MEMS Mirror Axial Deflection Limiting
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Solution Overview
Problem
Existing laser beam deflection devices, particularly those using MEMS technology with electromagnetic drives, face challenges in maintaining high dynamics and accuracy while being susceptible to plastic deformation or breakage due to high axial forces during impacts.
Innovation Solution
Incorporating end stop arms with higher spring stiffness than the spring arms, positioned outside the drive-related tilting angle range, to limit axial deflection and prevent plastic deformation, along with a damper to absorb accelerations, ensuring the deflection remains within the elastic range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the spring membrane is designed to be very stiff to prevent plastic deformation and breakage during impacts, then the reliability and resistance to mechanical stress improve, but the dynamics (angular velocity and angular acceleration) and linearity of mirror tilting deteriorate
Solution Approach 1:
The spring membrane is designed with non-uniform geometry, featuring spring arms with specific configurations (straight, spiral, zigzag, or S-shaped) that provide localized flexibility where needed for dynamics, while the overall structure maintains sufficient stiffness to prevent catastrophic failure. This local variation in structural properties allows the membrane to be compliant during operation but resistant to permanent deformation under impact loads.
2Manufacturing precision
If the spring membrane is designed to be very stiff to maintain accuracy and prevent plastic deformation during impacts, then the manufacturing precision and reliability improve, but the device complexity increases due to the need for end stop arms and additional structural elements
Solution Approach 1:
The end stop arms are integrated directly into the spring membrane structure itself, forming a unified component rather than separate additions. This merging approach maintains the protective function against excessive deflection while minimizing the increase in device complexity, as the end stop arms are part of the same manufactured element as the spring arms.
Solution Approach 2:
The end stop arms are pre-positioned at specific locations along the movement path of the mirror component, establishing predetermined limits for axial deflection before impacts occur. This preliminary structural arrangement ensures that during high-g events, the deflection is naturally constrained within elastic ranges without requiring active control or complex additional mechanisms.
3Speed
If the spring membrane is made more flexible to achieve high dynamics, then the angular velocity and acceleration improve, but the susceptibility to plastic deformation and breakage during impacts worsens
Solution Approach 1:
The spring membrane utilizes a thin film structure with engineered spring arms that provide flexible, compliant behavior during normal operation, enabling high angular velocities and accelerations. The spring arms can be configured in various geometries (spiral, zigzag, S-shaped) to optimize flexibility while maintaining sufficient elastic range to absorb impact energies without permanent deformation.
Solution Approach 2:
The end stop arms function as pre-positioned cushioning elements that engage before plastic deformation can occur. These arms provide a mechanical stop that limits the maximum axial deflection of the spring membrane, effectively cushioning against excessive forces from impacts and preventing the membrane from entering the plastic deformation regime.
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 effectively prevents plastic deformation and breakage of the spring membrane, maintaining high accuracy and dynamics while minimizing forces during impacts by limiting axial deflection and absorbing accelerations, thus enhancing the device's resilience to mechanical stress.
Implementation Method 1
positioned in such a way that the maximum axial deflection of the spring membrane is limited to the elastic deflection range remains
Implementation Method 2
a magnetic or electrostatic drive for tilting the mirror against the restoring force of the spring arms
Implementation Method 3
a magnetic or electrostatic drive for tilting the mirror against the restoring force of the spring arms
Data Source
Figure 1a~2
Figure 3
Figure 4a~5
AI summary
In a device (1) for the two-dimensional deflection of a laser beam, comprising a substrate (4) with a substrate opening (5), a spring membrane (6) provided on the substrate (4), spring arms (7) extending into the substrate opening (5), and a central section (8) arranged in the substrate opening (5) and supported by the spring arms (7), which is mounted to be tiltable in two dimensions and axially displaceable in both directions (A, B) of the spring membrane central axis (9), a mirror (2) attached to the central section (8) of the spring membrane (6), and a magnetic or electrostatic drive (12) for tilting the mirror (2) against the restoring force of the spring arms (7), the invention provides for an axial deflection of the central section (8) beyond that caused by the drive-induced tilting of the mirror (2) by an end-stop device (15) which interacts with a component (3) rigidly attached to the mirror (2).limited at least in one axial direction (A).