Lateral Piezoelectric Bimorph for Optical Precision
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Solution Overview
Problem
Existing bimorph mirrors with laminated structures face limitations in dimension, polishing quality, and thermal stability due to the assembly of ceramic elements on parallel optical faces, leading to stability issues and visible junctions that affect curvature and precision.
Innovation Solution
A bimorph optical device with piezoelectric ceramic elements arranged laterally on opposite sides of the optical element, eliminating the laminated structure and using opposing pairs of ceramic bars to create curvature through length variation, rather than direct curvature of the ceramics, ensuring better coupling, stability, and thermal symmetry.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If ceramic elements are bonded on a face parallel to the optical face to form a laminated structure, then the mirror can be actuated to change curvature, but the manufacturing complexity increases and the polishing quality is limited
Solution Approach 1:
The patent transitions from bonding ceramics on the optical face (parallel arrangement) to bonding them on lateral faces (perpendicular arrangement). This dimensional change eliminates the laminated structure that limits polishing quality while maintaining the actuation function through lateral coupling of ceramic bars to the mirror body.
2Area of stationary object
If the mirror dimensions are larger than the ceramic elements, then larger mirrors can be constructed, but junctions between ceramic pieces become visible and affect curvature stability
Solution Approach 1:
By moving the ceramic bonding location from the optical face to the lateral faces, the patent positions junctions out of the optical path. This allows larger mirror constructions without visible junctions affecting curvature stability, as the ceramic connections are now on the sides rather than on the optical surface.
3Reliability
If bimorph ceramic bars are used with a laminated structure, then the mirror can be actuated, but thermal stability is limited by the bimetal effect
Solution Approach 1:
The patent extracts the ceramics from the laminated structure and positions them laterally on the sides of the mirror. This removes the source of bimetallic thermal effects that occur when different ceramic layers expand differently with temperature changes, thereby improving thermal stability while maintaining actuation capability.
4Reliability
If ceramics are bonded laterally on the sides of the optical element, then thermal stability and polishing quality improve, but the coupling between ceramic and mirror must be optimized
Solution Approach 1:
The patent incorporates coupling elements directly into the lateral faces of the optical element during manufacturing, before the ceramic bars are bonded. This preliminary preparation of coupling surfaces simplifies the subsequent ceramic attachment process and ensures optimized mechanical coupling without requiring complex post-manufacturing adjustments.
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 precision, stability, and thermal stability by maximizing ceramic-mirror interaction, reducing visible junctions, and allowing for larger mirror dimensions with improved curvature distribution and reduced bimetallic thermal effects.
Implementation Method 1
active elements in piezoelectric ceramic provided with electrodes, these elements being controlled in pairs in opposition to produce a displacement in compression for a first element of a pair and a displacement in extension for the second element of a pair
Implementation Method 2
the action on the ceramic bars causes their variation in length. It is the reaction of the bar to this variation in length which creates the curvature
Data Source
Figure 1~3
Figure 4a~5
Figure 6a~6c
AI summary
The Invention relates to a bimorphic optical device comprising a deformable optical element and piezoelectric ceramic active elements provided with electrodes, these elements being controlled in opposing pairs to produce a compressive displacement for a first element of a pair and an extractive displacement for the second element of a pair, characterized in that the optical element (1) has a first optically active principal surface (6) and a second principal surface (7) opposite the first principal surface, as well as at least a first (2) and a second (3) opposing lateral faces, and in that the ceramic active elements comprise at least two pairs of piezoelectric ceramic bars (21, 22; 31, 32) arranged opposite each other on said first (2) and second (3) lateral faces, each pair (21, 22;31, 32) comprising two bars arranged on one of the first (2) and second (3) lateral faces on either side of a median surface of the optical element (1) which constitutes its neutral fiber.;