Vehicle LiDAR Circulator Layout for Crosstalk-Free Velocity Sensing
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Solution Overview
Problem
Conventional LIDAR systems face challenges in accurately determining the range and velocity of objects, especially in bright sunlight and with low reflectivity objects, due to crosstalk and self-interference issues, which affect their performance in autonomous vehicle applications.
Innovation Solution
The implementation of a LIDAR sensor system that uses frequency modulation (FM) or phase modulation (PM) to encode optical signals, incorporating a circulator design with receive grating couplers aligned along the mechanical scan axis, which simplifies the optical design, reduces back reflections, and improves process efficiency by tilting the circulator optics to manage return beam displacement without affecting direction, enabling more accurate range and velocity determination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional LIDAR systems are used, then basic range detection is possible, but measurement precision deteriorates due to crosstalk and self-interference in bright sunlight and with low reflectivity objects
Solution Approach 1:
The return beam is split into multiple components using a circulator and receive grating couplers. The optical signal is segmented into different spatial paths, allowing separate processing of transmitted and received signals to eliminate crosstalk and self-interference effects.
Solution Approach 2:
A circulator is introduced as an intermediary optical component between the transmitter and receiver. This mediator directs the transmit beam toward scanning optics and redirects the reflected return beam to receive grating couplers, preventing direct interference between transmit and receive paths.
2Manufacturing precision
If receive grating couplers are aligned along the mechanical scan axis, then optical design is simplified and manufacturing precision is improved, but device complexity increases due to the circulator configuration
Solution Approach 1:
The circulator serves multiple functions simultaneously: it directs the transmit beam to scanning optics, receives the return beam from reflections, and routes the return beam to appropriate receive grating couplers. This multi-functionality reduces the need for separate components and simplifies overall system design.
Solution Approach 2:
The receive grating couplers are aligned along the mechanical scan axis rather than the optical axis. This dimensional reorientation allows the optical design to leverage the existing mechanical scanning movement, simplifying alignment and improving manufacturing precision without requiring additional complex positioning mechanisms.
3Productivity
If circulator optics are tilted to manage return beam displacement, then productivity is improved by reducing back reflections, but measurement precision may be affected by beam direction changes
Solution Approach 1:
The circulator optics are tilted at a specific angle to achieve optimal performance. This local geometric modification reduces back reflections and manages return beam displacement in the specific region where the circulator is located, while the overall beam direction and measurement precision are maintained through proper optical design.
Solution Approach 2:
The tilt angle of the circulator optics is optimized to balance two competing requirements: reducing back reflections to improve productivity and maintaining appropriate beam direction for measurement precision. By adjusting this parameter, the system achieves both goals simultaneously.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enhances the detection capability of the LIDAR system, allowing it to detect objects at greater distances with higher accuracy and reduce interference, leading to improved autonomous vehicle control by providing precise velocity measurements and reducing the need for additional hardware or complex software.
Implementation Method 1
The circulator is configured to receive the transmit beam and direct the transmit beam to the one or more scanning optics, receive a return beam from reflection of the transmit beam by an object, split the return beam into at least a first component and a second component
Implementation Method 2
The receiver includes a first receive grating coupler and a second receive grating coupler
Implementation Method 3
one or more scanning optics
Implementation Method 4
a transmitter configured to output a transmit beam
Implementation Method 5
a receiver... determine at least one of a range to an object or a velocity of the object based on the first component and the second component
Data Source
AI summary
A light detection and ranging (LIDAR) system for a vehicle includes a transmitter, a receiver, one or more scanning optics, and a circulator. The transmitter is configured to output a transmit beam. The receiver includes a first receive grating coupler and a second receive grating coupler. The circulator is configured to receive the transmit beam and provide the transmit beam to the one or more scanning optics, receive a return beam from reflection of the transmit beam by an object, split the return beam into at least a first component and a second component, and direct the first component to the first receive grating coupler and the second component to the second receive grating coupler.