LiDAR sensor for optically detecting a field of view and method for optically detecting a field of view

Abstract

A lidar sensor (100) for optically detecting a field of view (103), the lidar sensor comprising 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) that has been reflected and / or scattered by an object (104) within the field of view (103); at least one optical bandpass filter (109) disposed between the field of view (103) and the detector unit (105) for filtering out background light; and at least one heat conducting element (108) configured to thermally couple the light source (101) to the optical bandpass filter (109).

Description

Field of technology

[0001] The invention relates to a lidar sensor for optically detecting a field of view and a method for optically detecting a field of view. Background art

[0002] With the aid of a lidar sensor (English: "light detection and ranging"), the distance between the lidar sensor and an object within the field of view of the lidar sensor can be determined. Lidar sensors can be used for industrial applications, in autonomous driving or, for example, for military applications. For this purpose, primary light is emitted into the field of view and a suitable receiving unit is used to receive the secondary light that has been reflected and / or scattered by the object within the field of view. In order to minimize interfering background light, a band-pass filter can be used in front of the receiver. The band-pass filter can reduce the wavelength range to the desired range due to the emitted primary light. It is advantageous here for the band-pass filter to have as narrow a passband range as possible in order to achieve the best possible signal-to-noise ratio. However, depending on the type of light source used, the wavelength of the emitted primary light is not stable but can shift due to thermal effects (for example in the range of 0.3 nm / K). This effect limits the minimum possible passband range. To avoid this effect, the light source can be thermally stabilized, but this is accompanied by a high technical outlay. Summary of the invention

[0003] The invention starts from a lidar sensor for optically detecting a field of view. The lidar sensor includes at least one light source for generating and emitting primary light into the field of view; at least one detector unit for receiving the secondary light that has been reflected and / or scattered by the object within the field of view; at least one optical band-pass filter arranged between the field of view and the detector unit for filtering out background light; and at least one heat-conducting element configured to thermally couple the light source to the optical band-pass filter.

[0004] With a lidar sensor, it is possible to directly or indirectly determine the distance between the lidar sensor and an object within the field of view of the lidar sensor based on the signal propagation time (Time of Flight, TOF). With a lidar sensor, it is possible to determine the distance between the lidar sensor and an object within the field of view of the lidar sensor based on a frequency-modulated continuous wave signal (Frequency Modulated Continuous Wave, FMCW). The field of view of the lidar sensor can be scanned with the emitted primary light. The light source can be configured as at least one laser unit. The detector unit can be configured to detect the received secondary light. The lidar sensor optionally has at least one analysis and processing unit. With the analysis and processing unit, it is possible to analyze and process the detected secondary light. The result of this analysis and processing can be used, for example, for the driver assistance function of a vehicle. The result of this analysis and processing can be used, for example, to control an autonomously driving vehicle. The lidar sensor can in particular be configured for use in at least partially autonomously driving vehicles. Using this lidar sensor enables the vehicle to perform partially autonomous or autonomous driving on highways and in urban traffic.

[0005] The optical bandpass filter can have a passband range. The optical bandpass filter can have a center wavelength. Secondary light having a wavelength within the passband range can pass through the optical bandpass filter. Secondary light having a wavelength outside the passband range cannot pass through the bandpass filter.

[0006] The advantage of the present invention is that thermal regulation of the optical bandpass filter can be achieved. The light source and the optical bandpass filter can be directly thermally coupled. With a heat-conducting element, heat can be transferred from the light source to the optical bandpass filter, or from the optical bandpass filter to the light source. Thereby, thermal stabilization of the light source can be avoided or greatly reduced. An optical bandpass filter with a narrow passband range can also be used. The lidar sensor can be configured more simply and at lower cost. Since the optical bandpass filter itself does not generate heat, the optical bandpass filter can be thermally coupled without significant overhead. The temperature of the optical bandpass filter can be directly affected by the temperature change of the light source. The center wavelength of the optical bandpass filter can be directly affected by the temperature change of the light source.

[0007] If the influence on the center wavelength of the optical bandpass filter is not sufficient to fully cover the temperature range required by the light source, adjustment of the light source can be additionally combined. For this purpose, the lidar sensor can have an element configured to thermally adjust the light source. However, due to the thermal coupling between the light source and the optical bandpass filter, the adjustment of the light source only requires lower stability in an advantageous manner. The corresponding adjustment of the light source can be configured more easily, that is, more simply and at lower cost.

[0008] In an advantageous configuration of the present invention, the light source, the optical bandpass filter, and the heat-conducting element are arranged such that the light source and the optical bandpass filter each have direct contact with the heat-conducting element at least locally. "At least locally" can be understood here such that at least one region of the light source or the optical bandpass filter has direct contact with the heat-conducting element. Here, the region can include at least one section of at least one outer surface of the light source or the optical bandpass filter. Here, the region can include at least one 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 be affected by a small temperature change of the light source.

[0009] In another advantageous configuration of the present invention, at least one heat-conducting element is configured as a metal bridge. For example, the metal bridge is configured of aluminum or copper, for example. The metal bridge can be a solid metal bridge. The advantage of this configuration is that the heat-conducting element can be configured more simply and at lower cost.

[0010] In another advantageous configuration of the present invention, at least one heat-conducting element is configured as a heat pipe. A heat pipe can also be referred to as a Heatpipe. The heat pipe can have a tube made of a heat-conducting material. The inner side of the tube can be structured, for example. The inner side of the tube can have a capillary structure, for example. The heat pipe can have an evaporable liquid inside the tube. The advantage of this configuration is that the heat-conducting element can transfer heat from the light source to the optical bandpass filter (or vice versa) very efficiently. The configuration of the heat pipe can be flexibly matched to the requirements of the lidar sensor.

[0011] In another advantageous configuration of the present invention, the optical bandpass filter includes amorphous silicon or includes at least one dielectric layer. The advantage of this configuration is that a temperature change of such an optical bandpass filter very easily causes a defined shift of the center wavelength of the optical bandpass filter.

[0012] In another advantageous configuration of the present invention, the optical bandpass filter has a temperature coefficient of greater than or equal to 0.1 nm / K for the center wavelength. The advantage of this configuration is that a temperature change of such an optical bandpass filter very easily causes a defined shift of the center wavelength of the optical bandpass filter.

[0013] In another advantageous configuration of the present invention, it is provided that the optical bandpass filter is configured as a Fabry - Perot interferometer with two parallel plates. Here, the distance between the two plates is temperature - dependent for the optical bandpass filter. If, for example, heat is transferred from a light source to the optical bandpass filter by means of a heat - conducting element, i.e., if the temperature of the optical bandpass filter rises, for example, the distance between the two plates can change. Thereby, the central wavelength of the optical bandpass filter can change. The Fabry - Perot interferometer can be constructed, for example, based on MEMS technology (English: “Micro - Electro - Mechanical Systems”). This distance can then be changed, for example, by mechanical movement of the two plates. Here, this mechanical movement can be triggered by a temperature change of the optical bandpass filter. Alternatively, the distance between the two plates can be adjusted by a thermal actuator. The adjustment of the distance by means of the thermal actuator can be triggered by a temperature change of the optical bandpass filter. The advantage of this configuration is that a temperature change of such an optical bandpass filter very easily leads to a shift in the central wavelength of the optical bandpass filter. In particular, a Fabry - Perot interferometer based on MEMS technology has no or almost no self - heat dissipation and can be thermally changed with little overhead.

[0014] The present invention further starts from a method for optically detecting a field of view with a lidar sensor. The method includes the following steps: generating and emitting primary light into the field of view with at least one light source; receiving secondary light that has been reflected and / or scattered by an object in the field of view with at least one detector unit; filtering out background light with at least one optical bandpass filter arranged between the field of view and the detector unit. Here, the lidar sensor has at least one heat - conducting element configured to thermally couple the light source to the optical bandpass filter. Description of the Drawings

[0015] Embodiments of the present invention will be further described below with reference to the accompanying drawings. The same reference numerals in the drawings denote the same or identically acting elements. The drawings show:

[0016] Figure 1 : An embodiment of a lidar sensor;

[0017] Figure 2 : An embodiment of a method for detecting a field of view. Detailed Description of the Invention

[0018] Figure 1Exemplarily, a first embodiment of a lidar sensor 100 is shown. The lidar sensor 100 is configured to detect a field of view 103. For this purpose, the lidar sensor 100 has a light source 101. The light source 101 is preferably a laser unit. The light source 101 is configured to generate and emit primary light 102 into the field of view 103. The lidar sensor 100 further has a detector unit 105, which is configured to receive secondary light 106 that has been reflected and / or scattered by an object 104 within the field of view 103. Other optical elements, such as an optical lens 107, may be arranged in the beam path of the detector unit 105. An optical bandpass filter 109 is arranged between the field of view 103 and the detector unit 105, and the optical bandpass filter is configured to filter out background light. The optical bandpass filter 109 may include amorphous silicon or include at least one dielectric layer. The optical bandpass filter 109 may have a temperature coefficient of greater than or equal to 0.1 nm / K for the central wavelength. The optical bandpass filter 109 may be configured as a Fabry - Perot interferometer with two parallel plates, wherein the distance between the two plates is temperature - dependent for the optical bandpass filter 109.

[0019] In order to avoid thermal stabilization of the light source as much as possible, while the optical bandpass filter 109 still has a narrow passband range, thermal regulation of the optical bandpass filter 109 is achieved. For this purpose, the lidar sensor 100 further includes a heat - conducting element 108, which is configured to thermally couple the light source 101 to the optical bandpass filter 109. With the help of the heat - conducting 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 heat - conducting element 108 are arranged such that the light source 101 and the optical bandpass filter 109 each have at least partial direct contact with the heat - conducting element 108. The heat - conducting element 108 may be configured as a metal bridge. The heat - conducting element 108 may be configured as a heat bridge

[0020] Figure 2 An embodiment of a method 200 for detecting a field of view with a lidar sensor as described in Figure 1 is shown. The lidar sensor has at least one heat - conducting element configured to thermally couple a light source to an optical bandpass filter. The method 200 starts with step 201. In step 202, primary light is generated and emitted into the field of view with the help of at least one light source. Subsequently, in step 203, background light is filtered out with the help of an optical bandpass filter arranged between the field of view and the detector unit. In step 204, secondary light that has been reflected and / or scattered by an object within the field of view is received with the help of at least one detector unit. The method 200 ends with step 205.

Claims

1. A lidar sensor (100) for optically detecting a field of view (103), the lidar sensor comprising: 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) that has been reflected and / or scattered by an object (104) within the field of view (103); At least one optical bandpass filter (109) arranged between the field of view (103) and the detector unit (105) for filtering background light; and At least one heat conducting element (108) configured to thermally couple the light source (101) to the optical bandpass filter (109).

2. The lidar sensor (100) according to claim 1, wherein, The light source (101), the optical bandpass filter (109), and the heat conducting element (108) are arranged such that the light source (101) and the optical bandpass filter (109) each have at least partial direct contact with the heat conducting element (108).

3. The lidar sensor (100) according to claim 1 or 2, wherein, At least one heat conducting element is configured as a metal bridge.

4. The lidar sensor according to any one of the preceding claims, wherein, At least one heat conducting element is configured as a heat pipe.

5. The lidar sensor (100) according to any one of the preceding claims, wherein, The optical bandpass filter (109) comprises amorphous silicon or comprises at least one dielectric layer.

6. The lidar sensor (100) according to any one of the preceding claims, wherein, The optical bandpass filter (109) has a temperature coefficient of greater than or equal to 0.1 nm / K for the center wavelength.

7. The lidar sensor (100) according to any one of the preceding claims, wherein, The optical bandpass filter (109) is configured as a Fabry - Perot interferometer having two parallel plates, and wherein the distance between the two plates is temperature - dependent for the optical bandpass filter (109).

8. A method (200) for optically detecting a field of view by means of a lidar sensor, the method comprising the steps of: 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 by an object within the field of view by means of at least one detector unit; And Filtering (203) background light by means of at least one optical bandpass filter arranged between the field of view and the detector unit; Wherein the lidar sensor has at least one heat conducting element configured to thermally couple the light source to the optical bandpass filter.

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