Arrayed MEMS Mirrors for LIDAR Aperture Scaling
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Solution Overview
Problem
Large aperture LIDAR systems face challenges in power requirements and torque needed to move mirrors quickly due to the moment of inertia and torque being proportional to the square of the mirror's radius, making it difficult to achieve high sensitivity and efficient photon collection.
Innovation Solution
The use of arrayed MEMS mirrors in LIDAR systems that scan in two dimensions, allowing for a fanned beam to be emitted and received, with synchronized movement of transmit and receive modules to increase the receive aperture without increasing power requirements, and adjustable angular extents to enhance angular resolution and range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the mirror size is increased to improve photon collection, then detection sensitivity is improved, but power requirements and torque increase significantly
Solution Approach 1:
The patent divides a single large mirror into multiple smaller MEMS mirrors arranged in an array. Each small mirror independently scans a portion of the field of view, collectively achieving the photon collection capability of a large mirror without the associated moment of inertia and power requirements. The segmentation allows parallel operation of multiple small mirrors to simulate the function of one large mirror.
Solution Approach 2:
The patent replaces a mechanical large mirror system with an array of small MEMS mirrors that use electrostatic actuation instead of mechanical torque. The MEMS mirrors utilize electric fields to achieve rapid scanning movements, substituting the mechanical torque-based system with an electrostatic field-based system that requires significantly less power.
2Measurement precision
If the mirror size is increased to improve photon collection, then detection sensitivity is improved, but torque requirements increase significantly
Solution Approach 1:
The patent segments the large mirror function into multiple small MEMS mirrors, each with negligible moment of inertia. The array of small mirrors collectively provides the aperture area of a large mirror while requiring minimal torque to actuate each individual mirror element.
Solution Approach 2:
The patent substitutes the mechanical torque-based large mirror actuation with electrostatic actuation of small MEMS mirrors. The electrostatic force generated by voltage application to the MEMS mirror electrodes provides sufficient torque for rapid scanning without the mechanical constraints of a large rotating mirror.
3Productivity
If the mirror speed is increased to improve scanning rate, then productivity is improved, but power requirements and torque increase significantly
Solution Approach 1:
The patent employs dynamic scanning patterns where the array of MEMS mirrors can independently adjust their scanning speeds and patterns. The system achieves high productivity through coordinated dynamic movement of multiple mirrors rather than relying on a single high-speed large mirror, allowing flexible adaptation to different scanning requirements.
Solution Approach 2:
The patent replaces the mechanical inertia-based high-speed mirror system with electrostatically actuated MEMS mirrors that can achieve high scanning rates with minimal power consumption. The electrostatic actuation mechanism allows for rapid acceleration and deceleration without the energy penalties associated with moving large masses at high speeds.
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 enables efficient photon collection and increased sensitivity while reducing power consumption and torque requirements, allowing for high-resolution scanning with improved range and angular resolution without the need for excessive power or torque.
Implementation Method 1
LIDAR mirrors are typically required to move very fast (up to many kHz), rotating about an axis to collect photons from different directions
Data Source
AI summary
A light detection and ranging system includes multiple scanning mirror assemblies to increase a receive aperture. The multiple scanning mirror assemblies are controlled to mimic the operation of one large scanning mirror. The multiple scanning mirror assemblies may be arranged in one-dimensional arrays or two-dimensional arrays. Two arrays of scanning mirror assemblies provide for scanning in two dimensions.