Coherent Mechanical LiDAR ADC Switching for Angle Lag Compensation
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Solution Overview
Problem
Mechanical LiDAR systems face challenges in accurately capturing returning light due to scanner-induced angle offset, which affects the precision of range measurement and image definition, especially when multiple laser pulses are in flight, requiring efficient management of analog-to-digital conversion resources to mitigate positional offset and noise.
Innovation Solution
The implementation of a photonic integrated circuit (PIC) chip with spatially separate detection channels and advanced switching architectures to reduce the number of analog-to-digital converters (ADCs) needed, while using free-space couplers and optical splitters to optimize light transmission and reception, aligning detectors to compensate for angle lag and enhance signal processing efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple detector channels are used to capture returning light at different angles, then measurement precision is improved, but device complexity increases due to the need for multiple ADCs
Solution Approach 1:
The patent combines multiple detector channels into a single ADC by using optical switching to multiplex the analog signals from multiple detectors through a single photonic integrated circuit path to one ADC, reducing the number of ADCs needed while maintaining the capability to measure multiple angles
Solution Approach 2:
The patent introduces a mechanical scanner as an intermediary component that actively compensates for angle-induced positional offsets by dynamically adjusting the beam direction, thereby enabling accurate range measurements without requiring separate ADCs for each angle
2Measurement precision
If multiple ADCs are used for each detector channel, then measurement precision is improved, but power consumption increases
Solution Approach 1:
The patent merges multiple detector channels into a single ADC processing path, reducing the total number of power-consuming ADC components while maintaining measurement precision through optical switching and mechanical angle compensation
3Adaptability or versatility
If mechanical scanner is used to transmit laser light at different angles, then field of view coverage is improved, but angle lag-induced positional offset increases
Solution Approach 1:
The patent implements feedback control where the system measures the angle lag induced by the mechanical scanner and actively compensates for the positional offset by adjusting the detector channel assignment or ADC sampling timing based on the known scanner angle, thereby maintaining measurement precision across the full field of view
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
This configuration improves the accuracy of range measurement and image definition by effectively managing angle lag-induced positional offsets, reducing noise, and maintaining high signal strength, while also reducing the number of ADCs required, thus lowering costs and power consumption.
Implementation Method 1
a detector including an array of discrete photodetector channels configured to convert incoming photons into electrical signals
Implementation Method 2
an optical mixer configured to combine the returning light signal with a local oscillator beam to produce an intermediate frequency signal
Data Source
AI summary
A LIDAR system includes a light source configured to generate light pulses, a mechanical scanner, a detector including an array of discrete detector channels configured to convert light input into electrical signals, a lens that focuses both light pulses generated at the light source onto the mechanical scanner and returning light reflected from the mechanical scanner for reception in sequence by the detector channels, a first analog to digital converter (ADC) connected to each of the detector channels in the array and configured to convert the electrical signals from the detector channels into digital data signals, and a signal processor coupled to the ADC to receive the digital data signals therefrom and configured to generate images of targets in a field of view of the LiDAR system from the digital data signals.