detector arrangement 20 is formed in the immediate vicinity of the line light source 65-1 of the lightwave arrangement 65.

FIG. 5 shows, in the manner of a schematic plan view, an embodiment of the transmitter optics 60 according to the invention with two transmission paths 61.

In this case, according to FIG. 5, a pair of line light sources 65 - 1 are formed as part of the light source unit 65. However, in both beam paths 61 the only once provided rotating mirror 63 used together to throw the respective images of the separate line light sources 65-1 on the intermediate image plane 69 of each also separately provided lens assemblies 68, which is then about separately provided projection optics 90 then the combined field of view 50 illuminated.

These and other features and characteristics of the present invention will be further elucidated with reference to the following statements:

The improvements proposed by the invention are e.g. from

Line scanners with macro mirrors or with rotating whole unit

out.

The embodiments are biaxially conceivable, i. Transmit path and receive path are optically configured separately. The embodiments may also be coaxial, i. Transmit path and receive path are defined via a common look.

A weakness of the macro scanners are (a) the existence of a

comparatively large mechanical mirror unit or a whole unit with high inertia forces and thereby with a higher wear risk of the axes, (b) the influence on the overall size of the sensor and depending on the version (c) the problem of energy and information transfer to the rotary platform.

Alternative solutions such as inductive coupling, coupling by radio or optical coupling usually generate additional costs and result in a reduction in performance.

A weakness in point level illumination concepts with inter-level 69 and two-dimensional mirrors is the need to pinpoint the microlenses used, which resonantly oscillates when used

two-dimensional mirror is difficult (Lissajousfiguren).

According to one aspect of the present invention, a combination of the interplane concept with a one-dimensional mirror and a line illumination is proposed. The mirror can either be a micro or μ mirror, which is operated resonantly or statically, or a miniaturized rotary mirror, such as a polygon mirror, with a constant

Angular velocity is operated.

The advantages are, among other things

- Comparatively low moving masses, both at the μ-level on

Silicon base as well as the miniature polygon mirror,

- a comparatively smaller size and a more dynamic operation than with a macro scanner, whereby higher frame rates are possible,

a separation of the rotation unit and the transceiver unit with consequently less complexity in the control of the laser and detector,

- An easily controllable trajectory of the light beam, as no

Lissajousfiguren can occur

- The ability to build a coaxial system with fast mirrors, which brings no beam splitter losses.

A possible construction is shown in FIG.

The line laser 64-1, e.g. in the form of an edge emitter, is transmitted via an optic 71, e.g. with fast-axis collimation, a beam splitter 80 and an optic 72 as

Focusing optics on the mirror surface of a prism or polygon mirror 63 shown on a microlens array 68.

In another embodiment, the optics 72 with the prism or polygon mirror 63 is arranged reversed in the order, so that by using the in Fig. 3 as dashed optionally indicated optics 73 first the deflection or deflection of the laser radiation 57 takes place and then the image the microlens array 68 in the intermediate plane 69.

The optics 73 can be designed as a focusing optics with a constant f-theta ratio and / or with telecentricity. In a further alternative of the present invention, the optics 72 and 73 may be formed together.

The microlens array 68 may consist of rod lenses that expand or magnify the laser beam in one direction. The individual can

Rod lenses can be constructed from spherical or aspherical elements. The individual elements can be concave or convex. Both sides of the microlens array 68 can be provided with a curvature. However, there are also variants of microlens arrays in which one side is designed plan.

Alternatively, the lens properties, e.g. an expansion or a deflection of the laser light, the microlens array 68 are generated by a DOE or diffractive optical element or by a hologram.

The expanded beam 57 is projected via the projection optics 90 into the environment, namely the field of view 50. The light scattered back by objects 52 is directed onto the beam splitter 80 via the projection optics 90, the microlens array 68, the mirror 63 and the optics 72.

A portion of the light is transmitted via the optic 35 to a line detector 20, e.g. an APD line, pictured.

The horizontal resolution of the system is given by the spacings of the microlenses 68 and the imaging factor of the projection optics 90.

The vertical resolution is given by the pixels on the line detector 20.

All optics 70, 71, 72, 73, 35 are coated with a coating for high light transmission.

FIG. 3 shows an embodiment with prism or polygon mirror 63 and beam splitter 80 for a coaxial system.

Further possible variants are shown in FIGS. 4 and 5. With comparatively slowly moving mirrors and many shots per microlens, the point of impact shifts across the lens, which increases

lower angular resolution leads.

With relatively fast moving mirrors, the weft pattern can be laid so that the microlens is always hit in the middle.

FIG. 4 shows a transmitter optics 60 according to the invention with a beam path 61, 31 without a beam splitter 80 and with a detector 20 outside the transmission axis 61, as can be used, for example, in mirrors 63 which move very fast.

The returning light as secondary light 58 can be directed in the direction of the detector arrangement 20 with the detector elements 22 via the meanwhile further moving mirror 63.

Figure 5 shows another embodiment in which the mirror 63 is used so that it can serve two systems. As a result, a version with an expanded field of view (Field of View: FoV) is created. Receive paths 31 and

Reverse paths are not drawn, but could also be in a separate optical path, ie in a biaxial arrangement.

According to the following list, various embodiments and combinations can be realized in the context of the present invention, wherein the following components and / or properties can be combined with each other without departing from the essence of the present invention.

Alternatives to the system

- coaxial

- with classic 50/50 beam splitter or with polarizing beam splitter for high extinction ratio,

- with perforated mirror beam splitter and / or

- With detector directly next to the laser and possibly without beam splitter biaxial with separate receiving path Alternatives to the laser

- edge emitter laser (English: edge-emitting laser) a broad-area laser (laser-beam) b as a simple laser bar or laser bar

ii as a multiple laser bar soldered in series, e.g. two pieces, thus a simultaneous bombardment of two microlenses is possible.

- surface laser (English: surface emitting laser array) a vertical emitter (vertical cavity surface emitting laser (VCSEL)) i in line design,

ii as a line array (e.g., 50 emitters),

iii as a low-dimensional two-dimensional array (e.g., 50x2 emitter), thereby enabling simultaneous bombardment of two microlenses, and / or

iv as gas lasers or solid-state lasers, which are or are widened in their beam form on a line. b Vertical emitter with external resonator (English: vertical external cavity surface emitting laser (VeCSEL)) i in line design,

ii as a line array and / or

iii as a low-dimensional two-dimensional array (e.g., 50x2 emitter), this allows simultaneous bombardment of two microlenses.

Alternatives at the mirror

- Polygon mirror

- with different number of surfaces and / or - with curved polygon surfaces (imaging feature, eg to shape the beam in the vertical direction).

- Micromirror, z. B. based on silicon

- operated resonantly or

- statically operated.

Alternatives with the detector - APD detector (English: avalange photodiode) i as a line array (eg 50 single detectors) and / or

ii as a low-dimensional two-dimensional array (eg 50 x 2 detectors) - SPAD detector (single photon counting avalange diode) i as a line array (eg 50 single detectors),

ii as a low-dimensional two-dimensional array (eg 50 x 2 detectors) and / or

iii as single- or multi-dimensional silicon-based

Photomultiplier (SiPM: silicon photo multiplyer).

Alternatives for the optics: - Optics 2: i as a beam-forming optic for generating a laser line

ii as a telecentric f-theta optics for generating a flat image field in the intermediate plane with normal incidence of light and a constant ratio between mechanical deflection angle and image enhancement

iii Combination of the two variants

- Transmitting / receiving optics i as a simple optic (eg 1 to 3 individual lenses) for a small field of view (Field of View: FoV) ii as complex optics (eg more than 3, ie approx. 3 to 8 individual lenses) for a large field of view microlens array a rod lenses which expand the laser beam in one direction

enlarge i spherical or aspherical elements,

ii concave or convex elements and / or

iii both sides of the microlens array curved (bi-concave or biconvex) or one side flat (plano-concave or plano-convex) b DOE design (diffractive optical element) c Hologram design

Claims

Transmitter optics (60) for a LiDAR system (1) for illuminating a

Field of view (50) with light,

with a line light source (65-1) for generating and outputting

Primary light (57) in line form and

- With a deflection optics (62), which

a lens arrangement (68) in an intermediate image plane (69) of the

Deflection optics (62) for outputting received primary light (52) in the field of view (50) and

- One-dimensional about an axis (64-1) pivotable

Deflection mirror (64) for receiving primary light (57) from the line light source (65-1) and for directing the primary light (57) on the lens assembly (68) and thereby optically imaging the

Line light source (65-1) on the lens assembly (68) such that the image of the line light source (65-1) with a pivoting movement of the deflection mirror (63) sweeps over the lens assembly (68) or a part thereof.

Transmitter optics (60) according to claim 1,

wherein the lens assembly (68) comprises

a segmented lens array, a lens array, a lens array, a microlens array, a rod lens array having a plurality of rod lenses with parallel beam axes, in particular with beam axes aligned parallel to a pivot axis (64-1) of the

Pivoting mirror (63),

a diffractive optical element, in particular a DOE, and / or

- a hologram.

Transmitter optics (60) according to one of the preceding claims,

in which the line light source (65-1) has

a laser, an edge emitter laser, a surface laser, a VCSEL, a VeCSEL, a gas laser, a solid state laser and / or an arrangement with an illuminable or illuminated gap.

Transmitter optics (60) according to one of the preceding claims,

in which the deflecting mirror (63) is formed

perform a pivotal movement or a rotational movement, in particular about a fixed axis of rotation (64-1), in a continuous manner and / or in the manner of a torsional vibration,

with a prism mirror or a polyhedral mirror with a polygonal cross-sectional or base area,

with a planar, convex and / or concave mirror surface,

- with a micromirror,

- silicon-based,

to be operated statically and / or resonantly or to be operable.

Transmitter optics (60) according to one of the preceding claims,

which has an intermediate image optics (70), which is formed

for imaging the line light source (65-1) on the lens arrangement (68),

as optics between the deflection mirror (63) and the line light source (65-1),

- As optics between the line light source (65-1) and the deflection mirror

(63)

- As a beam-shaping optics for generating a line illumination on the lens assembly (68), in particular in the manner of a laser line, and / or

- As a telecentric and / or f-theta optics for generating a flat image field in the intermediate image plane (69).

Optical arrangement (10) for a LiDAR system (1) for optical

Detecting a field of view (50), in particular for a working device and / or a vehicle,

- With a transmitter optics (60) for illuminating a field of view (50) with primary light (57), which is designed according to one of claims 1 to 5, and

- With a receiver optics (30) for receiving secondary light (58) from the field of view (50).

Optical arrangement (10) according to claim 6, in which the transmitter optics (60) and the receiver optics (30) are formed

- With at least partially or partially mutually coaxial beam paths (31, 61) and

- With a beam splitter (80) or without beam splitter (80) with a

Detector arrangement (20) of the receiver optics (30) in the immediate vicinity of the line light source (65-1) and / or next to the line light source (65-1). 8. An optical arrangement (10) according to claim 6,

in which the transmitter optics (60) and the receiver optics (30) are formed with mutually biaxial beam paths.

9. LiDAR system (1) for optically detecting a field of view (50),

in particular for a working device and / or a vehicle, having an optical arrangement (10) according to one of claims 6 to 8.

10. working device and in particular a vehicle,

with a LiDAR system (1) according to claim 9 for the optical detection of a field of view (50).