Optical Phased Array Lidar Beam Steering
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Solution Overview
Problem
Solid-state lidar systems face challenges in designing efficient 2D optical phased arrays due to emitter spacing requirements, leading to reduced power efficiency and multiple beam emissions, which interfere with accurate object ranging.
Innovation Solution
A time-of-flight lidar system incorporating a transmitter with a laser and an optical phased array that emits a plurality of beams, coupled with a photodetector array to receive scattered light, allowing for beam steering and accurate object ranging by determining arrival times of scattered light from each beam.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If thinned phased arrays with larger emitter spacing are used, then the device complexity and fabrication difficulty are reduced, but power efficiency deteriorates and multiple beam emissions occur that interfere with accurate ranging
Solution Approach 1:
The patent divides the detection function into multiple independent photodetectors arranged in an array, with each photodetector assigned to detect a specific beam from the multiple beams emitted by the thinned phased array. This segmentation allows the system to handle the multiple beams separately, preventing interference and maintaining ranging accuracy while using the easier-to-fabricate thinned array structure
Solution Approach 2:
The photodetector array serves multiple functions simultaneously: it detects multiple beams from different directions, determines arrival times for each beam, and enables accurate ranging despite the multiple beam emissions. This multi-functional approach resolves the contradiction by making the detection system capable of handling the complex output from thinned phased arrays
2Ease of manufacture
If thinned phased arrays with larger emitter spacing are used, then the device complexity and fabrication difficulty are reduced, but multiple beam emissions occur that interfere with accurate ranging
Solution Approach 1:
The patent segments the multiple beams into separate detection channels, with each photodetector dedicated to a specific beam. This allows the system to process each beam's scattered light independently and determine arrival times for each beam separately, eliminating cross-interference and maintaining precise ranging measurements despite the multiple beam emissions from the thinned array
Solution Approach 2:
The system uses the detection results from the photodetector array to provide feedback information about arrival times for each beam. This feedback mechanism enables the system to accurately determine ranging information by analyzing the temporal characteristics of each beam's return signal, compensating for the complexity introduced by multiple beam emissions
3Measurement precision
If a photodetector array is used to detect multiple beams, then accurate ranging is achieved, but device complexity increases
Solution Approach 1:
The patent divides the detection task into multiple independent photodetectors, each handling a specific beam. This segmentation approach, while increasing the number of components, simplifies the overall system architecture by assigning clear, dedicated functions to each detector, making the complex task of handling multiple beams manageable through modular design
Solution Approach 2:
Each photodetector in the array independently performs its detection function without requiring complex coordination or control mechanisms. The detectors self-organize to detect their respective beams, and the system automatically processes the individual detection results to achieve accurate ranging, reducing the need for additional complex control systems
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 achieves accurate and efficient object ranging with improved power efficiency by utilizing a photodetector array to handle multiple beams, reducing interference and enhancing the lidar's ability to scan a field of view.
Implementation Method 1
an optical phased array coupled to the laser for receiving the laser pulse and providing a plurality of beams which fan out from the optical phased array
Implementation Method 2
a photodetector array coupled to the optical receiving unit. The photodetector array includes a plurality of photodetectors such that at least one particular photodetector of the photodetector array is disposed for receiving scattered light from each particular beam
Implementation Method 3
The transmitter includes a laser for providing a laser pulse
Implementation Method 4
The "time of flight" between the transmission of a pulse and detection of the corresponding scattered light is indicative of a distance to the point from which the light was scattered
Data Source
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AI summary
A time-of-flight apparatus includes a transmitter and a receiver. The transmitter includes a laser for providing a laser pulse and an optical phased array coupled to the laser for receiving the laser pulse and providing a plurality of beams which fan out from the optical phased array. The receiver includes an optical receiving unit for receiving scattered light from the plurality of beams and a photodetector array coupled to the optical receiving unit. The photodetector array includes a plurality of photodetectors such that at least one particular photodetector of the photodetector array is disposed for receiving scattered light from each particular beam of the plurality of beams.