DE102017210591A1 - Macroscopic lidar device - Google Patents

Abstract

Macroscopic lidar device (100) comprising:
a stator (1); and
a rotor (2); in which
- On the rotor (2) a laser element (20) and a transmitting device are arranged; in which
- In the intended mounting position of the lidar device (100) on a vehicle during each half-turn of the rotor (2), a beam of the laser element (20) substantially permanently in a forwardly directed field of view (FOV) is emitted.

Description

The invention relates to a macroscopic lidar device. The invention further relates to a method for producing a macroscopic lidar device.

State of the art

Lidar macroscanners in which all optical elements, as well as the laser and the detector are arranged on a rotor, and which have a rotating macro mirror with a diameter in the centimeter range, are known. As a result, a beam with a diameter in the centimeter range can be guided over the rotating macro mirror in the transmission path. Advantageously, with systems of this kind in which all components "rotate", a horizontal field of view (FOV) of 360 ° can be scanned systemically.

However, this is a disadvantage in particular when installed in a vehicle body (i.e., not on the vehicle roof) because up to 2/3 of the time can not be measured, namely, when the laser on the rotor points toward the vehicle body. In addition, the selection of a large field of view creates further disadvantages for the system, e.g. The requirements for imaging optics or optical filters increase with increasing angle of incidence. For this reason, a smaller field of view is often chosen than would actually be possible by the installation location.

1 shows a schematic plan view of a conventional Lidar device 100 , Recognizable is a rotor 1 , on which a first transmission lens 10 and a second transmission lens 11 are arranged. A visual field FOV, which is in a position of attachment of the lidar device as intended, is indicated 100 on a vehicle 200 points to the front. Transmission beams of a laser are indicated by arrows. An installation of the lidar device 100 in the vehicle is therefore desirable because the lidar device should be integrated as inconspicuously in the vehicle. Due to a hidden installation location, however, the field of view FOV can no longer be used by 360 °. However, a reduction of the field of view FOV is always associated with a reduction of the measuring time for the described system when the part of the rotor 1 taking the measurement just outside the field of view FOV.

Disclosure of the invention

It is therefore an object of the invention to provide an improved scanning macroscopic lidar system.

• - einen Stator; und
• - einen Rotor; wobei
• - auf dem Rotor ein Laser-Element und eine Sendeinrichtung angeordnet sind; wobei
• - in bestimmungsgemäßer Anbringlage der Lidar-Vorrichtung an einem Fahrzeug während jeder Halbdrehung des Rotors ein Strahl des Laser-Elements im Wesentlichen dauerhaft in ein nach vorne gerichtetes Sichtfeld emittierbar ist.

In a first aspect, the invention provides a macroscopic lidar device comprising:

• a stator; and
• a rotor; in which
• - On the rotor, a laser element and a transmitting device are arranged; in which
• - In the intended mounting position of the lidar device on a vehicle during each half-turn of the rotor, a beam of the laser element is substantially permanently emitted in a forwardly directed field of view.

In this way, a scanning, macroscopic lidar device is provided which has two transmission paths which provide forward laser power during each half-rotation or each full revolution of the rotor. In this way, advantageously, a frame rate of the lidar device can be doubled because a useful time of the lidar device is fully utilized. Advantageously, thereby only a single laser element is required and the lidar device is very well suited for concealed installation in the chassis of a vehicle. As a result, the proposed device has no or only a minimal dead time when scanning the environment.

• - Bereitstellen eines Stators; und
• - Bereitstellen eines Rotors; wobei
• - auf dem Rotor ein Laser-Element und eine Sendeinrichtung angeordnet werden; wobei
• - die Sendeeinrichtung derart ausgebildet wird, dass in bestimmungsgemäßer Anbringlage der Lidar-Vorrichtung an einem Fahrzeug während jeder Halbdrehung des Rotors ein Strahl des Laser-Elements im Wesentlichen dauerhaft in ein nach vorne gerichtetes Sichtfeld (FOV) emittierbar ist.

According to a second aspect, the object is achieved with a method for producing a macroscopic lidar device, comprising the steps:

• - Providing a stator; and
• - Providing a rotor; in which
• - On the rotor, a laser element and a transmitting device are arranged; in which
• - The transmitting device is designed such that in the intended mounting position of the lidar device on a vehicle during each half-turn of the rotor, a beam of the laser element is substantially permanently emitted in a forwardly directed field of view (FOV).

Preferred embodiments of the lidar device are the subject of dependent claims.

An advantageous development of the lidar device is characterized in that the beam of the laser element can be emitted by means of a modulation device into the field of vision directed to the front. In this way, different modulation means for emitting the laser beam forward can be used.

An advantageous development of the lidar device provides that the modulation device comprises a non-polarizing beam splitter. In this way, a particularly simple and inexpensive variant of the modulation device is provided.

A further advantageous development of the lidar device provides that the modulation device comprises a polarization rotator and a polarizing beam splitter. In this way, a polarization of the laser beam can be set defined and in this way in combination with the polarizing beam splitter, a forwardly emitted laser power can be adjusted. As a result, a power adjustment due to different polarizations of the laser beam is thereby achieved with a different range of the lidar device realized thereby.

A further advantageous development of the lidar device is characterized in that the polarization rotator can be switched between extreme values of horizontal and vertical polarization. This functionality can be advantageously realized with can with a slow and inexpensive polarization rotator.

A further advantageous lidar device is characterized in that the polarization rotator can be switched in defined positions as a function of a reflected beam of the laser element. In this way, a rapid switching of the polarization is advantageously provided, which is particularly advantageous if an eye safety aspect is to be considered. This is important for adjustment of radiant power in detection of on-vehicle creatures.

Further advantageous developments of the lidar device are characterized in that the polarization rotator is a Pockels cell or a mechanical polarization rotator. In this way, advantageously different types of polarization rotors can be used for the lidar device.

A further advantageous development of the lidar device is characterized in that a transmission path and a reception path of the lidar device are not superimposed. In this way, a biaxial embodiment of the lidar device of FIG. 12 is provided in which two separate transmitting and receiving optics are formed.

A further advantageous development of the lidar device is characterized in that a transmission path and a reception path of the lidar device are superimposed. In this way, a coaxial system is provided in which a reduced parallax effect compared with the biaxial system can be realized. Advantageously, only a single detector in the same light path is required in this variant, because a transmission optics can also be used for the reception path.

The invention will be described below with further features and advantages with reference to several figures in detail. Same or functionally identical components have the same reference numerals. The figures are particularly intended to illustrate the principles essential to the invention and are not necessarily to scale. For better clarity, it can be provided that not all the figures in all figures are marked.

Disclosed device features result analogously from corresponding disclosed method features and vice versa. This means, in particular, that features, technical advantages and embodiments relating to the macroscopic lidar device result analogously from corresponding embodiments, features and advantages of the method for producing a macroscopic lidar device and vice versa.

• 1 eine prinzipielle Darstellung einer Draufsicht auf eine herkömmliche scannende makroskopische Lidar-Vorrichtung;
• 2 und 3 schematische Darstellungen einer ersten Ausführungsform der vorgeschlagenen makroskopischen Lidar-Vorrichtung ;
• 4 eine schematische Darstellung einer weiteren Ausführungsform der vorgeschlagenen makroskopischen Lidar-Vorrichtung;
• 5 und 6 Darstellungen einer weiteren Ausführungsform der vorgeschlagenen makroskopischen Lidar-Vorrichtung; und
• 7 eine prinzipielle Darstellung des Ablaufs einer Ausführungsform eines Verfahrens zum Herstellen einer makroskopischen Lidar-Vorrichtung.

In the figures shows:

• 1 a schematic representation of a plan view of a conventional scanning macroscopic lidar device;
• 2 and 3 schematic representations of a first embodiment of the proposed macroscopic Lidar device;
• 4 a schematic representation of another embodiment of the proposed macroscopic Lidar device;
• 5 and 6 Representations of another embodiment of the proposed macroscopic lidar device; and
• 7 a schematic representation of the sequence of an embodiment of a method for producing a macroscopic Lidar device.

Description of embodiments

A key concept of the present invention is, in particular, to provide an efficiently operable macroscopic, scanning lidar system.

This is accomplished by forming the lidar device such that during each half-turn the field of view of the lidar device is permanently directed forward. This is going through explained in more detail below provided different technical means.

In the simplest (not shown in figures) variant, a non-polarizing beam splitter is provided for the macroscopic lidar device, which divides a laser beam in half in both directions, so that both directions of the field of view are illuminated by a scanning laser beam.

The 2 and 3 show a further embodiment of the proposed lidar device 100 , Visible is a stator 1 on which a rotor 2 arranged, being on the rotor 2 a laser element 20 is arranged. A beam of the laser element 20 meets a polarization rotator 30 , with the help of which the polarization of the laser beam can be modulated or defined adjustable. The polarization rotator 30 In its polarization changed beam hits a downstream polarizing beam splitter 31 , the intensity of the incident beam as a function of the polarization direction through the first transmission lens 10 passes. A dependence of the switching of the polarization rotator 30 is through a polarization rotator 30 supplied rotational frequency f of the rotor 2 indicated.

3 shows the arrangement of 2 rotated by 180 °, with the beam of the laser element 20 on the polarization rotator 30 which has now switched the polarization, so that on the polarizing beam splitter 31 a beam changed in polarization impinges, so that as a result the beam passes through the second transmission lens 11 on the rotor 2 180 ° opposite the first transmitter lens 10 is arranged, exit. As a result, it is achieved that in each half-turn the beam of the lidar device 100 is radiated forward.

In this way, with the macroscopic lidar device 100 advantageously a higher frame rate can be achieved because the scanning beam is always directed forward.

The polarization rotator 30 can be designed as a slow (about 10 ms switching time, English rise time) or as a fast (about 100 ns switching time) element, whereby the polarization of the laser beam can be switched accordingly slow or fast.

Slow polarization rotators 30 are usually cheaper than fast and advantageously also require less electrical voltage or energy input. Since the adjustment of the polarization of the laser beam to the rotational frequency f of the scanning Lidar device 100 must be coordinated, a switching frequency of about 10 ... 20 Hz is sufficient for switching the polarization, because between the two orthogonal polarization states H (horizontal) and V (vertical) only a binary switching must be done. This results in a constant, maximum exit efficiency on the front and on the back of the lidar device 100 , The fast-switching polarization rotator can be designed, for example, in the form of a Pockels cell.

In the case of rapid polarization switching, for the lidar device 100 an eye safety aspect can be taken into account, because in this case a feedback information can be processed, which is a statement about a before the Lidar device 100 Living being (eg, a child) meets, whereupon the polarization direction is switched so fast that an emerging radiation power is reduced due to the changed polarization in a suitable manner. For example, this can be achieved by detecting reflected radiation of a target object by means of a detector device (not shown).

The leakage power can be varied continuously through this switching (e.g., through a sinusoidal drive signal pattern) across the horizontal field of view FOV.

The proposed lidar device 100 can be formed in advantageous embodiments as a coaxial system (with identical transmit and receive path) or as a biaxiaes system (with separate transmit and receive path), as explained in more detail below.

A schematic sketch of a biaxial system shows 4 , After the laser element 20 the laser beam passes through the polarization rotator or polarization switch 30 which, as mentioned above, can be slow or fast. The laser beam leaves the polarization rotator 30 with a certain polarization direction (H or V or P or S) and strikes a downstream polarizing beam splitter 31 (PBS, polarizing beam splitter).

It can be seen that in the biaxial lidar device 100 from 4 in each case two transmit and receive paths are formed. It will do this via the first transmission lens 10 emitted laser light via a first receiving lens 12 received and a first detector element 50 fed. In the case of the second Sendelinse 11 emitted laser light is the received laser light via a second receiving lens 13 received and a second detector element 51 fed. Between the first detector element 50 and the polarizing beam splitter 31 can optionally have a lens 70 be arranged.

5 shows a principle of another variant in the form of a coaxial lidar device 100 , When the laser light is H-polarized or horizontally polarized, it becomes at the polarizing beam splitter 31 reflected ("way 1"). When the laser light is in the V state or vertically polarized, it becomes at the polarizing beam splitter 31 transmitted and through a mirror 40 through the second transmitter lens 11 guided ("way 2").

As a result, this makes it possible to realize two different beam paths by means of the polarization of the laser beam, wherein in each case one transmission path and one reception path are identical.

The laser light reflected at a target (not shown) becomes in the time between t = 0 and t = revolution time / 2 by means of the first transmitting lens functioning as a receiving lens 10 or in the time between t = revolution time / 2 and t = revolution time by means of the second transmission lens acting as a reception lens 11 collected and on the detector element 50 guided. It is advantageous in this case only a single detector element 50 required, whereby over the biaxial system a detector element can be saved.

This is achieved by the emitted laser beam from the polarizing beam splitter 31 is reflected by a lambda / 4 plate 60 is guided, whereby the laser beam is circularly polarized. On the way back from the target object, the receive beam is again when the lambda / 4 plate passes 60 again linearly polarized and is thereby rotated by 90 °. This will cause the beam through the polarizing beam splitter 31 through to the detector element 50 directed. This method of "optical isolation of optical paths" is already known per se. In the right section of 5 the previously explained "path 1" of the laser beam is again shown schematically.

In 6 is the above "way 2" of the lidar device 100 shown in principle. In this case, when the laser beam passes twice through a second lambda / 4 plate 61 the beam is no longer transmitted in the return path, but at the polarizing beam splitter 31 deflected and the detector element 50 fed. The thus realized "path 2" of the laser beam is in the right section of 6 again shown schematically.

With the above-explained variants of the proposed lidar device 100 It is advantageous that allows the entire rotation time of the rotor 2 the lidar device 100 can be used as active measuring time.

7 shows a basic sequence of an embodiment of the proposed method for producing a lidar device 100 ,

In one step 300 a stator is provided.

In one step 310 becomes a rotor 2 provided, being on the rotor 2 a laser element 20 and a transmitting device are arranged.

In one step 320 the transmitting device is so on the rotor 2 designed that in the intended attachment position of the lidar device 100 on a vehicle 200 during each half turn of the rotor 2 a beam of the laser element 20 in a forward looking field of view FOV is emissive.

Advantageous is the order of the step 300 with the steps 310 and 320 any.
Those skilled in the art will recognize that a variety of modifications of the invention are possible without departing from the gist of the invention.

Claims (10)

Macroscopic lidar device (100) comprising: a stator (1); and a rotor (2); in which - On the rotor (2) a laser element (20) and a transmitting device are arranged; in which - In the intended mounting position of the lidar device (100) on a vehicle during each half-turn of the rotor (2) a beam of the laser element (20) substantially permanently in a forwardly directed field of view (FOV) is emitted. Lidar device (100) after Claim 1 , characterized in that the beam of the laser element (20) is emissive by means of a modulation device in the front-facing field of view (FOV). Lidar device (100) after Claim 2 , characterized in that the modulation means comprises a non-polarizing beam splitter. Lidar device (100) after Claim 2 , characterized in that the modulation means comprises a polarization rotator (30) and a polarizing beam splitter (31). Lidar device (100) after Claim 4 , characterized in that the polarization rotator (30) is switchable between extreme values of horizontal and vertical polarization. Lidar device (100) after Claim 4 , characterized in that the polarization rotator (30) is switchable in defined positions as a function of a reflected beam of the laser element (20). Lidar device (100) according to one of Claims 4 to 6 , characterized in that the polarization rotator (30) is a Pockels cell or a mechanical polarization rotator. Lidar device (100) according to one of the preceding claims, characterized in that a transmission path and a reception path of the lidar device (100) are not superimposed. Lidar device (100) after one of the Claims 1 to 7 , characterized in that a transmission path and a reception path of the lidar device (100) are superimposed. A method of making a macroscopic lidar device (100) (200), comprising the steps of: - Providing a stator (1); and - Providing a rotor (2); in which - On the rotor (2) a laser element (20) and a transmitting device are arranged; in which - The transmitting device is formed such that in the intended mounting position of the lidar device (100) on a vehicle during each half rotation of the rotor (2) a beam of the laser element (20) substantially permanently in a forwardly directed field of view (FOV) is emissive.

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