Deformable mirror with variable curvature and associated method of manufacturing a mirror

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Solution Overview

Problem

Existing deformable mirrors for adaptive optics require a large number of actuators, leading to complexity, high manufacturing costs, fragility, and difficulty in precision, making them expensive and prone to downtime due to actuator malfunctions and complex connections.

Innovation Solution

A deformable mirror design featuring a plate with primary and secondary portions of varying stiffness, where secondary portions are interposed between primary portions, and a limited number of actuators are used to exert force on the hidden face, allowing for precise deformation and correction of optical aberrations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If a large number of actuators are used to deform the mirror plate, then the deformation precision is improved, but the device complexity and manufacturing cost increase significantly

Engineering Contradiction:
Improvedeformation precisionVSAvoidactuator quantity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The mirror plate is segmented into multiple zones with different thickness profiles, allowing each zone to be independently controlled by fewer actuators. This segmentation enables precise deformation control while reducing the total number of actuators required, as each actuator controls a specific radial zone rather than requiring one actuator per mirror surface point.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Different regions of the mirror plate are given different local properties through variable thickness design. The plate has varying thickness from center to periphery, with specific thickness profiles in different radial zones that allow targeted deformation control. This local quality variation enables precise optical correction with minimal actuators by exploiting the different mechanical responses of different plate regions.

Inventive Principle:
Principle #3Local quality

2Manufacturing precision

If multiple actuators with complex connections are used, then the deformation control is improved, but the reliability decreases due to more connection points and potential failure modes

Engineering Contradiction:
Improvedeformation controlVSAvoidsystem reliability
Core Design Contradiction:
Manufacturing precisionVSReliability

Solution Approach 1:

The invention extracts and eliminates the complex connection network between multiple actuators and the mirror plate by reducing the actuator system to a single actuator with simple central connection. This extraction of unnecessary complexity maintains deformation control capability while significantly improving reliability by removing multiple potential failure points in the connection system.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The mirror plate's own structural properties (variable thickness profile) are utilized to enable self-deformation control. The plate's geometry is designed such that a single actuator applying force at the center can induce controlled deformation patterns across the entire plate surface, making the system self-regulating and eliminating the need for complex multi-actuator coordination systems.

Inventive Principle:
Principle #25Self-service

3Manufacturing precision

If a particular thickness profile according to complex mathematical formulas is used, then the optical precision is improved, but the manufacturing difficulty and cost increase

Engineering Contradiction:
Improveoptical precisionVSAvoidmanufacturing ease
Core Design Contradiction:
Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The invention changes the manufacturing parameters from requiring ultra-precise complex mathematical thickness profiles to using simpler, piecewise thickness variations that can be manufactured with standard techniques. The thickness profile is defined in discrete radial zones rather than as a continuous complex function, making it manufacturable with conventional precision while maintaining optical performance.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The invention accepts that the mirror plate may need replacement rather than investing in extremely complex and expensive manufacturing processes. By using simpler manufacturing methods that produce good enough (not perfect) thickness profiles, the system becomes more cost-effective, allowing economical replacement if needed rather than requiring flawless single-unit manufacturing.

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

4Manufacturing precision

If the plate thickness is precisely reduced according to radius, then the optical performance is improved, but the manufacturing time and scrap rate increase

Engineering Contradiction:
Improvethickness precisionVSAvoidmanufacturing productivity
Core Design Contradiction:
Manufacturing precisionVSProductivity

Solution Approach 1:

The continuous thickness variation is segmented into discrete radial zones with stepwise thickness changes. This segmentation allows manufacturing using standard stepped machining or molding techniques rather than requiring continuous precision material removal, dramatically reducing manufacturing time and increasing yield by avoiding the scrap associated with complex precision thickness profiling.

Inventive Principle:
Principle #1Segmentation

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 results in a reliable, compact, and cost-effective deformable mirror that is easy to install and adapt, capable of precise focusing or defocusing of optical beams with reduced actuator requirements, enhancing optical system performance and reducing manufacturing complexities.

Implementation Method 1

at least one actuator intended to exert a force on said hidden face to deform said plate

Methodology Applied
Scientific EffectMechanical Force: Mechanical Force

Data Source

PatentEP3392697B1Deformable mirror with variable curvature and associated method of manufacturing a mirror
Publication Date: 2021.03.31 ALPAO
  • EP3392697B1 patent drawingFigure 1
  • EP3392697B1 patent drawingFigure 2~3
  • EP3392697B1 patent drawingFigure 4~5

AI summary

The invention relates to a deformable mirror (1) comprising: - on the one hand, a plate (2) having a reflective face (4) and an opposite hidden face (5) and whose shape has a center (C) and radii (r), and - on the other hand, at least one actuator for exerting a force on said hidden face (5) to deform said plate (2), characterized in that said plate (2) comprises a plurality of primary (6) and secondary (7) portions, said secondary portions (7) being interposed between said primary portions (6), each of said primary portions (6) extending substantially locally along and on either side of a respective radius (r') among said radii (r), and having a stiffness different from that of said secondary portions (7) adjacent to it. The deformable mirror according to the invention is particularly intended for introducing or correcting optical aberration in a light beam.