Multi-Wavelength LiDAR Reference Superposition for FMCW Nonlinearity
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Solution Overview
Problem
Existing high-resolution FMCW LiDAR systems face challenges in maintaining signal-to-noise ratio (SNR) due to non-linear transmit signals, which increases system complexity and cost when attempting to ensure linearity, making them inefficient for practical applications.
Innovation Solution
A LiDAR system utilizing a signal generator that produces multiple wavelengths, a transceiver with a focal plane array, and a circuit that corrects target signals by superposing them with frequency-modulated reference signals, using a processor to extract and demodulate these signals to improve SNR without increasing system complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a reference arm with optical delay is used to generate a reference signal to improve SNR, then the signal-to-noise ratio is improved, but the system complexity increases
Solution Approach 1:
The patent combines the reference signal generation and target signal processing into a single integrated receiver channel. The superposer merges the reference signal (generated through optical delay) with the target signal in the same detection path, allowing SNR improvement without requiring separate complex reference and measurement channels. This integration reduces overall system complexity while maintaining the benefits of reference signal-based noise suppression.
Solution Approach 2:
The receiver is designed to handle both reference signal generation and target signal detection within a single multi-functional unit. The same photodetector and signal processing circuitry process both the reference signal (from the reference arm) and the target signal (from the measurement arm), eliminating the need for separate dedicated reference signal processing hardware and reducing system complexity.
2Measurement precision
If multiple wavelengths are used to achieve high resolution, then the measurement precision is improved, but the computational amount increases
Solution Approach 1:
The patent performs preliminary signal processing by generating a reference signal that contains the same non-linearity characteristics as the transmit signal. This reference signal is processed in advance through the same optical path and mixed with local oscillator signals before being combined with the target signal. By pre-characterizing the non-linearity in the reference signal, the system avoids the need for complex post-processing computational corrections for multi-wavelength data.
Solution Approach 2:
The reference signal serves as a copy of the transmit signal's non-linearity characteristics. By creating this reference copy through the reference arm and using it to correct the target signal through superposition and processing, the system eliminates the need for complex computational algorithms to model and correct non-linearity effects for each wavelength individually, thereby reducing computational burden while maintaining multi-wavelength resolution capabilities.
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 solution enhances SNR by correcting target signals through superposition and modulation, reducing distortion and maintaining system efficiency while avoiding increased complexity and cost.
Implementation Method 1
a receiver configured to generate a target signal by mixing a first local oscillator signal with a receive signal incident after the transmit signal is reflected from a target
Implementation Method 2
generate a reference signal by mixing a second local oscillator signal with a light delay signal generated through a reference arm
Implementation Method 3
a superposer configured to generate a superposed signal by superposing the target signal and the reference signal
Implementation Method 4
The circuit may include a processor configured to correct the target signal based on the reference signal
Implementation Method 5
frequency-modulate the reference signal based on a carrier frequency
Implementation Method 6
extract the frequency-modulated reference signal by band-pass-filtering the superposed signal
Implementation Method 7
extract the reference signal by demodulating and low-pass-filtering the frequency-modulated reference signal
Implementation Method 8
extract the reference signal by demodulating and low-pass-filtering the frequency-modulated reference signal
Implementation Method 9
The a processor may be further configured to remove distortion of the target signal to generate the corrected target signal based on the reference clock signal
Data Source
AI summary
Provided is a light detection and ranging (LiDAR) system including a signal generator configured to generate a plurality of pieces of light having different wavelengths, a transceiver including a transmitter configured to output the plurality of pieces of light as a transmit signal, and a receiver configured to generate a target signal by mixing a first local oscillator signal with a receive signal incident after the transmit signal is reflected from a target, and generate a reference signal by mixing a second local oscillator signal with a light delay signal generated through a reference arm, and a circuit operably connected to the signal generator and the transceiver, the circuit being configured to control an operation of the signal generator and an operation of the transceiver, wherein the receiver includes a superposer configured to generate a superposed signal by superposing the target signal and the reference signal.