Edge-Constrained Optical Membrane Deformable Mirror
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Solution Overview
Problem
Deformable mirrors face issues with ripple effects and surface accuracy due to lap normal and shear forces during polishing, which constrain actuator design and membrane flexibility, leading to suboptimal surface finishes and limited inter-actuator stroke.
Innovation Solution
An edge-constrained optical membrane deformable mirror design featuring actuators supported by a stiffer support structure, with an optical membrane elastically decoupled to accommodate polishing forces, allowing for higher aspect ratios and thinner, more flexible membranes, and improved sealing during lapping.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the membrane is edge constrained more rigidly to reduce rippling during polishing, then the ripple effect is reduced, but when the clamping force is released the mirror surface loses surface accuracy and more polishing is necessary
Solution Approach 1:
A compliant shim is introduced as an intermediary element between the membrane and the rigid clamp. The shim has sufficient stiffness to resist polishing loads and reduce rippling, yet is compliant enough to allow the membrane to maintain its polished shape after clamping is released, eliminating the need for repeated polishing
Solution Approach 2:
The stiffness parameter of the support structure is optimized to provide adequate rigidity during polishing to prevent rippling, while the compliant shim provides controlled compliance to maintain surface accuracy after polishing. This parameter optimization resolves the contradiction between reducing ripple and maintaining surface accuracy
2Length of moving object
If longer, thinner actuators are used to produce more compact deformable mirrors with long stroke, then the mirror becomes more compact with higher authority, but the actuators lack sufficient stiffness to withstand polishing forces without distortion
Solution Approach 1:
The support structure is segmented into a rigid portion that provides overall structural support and stiffness during polishing, and a compliant portion that allows actuator movement. This segmentation enables long-stroke actuators to maintain sufficient stiffness during polishing while achieving their full stroke range during operation
Solution Approach 2:
Different regions of the support structure have different stiffness properties: the region supporting the actuators during polishing is made rigid to withstand polishing forces, while the region allowing actuator movement is made compliant to enable long stroke. This local quality differentiation resolves the contradiction between actuator length and stiffness
3Manufacturing precision
If the shim is made more stiff to reduce rippling, then the ripple effect is reduced, but the membrane becomes vulnerable to damage and the clamping force causes relaxation loss of surface accuracy
Solution Approach 1:
The shim stiffness parameter is optimized to provide adequate rigidity to resist polishing loads and reduce rippling, while remaining compliant enough to allow the membrane to maintain its polished shape after clamping is released. This optimal parameter selection prevents both rippling and relaxation damage
Solution Approach 2:
The compliant shim acts as a mediator between the rigid clamp and the delicate membrane, providing sufficient support to prevent rippling while being gentle enough to prevent membrane damage and maintain surface accuracy after polishing
4Adaptability or versatility
If thinner membranes are used to increase flexibility and eliminate inter-actuator stroke limits, then the membrane becomes more flexible, but the membrane lacks sufficient stiffness to withstand polishing forces
Solution Approach 1:
The support structure provides localized rigid support to thin membranes during polishing, while allowing flexibility during actuator operation. This local quality differentiation enables thin, flexible membranes to withstand polishing forces without requiring increased overall membrane thickness
Solution Approach 2:
The support structure acts as an intermediary that provides temporary rigid support to thin membranes during the polishing process, enabling them to withstand polishing forces, while allowing them to remain flexible during operational actuation
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 design reduces ripple distortion, enables higher accuracy finishes, and increases inter-actuator stroke, maintaining surface accuracy without relaxation after polishing, with improved sealing and reduced liquid absorption.
Implementation Method 1
an intermediate area elastically decoupling the first and second areas of the optical membrane
Implementation Method 2
bonded to the actuators using a bonding medium such as epoxy
Data Source
AI summary
Fabricating a deformable mirror by providing a plurality of actuators and a support structure supporting and at least partially surrounding the actuators; applying an optical membrane across the actuators and at least a portion of the support structure; the optical membrane including a first area, a second area and an intermediate area elastically decoupling the first and second areas; bonding the first area to the actuators and the second area to the support structure; and polishing the optical membrane.