Transmitting unit and lidar device using at least two radiation sources having at least one of a settable operating temperature and a settable emission wavelength to generate and emit punctiform or linear electromagnetic beams for scanning a scanning range

Abstract

A transmitting unit of a LIDAR device includes at least two radiation sources for generating and emitting punctiform or linear electromagnetic beams into a scanning range, at least one of the radiation sources including an operating temperature settable as a function of an emission angle of the electromagnetic beams generated by the at least one radiation source. The different operating temperatures can generate beams having angle-dependent emission wavelengths, which can result in an improvement of the signal-to-noise ratio of a LIDAR device.

Claims

1. A transmitting unit of a LIDAR device, the transmitting unit comprising: at least two radiation sources configured to generate and emit punctiform or linear electromagnetic beams in a scanning range, wherein at least one of the radiation sources has at least one of an operating temperature and an emission wavelength that is settable as a function of an emission angle of the electromagnetic beams generated by the at least one radiation source.

2. The transmitting unit of claim 1, wherein the operating temperature of the at least one radiation source is settable by outputting operating heat to surroundings or to an active or passive cooling body.

3. The transmitting unit of claim 1, wherein the operating temperature of the at least one radiation source is settable at least one of by an active heating element and by outputting operating heat to at least one of an active cooling element.

4. The transmitting unit of claim 1, wherein the operating temperature of the at least one radiation source is controllable as a function of an emission angle of the at least one radiation source.

5. The transmitting unit of claim 4, wherein the at least one radiation source is provided such that the operating temperature of the at least one radiation source decreases when the emission angle increases.

6. The transmitting unit of claim 1, further comprising at least one optical element situated to be in a beam path of the emitted electromagnetic beams.

7. The transmitting unit of claim 1, wherein the at least two radiation sources are configured to generate the electromagnetic beams simultaneously.

8. The transmitting unit of claim 1, wherein the at least two radiation sources are configured to generate the electromagnetic beams in succession.

9. The transmitting unit of claim 1, wherein the at least two radiation sources are surface emitters or edge emitters situated stacked or adjacent to one another.

10. A LIDAR device for scanning a scanning range defined by a vertical and a horizontal scanning angle using electromagnetic beams, the LIDAR device comprising: at least one transmitting unit that: includes at least two radiation sources configured to generate and emit punctiform or linear electromagnetic beams in a scanning range, wherein at least one of the radiation sources has at least one of an operating temperature and an emission wavelength that is settable as a function of an emission angle of the electromagnetic beams generated by the at least one radiation source; and is configured to distribute or deflect the electromagnetic beams at least along the vertical scanning angle; at least one receiving unit for receiving beams reflected on at least one object situated in the scanning range; a bandpass filter for absorbing or reflecting interfering reflections; and an analysis unit, wherein the analysis unit is configured to analyze the received reflected beams.

11. The LIDAR device of claim 10, further comprising at least one temperature sensor that is configured to ascertain the operating temperature of the at least one radiation source and that is connected to a control unit for actively setting the operating temperature of the at least one radiation source using at least one of an active cooling element and (b) an active heating element.

Description

BRIEF DESCRIPTION OF THE DRAWING

(1) FIG. 1 shows a schematic view of a LIDAR device according to an example embodiment of the present invention.

(2) FIG. 2 shows a schematic view of a radiation source arrangement of a transmitting unit according to an example embodiment of the present invention.

(3) FIG. 3 shows a schematic view of a radiation source arrangement of a transmitting unit according to another example embodiment of the present invention.

(4) FIG. 4 shows a schematic view of a dependence of the transmitted wavelength of a bandpass filter on an emission angle of the incoming beams.

DETAILED DESCRIPTION

(5) FIG. 1 shows a schematic view of a LIDAR device 1 according to an example embodiment. Device 1 includes a transmitting unit 2 made up of multiple emitters or radiation sources 4, 5. Beams 6, 7, which are generated and emitted by radiation sources 4, 5, can be changed in their divergence by an optical element 8 connected downstream. According to the example embodiment, beams 6, 7 are bundled. Due to spacing of a radiation source 4 apart from the optical axis of optical element 8, correspondingly formed beams 6 have an emission angle which deviates from 0°. Due to the beamforming, the emission angle of generated beams 6 thus changes as a function of a position of the emitters or radiation sources 4, 5.

(6) Generated beams 6, 7 are emitted in a scanning range A and can be incident on an object 10. Generated beams 6, 7 can be at least partially reflected on object 10 and thus become reflected beams 12, 13.

(7) Reflected beams 12, 13 are subsequently filtered by an optical bandpass filter 14 and can subsequently be detected by receiving unit 16 and analyzed by analysis unit 18.

(8) Reflected beams 13 of first radiation source 5 are incident in this case at an emission angle of 0° on bandpass filter 14 and can be transmitted unobstructed through it.

(9) Beams 6 emitted at an emission angle of greater or less than 0° and corresponding reflected beams 12 are no longer incident perpendicularly on bandpass filter 14. Bandpass filter 14 has a transmission range shifted toward shorter wavelengths. This relationship is illustrated by way of example in FIG. 4. The wavelength of generated beams 6 can be reduced in accordance with the emission angle by a thermal adaptation of radiation source 4, whereby reflected beams 12 can pass bandpass filter 14 unobstructed in spite of the shifted transmission range.

(10) FIG. 2 schematically illustrates a radiation source arrangement of a transmitting unit 2 according to an example embodiment. Radiation sources 4, 5 are semiconductor lasers according to the example embodiment. In this case, the operating temperature of radiation sources 4, 5 is actively controlled. For this purpose, transmitting unit 2 has a temperature sensor 20 on each radiation source 4, 5. All temperature sensors 20 are read out by a shared control unit or are each read out by a separate control unit 22.

(11) Control unit 22 can activate Peltier elements 24, which are situated on radiation sources 4, 5, as heating or cooling elements to act on radiation sources 4, 5 based on the ascertained temperature of temperature sensors 20. Beams 7 along the optical axis of optical element 8 and/or generated by a centrally situated radiation source 5 have a reference temperature T0, which is adapted to bandpass filter 14. The farther additional radiation sources 4 are spaced apart from centrally situated radiation source 5, the lower their operating temperature T1, T2 is set in comparison to reference temperature T0. In this way, generated beams 6 are generated having a shortened wavelength in accordance with the emission angle and/or a shift of the transmission range of bandpass filter 14.

(12) FIG. 3 shows a schematic view of a radiation source arrangement of a transmitting unit 2 according to another example embodiment. In contrast to the previous example embodiment, radiation sources 4, 5 are connected to one another to form a stack. Radiation sources 4, 5 are coupled in a thermally conductive manner in this case. The two radiation sources 4 situated on an outer edge of the stack are each connected in a thermally conductive manner to a passive or active cooling body 26. In this way, a heat output illustrated according to the arrows results, which generates two temperature gradients. Emitter or radiation source 5 situated in the middle of the stack has the highest operating temperature. The temperature of radiation sources 4 drops toward the outer edges due to cooling body 26. In this way, beams 6, 7 adapted to the wavelength shift shown by way of example in FIG. 4 can be implemented by thermally set radiation sources 4, 5. The temperature gradient can be varied or influenced in this case by additional thermal resistors situated between radiation sources 4, 5.

(13) FIG. 4 shows a schematic view of a dependence of the transmitted wavelength of a bandpass filter 14 on an emission angle of incoming beams 12, 13.