LiDAR Beam Combining for Simultaneous Range and Velocity

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Solution Overview

Problem

Traditional LiDAR systems are unable to simultaneously measure range and velocity due to significant losses in the receive path, leading to limited power output and shorter ranges, and are often bulky.

Innovation Solution

A frequency-modulated LiDAR system with two optical sources of opposite polarizations, split into high-power and low-power paths, combined into a single spatial mode beam, and mixed with local oscillators to produce beat frequencies for range and velocity determination, using balanced optical detectors and optical amplifiers to enhance signal-to-noise ratio.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If traditional pulsed LiDAR systems are used, then the system structure is simple, but they cannot measure range and velocity simultaneously and suffer from significant receive path losses

Engineering Contradiction:

Improvesimultaneous range and velocity measurementVSAvoidreceive path losses

Core Design Contradiction:

Measurement precisionVSLoss of energy

Solution Approach 1:

The optical beam is segmented into two orthogonal polarization components (s-polarized and p-polarized). Each polarization component is processed through separate optical paths with dedicated mixers and detectors, allowing simultaneous measurement of range and velocity without cross-interference between measurement channels

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Local oscillator beams are introduced as intermediary elements to mix with the return signal beams. The local oscillators serve as reference signals that enable heterodyne detection, converting the optical frequency information into measurable beat frequencies that contain both range and velocity data

Inventive Principle:

Principle #24Intermediary (Mediator)

2Measurement precision

If FM LiDAR systems are used to enable simultaneous measurement, then measurement capability is improved, but the systems become bulky and large

Engineering Contradiction:

Improvesimultaneous range and velocity measurementVSAvoidsystem size

Core Design Contradiction:

Measurement precisionVSVolume of moving object

Solution Approach 1:

Multiple optical beams (return signal beams from different polarization components and local oscillator beams) are combined into a single spatial mode beam using polarization beam splitters and combiners. This merging reduces the number of separate optical paths and compactes the overall system structure while maintaining the capability for simultaneous range and velocity measurement

Inventive Principle:

Principle #5Merging (Combining)

3Measurement precision

If receive path losses are reduced, then measurement accuracy is improved, but power output requirements increase which is limited by eye safety

Engineering Contradiction:

Improvesignal-to-noise ratioVSAvoidpower output

Core Design Contradiction:

Measurement precisionVSPower

Solution Approach 1:

The system changes the polarization state parameter of the optical beams to separate measurement channels. By utilizing orthogonal polarization states, the system can process multiple measurement signals simultaneously without requiring increased power output, as each polarization component is independently detected through dedicated mixers and balanced detectors

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

Enables simultaneous measurement of range and velocity without major losses in the receive path, in a compact and mass-manufacturable form, suitable for applications like automated driver assist systems and self-driving vehicles, with improved accuracy and range.

Implementation Method 1

a first polarization beam splitter configured to combine the first high-power path optical beam and the second high-power path optical beam into a single spatial mode optical beam

Methodology Applied

Scientific EffectPolarization beam splitting: Polarisation

Implementation Method 2

a second polarization beam splitter configured to split the return optical beam into a first spatial mode optical beam and a second spatial mode optical beam

Methodology Applied

Scientific EffectPolarization beam splitting: Polarisation

Implementation Method 3

a first mixer configured to mix the first spatial mode optical beam and the first low-power path optical beam to produce an optical beam having a first beat frequency

Methodology Applied

Scientific EffectBeat frequency mixing: Beat (acoustics)

Implementation Method 4

a second mixer configured to mix the second spatial mode optical beam and the second low-power path optical beam to produce an optical beam having a second beat frequency

Methodology Applied

Scientific EffectBeat frequency mixing: Beat (acoustics)

Implementation Method 5

the LiDAR system further comprises an optical amplifier between the first polarization beam splitter and lensing optics, the optical amplifier configured to amplify the single spatial mode optical beam

Methodology Applied

Scientific EffectOptical amplification:

Data Source

PatentUS20240295642A1Techniques for Combining Optical Beams into Shared Spatial Mode

Publication Date: 2024.09.05 AEVA INC

AI summary

A light detection and ranging (LiDAR) system includes a beam combining component to combine a first optical beam including a first polarization and a second optical beam including a second polarization into a single spatial mode optical beam, and a first beam splitting component to split the single spatial mode optical beam into a plurality of single spatial mode optical beams.