Adaptive LiDAR Laser Power Control for Detector Saturation
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Solution Overview
Problem
LiDAR systems face challenges in uncontrolled environments due to environmental factors like background light, low-reflectivity surfaces, and limited optical collection aperture, leading to saturation errors in detector arrays, which distort time-of-flight measurements and reduce the dynamic range of depth mapping.
Innovation Solution
An electro-optical device with a controller that adjusts laser power based on the number of detectors responding to each pulse, reducing power when saturation is detected to prevent temporal bias errors and extend the dynamic range of LiDAR systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If high power laser pulses are used to improve signal detection for distant or low-reflectivity targets, then the detection range and sensitivity are improved, but detector saturation occurs causing measurement errors and reduced accuracy
Solution Approach 1:
The patent applies dynamics by making the laser pulse power adjustable and adaptive rather than fixed. The controller dynamically modifies the power level of successive pulses based on real-time detector response, switching between high power (for distant/low-reflectivity targets) and low power (for nearby/high-reflectivity targets) to prevent saturation while maintaining detection sensitivity across varying scene conditions
Solution Approach 2:
The patent implements parameter changes by varying the power level of laser pulses as a controllable parameter. The controller changes the power parameter adaptively based on the number of detector responses, allowing the system to optimize between high power for extended range and low power for preventing saturation, thereby resolving the contradiction between measurement precision and detector saturation
2Measurement precision
If the laser power is reduced to prevent detector saturation, then measurement accuracy is improved, but the detection range and ability to detect distant targets deteriorates
Solution Approach 1:
The system uses dynamics to adapt laser power in real-time based on scene conditions. By making power adjustable and controlling it dynamically through feedback from detector responses, the system can extend detection range when needed (high power) while maintaining accuracy when detectors are at risk of saturation (low power), resolving the contradiction between range and precision
Solution Approach 2:
The patent applies preliminary action by using early pulses at higher power to establish detection capability for distant targets, then preemptively reducing power in subsequent pulses before saturation can occur. This preliminary high-power detection followed by power reduction allows the system to extend range while preventing the accuracy degradation that would result from sustained high power
3Adaptability or versatility
If fixed high power is used to ensure detection of all targets, then detection coverage is improved, but saturation errors increase for nearby or high-reflectivity targets
Solution Approach 1:
The patent resolves this contradiction by making laser power dynamic and adaptive rather than fixed. The controller adjusts power based on real-time detector response, providing high power for distant/low-reflectivity targets (improving coverage) while automatically reducing power for nearby/high-reflectivity targets (maintaining reliability), achieving both broad detection coverage and consistent measurement reliability across all conditions
Solution Approach 2:
The system implements parameter changes by varying the power level as a controllable parameter based on scene conditions. This allows the system to maintain broad detection coverage through high power when needed while ensuring measurement reliability through power reduction when saturation risk is detected, resolving the contradiction between adaptability and reliability
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 adaptive power control mitigates saturation, enabling accurate time-of-flight measurements and improved depth mapping across a wider range of distances and reflectivity levels, reducing errors and enhancing the dynamic range of LiDAR systems.
Implementation Method 1
a laser, which is configured to emit toward a scene pulses of optical radiation
Implementation Method 2
an array of single-photon detectors, which are configured to receive the optical radiation that is reflected from points in the scene and to fire, upon detecting a photon, an output signal indicative of a respective time of arrival of the detected photon
Data Source
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AI summary
An electro-optical device (20) includes a laser (28), which is configured to emit toward a scene (38) pulses (36) of optical radiation. An array (34) of detectors (79) are configured to receive the optical radiation that is reflected from points in the scene and to output signals indicative of respective times of arrival of the received radiation. A controller (26) is coupled to drive the laser to emit a sequence of pulses of the optical radiation toward each of a plurality of points in the scene and to find respective times of flight for the points responsively to the output signals, while controlling a power of the pulses emitted by the laser by counting a number of the detectors outputting the signals in response to each pulse, and reducing the power of a subsequent pulse in the sequence when the number is greater than a predefined threshold.