Metalens Array Lidar for Wide Field of View
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Solution Overview
Problem
Existing LIDAR systems face limitations in scanning time, field of view, and working distance due to mechanical sensitivity, vibration issues, and the need for precise alignment, while flash LIDAR systems suffer from reduced intensity and narrow field of view.
Innovation Solution
A LIDAR device employing an array of metalenses to focus sub-beams onto specific pixels within predetermined ranges of incident angles, allowing for a larger field of view and greater working distance, with each metalens optimized to focus light within a unique range of angles, reducing cross-talk and enhancing point cloud density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If mechanical scanning devices are used to scan space with an optical beam, then the field of view and coverage area can be adjusted, but the system becomes sensitive to vibration and acceleration, requiring precise alignment
Solution Approach 1:
The patent divides the optical system into multiple metalenses arranged in an array, where each metalens is optimized for a specific angular range. This segmentation allows the system to cover a wide field of view without mechanical scanning, as each metalens independently handles a portion of the angular spectrum, eliminating vibration sensitivity while maintaining broad coverage.
Solution Approach 2:
The patent replaces the mechanical scanning system with a static array of metalenses. Instead of physically moving mirrors or the entire optical assembly to scan the scene, the system uses the angular-selective focusing properties of multiple metalenses to simultaneously capture light from different directions, substituting mechanical motion with optical design.
2Reliability
If interferential optical systems are used to deflect the optical beam, then moving parts are eliminated, but large angular scans on two axes require multiple systems to be switched
Solution Approach 1:
The patent combines the functions of multiple interferential systems into a single integrated array of metalenses. Each metalens in the array performs the angular deflection function that would otherwise require separate interferential systems, merging multiple complex subsystems into one compact structure that achieves the same multi-axis scanning capability.
Solution Approach 2:
The patent transitions from sequential switching of multiple interferential systems to a spatially distributed array of metalenses. By arranging metalenses in a two-dimensional array with specific spacing and orientations, the system achieves multi-axis angular coverage through spatial distribution rather than temporal switching, adding a dimensional aspect to the solution.
3Area of stationary object
If photodetector arrays are mounted on a moving turret to achieve wide angle detection, then coverage area increases, but scanning time increases and point cloud density decreases
Solution Approach 1:
The patent eliminates the moving turret by using a fixed array of metalenses. Each metalens is statically positioned and optimized for specific angular ranges, allowing the system to capture wide-angle coverage simultaneously without mechanical rotation. This substitution of mechanical scanning with optical angular multiplexing dramatically reduces scanning time while maintaining point cloud density.
Solution Approach 2:
The patent enables continuous capture of light from all angular directions simultaneously through the metalens array, rather than sequentially scanning through different angles. This continuity allows the system to build up point clouds from all directions at once, eliminating the time loss associated with mechanical scanning while maintaining high spatial resolution.
4Area of stationary object
If beam path is altered by mirror or prism to achieve broader field of view, then coverage area increases, but point cloud density decreases
Solution Approach 1:
The patent applies local quality by optimizing each metalens for its specific angular range rather than using a single optical element for all angles. Each metalens in the array has tailored focusing properties matched to its position and orientation, ensuring that light from each angular sector is concentrated with high precision onto the corresponding photodetector pixels, maintaining point cloud density across the entire field of view.
Solution Approach 2:
The patent introduces dynamic angular selectivity through the metalens array configuration. By carefully designing the spacing, orientation, and focal lengths of individual metalenses, the system dynamically routes light from different angular directions to appropriate detectors, achieving both broad coverage and high density without the compromises of static beam-altering optics.
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 a LIDAR device with an expanded field of view and increased working distance, improving scanning efficiency and reducing the limitations of existing systems by ensuring each sub-beam is focused onto the correct pixel, thereby enhancing the accuracy and density of 3D point cloud generation.
Implementation Method 1
an array of N > 1 metalenses, each adapted to collect a respective portion, called a sub-beam, of the reflected laser beam and to focus it onto a same focal plane; wherein each i-th metalens is adapted to focus the respective sub-beam onto a respective pixel only when said respective sub beam is incident onto said metalens within a predetermined range of incident angles
Implementation Method 2
A portion of the light reflects from the object and returns to a detector of the LIDAR system. Based on the time elapsed between emission of the pulse of light and detection of the returned pulse of light, a distance is estimated.
Implementation Method 3
measure the distance to an object based on the time of flight (TOF) of each pulse of light
Data Source
Figure 1~2A
Figure 2B~3
Figure 4~5
AI summary
A LIDAR device (1) to image a three dimensional environment (Obj) comprising : - a laser source (SL) adapted to emit an incident laser beam (LI) presenting a wavelength λ and illuminating said three dimensional environment thus forming a reflected laser beam (LR); - an array (AM) of N > 1 metalenses (ML1-MLN), each adapted to collect a respective portion, called a sub-beam, of the reflected laser beam (LR) and to focus it onto a same focal plane ; - a photodetector (DT) disposed in said focal plane to detect said sub-beams and comprising at least N pixels noted P1 to PN, wherein each i-th metalens (MLi), i = 1... N is adapted to focus the respective sub-beam (SBi) onto a respective pixel Pi only when said respective sub beam is incident onto said metalens within a predetermined range [Δ θi, Δ ϕi] of incident angles centered on a respective pair of optimal incident angle [θopt,i; ϕopt,i ] different from and not overlapping with the predetermined ranges of optimal incident angle associated to other metalenses [Δθj, Δϕj],j ≠ i,j = 1... N; - a scanning element (SE) adapted to induce a plurality of controllable shifts of a direction of propagation of said incident laser beam (LI) onto said three dimensional environment; - a processing unit (PU) connected to the photodetector and the scanning element and configured to acquire an image with the photodetector for each controllable shift induced by the scanning element.