BEAM SPLITTER ARRANGEMENT FOR OPTOELECTRONIC SENSOR, OPTOELECTRONIC SENSOR HAVING SAME, AND METHOD OF BEAM SPLITTING IN AN OPTOELECTRONIC SENSOR

Abstract

A beam splitter arrangement for an optoelectronic sensor, an optoelectronic sensor having such a beam splitter arrangement, and a method of beam splitting in an optoelectronic sensor are provided, wherein the beam splitter arrangement has at least one input for coupling first transmitted light beams having first transmitted light pulses into the beam splitter arrangement. At least one beam splitter splits the first transmitted light beams into a plurality of second transmitted light beams having second transmitted light pulses. The beam splitter arrangement further has a plurality of outputs for decoupling the second transmitted light beams from the beam splitter arrangement, with the number of outputs being greater than the number of inputs. Optical compression paths that compress the second transmitted light pulses such that a second pulse length of the second transmitted light pulses is shorter than a first pulse length of the first transmitted light pulses are arranged downstream of at least one beam splitter.

Claims

1. A beam splitter arrangement for an optoelectronic sensor that has at least one input for coupling first transmitted light beams having first transmitted light pulses into the beam splitter arrangement, at least one beam splitter for splitting the first transmitted light beams into a plurality of second transmitted light beams having second transmitted light pulses, and a plurality of outputs for decoupling the second transmitted light beams from the beam splitter arrangement, with the number of outputs being greater than the number of inputs, characterized in that optical compression paths are arranged downstream of the at least one beam splitter and compress the second transmitted light pulses such that a second pulse length of the second transmitted light pulses is shorter than a first pulse length of the first transmitted light pulses.

2. The beam splitter arrangement in accordance with claim 1, wherein the optical compression paths are configured as resonant structured waveguides.

3. The beam splitter arrangement in accordance with claim 2, wherein the resonant structured waveguides are slow light photonic crystal waveguides.

4. The beam splitter arrangement in accordance with claim 1, wherein the beam splitter arrangement has a plurality of beam splitters arranged cascaded.

5. The beam splitter arrangement in accordance with claim 1, wherein the optical compression paths and the beam splitters are combined in an integrated optical circuit.

6. The beam splitter arrangement in accordance with claim 1, wherein at least one optical stretching path for stretching of transmitted light pulses emitted by a light source is arranged upstream of at least one input of the beam splitter arrangement.

7. The beam splitter arrangement in accordance with claim 6, wherein the at least one optical stretching path is configured as an optical fiber and/or an optical grating and/or a prism.

8. The beam splitter arrangement in accordance with claim 1, wherein phase shifting elements for influencing phase shifts of the second transmitted light beams with respect to one another are arranged downstream of the outputs of the beam splitter arrangement.

9. The beam splitter arrangement in accordance with claim 8, wherein the beam splitters, compression paths, and phase shifting elements are combined in an integrated optical circuit.

10. The beam splitter arrangement in accordance with claim 1, wherein semiconductor optical amplifiers for boosting a light power of the second transmitted light pulses are arranged downstream of the at least one beam splitter

11. An optoelectronic sensor for detecting an object in a monitored zone having at least one light source for transmitting transmitted light beams having transmitted light pulses, a beam splitter arrangement arranged downstream of the light source for splitting the transmitted light beams into a plurality of second transmitted light beams, a transmission optics for projecting the second transmitted light beams into the monitored zone as transmitted light, a light receiver having a reception optics arranged upstream for generating received signals from light beams remitted at the object, and a control and evaluation unit for acquiring information on the object from the received signals, wherein the beam splitter arrangement is configured in accordance with one of the preceding claims.

12. The optoelectronic sensor in accordance with claim 11, wherein the control and evaluation unit is configured to determine a distance of the object from a time of flight between the transmission of the transmitted light and the reception of the light beams remitted by the object.

13. A method of splitting transmitted light beams in an optoelectronic sensor, said method comprising the following steps: coupling first transmitted light beams having first transmitted light pulses into a beam splitter arrangement; splitting the first transmitted light beams into a plurality of second transmitted light beams having second transmitted light pulses, with the number of second transmitted light beams being greater than the number of first transmitted light beams, characterized by the further step: compressing the second transmitted light pulses such that a second pulse length of the second transmitted light pulses is shorter than a first pulse length of the first transmitted light pulses.

14. The method in accordance with claim 13, further comprising the further step: influencing a phase shift of the second transmitted light beams with respect to one another.

Description

[0041] The invention will be explained in more detail in the following also with respect to further features and advantages by way of example with reference to embodiments and to the enclosed drawing. The Figures of the drawing show in:

[0042] FIG. 1 a schematic representation of an embodiment of the invention;

[0043] FIG. 2 a schematic representation of an alternative embodiment of the invention;

[0044] FIG. 3 a schematic representation of an embodiment of the invention with a beam splitter arrangement having beam splitters arranged cascaded;

[0045] FIG. 4 a schematic representation of an embodiment of the invention with a beam splitter arrangement configured as an optical phased array; and

[0046] FIG. 5 a schematic representation of an optoelectronic sensor having a beam splitter arrangement in accordance with the invention.

[0047] FIG. 1 shows a schematic representation of an embodiment of the invention with a beam splitter arrangement 10, with the beam splitter arrangement 10 having only one beam splitter 12 for reasons of simplicity. A light source 14 emits transmitted light that is coupled as a first transmitted light beam 16 having first transmitted light pulses 18 that have a first pulse length into an input 20 of the beam splitter arrangement 10. The beam splitter 12 splits the first transmitted light beam 16 into two second transmitted light beams 22a, 22b having two second transmitted light pulses 24a, 24b. Two optical compression paths 26a, 26b are arranged downstream of the beam splitter 12 and compress the second transmitted light pulses 24a, 24b such that a pulse length of the second transmitted light pulses 24a, 24b is shorter than the pulse length of the first transmitted light pulses 18. The second transmitted light beams 22a, 22b can be decoupled from the beam splitter arrangement 10 via the outputs 28a, 28b of the beam splitter arrangement 10.

[0048] FIG. 2 shows a schematic representation of an alternative embodiment of the invention. Unlike the embodiment shown in FIG. 1, an optical stretching path 28 is arranged upstream of the input 20 of the beam splitter arrangement 10. The transmitted light pulses 30 emitted by the light source 14 cannot be coupled into the beam splitter arrangement due to too high a power density. The transmitted light pulses 32 emitted by the light source 12 are stretched by the optical stretching path 30 so that their power density is reduced. The transmitted light pulses stretched in this manner can then be coupled as first transmitted light pulses 18 into the input 20 of the beam splitter arrangement 10 and can, as in the embodiment shown in FIG. 1, be recompressed after beam splitting to increase the power density.

[0049] FIG. 3 shows a schematic representation of an embodiment of the invention with a beam splitter arrangement 40 having beam splitters arranged cascaded. The beam splitter arrangement 40 here has 2 planes 42.1, 42.2 with beam splitters 12.1, 12.2a, 12.2b that each split an input beam into two output beams. The beam splitter arrangement 40 thus generates 4 second transmitted light beams 22a, 22n. As in the above-presented embodiment, a first transmitted light beam 16 having first transmitted light pulses 18 that have a first pulse length is coupled into an input 20 of the beam splitter arrangement 40. On the first plane 42.1 of the beam splitter arrangement 40, a beam splitter 12.1 splits the first transmitted light beam 16 into two transmitted light beams that are split on the second plane 42.2 by two further beam splitters 12.2a, 12.2b into four second transmitted light beams 22a, 22n having second transmitted light pulses 24a, 24n. Four optical compression paths 26a, 26n are arranged downstream of the beam splitters 12.2a, 12.2b of the second plane 42.2 and compress the second transmitted light pulses 24a-24n of the second transmitted light beams 22a, 22n such that a pulse length of the second transmitted light pulses 24a, 24n is shorter than the pulse length of the first transmitted light pulses 18. The second transmitted light beams 22a, 22n can be decoupled from the beam splitter arrangement 40 via the outputs 28a, 28n of the beam splitter arrangement 40.

[0050] To compress the transmitted light pulses, optical compression paths can also be arranged between the planes 42.1, 42.2 within the beam splitter arrangement so that a successive pulse compression takes place up to the output of the beam splitter arrangement.

[0051] The restriction to 2 planes in the representation of this embodiment is to be understood as purely exemplary. As indicated by the dots between the planes 42.1, 42.2, the beam splitters 12.2a, 12.2b, the optical compression paths 26a, 26n, and the second transmitted light beams 22a, 22n, the beam splitter arrangement can also have more than two planes and can generate correspondingly more transmitted light beams. A beam splitter arrangement can typically have 16-512 outputs for an optoelectronic sensor for object detection.

[0052] FIG. 4 shows a schematic representation of a further embodiment of the invention, with, in a further development of the embodiment shown in FIG. 3, phase shifting elements 52a, 52b being arranged downstream of the outputs 28a, 28n of the beam splitter arrangement 50. The phase shifting elements 52a, 52n are controlled via a control unit 54 and are configured to influence phase shifts of the transmitted light beams 22a, 22n with respect to one another. The beam splitter arrangement 50 together with the phase shifting elements 52a, 52n thus forms an optical phased array by which a direction of propagation 56 of a wavefront 58 generated by superposition of the transmitted light beams 22a, 22n can be controlled in a known manner.

[0053] FIG. 5 shows a schematic representation of an optoelectronic sensor 60 having a beam splitter arrangement 62 in accordance with the invention. The sensor 60 has a light source 64, for example a laser diode. The tight source 64 emits transmitted light pulses 66 that cannot be directly coupled into the beam splitter arrangement 62 due to too high a power density. The sensor 60 therefore comprises an optical stretching path 68 in which the transmitted light pulses 66 emitted by the light source 64 are stretched so that their power density is reduced. The transmitted light pulses stretched in this manner can then be coupled as first transmitted light beams 70 having first transmitted light pulses 72 into the input 74 of the beam splitter arrangement 62. The first transmitted light beams 70 are, as in the above-described embodiments, split into a plurality of second transmitted light beams 76 having compressed second transmitted light pulses 78 in the beam splitter arrangement 62. Phase shifting elements 80 for influencing the phase shifting of the second transmitted light beams 76 with respect to one another are arranged downstream of the outputs 82 of the beam splitter arrangement 62. The second transmitted light beams 76 can be projected as transmitted light 86 into a monitored zone 88 by a transmission optics 84. The transmitted light remitted by an object 90 in the monitored zone 88 is conducted as received light 92 onto a light receiver 96 via a reception optics 94.

[0054] The light receiver 96 is configured as a matrix from a plurality of light reception elements, preferably as a matrix of photodiodes APDs (avalanche photodiodes) or SPAD (single photon avalanche diode) receivers or also as an image sensor having correspondingly associated single pixels or pixel groups.

[0055] A control and evaluation unit 98 that is connected to the light source 64, to the beam splitter 62, and to the light receiver 96 is furthermore provided in the sensor 60. The control and evaluation unit 98 comprises a light source control 100, a control unit 102 for the phase shifting elements 80, a time of flight measuring unit 104, and an object distance estimation unit 106, with this initially only being functional blocks that can also be implemented in the same hardware or in other functional units such as in the light source 64, in the beam splitter arrangement 62, or in the light receiver 96. The control and evaluation unit 98 can output measured data via an interface 108 or can conversely accept control and parameterization instructions. The control and evaluation unit 98 can also be arranged in the form of local evaluation structures on a chip of the light receiver 96 or can interact as a partial implementation with the functions of a central evaluation unit (not shown).