Movable Mirror Segmentation for Fabry-Perot Filter Flatness
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Solution Overview
Problem
Existing Fabry-Perot interference filters face challenges in enhancing the flatness and durability of movable mirrors in the light transmission region during operation.
Innovation Solution
The solution involves forming multiple annular grooves and through-holes in the movable mirror to distribute stress and improve deformability, along with the use of additional electrodes and compensation electrodes to enhance electrostatic force control, ensuring the movable mirror remains flat and durable.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the movable mirror is made rigid to improve durability, then strength increases, but flatness upon driving deteriorates
Solution Approach 1:
The movable mirror is segmented into a light transmission region and a surrounding portion through annular grooves. The surrounding portion contains multiple through-holes that divide it into multiple regions, allowing independent deformation. This segmentation enables the light transmission region to maintain flatness while the surrounding portion absorbs stress through controlled deformation, resolving the contradiction between durability and flatness.
Solution Approach 2:
Different regions of the movable mirror are given different structural properties. The light transmission region is designed to remain flat and rigid for optical performance, while the surrounding portion is made more deformable through annular grooves and through-holes to absorb stress. This local differentiation allows the mirror to simultaneously achieve durability and flatness in different areas.
2Manufacturing precision
If the movable mirror is made flexible to improve flatness upon driving, then manufacturing precision improves, but durability deteriorates
Solution Approach 1:
The movable mirror is divided into a rigid light transmission region and a flexible surrounding portion with multiple through-holes. The surrounding portion's segmented structure allows it to flex and absorb stress during driving, preventing crack propagation and improving durability, while the light transmission region maintains its flatness for optical precision.
Solution Approach 2:
The structural parameters of the movable mirror are changed by introducing annular grooves and through-holes in the surrounding portion. These structural modifications alter the mechanical properties, making the surrounding portion more compliant while preserving the flatness and rigidity of the light transmission region, thus achieving both flatness and durability.
3Strength
If multiple annular grooves and through-holes are formed in the movable mirror to distribute stress, then durability improves, but device complexity increases
Solution Approach 1:
The movable mirror is segmented into a light transmission region and a surrounding portion with multiple through-holes. This segmentation distributes stress across multiple locations, preventing stress concentration and improving durability. The segmented structure is achieved through standard micromachining techniques, keeping manufacturing complexity manageable.
Solution Approach 2:
The surrounding portion of the movable mirror is designed with a porous-like structure containing multiple through-holes. This porous structure reduces the overall mass of the movable mirror, lowering the actuation force required and reducing stress during driving, thereby improving durability without significantly increasing manufacturing complexity.
4Manufacturing precision
If the surrounding portion is made easily deformable to enhance flatness, then manufacturing precision improves, but stress concentration increases reducing durability
Solution Approach 1:
The surrounding portion is segmented into multiple regions by through-holes, which prevents stress concentration in any single location. When the surrounding portion deforms to maintain flatness of the light transmission region, the stress is distributed across multiple segments rather than concentrated, thereby improving both flatness and durability simultaneously.
Solution Approach 2:
The movable mirror exhibits local quality differentiation where the light transmission region maintains high rigidity and flatness, while the surrounding portion is designed to be more deformable with multiple through-holes. This local quality variation allows the surrounding portion to absorb stress through controlled deformation without compromising the flatness or durability of the critical light transmission region.
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 significantly enhances the flatness and durability of the movable mirror in the light transmission region, maintaining resolution and reducing distortion due to stress and heat, while also optimizing the etching process for gap formation.
Implementation Method 1
the plurality of first through-holes opening to the gap side and the opposite side is formed at the surrounding portion surrounding the light transmission region in the movable mirror. This results in good balance of stress generated in the movable mirror upon driving.
Implementation Method 2
when a distance between the fixed mirror and the movable mirror in the light transmission region is adjusted by electrostatic force
Data Source
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AI summary
A Fabry-Perot interference filter 10A includes a fixed mirror 31 and a movable mirror 41 disposed opposite to the fixed mirror 31 via a gap S, distance between the fixed mirror 31 and the movable 41 in a light transmission region 11 being adjusted by electrostatic force. A plurality of first annular grooves 44 surrounding the light transmission region 11 and a plurality of first through-holes 45 opening to the gap S side and the opposite side are formed at a surrounding portion 41 a surrounding the light transmission region 11 in the movable mirror 41.