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US-20260126533-A1 - LASER SYSTEM FOR MEASURING DISTANCE AND METHOD OF MEASURING DISTANCE

US20260126533A1US 20260126533 A1US20260126533 A1US 20260126533A1US-20260126533-A1

Abstract

A laser system for measuring distance includes a laser, a beam splitter configured to split laser radiation emitted by the laser into a first laser radiation and a second laser radiation. The first laser radiation and the second laser radiation each include a portion of the laser radiation emitted by the laser. The laser system includes a modulation module which is configured to change the intensity of the first laser radiation for the duration of a first time interval, and a detector, wherein the beam splitter is arranged between the laser and the modulation module. The laser is configured to continuously emit laser radiation whose frequency changes at least during a second time interval, and the detector is configured to detect at least a portion of the first laser radiation reflected at an object and at least a portion of the second laser radiation.

Inventors

  • Reiner Windisch

Assignees

  • AMS-OSRAM INTERNATIONAL GMBH

Dates

Publication Date
20260507
Application Date
20220808
Priority Date
20210816

Claims (19)

  1. 1 . A laser system for measuring distance, the laser system comprising: a laser, a beam splitter configured to split laser radiation emitted by the laser into a first laser radiation and a second laser radiation, wherein the first laser radiation and the second laser radiation each comprise a portion of the laser radiation emitted by the laser. a modulation module configured to change an intensity of the first laser radiation for the duration of a first time interval, and a detector, wherein the beam splitter is arranged between the laser and the modulation module, the laser configured to continuously emit laser radiation whose frequency changes at least during a second time interval, and the detector is configured to detect at least a portion of the first laser radiation, which was reflected at an object, and at least a portion of the second laser radiation, and the modulation module is configured to change the intensity of the first laser radiation in a pulse-like manner during the first time interval.
  2. 2 . The laser system according to claim 1 , wherein the modulation module configured to change the intensity of the first laser radiation for the duration of the first time interval by at most a factor of 10,000 compared to the intensity of the first laser radiation impinging on the modulation module/
  3. 3 . The laser system according to claim 1 , wherein the modulation module is configured to reduce the intensity of the first laser radiation at one or more points in time outside the first time interval compared to the intensity of the first laser radiation during the duration of the first time interval or to increase the intensity of the first laser radiation for the duration of the first time interval compared to the intensity of the first laser radiation impinging on the modulation module.
  4. 4 . The laser system according to claim 1 , wherein the modulation module comprises an electro-optical modulator.
  5. 5 . The laser system according to claim 1 , wherein the modulation module comprises an amplifier.
  6. 6 . The laser system according to claim 1 , wherein the laser system comprises a waveguide for guiding the first laser radiation wherein the waveguide is at least 50 cm long.
  7. 7 . The laser system according to claim 1 , wherein the laser is configured to continuously emit laser radiation so that the frequency of the laser radiation emitted by the laser changes linearly with time during the second time interval.
  8. 8 . The laser system according to claim 1 , wherein the laser is configured to continuously emit laser radiation so that the frequency of the laser radiation emitted by the laser changes during the second time interval by a total of at least 500 MHz.
  9. 9 . The laser system according to claim 1 , wherein the duration of the first time interval is at least 1 ns and at most 200 ns.
  10. 10 . The laser system according to claim 1 , wherein the duration of the second time interval is at least 1 μs and at most 100 μs.
  11. 11 . A method of measuring distance, the method comprising: continuous emission of laser radiation by a laser, splitting of the laser radiation emitted by the laser into a first laser radiation and a second laser radiation, wherein the first laser radiation and the second laser radiation each comprise a portion of the laser radiation emitted by the laser, changing an intensity of the first laser radiation for the duration of a first time interval, and detecting of at least a portion of the first laser radiation reflected at an object and at least a portion of the second laser radiation with a detector, wherein the frequency of the laser radiation emitted by the laser changes at least during a second time interval, and wherein the intensity of the first laser radiation is changed in a pulse-like manner during the first time interval.
  12. 12 . The method of measuring distance according to claim 11 , wherein at one or more points in time outside the first time interval at least 40% of the first laser radiation is absorbed by an electro-optical modulator and during the first time interval at most 10% of the first laser radiation is absorbed by the electro-optical modulator.
  13. 13 . The method of measuring distance according to claim 11 , wherein the intensity of the first laser radiation during the first time interval is increased by an amplifier compared to the intensity of the first laser radiation at at least some points in time outside the first time interval.
  14. 14 . The method of measuring distance according to claims 11 , wherein the distance of the object from the detector is determined from the transit time of the first laser radiation with the changed intensity across the object to the detector.
  15. 15 . The method of measuring distance according to claim 14 , wherein a speed of the object relative to the detector is determined from the determined distance and from the difference between the frequency of the second laser radiation and the frequency of the first laser radiation reflected at the object for first laser radiation and second laser radiation which impinge simultaneously on the detector at a point of time outside the first time interval.
  16. 16 . The method of measuring distance according to claim 11 , wherein the distance of the object from the detector is determined from the difference between the frequency of the second laser radiation and the frequency of the first laser radiation reflected at the object for first laser radiation and second laser radiation, which are simultaneously impinging on the detector at a point of time outside the first time interval.
  17. 17 . The method of measuring distance according to claims 11 , wherein the frequency of the laser radiation emitted by the laser increases linearly with time during the second time interval and the frequency of the laser radiation emitted by the laser decreases linearly with time during a third time interval.
  18. 18 . The method of measuring distance according to claim 11 , wherein the first time interval and the second time interval start simultaneously or the first time interval starts at most 200 ns after the second time interval.
  19. 19 . The method of measuring distance according to claim 11 wherein the method is used to scan a plurality of points.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS The present application is a U.S. National Stage Application of International Application PCT/EP2022/072241, filed on Aug. 8, 2022 and claims the priority of the German application DE 10 2021 121 211.1, filed Aug. 16, 2021, the entire disclosures of the above-listed applications are hereby incorporated by reference. FIELD Various embodiments of the present disclosure relate to a laser system for measuring distance and a method of measuring distance. BACKGROUND For distance measurements often systems with a laser are used. One example of such systems are so-called lidar (light detection and ranging) systems. Thereby, an area is scanned with a laser from the system and, thus, the distances to various objects in this area can be determined. Distance measurements are used, for example, in the field of autonomous driving. Here, it is necessary to carry out a plurality of distance measurements in the vehicle's surroundings. In many applications in which distance measurements are carried out, it is necessary that both the distance to an object in the environment as well as its relative speed are determined. This should be done in the shortest possible time intervals in order to achieve a high resolution. One task to be solved is to provide an efficient laser system for distance measurement. Another task to be solved is to provide an efficient method for distance measurement. SUMMARY According to at least one embodiment of the present disclosure, a laser system for measuring distance includes a laser. The laser may include a laser diode. The laser is designed to emit laser radiation during operation. The wavelength of the emitted laser radiation is arbitrary. For example, the wavelength of the emitted laser radiation can be in the infrared range. According to at least one embodiment of the laser system for measuring distance, the laser system includes a beam splitter, which is designed to split laser radiation emitted by the laser into a first laser radiation and a second laser radiation, wherein the first laser radiation and the second laser radiation each include a portion of the laser radiation emitted by the laser. The first laser radiation can be used for distance measurement. This means that the first laser radiation can be guided to further optical elements via a waveguide and then emerge from the laser system. Thus, the laser system is designed to emit the first laser radiation. The second laser radiation can be reference radiation, which is often referred to as local oscillator. The laser system is designed in such a way that the second laser radiation remains at least mostly in the laser system. The beam splitter can include a mechanical mirror, a MEMS (micro-electro-mechanical system) mirror, an optical parametric amplifier or a grating coupler. The laser can be connected to the beam splitter via a waveguide. Thus, laser radiation emitted by the laser can reach the beam splitter via the waveguide. According to at least one embodiment of the laser system for measuring distance, the laser system includes a modulation module, which is designed to change the intensity of the first laser radiation for the duration of a first time interval. This means that the modulation module is designed to modulate the intensity of the first laser radiation for the duration of the first time interval. Thus, during the first time interval, the first laser radiation exiting the modulation module can include a different intensity than the first laser radiation entering the modulation module. For example, the modulation module is designed to increase or amplify the intensity of the first laser radiation for the duration of the first time interval. Alternatively, the modulation module is designed to reduce or attenuate the intensity of the first laser radiation for the duration of the first time interval. Thereby, the change in the intensity of the first laser radiation relates to points in time immediately before and/or after the first time interval or to the first laser radiation entering the modulation module. According to at least one embodiment of the laser system for measuring distance, the laser system includes a detector. The detector can be designed to detect laser radiation. The detector may be a photodetector. According to at least one embodiment of the laser system for measuring distance, the beam splitter is arranged between the laser and the modulation module. The beam splitter can be connected to the modulation module via a waveguide. Thus, first laser radiation can pass from the beam splitter to the modulation module via the waveguide. The laser system can thus include at least two waveguides in total. The waveguides of the laser system can be single-mode fibers. According to at least one embodiment of the laser system for measuring distance, the laser is designed to continuously emit laser radiation, whose frequency changes at least during a second time interval. It is pos