Holographic LiDAR Pulse Control for Near-Far Depth Resolution
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Solution Overview
Problem
LiDAR systems face challenges in balancing depth resolution for near and far objects, particularly when vehicle speed changes, leading to inefficiencies in optical power usage and data processing.
Innovation Solution
A method of dynamically adjusting light patterns using holographic projectors, where pulse properties such as duration, peak power, and repetition rate are optimized based on vehicle speed and range requirements, allowing for adaptive scanning and improved energy efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If optical pulses of fixed pulse duration and repetition frequency are used, then the LiDAR system operates with constant parameters, but depth resolution for near objects and optical power for far objects cannot be simultaneously optimized
Solution Approach 1:
The patent applies dynamics by making the LiDAR system adaptively change pulse duration and repetition frequency based on detected object distance. The controller dynamically adjusts pulse parameters: using shorter pulses for near objects to improve depth resolution, and longer pulses for far objects to increase optical power, thereby resolving the contradiction between measurement precision and energy usage across different ranges
Solution Approach 2:
The patent implements parameter changes by varying pulse duration and repetition frequency according to range requirements. The system transitions from fixed parameters to variable parameters, optimizing the balance between depth resolution and optical power consumption based on real-time distance measurements and vehicle speed
2Speed
If high pulse repetition frequency is used for far field detection, then far objects can be detected, but depth resolution for near objects deteriorates
Solution Approach 1:
The patent applies local quality by implementing different pulse repetition frequencies for different spatial regions (near field vs. far field). The system uses high repetition frequency for far field detection and low repetition frequency for near field detection, allowing each region to have optimized parameters for its specific detection requirements
3Ease of operation
If constant optical power is emitted, then the system is simple to control, but efficiency is reduced when vehicle speed changes
Solution Approach 1:
The patent implements feedback by using detected object distance and vehicle speed information to dynamically adjust pulse duration and repetition frequency. The controller receives feedback from range detection and adapts the optical emission parameters accordingly, optimizing scanning efficiency for varying vehicle speeds while maintaining simple control architecture
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 optimizing light patterns for specific ranges and vehicle speeds, reducing resource waste and improving depth resolution and optical scanning efficiency.
Implementation Method 1
Each pixel is an individually-addressable liquid crystal cell having birefringence. Each pixel may modulate the amplitude and/or phase of light in accordance with a corresponding hologram pixel.
Implementation Method 2
The light is diffracted by the spatial light modulator. The complex light pattern emanating from the display device interferes at a replay plane to form a holographic reconstruction corresponding to the target image.
Implementation Method 3
LiDAR light sources typically utilise optical pulses of fixed pulse duration and repetition frequency. A light source arranged to illuminate each displayed light modulation pattern in turn with pulsed light having a pulse duration and a pulse repetition frequency.
Data Source
AI summary
A method of light detection and ranging comprises a displaying a first hologram of a first light pattern on a first array of light-modulating pixels and illuminating the first hologram with first pulsed light in order to project the first light pattern onto the scene. The method comprises a displaying a second hologram of a second light pattern on a second array of light-modulating pixels and illuminating the second hologram with second pulsed light in order to project the second light pattern onto the scene. At least one pulse property of the first pulsed light is different to that of the second pulsed light.