Deformable Mirrors for Variable Focal Length in X-Ray Optical Systems

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Solution Overview

Problem

Existing optical systems, such as KB type systems, face challenges in finely adjusting the focus point of high-energy radiation, particularly X-rays, EUV, or gamma rays, due to fixed mirror curvatures or complex actuator systems, which can lead to precision issues and potential mirror breakage.

Innovation Solution

An optical system with interchangeable mirrors and a deformation mechanism that allows for adjustable focal lengths by varying the width and curvature of the mirrors, enabling precise control of the focal distance through a control module that adjusts curvature parameters and positioning mechanisms.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If mirrors with fixed curvatures are used, then the optical system structure is simple, but the focus point cannot be finely adjusted

Engineering Contradiction:
Improveoptical system structureVSAvoidfocus point adjustment precision
Core Design Contradiction:
Device complexityVSMeasurement precision

Solution Approach 1:

The patent applies the dynamics principle by replacing fixed curvature mirrors with deformable mirrors that can dynamically change their curvature. The deformable mirror surface allows continuous adjustment of the focal length by varying the deformation amplitude, enabling precise focus point adjustment while maintaining a relatively simple overall system structure. This resolves the contradiction by introducing adaptability without requiring complex mechanical adjustment mechanisms.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent implements parameter changes by modifying the curvature parameter of the mirror surface through controlled deformation. By changing the deformation amplitude of the deformable mirror, the focal length parameter can be continuously adjusted within a predetermined range. This allows fine tuning of the focus point without adding complex mechanical components, thus resolving the contradiction between structural simplicity and adjustment precision.

Inventive Principle:
Principle #35Parameter changes

2Measurement precision

If flexible mirrors are used to adjust focus, then the focus point can be adjusted, but the mirrors may break due to excessive bending

Engineering Contradiction:
Improvefocus point adjustmentVSAvoidmirror integrity
Core Design Contradiction:
Measurement precisionVSReliability

Solution Approach 1:

The patent applies parameter changes by limiting the deformation amplitude to a predetermined range that does not cause mirror breakage. The deformation is controlled to vary only within safe boundaries, allowing focus adjustment while maintaining mirror integrity. This resolves the contradiction by achieving adjustability through controlled parameter variation rather than excessive bending.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent implements beforehand cushioning by designing the deformable mirror system with predetermined safety margins in the deformation range. The mirror structure is designed to withstand the maximum expected deformation without breaking, providing a cushion against failure before it occurs. This ensures reliable operation during focus adjustment while preventing mirror breakage.

Inventive Principle:
Principle #11Beforehand cushioning (Prior cushioning)

3Measurement precision

If mirrors with many actuators are used, then the focus point can be adjusted, but the system complexity increases significantly

Engineering Contradiction:
Improvefocus point adjustmentVSAvoidnumber of actuators
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent applies segmentation by dividing the mirror into multiple independent deformable segments or zones. Each segment can be controlled independently to achieve the desired focal length adjustment. This segmentation allows precise focus control with fewer actuators compared to traditional systems with many actuators, as each segment contributes to the overall deformation in a coordinated manner, reducing total system complexity.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent implements universality by designing the deformable mirror system where a single mirror structure performs multiple functions: it acts as both the optical reflecting surface and the adjustable focal element. The deformable mirror integrates the focusing function and the adjustment function into one component, eliminating the need for separate actuators for each function, thus reducing overall system complexity while maintaining adjustment precision.

Inventive Principle:
Principle #6Universality (Multi-functionality)

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 system achieves precise adjustment of focal lengths within a predetermined range, enhancing precision and reducing complexity, while being less sensitive to manufacturing inaccuracies and minimizing the risk of mirror breakage.

Implementation Method 1

the mirrors installed in such a system allow to reflect and concentrate high-energy rays at the focus point after reflection at grazing incidence

Methodology Applied
Scientific EffectGrazing incidence reflection: Reflection

Implementation Method 2

a deformation mechanism (41a, 41b) for each of the mirrors (12a, 12b) capable of generating an elliptical curvature of the mirror by generating a bending moment respectively M1, M2 on each of the ends (31, 32) of the mirror

Methodology Applied
Scientific EffectElastic deformation: Elasticity

Data Source

PatentEP3913418B1Optical system with variable focal distance and optical assembly comprising such a system
Publication Date: 2024.03.27 THALES SA
  • EP3913418B1 patent drawingFigure 1
  • EP3913418B1 patent drawingFigure 2
  • EP3913418B1 patent drawingFigure 3

AI summary

The present invention relates to a variable focal length optical system within a predetermined focal length range, comprising two mirrors (12a, 12b) and a mechanical assembly KB (13) having two supports (21a, 21b) adapted to support the mirrors (12a, 12) one after the other along their principal axis so as to form a propagation path (25). The system (10) is characterized in that each mirror (12a, 12b) has a working portion (30) whose width and/or thickness is/are variable and chosen according to said predetermined distance range, and in that, for each mirror (12a, 12b), it further comprises a deformation mechanism (41a, 41b) capable of generating a corresponding curvature of the mirror (12a, 12b) along its length to adjust the focal length within said predetermined distance range.