Preamble Pulse LiDAR for Eye-Safe Long-Range Detection
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Solution Overview
Problem
LiDAR systems face challenges in detecting objects at long distances due to low signal-to-noise ratio (SNR) caused by the inverse proportional relationship between reflected light power and distance, which is exacerbated by eye safety regulations limiting the power of laser pulses.
Innovation Solution
A LiDAR system that emits a preamble light pulse to determine the presence of objects, adjusting the energy of subsequent scanning light pulses based on the detection, using energy levels below the peak admissible exposure limit to enhance SNR while maintaining eye safety, with the processor calculating optimal preamble distances and pulse widths to optimize detection efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the power of laser pulses is increased to improve signal-to-noise ratio for long distance detection, then detection capability is improved, but eye safety is compromised due to exceeding admissible exposure limits
Solution Approach 1:
The system transmits a preamble light pulse before the main scanning light pulse to detect the presence of objects in advance. Based on the detection result of the preamble pulse, the system dynamically adjusts the energy of the subsequent scanning pulse. This preliminary detection action allows the system to use high energy only when necessary (when no object is present), thereby improving SNR for long-distance detection while maintaining eye safety when objects are detected.
2Length of stationary object
If the energy of scanning light pulses is increased to extend maximum scanning range, then detection distance is extended, but the risk of eye exposure increases
Solution Approach 1:
The system dynamically adjusts the energy of scanning light pulses based on real-time detection results from preamble pulses. When no object is detected in the preamble phase, the system transitions to high energy mode to extend scanning range. When objects are detected, the system switches to low energy mode to ensure eye safety. This dynamic energy adjustment allows the system to optimize between scanning range and safety continuously during operation.
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 system effectively improves the detection of objects at longer distances by increasing the energy of scanning light pulses when no objects are detected, enhancing the signal-to-noise ratio and extending the maximum scanning range while ensuring eye safety.
Implementation Method 1
measuring reflected light pulses with a detector
Implementation Method 2
The position and distance of the object can be computed using time-of-flight (TOF) calculations of the emitted and detected light pulses
Implementation Method 3
the power of the reflected light pulses is inversely proportional to the square of distance traveled by the light pulses
Data Source
AI summary
The disclosed systems, structures, and methods are directed to a LiDAR system comprising a radiation source configured to emit light pulses towards a region of interest (ROI), a detector configured to detect light pulses reflected from the ROI, a processor, communicatively coupled to the radiation source and the detector, configured to cause the radiation source to emit a preamble light pulse having an energy EP and a pulse width W1 towards the ROI, determine, if the preamble light pulse is detected by the detector and whether there is an object in the ROI, responsive to a determination that there is an object in the ROI, cause the radiation source to emit a scanning light pulse having an energy EL and a pulse width W2 towards the ROI, else the radiation source to emit a scanning light pulse having an energy EH and the pulse width W2 towards the ROI.