LiDAR Optical Path Separation for High-SNR Distance Measurement
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Solution Overview
Problem
Existing monostatic LiDAR devices face challenges in maintaining a high signal-to-noise ratio (SNR) due to the mixing of backscattered light from optical switches, which affects the reliability and efficiency of distance and speed calculations.
Innovation Solution
The LiDAR device employs a demultiplexer/distributor to separate transmission and reception paths, preventing backscattered light from mixing with reception signals, and uses multiple amplifiers and transmission/reception separation devices to maintain high SNR while allowing directional emission and reception of laser light.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an optical switch is used to switch the irradiation direction of laser light, then the device size is reduced and reliability is improved, but backscattered light from the optical switch mixes into reception light, degrading the signal-to-noise ratio
Solution Approach 1:
The patent divides the optical path into separate transmission and reception paths using a demultiplexer/distributor. The transmission light and reception light are separated into different optical channels, preventing backscattered light from mixing into the reception signal. This segmentation maintains the reliability benefits of optical switching while eliminating the noise contamination problem.
Solution Approach 2:
The patent extracts the problematic backscattered light component from the reception path by using a demultiplexer/distributor to separate transmission and reception lights into different optical channels. By taking out the transmission light path from the reception path, the system eliminates the source of noise while preserving the optical switching functionality.
2Device complexity
If transmission light and reception light share the same optical path, then the device structure is simplified, but backscattered light from the optical switch contaminates the reception signal, reducing measurement accuracy
Solution Approach 1:
The patent segments the optical path into distinct transmission and reception channels using a demultiplexer/distributor. This segmentation adds a separation component but maintains relatively simple device structure while dramatically improving reception signal accuracy by preventing backscattered light contamination.
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 enhances the SNR by preventing backscattered light from entering the signal processing system, maintaining reliability and reducing energy consumption, thus improving the accuracy of distance and speed calculations.
Implementation Method 1
a wavelength division (WD) demultiplexer configured to redirect the light in different directions based on the different wavelengths, respectively
Implementation Method 2
a lens array including an array of lenses configured to collimate the light from the WD demultiplexer for transmission in different directions, respectively
Implementation Method 3
a laser source configured to generate light with different wavelengths, respectively
Data Source
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AI summary
Herein disclosed is a LiDAR device including: a light source (1) to output laser light; a demultiplexer/distributor (2) to receive the laser light output from the light source (1) and to output local oscillation light and a plurality of signal light beams; a plurality of amplifiers (5) corresponding to the respective signal light beams output from the demultiplexer/distributor (2), the plurality of amplifiers (5) being configured to amplify the respective signal light beams; a plurality of light transmission/reception devices (7) corresponding to the respective amplifiers (5), to emit, as transmission light, the signal light beams output from the corresponding amplifiers (5) into space, and to receive, as reception light, scattered light from a measurement target present in space; a signal processing device (8) to calculate a distance to the measurement target and a property of the measurement target on a basis of the reception light from the plurality of light transmission/reception devices (7) and the local oscillation light from the demultiplexer/distributor (2); and a plurality of transmission/reception separation devices (6) corresponding to the respective amplifiers (5) and the respective light transmission/reception devices (7), the plurality of transmission/reception separation devices (6) being configured to couple the transmission light from the amplifiers (5) to the respective light transmission/reception devices (7) and to couple the reception light received by the respective light transmission/reception devices (7) to the corresponding signal processing device (8).