Coherent Optical Object Analysis Using Dual-Polarization Detection
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Solution Overview
Problem
Traditional lidar and depth camera systems face challenges in achieving high accuracy and reliability, particularly in dynamic or complex environments, due to sensitivity to interference from ambient light and other sources, leading to degraded performance.
Innovation Solution
The use of multi-polarization coherent modulation and off-the-shelf coherent optical modems for generating and processing optical signals to enhance detection and identification of objects, enabling simultaneous measurement of distance, axial velocity, and polarization, with improved robustness to interference and enhanced accuracy through a time-resolved image formation model and maximum-likelihood reconstruction algorithms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If traditional incoherent lidar systems use intensity modulation to recover scene geometry, then the system structure is simpler, but the system becomes sensitive to interference from ambient light which degrades performance
Solution Approach 1:
The patent transitions from incoherent intensity modulation to coherent detection, fundamentally changing the detection parameter from intensity only to amplitude and phase. This parameter change enables the system to measure both the amplitude and phase of backscattered light by interfering it with a reference beam, thereby achieving improved signal-to-noise ratio and robustness to ambient light interference while maintaining practical system complexity
2Reliability
If coherent lidar systems detect amplitude and phase of backscattered light by interfering with a reference beam, then signal-to-noise ratio and robustness to ambient light interference are improved, but system complexity increases
Solution Approach 1:
The patent employs off-the-shelf coherent optical modems originally designed for telecommunications to perform both communication and lidar functions. This multi-functionality approach allows the system to leverage existing mature coherent detection technology, reducing overall system complexity while maintaining the advantages of coherent detection including improved signal-to-noise ratio and robustness to ambient light interference
3Measurement precision
If depth cameras use time-of-flight technology to measure distance, then precise distance calculations are achieved, but multipath interference degrades performance
Solution Approach 1:
The patent measures both the amplitude and phase of backscattered light rather than only intensity or time of flight. By detecting the phase of the coherent signal, the system can distinguish direct path signals from multipath reflected signals based on their different phase characteristics, thereby achieving precise distance calculations while maintaining robustness against multipath interference
4Measurement precision
If structured light systems project known patterns to calculate depth, then three-dimensional information is captured, but ambient light affects performance
Solution Approach 1:
The patent replaces the structured light projection mechanism with coherent optical detection. Instead of projecting patterns and analyzing deformations, the system uses coherent laser illumination and detects the phase and amplitude of backscattered light. This substitution eliminates sensitivity to ambient light while maintaining the ability to capture three-dimensional information through phase-based ranging
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 provides mm-scale ranging accuracy, reliable velocimetry, and robustness to ambient light interference, with improved performance at short exposure times, enabling accurate 3D imaging in challenging environments.
Implementation Method 1
generating a first optical signal from a dual-polarization coherent modulator, wherein the dual-polarization coherent modulator receives a first electrical signal and optical signals generated by an optical source
Implementation Method 2
multi-polarization coherent modulation and off-the-shelf coherent optical modems for generating and processing optical signals
Implementation Method 3
receiving a second optical signal from the target scene, wherein the second optical signal corresponds to a reflection of the first optical signal from the objects of the target scene
Implementation Method 4
the second optical signal is converted in a dual-polarization coherent receiver to generate a second electrical signal
Data Source
AI summary
Aspects of the subject disclosure may include, for example, a method, apparatus and computer readable media for analyzing objects using a coherent optical system. This innovative approach leverages dual-polarization coherent modulation to generate optical signals encoded with digital information across multiple dimensions, such as amplitude, phase, and polarization. These signals are transmitted to a target scene resulting in reflected signals that are received and processed to detect and identify objects based on a comparison with the original transmitted signals. These techniques offer significant improvements in accuracy and robustness, overcoming limitations of traditional lidar and depth camera systems, particularly in dynamic or complex environments. The disclosed technology is applicable across various industries, including autonomous vehicles and environmental monitoring, providing enhanced precision in distance, velocity, and polarization measurements. Other embodiments are disclosed.