Bimorph Optical Element Lateral Piezo Bonding
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Solution Overview
Problem
Existing bimorph mirrors face challenges in stability and dimension limitations due to laminated structures, where ceramic elements are adhesively bonded parallel to the optical face, leading to limited curvature quality and thermal instability, especially when dimensions exceed ceramic element sizes.
Innovation Solution
A bimorph optical device with piezoelectric ceramic elements placed laterally on opposite sides of the optical element's neutral axis, allowing for compression and extension movements, eliminating the need for laminated structures and reducing thermal effects by bonding ceramics to lateral faces rather than the optical face.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If ceramic elements are adhesively bonded parallel to the optical face in a laminated structure, then the mirror can be manufactured with controlled curvature, but the structure becomes complex and thermally unstable with limited dimensions
Solution Approach 1:
The patent transitions from bonding ceramic elements parallel to the optical face (laminated structure) to bonding them laterally on the sides of the optical element. This dimensional repositioning eliminates the complex laminated structure while maintaining curvature control capability through pairs of opposite ceramics acting in opposition.
Solution Approach 2:
The patent uses pairs of asymmetrically positioned ceramic bars on opposite lateral faces of the optical element, with each pair comprising bars at different distances from the neutral axis. This asymmetric arrangement enables independent control of curvature while simplifying the overall structure compared to traditional laminated approaches.
2Manufacturing precision
If ceramic elements are adhesively bonded parallel to the optical face, then curvature can be controlled, but thermal stability deteriorates due to bimetal type effects
Solution Approach 1:
The patent employs pairs of ceramic bars positioned asymmetrically on opposite lateral faces at different distances from the neutral axis. This asymmetric configuration allows the opposing ceramics to counterbalance each other's thermal expansion effects, eliminating bimetal type thermal instability while preserving curvature control.
Solution Approach 2:
The opposing ceramic bars act as counterweights to each other, with one bar in compression and the other in extension. This counterbalancing arrangement compensates for thermal effects, as the symmetric-opposite positioning ensures that thermal expansions in one direction are offset by contractions in the opposite direction.
3Area of stationary object
If the mirror dimensions exceed ceramic element dimensions, then larger mirrors can be manufactured, but junctions between ceramic pieces become visible and reduce quality
Solution Approach 1:
The patent positions ceramic bars laterally on the sides of the optical element rather than end-to-end on the optical face. This repositioning in a different spatial dimension hides the junctions between ceramic pieces from the optical path, allowing larger mirror dimensions without compromising surface quality or visibility of seams.
4Stability of the object's composition
If pairs of opposite ceramics are placed on lateral faces, then thermal stability improves and junctions are hidden, but the device complexity increases
Solution Approach 1:
The opposing ceramic bars serve multiple functions simultaneously: they provide curvature control through differential expansion, counterbalance thermal effects through symmetric-opposite positioning, and hide junctions by being located on lateral faces rather than the optical surface. This multi-functionality reduces overall system complexity despite the paired configuration.
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 enhances the accuracy and stability of the mirror curvature, reduces visibility of ceramic junctions, and provides better thermal stability, enabling larger dynamic ranges without bimetal-type thermal effects.
Implementation Method 1
active elements made of piezoelectric ceramic that are actuated in opposition
Data Source
AI summary
The invention relates to a bimorph optical device comprising a deformable optical element and active elements made of piezoelectric ceramic provided with electrodes, said elements being controlled in pairs and in opposition so as to produce a compression movement for a first element of a pair and an extension movement for the second element of a pair, the device being characterized in that the optical element (1) presents an optically active first main surface (6) and a second main surface (7) opposite to the first main surface, together with at least first and second opposite lateral faces (2, 3), and in that the ceramic active elements comprise at least two pairs of bars (21, 22; 31, 32) of piezoelectric ceramic placed facing each other on said first and second lateral faces (2, 3), each pair comprising two bars (21, 22; 31, 32) placed on one of the first and second lateral faces (2, 3) on either side of a middle surface of the optical element (1) that constitutes the neutral axis thereof.