MEMS Mirror Arrangement With Tunable Dual-Axis Sweep Control
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Solution Overview
Problem
MEMS mirrors in LIDAR systems suffer from pixel inaccuracies and image distortion due to non-uniform scanning density in Raster and Lissajous scanning modes, with more points scanned near the edges and fewer in the center, leading to poor image quality.
Innovation Solution
A MEMS mirror arrangement with a fixed structure, a mirror attached via a suspension, and sets of actuators controlled by superimposed electrical signals with tunable frequencies to achieve 2-axis movement, compensating for non-ideal time-spread of measurement points and enhancing scanning accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If Raster or Lissajous scanning modes are used with MEMS mirrors, then the scanning coverage is complete, but the scanning points are non-uniformly distributed with higher density at edges and lower density at center, causing pixel inaccuracies and image distortion
Solution Approach 1:
The patent applies dynamics by making the scanning pattern adaptable and variable rather than fixed. The Lissajous scanning mode uses adjustable frequency ratios between orthogonal oscillations, allowing the scanning trajectory to be dynamically tuned to achieve uniform point distribution. This dynamic adjustment resolves the contradiction by enabling the system to adapt its scanning behavior to compensate for the inherent non-uniformity of traditional patterns.
Solution Approach 2:
The patent changes the parameters of the scanning motion by introducing adjustable frequency ratios in the Lissajous pattern. By modifying the frequency relationship between the x and y axis oscillations, the scanning trajectory transforms from the conventional edge-heavy distribution to a more uniform distribution across the field of view. This parameter adjustment directly addresses the pixel accuracy issue while maintaining complete scanning coverage.
2Productivity
If conventional scanning modes are used, then the scanning speed is high, but the image quality deteriorates due to non-uniform point distribution
Solution Approach 1:
The dynamic Lissajous scanning pattern allows the system to maintain high scanning speeds while improving image quality. By adjusting the frequency ratios, the patent creates a scanning trajectory that distributes points uniformly across the entire field, including the center region. This eliminates the need to reduce scanning speed to achieve uniform coverage, thus resolving the contradiction between productivity and measurement precision.
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 improved scanning modes with higher pixel accuracy in the central area of the image by uniformly distributing scanning points, reducing distortions and enhancing image quality.
Implementation Method 1
a first set of actuators connected to the mirror and a second set of actuators connected to the mirror, the first set of actuators and the second set of actuators each being configured to move the mirror in relation to the xy-plane
Implementation Method 2
the mirror having a zero-position and being configured to reflect a light beam
Data Source
AI summary
An arrangement is provided for highly versatile sweep motion control of MEMS mirrors. The arrangement provides for controlling the 2-axis movement of MEMS mirrors via superimposed first set and second set of electrical signals having tunable frequencies. Moreover, mirror motion may be used to compensate for the non-ideal time-spread of measurement points.