CN-116324488-B - Vibratory polarizing beam splitter for improved return light detection

Abstract

A vibratory polarizing beam splitter for improved return light is disclosed. An example method may involve transmitting, by an emitter, a first light pulse and reflecting the first light pulse by a polarizing beam splitter in a first position, wherein the polarizing beam splitter is at a first angle of incidence in the first position. The example method may also involve adjusting a position of the polarizing beam splitter from the first position to a second position after the polarizing beam splitter reflects the first light pulse, wherein the polarizing beam splitter is at a second angle of incidence in the second position. The example method may also involve transmitting, by a polarizing beam splitter, a return light pulse through the polarizing beam splitter, the return light pulse being based on the first light pulse. The example method may also involve detecting the return light pulse by a detector.

Inventors

• R.T. Davis
• M. S. Segilani
• R. S. dallo

Assignees

• 阿尔戈人工智能有限责任公司

Dates

Publication Date

20260508

Application Date

20210729

Priority Date

20200729

Claims (20)

1. 1. A system, comprising: a transmitter configured to transmit a first pulse of light; a detector configured to receive a return light pulse, the return light pulse comprising a reflection of the first light pulse; a polarizing beam splitter having a first position at which the polarizing beam splitter reflects the first light pulse and a second position at which the polarizing beam splitter transmits the return light pulse, and An actuator selectively moving the polarizing beam splitter between a first position and a second position, Wherein the frequency of rotation of the polarizing beam splitter between the first position and the second position corresponds to the frequency of light emitted by the emitter.
2. 2. The system of claim 1, wherein the actuator is configured to move the polarizing beam splitter from the first position to the second position after the first light pulse is emitted by the emitter and before the return light pulse is transmitted by the polarizing beam splitter.
3. 3. The system of claim 1, wherein the actuator is configured to move the polarizing beam splitter from the second position to the first position after the return light pulse is transmitted by the polarizing beam splitter and before the transmitter transmits the second light pulse.
4. 4. The system of claim 1, wherein the actuator comprises at least one of a voice coil motor or a non-vibration motor.
5. 5. The system of claim 1, wherein the first light pulse is in a first polarization state, wherein the return light pulse comprises light in the first polarization state and light in a second polarization state, and wherein the polarizing beam splitter is configured to transmit at least a portion of both the light in the first polarization state and the light in the second polarization state.
6. 6. The system of claim 5, wherein at least 90% of the light in the first polarization state and the light in the second polarization state is transmitted by the polarizing beam splitter in the second position.
7. 7. The system of claim 1, wherein the difference between the first position and the second position is less than 5 degrees.
8. 8. The system of claim 1, wherein the first position corresponds to an angle of incidence of approximately 45 degrees and the second position corresponds to an angle of incidence of approximately 43.5 degrees.
9. 9. A method, comprising: emitting, by an emitter, a first pulse of light; Reflecting the first light pulse by a polarizing beam splitter in a first position, wherein the polarizing beam splitter is at a first angle of incidence in the first position; After the polarizing beam splitter reflects the first light pulse, adjusting a position of the polarizing beam splitter from a first position to a second position, wherein the polarizing beam splitter is at a second angle of incidence in the second position; transmitting a return light pulse through the polarizing beam splitter by the polarizing beam splitter in the second position, the return light pulse being based on the first light pulse, and The return light pulse is detected by a detector, Wherein the frequency of rotation of the polarizing beam splitter between the first position and the second position corresponds to the frequency of light emitted by the emitter.
10. 10. The method of claim 9, wherein adjusting the angle of incidence to the second angle of incidence occurs after the transmitter transmits the first pulse of light and before the return pulse of light is received at the polarizing beam splitter.
11. 11. The method of claim 9, further comprising: after receiving the return light pulse, the polarizing beam splitter is adjusted from the second position to the first position.
12. 12. The method of claim 9, wherein adjusting the angle of incidence comprises adjusting the angle of incidence using at least one of a voice coil motor or a non-vibrating motor.
13. 13. The method of claim 9, wherein the first light pulse is in a first polarization state, and wherein the return light pulse comprises light in the first polarization state and light in a second polarization state, and wherein the polarizing beam splitter is configured to transmit at least a portion of both the light in the first polarization state and the light in the second polarization state.
14. 14. The method of claim 13, wherein at least 90% of the light in the first polarization state and the light in the second polarization state is transmitted by the polarizing beam splitter in the second position.
15. 15. The method of claim 9, wherein the difference between the first position and the second position is less than 5 degrees.
16. 16. The method of claim 9, wherein the first angle of incidence is about 45 degrees and the second angle of incidence is about 43.5 degrees.
17. 17. A non-transitory computer-readable medium comprising computer-executable instructions stored thereon that, when executed by one or more processors, cause the one or more processors to: adjusting a position of the polarizing beam splitter to a first position, wherein the polarizing beam splitter is at a first angle of incidence in the first position with respect to a path of light emitted by the emitter; emitting, by an emitter, a first light pulse in a path directed to a polarizing beam splitter; after the first light pulse is reflected by the polarizing beam splitter, adjusting a position of the polarizing beam splitter from a first position to a second position, wherein the polarizing beam splitter is at a second angle of incidence in the second position, and Receiving, by the detector, a return light pulse based on the first light pulse, the return light pulse being transmitted by the polarizing beam splitter in the second position, Wherein the frequency of rotation of the polarizing beam splitter between the first position and the second position corresponds to the frequency of light emitted by the emitter.
18. 18. The non-transitory computer readable medium of claim 17, wherein a difference between the first angle of incidence and the second angle of incidence is five degrees or less.
19. 19. The non-transitory computer readable medium of claim 17, wherein adjusting the angle of incidence to the second angle of incidence is after the transmitter transmits the first pulse of light and before the return pulse of light is received at a polarizing beam splitter.
20. 20. The non-transitory computer-readable medium of claim 17, wherein the computer-executable instructions further cause the one or more processors to: after receiving the return light pulse, the polarizing beam splitter is adjusted from the second position to the first position.

Description

Vibratory polarizing beam splitter for improved return light detection Background In a LIDAR system (e.g., a vehicular LIDAR system), a transmitter may be used to transmit pulses of light into the environment. These light pulses may reflect from objects in the environment back to the LIDAR system, and the detector of the LIDAR system may detect the returned light. The timing of the detected return light may then be used to determine the distance of the object relative to the LIDAR system. In some cases, the LIDAR system may also include a reflective element for reflecting the emitted light into the environment. For example, the reflective element may be a mirror and may be used in a coaxial LIDAR system to address parallax problems that may occur in other types of LIDAR systems. One potential drawback to using such reflective elements is that the reflective elements may also be disposed in the path of the detector. In view of this, the reflective element may prevent the return light pulse from reaching the detector (since the return light may be reflected from the reflective element and away from the detector). To solve this problem, a polarizing beam splitter may be used as a reflecting element instead of a standard mirror. Polarizing beamsplitters may provide the benefit of reflecting light of certain polarization states and allowing light of other polarization states to be transmitted through (pass through). As an example, a polarizing beam splitter may reflect s-polarized light and allow p-polarized light to pass through. Since the return light reflected from the object may be a mixture of s-and p-polarization, the polarizing beam splitter may allow some of the return light to be transmitted through to the detector (e.g., p-polarized light). But s-polarized light may still reflect from the polarizing beamsplitter and never reach the detector. Thus, in the best case scenario, about half of the return light is lost, while in the worst case no light will pass through the polarizing beam splitter to the detector device. This reduces the amount of return light detected by the detector. Thus, the overall efficiency of the system to detect the return light may be reduced. Drawings The detailed description is set forth with reference to the drawings. The drawings are provided for illustration purposes only and depict only example embodiments of the disclosure. The figures are provided to facilitate an understanding of the disclosure and should not be considered to limit the breadth, scope, or applicability of the disclosure. In the figures, the leftmost bit(s) of a reference number may identify the figure in which the reference number first appears. The use of the same reference numbers indicates similar but not necessarily identical or identical components. Different reference numerals may be used to identify similar components. Various embodiments may utilize elements or components other than those shown in the figures, and some elements and/or components may not be present in the various embodiments. The use of singular terms to describe a component or element may encompass a plurality of such components or elements and vice versa, depending on the context. 1A-1C depict example schematic diagrams of a vibratory polarizing beam splitter system according to one or more example embodiments of the disclosure. Fig. 2 depicts example graphs depicting transmitted and reflected intensities based on various angles of a polarizing beam splitter in accordance with one or more example embodiments of the present disclosure. Fig. 3 depicts an example diagram depicting various characteristics of a LIDAR system at different times in accordance with one or more example embodiments of the present disclosure. Fig. 4 depicts an example method in accordance with one or more example embodiments of the present disclosure. Fig. 5 depicts an example LIDAR system architecture in accordance with one or more example embodiments of the present disclosure. Detailed Description SUMMARY The present disclosure relates particularly to systems and methods for improving return light detection in LIDAR systems using a vibrating polarizing beam splitter. At a high level, the LIDAR system may include at least one or more emitter devices for generating emitted light, one or more detector devices for detecting return light resulting from the emitted light being reflected from objects in the environment, and one or more polarizing beam splitters (hereinafter "emitter device", "detector device", or "polarizing beam splitter" may be referred to, but such references may similarly apply to any number of such components). More particularly, the present disclosure may relate to LIDAR systems that use an actuator to selectively change the position of a polarizing beam splitter from a first position to a second position in order to improve return light detection in the LIDAR system. As described above, some LIDAR systems may employ polarizing beam splitters