MEMS Mirror Array for Light Steering Actuation Force Reduction
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Solution Overview
Problem
Conventional light steering systems using a single mirror for two-dimensional field of view (FOV) require high actuation force, leading to reduced reliability and increased risk of mechanical failure, as they need to match the mirror size with the light beam width, resulting in higher mass and inertia, and increased torque requirements for MEMS actuators.
Innovation Solution
The system employs a pair of rotatable mirrors with orthogonal axes of rotation, where each mirror can be independently optimized for actuation force, reducing the overall torque needed and distributing the burden across multiple mirrors, thereby enhancing reliability and precision while maintaining or improving the FOV and dispersion performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single large mirror is used to match the light beam width, then the field of view and dispersion performance are maintained, but the actuation force and torque requirements increase significantly
Solution Approach 1:
The patent divides the single large mirror into multiple smaller mirrors arranged in an array. Each mirror handles a portion of the light beam, reducing the size and mass of individual mirrors. This segmentation allows the use of smaller, more reliable MEMS actuators for each mirror while collectively maintaining the required field of view and beam width coverage.
2Reliability
If a single large mirror is used, then the FOV is maintained, but the mass and inertia of the mirror increase, requiring higher torque
Solution Approach 1:
The mirror array consists of multiple smaller mirrors instead of one large mirror. Each small mirror has reduced mass and inertia, making it easier and more reliable to actuate. The collective arrangement of these lightweight mirrors maintains the effective aperture and field of view equivalent to a single large mirror.
3Device complexity
If a single mirror is used for two-dimensional FOV, then the system is simpler, but the actuation system requires higher power and has single point of failure risk
Solution Approach 1:
The system uses multiple mirrors each actuated by independent low-power MEMS actuators. While this increases the number of components, each actuator requires significantly less power than a single large actuator would need. The distributed architecture eliminates single points of failure and improves overall system reliability.
4Force
If mirror size is reduced, then actuation force is reduced, but the ability to maintain FOV and dispersion performance is compromised
Solution Approach 1:
Multiple small mirrors are combined in an array configuration where their collective optical effect equals or exceeds that of a single large mirror. The coordinated actuation of all mirrors in the array maintains the required field of view and dispersion performance while each individual mirror requires minimal actuation force.
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 configuration reduces the actuation force and power required, increases the lifespan of MEMS actuators, and mitigates the risk of a single point of failure, resulting in improved reliability and performance of the light steering system by distributing the steering task across multiple smaller mirrors.
Implementation Method 1
Each micro-mirror can be rotated by a rotation angle to reflect (and steer) light from a light source towards at a target direction
Data Source
AI summary
Methods and systems for light steering are proposed. In one example, an apparatus comprises: a light source; a receiver; a microelectromechanical system (MEMS) and a controller. The MEMS comprises: an array of first rotatable mirrors to receive and reflect the light beam from the light source and a second rotatable mirror to receive the light beam reflected by the array of first rotatable mirrors. The controller is configured to rotate, respectively, the array of first rotatable mirrors and the second rotatable mirror to set a first angle of light path with respect to a first dimension and to set a second angle of the light path with respect to a second dimension orthogonal to the first dimension to perform at least one of: reflecting light from the light source along the light path, or reflecting input light propagating along the light path to the receiver.