Coherent LiDAR Grating Pitch Variation for Mirrorless 3D Scanning

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Solution Overview

Problem

Conventional LIDAR scanning systems rely on moveable mirrors, which are expensive and prone to failure, and direct detection methods that limit resolution and are sensitive to interference, especially in environments with partial reflections like trees.

Innovation Solution

A coherent light-based LIDAR system using an array of coherent receivers and gratings with varying pitch, where a frequency-swept laser illuminates a scene, and the received light is processed using a digital signal processor to determine depth and location, eliminating the need for phase shifters and allowing for high-resolution 3D imaging.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If moveable mirrors are used for LIDAR scanning, then scanning function is achieved, but system cost increases and reliability decreases

Engineering Contradiction:

Improvesystem reliabilityVSAvoidscanning mechanism complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent replaces moveable mechanical mirrors with a fixed photonic integrated circuit containing gratings. The mechanical scanning system is substituted with an optical system using diffraction gratings to steer light beams, eliminating moving parts and improving reliability while reducing mechanical complexity.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent uses grating structures that replicate the scanning function through diffraction patterns. Instead of physically moving mirrors to scan beams, the grating structures create multiple diffracted beams that cover the scanning area, copying the scanning effect through optical interference rather than mechanical motion.

Inventive Principle:

Principle #26Copying

2Measurement precision

If direct detection methods are used, then system simplicity is maintained, but measurement precision and resolution are limited

Engineering Contradiction:

Improvedepth measurement precisionVSAvoiddetection system complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent transitions from direct detection to coherent detection, changing the detection parameter from intensity measurement to phase and amplitude measurement. This allows for precise depth measurement through interferometric techniques, where the phase difference between reference and reflected light provides accurate distance information.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent introduces a reference light beam as an intermediary in the detection process. The reference beam interferes with the reflected beam from the target, creating an interferogram that contains depth information. This intermediary reference beam enables precise measurement without directly measuring the weak reflected signal alone.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Manufacturing precision

If conventional gratings with uniform pitch are used, then manufacturing is simplified, but beam steering precision and resolution are reduced

Engineering Contradiction:

Improvebeam steering precisionVSAvoidgrating fabrication complexity

Core Design Contradiction:

Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The patent employs gratings with non-uniform pitch where different regions of the grating have different spacing. This local variation in grating pitch allows for precise control of beam steering angles and focal positions, enabling high-resolution depth imaging and selective focusing on specific spatial locations.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent uses asymmetric grating structures with varying pitch patterns rather than symmetric uniform gratings. The asymmetric design enables differential beam steering in different directions and allows for optimized focusing characteristics, improving depth resolution and spatial discrimination capabilities.

Inventive Principle:

Principle #4Asymmetry

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 solution provides significantly improved resolution, resilience to interference, and the ability to measure depth and movement, enabling four-dimensional scanning with enhanced sensitivity and accuracy, while being scalable and cost-effective by eliminating complex waveguide routing and phase shifters.

Implementation Method 1

a receiver that receives the reflection of the light. In conventional systems, a Tx scans a beam in 2D using a moveable mirror... an array of coherent receivers and gratings with varying pitch... where a frequency-swept laser illuminates a scene

Methodology Applied

Scientific EffectDiffraction: Diffraction

Implementation Method 2

A coherent light-based LIDAR system using an array of coherent receivers and gratings with varying pitch, where a frequency-swept laser illuminates a scene

Methodology Applied

Scientific EffectCoherent Light: Coherent Light