Redundant APD Bias Timing for LIDAR Blinding Mitigation
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Solution Overview
Problem
Avalanche photodiodes (APDs) in LIDAR systems experience blinding spots due to saturation, limiting the ability to detect multiple return light signals accurately.
Innovation Solution
Implementing redundant APDs with space and time diversity to mitigate blinding spots, using attenuated secondary APDs positioned off the main optical plane and delayed bias signals to support primary APDs during saturation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single APD is used for light detection, then the device complexity is low, but the reliability of detecting multi-return light signals deteriorates due to saturation blinding
Solution Approach 1:
The detection system is segmented into multiple independent APDs (first APD and second APD) that operate in parallel. Each APD independently detects light signals, allowing the system to segment the detection function across multiple components. This segmentation enables the system to overcome the blinding limitation of a single APD by having redundant detection paths.
Solution Approach 2:
The patent applies local quality by positioning the second APD at a different location (second position) relative to the first APD, with the second APD being offset from the main optical axis. This spatial differentiation creates locally optimized detection zones where each APD experiences different saturation characteristics, allowing one APD to detect signals that another may miss due to saturation.
2Measurement precision
If APDs are positioned on the main optical plane, then the detection sensitivity is high, but the susceptibility to saturation blinding increases
Solution Approach 1:
The system introduces asymmetry by positioning the second APD at a different spatial location offset from the main optical axis compared to the first APD. This asymmetric configuration creates differentiated detection characteristics where the second APD experiences reduced saturation effects while maintaining detection capability, thereby balancing sensitivity with resistance to blinding.
Solution Approach 2:
The patent transitions from a single-dimensional detection setup (single APD on optical axis) to a multi-dimensional configuration by introducing the second APD at a spatial offset. This dimensional expansion adds a spatial degree of freedom that allows the system to exploit different optical paths and reduce saturation effects through geometric diversity.
3Reliability
If multiple APDs are used to mitigate blinding, then the detection of hidden pulses improves, but the device complexity increases
Solution Approach 1:
The patent merges the detection outputs from multiple APDs by combining the signals from the first APD and the second APD. This merging process integrates the complementary detection information from both APDs, allowing the system to achieve enhanced reliability for detecting hidden pulses while managing complexity through signal combination rather than independent processing of multiple channels.
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 the detection of hidden pulses in multi-return light signals by minimizing saturation effects, improving the accuracy and reliability of LIDAR systems.
Implementation Method 1
a first avalanche photodiode (APD) operable to detect the multi-return light signal when activated by a first bias signal
Implementation Method 2
the APD may saturate and exhibit reverse bias avalanche recovery phenomena
Data Source
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AI summary
Described herein are systems and methods that that mitigate avalanche photodiode (APD) blinding and allow for improved accuracy in the detection of a multi-return light signal. A blinding spot may occur due to saturation of a primary APD. The systems and methods include the incorporation of a redundant APD and the utilization of time diversity and space diversity. Detection by the APDs is activated by a bias signal. The redundant APD receives a time delayed bias signal compared to the primary APD. Additionally, the redundant APD is positioned off the main focal plane in order to attenuate an output of the redundant APD. With attenuation, the redundant APD may not saturate and may have a successful detection during the blinding spot of the primary APD. Embodiments may include multiple primary APDs and multiple secondary APDs.