Optical Phased Array 3D Range Imaging Resolution
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Solution Overview
Problem
Current 3D range imaging methods, such as scanning LiDAR, face limitations in frame rate due to mechanical scanning and suffer from optical aberrations, while flash LiDAR struggles with resolution and scalability, especially for long-distance targets, and the complexity of optical coupling between multiple optical phased arrays (OPAs) hinders scalable and cost-effective solutions.
Innovation Solution
A method utilizing a large-scale optical phased array (OPA) system that simultaneously produces and steers multiple light beams, combined with a photo sensor array, to achieve finer range imaging resolution and reduce optical aberrations while maintaining high frame rates, by controlling phase shifting and amplitude tuning elements to illuminate specific segments of the scene and correct for aberrations through linear equation systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If scanning LiDAR uses mechanical rotating setup or MEMS movable mirror to steer light beam, then scene-mapping resolution is improved, but frame rate deteriorates due to low scanning speed and integration time requirements
Solution Approach 1:
The patent replaces mechanical rotating setups and MEMS movable mirrors with an optical phased array (OPA) that uses phase modulation to steer light beams. The OPA electronically controls the phase of light at multiple antenna elements to achieve beam steering without mechanical moving parts, thereby maintaining high resolution while dramatically increasing frame rate.
Solution Approach 2:
The patent implements dynamic beam steering by rapidly changing the phase distribution across the OPA antenna elements. This allows the system to switch between different scanning points and directions electronically at high speeds, enabling high frame rates while maintaining the ability to resolve fine scene details through controlled beam direction.
2Productivity
If flash LiDAR uses imaging system with large pixel array size to measure whole scene, then frame rate is improved, but scene-mapping resolution deteriorates due to optical aberrations and difficulty in scaling pixel size
Solution Approach 1:
The patent divides the scene into multiple scene region units, each corresponding to a sensor pixel. For each pixel, the OPA sequentially illuminates different segments within the corresponding scene region unit. This segmentation approach allows the system to achieve fine resolution through sequential scanning while maintaining high frame rate through parallel processing of multiple pixels simultaneously.
Solution Approach 2:
The patent makes each sensor pixel serve multiple functions: it can detect light from different segments of its corresponding scene region unit at different time points. This multi-functionality allows the system to achieve both high frame rate (by processing multiple pixels in parallel) and fine resolution (by sequentially scanning segments within each pixel's field of view).
3Productivity
If multiple OPAs are arranged to scan light in two dimensions to improve frame rate, then productivity is improved, but device complexity deteriorates due to complicated optical path interconnect design and requirement for moving components
Solution Approach 1:
The patent merges the functions of multiple OPAs into a single large-scale OPA with many antenna elements. Instead of using multiple separate OPA devices that would require complex optical coupling and alignment, the invention integrates all beam steering capabilities into one unified OPA structure, dramatically simplifying the optical path while maintaining the ability to scan in two dimensions and achieve high frame rates.
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 approach enhances spatial resolution and frame rate, reduces optical aberrations, and allows for scalable and flexible 3D range imaging without the need for complex optical coupling or moving components, enabling more accurate and efficient distance measurement across larger scenes.
Implementation Method 1
An optical phased array device is generally made of many antenna units which are arranged in one- or two-dimensional array and are individually or group tunable in phase and sometimes amplitude in order to form a specific output beam pattern through interference effect.
Implementation Method 2
measuring the reflected light of each illuminated region for distance calculation via a variety of direct (by time measurement) or indirect (by phase or frequency measurement) time-of-flight schemes
Data Source
AI summary
A 3D range imaging method using a LiDAR system includes sequentially generating multiple far field patterns to illuminate a target scene, each far field pattern including a plurality of light spots where each spot illuminates only a segment of a scene region unit that corresponds to a sensor pixel of the LiDAR receiver. Within each scene region unit, the multiple segments illuminated in different rounds are non-overlapping with each other, and they collectively cover the entire scene region unit or a part thereof. With each round of illumination, the signal light reflected from the scene is detected by the sensor pixels, and processed to calculate the depth of the illuminated segments. The calculation may take into consideration optical aberration which causes reflected light from an edge segment to be received by two sensor pixels. The depth data calculated from the sequential illuminations are combined to form a ranged image.