LiDAR Multi-Pulse Sequencing for Near- and Far-Field Detection
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Solution Overview
Problem
Conventional Lidar systems suffer from measurement blind zones due to stray light interference, particularly in near-field obstacles, leading to inaccurate distance measurements and detection challenges.
Innovation Solution
Implementing a multi-pulse sequence with varying peak powers and a predefined temporal profile to enhance the dynamic range of the detector, allowing for accurate near-field obstacle detection while preserving far-field measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If a single high-power laser pulse is emitted to detect far-field obstacles, then the measurement range is extended, but the detector enters saturation region due to stray light, creating a measurement blind zone for near-field obstacles
Solution Approach 1:
The patent divides the measurement range into near-field and far-field regions, using different pulse powers for each region. A low-power pulse sequence is used for near-field obstacles to avoid detector saturation, while a high-power pulse is used for far-field obstacles to extend measurement range. This segmentation allows the system to handle different distance ranges with appropriate power levels.
Solution Approach 2:
The patent employs periodic pulse sequences with specific temporal profiles to separate near-field and far-field measurements in time. The low-power pulse sequence is emitted first to detect near-field obstacles before the detector saturates, followed by a time delay, then the high-power pulse is emitted for far-field detection. This periodic action with timing separation resolves the contradiction between near-field and far-field measurement capabilities.
2Measurement precision
If the detector operates with high sensitivity to detect weak echo signals, then the signal-to-noise ratio is improved, but the detection circuit enters nonlinear saturation region when receiving stray light, reducing dynamic range
Solution Approach 1:
The patent implements dynamic adjustment of pulse power based on the detection range. The system selectively switches between low-power and high-power pulse sequences depending on whether near-field or far-field obstacles are being detected. This dynamic adaptation allows the detector to maintain optimal sensitivity for each scenario without entering saturation, preserving both high signal-to-noise ratio and wide dynamic range.
Solution Approach 2:
The patent changes the power parameter of the emitted laser pulses based on the target distance. For near-field obstacles, low-power pulses are used to keep the echo signal within the linear detection range while maintaining adequate signal-to-noise ratio. For far-field obstacles, high-power pulses are used to compensate for signal attenuation. This parameter change strategy resolves the contradiction between sensitivity and dynamic range.
3Measurement precision
If a low-power laser pulse is emitted to avoid detector saturation, then the measurement blind zone is reduced, but the measurement range for far-field obstacles is limited
Solution Approach 1:
The patent segments the measurement task into two distinct operations: near-field detection using low-power pulses and far-field detection using high-power pulses. By separating these functions into different pulse sequences emitted at different times, the system achieves both accurate near-field measurement (without saturation) and extended far-field range (with sufficient power).
Solution Approach 2:
The patent uses periodic emission of low-power and high-power pulse sequences to alternately serve near-field and far-field detection needs. The temporal separation between pulse types allows the detector to recover from each pulse type before the next is emitted, enabling both measurement modes to function effectively within the same system without compromising either near-field accuracy or far-field range.
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
The method effectively reduces measurement blind zones by separating near-field and far-field echo signals, improving imaging accuracy and extending the measurement range with reduced costs and interference.
Implementation Method 1
The pulse of light can be generated by a laser emitter then focused through a lens or lens group
Implementation Method 2
a detector configured to receive returned pulse of light... The returned pulse of light may be scattered light from the surface of an object
Data Source
AI summary
A light detection and ranging system is provided for improving imaging accuracy and measurement range. The light detection and ranging system may comprise: a light source configured to emit a multi-pulse sequence into a three-dimensional environment, in which the multi-pulse sequence comprises multiple light pulses having a temporal profile; a photosensitive detector configured to detect light pulses returned from the three-dimensional environment and generate an output signal indicative of an amount of optical energy associated with a subset of the light pulses; and one or more processors electrically coupled to the light source and the photosensitive detector, and the one or more processors are configured to: generate the temporal profile based on one or more real-time conditions; and determine one or more parameters for selecting the subset of light pulses.