WO2021013717A1

WO2021013717A1 - Lidar sensor for optically capturing a field of view and method for optically capturing a field of view

Info

Publication number: WO2021013717A1
Application number: PCT/EP2020/070264
Authority: WO
Inventors: Thomas Maurer; Nuno Monteiro; Mirko Hattass; Joao Oliveira
Original assignee: Robert Bosch Gmbh
Priority date: 2019-07-24
Filing date: 2020-07-17
Publication date: 2021-01-28
Also published as: DE102019210946A1; CN114174856A

Abstract

The invention relates to a lidar sensor (100) for optically capturing a field of view (103), comprising at least one light source (101) for producing primary light (102) and emitting the primary light into the field of view (103); at least one detector unit (105) for receiving secondary light (106), which has been reflected and/or scattered in the field of view (103) by an object (104); at least one optical band-pass filter (109) arranged between the field of view (103) and the detector unit (105), for filtering out background light; and at least one thermally conductive element (108), which is designed to thermally couple the light source (101) and the optical band-pass filter (109).

Description

description

title

LIDAR sensor for optical detection of a field of view and method for optical detection of a field of view

The present invention relates to a LIDAR sensor for optically detecting a field of view and a method for optically detecting a field of view.

State of the art

A distance between the LIDAR sensor and an object in the field of view of the LIDAR sensor can be determined by means of a LIDAR sensor (for "light detection and ranging"). LI DAR sensors can be used for industrial

Applications, automated driving or z. B. for military

Applications are used. For this purpose, primary light is emitted into a field of view and secondary light, which has been reflected and / or scattered in the field of view by an object, is received with a suitable receiving unit. Band-pass filters can be used in front of the receiver to minimize disturbing background light. A bandpass filter can reduce the wavelength range to the range to be expected from the emitted primary light. It is advantageous if the bandpass filter has the narrowest possible bandpass range in order to achieve the best possible signal-to-noise ratio. Depending on the type of light source used, the wavelength of the emitted primary light is not stable, but can be shifted by thermal effects (e.g. in the order of magnitude of

0.3 nm / K). This effect limits the minimum possible bandpass range. To avoid this, the light source can be thermally stabilized, which, however, is associated with a high level of technical effort.

Disclosure of the invention The present invention is based on a LIDAR sensor for the optical detection of a field of view. The LIDAR sensor comprises at least one light source for generating and emitting primary light into the field of view;

at least one detector unit for receiving secondary light that has been reflected and / or scattered in the field of view from an object; at least one, arranged between the field of view and the detector unit, optical bandpass filter for filtering out background light; and at least one thermally conductive element which is designed to thermally couple the light source and the optical bandpass filter.

By means of a LIDAR sensor, a distance between the LIDAR sensor and an object in the field of view of the LIDAR sensor can be based on a

Signal transit time (Time of Flight, TOF) can be determined directly or indirectly. Using a LIDAR sensor, a distance between the LIDAR sensor and an object in the field of view of the LIDAR sensor can be determined on the basis of a frequency-modulated continuous wave (FMCW) signal. The field of view of the LIDAR sensor can be scanned by means of the emitted primary light. The light source can be at least one

Be formed laser unit. The detector unit can be designed to detect the received secondary light. The LIDAR sensor optionally has at least one evaluation unit. The detected secondary light can be evaluated by means of the evaluation unit. The result of the evaluation can be used, for example, for a driver assistance function of a vehicle. The result of the evaluation can be used, for example, to control an autonomously driving vehicle. The LIDAR sensor can in particular be designed for use in an at least partially autonomous vehicle. With the LIDAR sensor

partially autonomous or autonomous driving of vehicles on highways and in city traffic can be realized.

The optical bandpass filter can have a bandpass range. The optical band pass filter can have a central wavelength. Secondary light with a wavelength within the bandpass range can cause the optical Pass bandpass filter. Secondary light with a wavelength outside the bandpass range cannot pass the bandpass filter.

The advantage of the invention is that thermal regulation of the optical bandpass filter can be implemented. The light source and the optical bandpass filter can be directly thermally coupled. By means of the thermally conductive element, heat can be transferred from the light source to the optical bandpass filter or from the optical bandpass filter to the light source. As a result, thermal stabilization of the light source can be avoided or greatly reduced. However, an optical band pass filter with a narrow band pass range can be used. The LIDAR sensor can be designed to be less complex and less expensive. Since the optical band pass filter does not have its own

Has heat development, it can be thermally coupled without much effort. The temperature of the optical band pass filter can be influenced directly by changing the temperature of the light source. The

The central wavelength of the optical band-pass filter can be influenced directly by changing the temperature of the light source.

If the influence on the central wavelength of the optical bandpass filter is not sufficient to completely cover a required temperature range of the light source, regulation for the light source can also be combined. For this purpose, the LIDAR sensor can have an element which is designed for thermal regulation of the light source. However, due to the thermal coupling of the light source and the optical bandpass filter, the regulation of the light source then advantageously only requires less stability. Appropriate regulation of the light source can be made simpler, that is to say less complex and less expensive.

In an advantageous embodiment of the invention it is provided that the light source, the optical bandpass filter and the thermally conductive element are arranged such that the light source and the optical bandpass filter each have direct contact with the thermally conductive element at least in some areas. At least in some areas this can be be understood that at least a region of the light source or the optical bandpass filter has direct contact with the thermally conductive element. A region here can be at least a section of at least one outer surface of the light source or the optical

Include band pass filter. A region here can include at least a complete outer surface of the light source or the optical bandpass filter. The advantage of this configuration is that the light source and the optical bandpass filter can be directly thermally coupled. The temperature of the optical bandpass filter can already be influenced by slight changes in the temperature of the light source.

In a further advantageous embodiment of the invention it is provided that at least one thermally conductive element is designed as a metal bridge. The metal bridge can be made of aluminum or copper, for example. The metal bridge can be a compact metal bridge. The advantage of this configuration is that the thermally conductive element can be configured to be less complex and more cost-effective.

In a further advantageous embodiment of the invention it is provided that at least one thermally conductive element is designed as a heat pipe. A heat pipe can also be called a heat pipe. A heat pipe can comprise a pipe made of a thermally conductive material. The tube can be structured on the inside. The tube can, for example, have a capillary structure on the inside. A heat pipe can have an evaporable liquid inside the pipe. The advantage of this configuration is that the thermally conductive element can very efficiently transport heat from the light source to the optical bandpass filter (or vice versa). The shape of a heat pipe can be flexibly adapted to the requirements of the LIDAR sensor.

In a further advantageous embodiment of the invention it is provided that the optical bandpass filter is amorphous silicon or at least one

includes dielectric layer. The advantage of this embodiment is that a change in the temperature of such an optical bandpass filter very simply leads to a defined shift in the central wavelength of the optical bandpass filter.

In a further advantageous embodiment of the invention it is provided that the optical bandpass filter for the central wavelength

Has temperature coefficients greater than or equal to 0.1 nm / K. The advantage of this embodiment is that it is very easy to change the temperature of such an optical bandpass filter to a defined one

Shifting the central wavelength of the optical band pass filter leads.

In a further advantageous embodiment of the invention it is provided that the optical bandpass filter is designed as a Fabry-Perot interferometer with two parallel plates. A distance between the two plates depends on the temperature of the optical band-pass filter. Is z. B. transferring heat from the light source to the optical bandpass filter by means of the thermally conductive element, i.e. if, for example, the temperature of the optical bandpass filter increases, the distance between the two plates can change. This allows the central wavelength of the optical

Change the bandpass filter. The Fabry-Perot interferometer can for example be based on MEMS technology ("Micro-Electro-Mechanical

Systems "). The distance can then be changed, for example, by mechanically moving the two plates. The mechanical process can be achieved by changing the temperature of the optical

Bandpass filter can be triggered. Alternatively, the distance between the two plates can be adjusted by thermal actuators. The adjustment of the distance by means of the thermal actuators can be triggered by a temperature change of the optical bandpass filter. The advantage of this refinement is that a change in the temperature of such an optical band-pass filter very simply leads to a shift in the central wavelength of the optical band-pass filter. In particular, a Fabry-Perot interferometer based on MEMS technology has no or hardly any of its own

Heat and can be changed thermally without much effort.

The invention is also based on a method for optically detecting a field of view by means of a LIDAR sensor. The procedure includes the Steps of generating and emitting primary light into the field of view by means of at least one light source; receiving secondary light which has been reflected and / or scattered in the field of view by an object, by means of at least one detector unit; filtering out background light by means of at least one between the field of view and the detector unit

arranged, optical band pass filter. Here, the LIDAR sensor has at least one thermally conductive element which is designed to thermally couple the light source and the optical bandpass filter.

drawings

In the following, exemplary embodiments of the present invention are explained in more detail with reference to the accompanying drawings. Identical reference symbols in the figures denote identical or identically acting elements. Show it:

Figure 1 shows an embodiment of a LIDAR sensor;

Figure 2 shows an embodiment of a method for detecting a

Field of view.

FIG. 1 shows, by way of example, a first exemplary embodiment of a LIDAR sensor 100. The LIDAR sensor 100 is designed to detect the field of view 103. For this, the LIDAR sensor 100 has the light source 101. The light source 101 is preferably a laser unit. The light source 101 is designed to generate primary light 102 and to emit it into the field of view 103. The LIDAR sensor 100 also has the detector unit 105, which is designed to receive secondary light 106 that has been reflected and / or scattered in the field of view 103 by an object 104. Further optical elements, such as an optical lens 107, can be arranged in the beam path of the detector unit 105. An optical bandpass filter 109, which is designed to filter out background light, is arranged between the field of view 103 and the detector unit 105. The optical bandpass filter 109 can comprise amorphous silicon or at least one dielectric layer. The optical band pass filter 109 may be one for the central wavelength

Have temperature coefficients greater than or equal to 0.1 nm / K. The optical band pass filter 109 can be used as a Fabry-Perot interferometer with two parallel plates, with a distance between the two plates depending on the temperature of the optical band pass filter 109.

In order to avoid thermal stabilization of the light source as far as possible, the optical bandpass filter 109 still being able to have a narrow bandpass range, thermal regulation of the optical bandpass filter 109 is implemented. For this purpose, the LIDAR sensor 100 furthermore has the thermally conductive element 108, which is designed to thermally couple the light source 101 and the optical bandpass filter 109. By means of the thermally conductive element 108, heat can be transferred from the light source 101 to the optical bandpass filter 109 or from the optical bandpass filter 109 to the light source 101. The light source 101, the optical bandpass filter 109 and the thermally conductive element 108 are arranged in such a way that the light source 101 and the optical bandpass filter 109 each have direct contact with the thermally conductive element 108 at least in some areas. The thermally conductive element 108 can be designed as a metal bridge. The thermally conductive element 108 can be used as a

Be formed thermal bridge.

FIG. 2 shows an embodiment of a method 200 for detecting a field of view by means of a LIDAR sensor, as was described in FIG. The LIDAR sensor has at least one thermally conductive element which is designed to have a light source and an optical one

To thermally couple bandpass filters. The method 200 starts in step 201.

In step 202, primary light is generated and emitted into the field of view by means of at least one light source. Then it comes in step

203 for filtering out background light by means of the optical band-pass filter arranged between the field of view and a detector unit. In step

204 it comes to receiving secondary light, which was reflected and / or scattered in the field of view from an object, by means of at least one

Detector unit. The method 200 ends in step 205.

Claims

Expectations

1. LIDAR sensor (100) for optical detection of a field of view (103)

full

• at least one light source (101) for generating and emitting primary light (102) into the field of view (103);

• at least one detector unit (105) for receiving secondary light (106) which has been reflected and / or scattered in the field of view (103) by an object (104);

• at least one optical bandpass filter (109) arranged between the field of view (103) and the detector unit (105) for filtering out background light; and

• at least one thermally conductive element (108) for this purpose

is designed to thermally couple the light source (101) and the optical bandpass filter (109).

2. LIDAR sensor (100) according to claim 1, wherein the light source (101), the

optical bandpass filter (109) and the thermally conductive element (108) are arranged such that the light source (101) and the optical

Bandpass filters (109) each have direct contact with the thermally conductive element (108) at least in some areas.

3. LIDAR sensor (100) according to claim 1 or 2, wherein at least one

thermally conductive element is designed as a metal bridge.

4. LIDAR sensor according to one of the preceding claims, wherein at least one thermally conductive element is designed as a heat pipe.

5. LIDAR sensor (100) according to any one of the preceding claims, wherein the

optical bandpass filter (109) comprises amorphous silicon or at least one dielectric layer.

6. LIDAR sensor (100) according to one of the preceding claims, wherein the optical bandpass filter (109) for the central wavelength

Has temperature coefficients greater than or equal to 0.1 nm / K.

7. LIDAR sensor (100) according to one of the preceding claims, wherein the

optical bandpass filter (109) is designed as a Fabry-Perot interferometer with two parallel plates and wherein a distance between the two plates is dependent on the temperature of the optical bandpass filter (109).

8. Method (200) for optical detection of a field of view by means of a

LIDAR sensors include the following steps:

• generating and emitting (202) primary light into the field of view by means of at least one light source;

• Receiving (204) secondary light that has been reflected and / or scattered in the field of view from an object, by means of at least one

Detector unit; and

• Filtering out (203) of background light by means of at least one optical band-pass filter arranged between the field of view and the detector unit;

wherein the LIDAR sensor has at least one thermally conductive element which is designed to thermally couple the light source and the optical bandpass filter.