FMCW LiDAR Optical Layout for Beam Walkoff Mitigation

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Conventional FMCW LIDAR systems suffer from beam walkoff due to the continuous motion of mirrors, leading to reduced system performance and additional optical loss when the transmitter and receiver are co-located, necessitating a separation of these components to mitigate these issues.

Innovation Solution

A LIDAR system with non-coaxial transmitter and receiver configurations, utilizing polarization-diverse coherent pixels and birefringent materials to correct beam walkoff by directing light through different optical paths based on the rotation direction of the mirror, employing optical switches to switch oscillator signals between mixers, and using beam displacement apparatuses to compensate for beam displacement.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Volume of moving object

If the transmitter and receiver are co-located in FMCW LIDAR systems, then the system structure is compact, but beam walkoff occurs due to continuous mirror motion causing reduced system performance and additional optical loss

Engineering Contradiction:

Improvesystem structure compactnessVSAvoidsystem performance

Core Design Contradiction:

Volume of moving objectVSReliability

Solution Approach 1:

The patent divides the optical path into separate transmit and receive paths using polarization-diverse coherent pixels. The transmit path sends light to the target while the receive path collects reflected light, with beam displacement apparatuses compensating for walkoff in each path independently. This segmentation allows compact co-location while maintaining performance by addressing beam walkoff through separate compensation mechanisms for each polarization channel.

Inventive Principle:

Principle #1Segmentation

2Volume of moving object

If the transmitter and receiver are co-located, then the device size is reduced, but optical loss increases due to beam walkoff effects

Engineering Contradiction:

Improvedevice sizeVSAvoidoptical loss

Core Design Contradiction:

Volume of moving objectVSLoss of energy

Solution Approach 1:

The patent introduces beam displacement apparatuses as intermediary components in the optical path. These apparatuses actively compensate for beam walkoff by adjusting the optical path of reflected light, ensuring that the beam remains properly aligned with the receiver optics. This intermediary compensation mechanism reduces optical loss while maintaining the compact co-located structure.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Device complexity

If beam walkoff is not mitigated, then the system is simpler, but measurement precision deteriorates

Engineering Contradiction:

Improvesystem complexityVSAvoidrange and velocity measurement accuracy

Core Design Contradiction:

Device complexityVSMeasurement precision

Solution Approach 1:

The patent employs polarization-diverse coherent pixels that utilize different polarization states (parameters) to separate transmit and receive paths. By changing the polarization parameter of light, the system can independently control and compensate for beam walkoff in each path using beam displacement apparatuses. This parameter-based approach enables precise measurement while managing the complexity through systematic polarization management.

Inventive Principle:

Principle #35Parameter changes

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

Enhances LIDAR performance by reducing beam walkoff effects, maintaining signal integrity, and minimizing optical loss, thereby improving range and velocity measurement accuracy.

Implementation Method 1

utilizing polarization-diverse coherent pixels and birefringent materials to correct beam walkoff by directing light through different optical paths based on the rotation direction of the mirror

Methodology Applied

Scientific EffectBirefringence: Birefringence

Implementation Method 2

employing optical switches to switch oscillator signals between mixers

Methodology Applied

Scientific EffectOptical mixing: Heterodyne

Implementation Method 3

using beam displacement apparatuses to compensate for beam displacement

Methodology Applied

Scientific EffectOptical refraction: Refraction

Data Source

PatentEP4208732B1Beam walkoff mitigation for light detection and ranging

Publication Date: 2025.10.15 AURORA OPERATIONS INC

Figure 1
Figure 2
Figure 3A

AI summary

A light detection and ranging (LIDAR) system includes a first receive optical coupler, a second receive optical coupler, a first optical mixer, a second optical mixer, and an optical switch. The first optical mixer is configured to receive a first receive signal from the first receive optical coupler. The second optical mixer is configured to receive a second receive signal from the second receive optical coupler. The optical switch is configured to switch an oscillator light signal between the first optical mixer and the second optical mixer.