Aperiodic MEMS Mirror Array for LiDAR Side Lobe Suppression
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Solution Overview
Problem
LiDAR systems face interference from side lobe beams due to the periodic structure of MEMS mirror arrays, which degrades the signal-to-noise ratio and affects the accuracy of object detection and ranging.
Innovation Solution
The use of aperiodic MEMS mirror arrays where the widths of mirrors in different rows vary, creating an irregular gap pattern that spreads diffraction nodes beyond the 0 order, thereby reducing the intensity of side lobes by more than 50% compared to periodic spacing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If periodic MEMS mirror arrays are used to enlarge the aperture, then the transmission and receiving capability is improved, but side lobe beams are generated that interfere with the signal beam
Solution Approach 1:
The patent applies asymmetry by varying the widths of mirrors in different rows of the MEMS mirror array, creating an aperiodic structure. This asymmetric configuration disrupts the periodic grating pattern that causes side lobe formation, thereby reducing side lobe interference while maintaining the enlarged aperture for improved transmission and receiving capability.
Solution Approach 2:
The patent implements local quality by making each row of mirrors have different widths tailored to specific positions within the array. This localized variation in mirror dimensions creates an aperiodic pattern that suppresses side lobe generation at specific locations, allowing the system to maintain large aperture while minimizing harmful interference effects.
2Ease of manufacture
If periodic mirror array structure is used, then manufacturing is simplified, but diffraction grating effects produce side lobe beams that degrade signal-to-noise ratio
Solution Approach 1:
The patent changes the geometric parameters of the mirror array by varying mirror widths across different rows, transitioning from a periodic to an aperiodic structure. This parameter variation maintains manufacturing feasibility while effectively suppressing the diffraction grating effects that degrade the signal-to-noise ratio, thus improving system reliability.
3Reliability
If aperiodic mirror widths are used to suppress side lobes, then signal-to-noise ratio is improved, but device complexity increases
Solution Approach 1:
The patent segments the mirror array into multiple rows with different width configurations. This segmentation approach allows the complex aperiodic pattern to be broken down into manageable row-by-row variations, making the device complexity controllable while still achieving the desired side lobe suppression and improved signal-to-noise ratio.
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 the signal-to-noise ratio by minimizing the interference from side lobes, improving the accuracy and reliability of LiDAR systems in object detection and ranging applications.
Implementation Method 1
the pattern of gaps between rows is aperiodic. This has the effect of spreading diffraction nodes beyond the O order, thus limiting the interference of diffracted nodes
Implementation Method 2
Each mirror has a reflective surface for intercepting the laser beam and redirecting it toward an environment to be detected
Data Source
AI summary
A micro-electromechanical system (MEMS) micro-mirror arrays with an aperiodic structure is described. This avoids the undesired noise of sidelobes generated by the gaps between rows of mirrors, where a periodic structure forms a diffraction pattern. A MEMS apparatus has a MEMS mirror array structure with a plurality of rows. The widths of the rows are sized to be different, so that the pattern of gaps between rows is aperiodic. This has the effect of spreading diffraction nodes beyond the 0 order, thus limiting the interference of diffracted nodes and improving the signal to noise ratio. In particular, the width of a mirror will vary in different rows, while all of the mirrors in a particular row will have the same width and same size.