Laser Radar With TE/TM Dual Channels for Weak Reflections
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Solution Overview
Problem
Existing LiDAR systems, particularly FMCW systems, face challenges in accurately determining obstacles due to the weak TM-mode polarized light in reflected beams, leading to inaccurate measurements and the need for high-power systems to compensate for the lack of usable TE-mode polarized light.
Innovation Solution
A LiDAR system with dual detection channels, one for TM-mode and one for TE-mode polarized light, allowing simultaneous utilization of both to improve measurement precision by comparing intensity ratios, thereby enhancing detection accuracy and surface topography determination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single detection channel is used in existing LiDAR systems, then the system structure is simple, but the measurement precision is insufficient due to weak TM-mode polarized light in reflected beams
Solution Approach 1:
The detection channel is segmented into two independent sub-channels: a first detection channel for receiving TM-mode polarized light and a second detection channel for receiving TE-mode polarized light. This segmentation allows each channel to specialize in detecting specific polarization modes, thereby improving overall measurement precision without requiring a complete redesign of the system architecture.
Solution Approach 2:
The light receiving end is designed with multi-functionality to handle both TM-mode and TE-mode polarized light through different detection channels. By integrating multiple detection capabilities into a single receiving end structure, the system achieves improved measurement precision while controlling device complexity through shared components.
2Reliability
If high-power systems are used to compensate for weak TM-mode polarized light, then detection capability is improved, but energy consumption increases
Solution Approach 1:
The system changes the detection parameter from relying on light intensity alone to utilizing polarization mode differentiation. By detecting both TM-mode and TE-mode polarized light separately through dedicated channels, the system maintains reliable detection capability for weak reflected signals without needing to increase laser transmission power, thus controlling energy consumption.
Solution Approach 2:
Polarization-selective optical components act as intermediaries between the reflected light and detectors. These components selectively guide TM-mode and TE-mode polarized light to their respective detection channels, enabling reliable detection of weak signals through polarization differentiation rather than increasing power.
3Measurement precision
If only TM-mode polarized light is utilized, then the detection system is simple, but detection accuracy fails when TM-mode light is weak
Solution Approach 1:
The detection system is segmented into specialized channels: the first detection channel processes TM-mode polarized light while the second detection channel processes TE-mode polarized light. This segmentation ensures that detection accuracy is maintained across different lighting conditions by utilizing both polarization modes, with each channel optimized for its specific mode.
Solution Approach 2:
The detection system employs a composite structure combining multiple detection channels with different polarization sensitivities. By integrating both TM-mode and TE-mode detection capabilities, the system achieves robust detection accuracy that compensates for the weakness of either individual polarization mode alone.
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 system improves measurement precision by fully utilizing both TM-mode and TE-mode polarized light, avoiding detection failures and providing accurate distance and speed measurements even with weak TM-mode light, thus optimizing LiDAR performance.
Implementation Method 1
the light transmitting/receiving end is configured to emit a detection light beam, the detection light beam is reflected to generate a reflected light beam after encountering an obstacle
Implementation Method 2
an optical splitter configured to split the laser into a detection laser and a local oscillation laser
Implementation Method 3
a first mixer configured to receive at least a part of the local oscillation laser and a first part of the reflected light beam, and perform a frequency-mixing operation
Implementation Method 4
a first detector configured to receive the first mixed beam and detect a first beat frequency between at least the part of the local oscillation laser and the first part of the reflected light beam
Implementation Method 5
a polarization beam-splitting apparatus arranged between the LiDAR chip and the lens assembly, wherein the polarization beam-splitting apparatus is configured to allow the TM-mode polarized light in the reflected light beam to pass
Data Source
AI summary
A laser radar is provided. The LiDAR system comprises: a LiDAR chip comprising at least one laser transmission-detection channel, each of which includes a primary transmission-detection channel and a secondary detection channel, wherein the primary transmission-detection channel is configured to transmit a detection light beam and have a light transmitting/receiving end configured to emit the detection light beam, the detection light beam is separately reflected after encountering an obstacle to generate a reflected light beam, and the light transmitting/receiving end further receives a first part of the reflected light beam; the secondary detection channel has a light receiving end which receives a second part of the reflected light beam, and the LiDAR system measures the distance and/or speed of the obstacle according to the first part and the second part of the reflected light beam.