Additive Manufacturing of Lightweight Optical Mirrors with Integrated Cooling Channels

Resolve Bottlenecks,
Find Innovative Solutions
Generate Solutions

Solution Overview

Problem

Existing methods for manufacturing lightweight optical mirrors struggle to achieve a balance between reduced weight and mechanical stiffness while incorporating cooling channels, often requiring complex processes and high costs.

Innovation Solution

A method involving iterative deposition and sintering of metallic powder layers, allowing for the formation of hollow mirror bodies with desired three-dimensional shapes and integrated cooling channels, enabling high mass reduction and mechanical stiffness with a simplified and cost-effective process.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Weight of moving object

If the mirror is made hollow or manufactured from separate components to reduce weight, then the weight is reduced, but the manufacturing process becomes more complex and mechanical stresses increase

Engineering Contradiction:
Improveweight of optical mirrorVSAvoidmanufacturing process complexity
Core Design Contradiction:
Weight of moving objectVSDevice complexity

Solution Approach 1:

The mirror is divided into multiple layers of metallic powder that are deposited and sintered iteratively. Each layer can be independently controlled to form the desired hollow structure, allowing complex geometries to be created through systematic layer-by-layer construction rather than assembling separate components

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The density of the metallic powder is controlled to be between 0.2 and 0.6 times the density of the bulk material, enabling the formation of hollow structures with optimized weight-to-stiffness ratios. The iterative deposition process allows precise control over the internal cavity geometry while maintaining structural integrity

Inventive Principle:
Principle #35Parameter changes

2Shape

If cavities are formed by cutting, drilling or grinding into a solid block, then the cavities can be created, but the cavities cannot be given desired shapes and the mechanical stiffness to weight ratio is not optimized

Engineering Contradiction:
Improvecavity shapeVSAvoidmechanical stiffness
Core Design Contradiction:
ShapeVSStrength

Solution Approach 1:

The desired cavity shapes are built into the structure during the iterative deposition process itself, rather than being created afterward by subtractive manufacturing. The metallic powder is deposited layer by layer with controlled density to form the exact three-dimensional cavity geometry required, optimizing both shape and mechanical properties simultaneously

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The mirror structure uses composite construction with varying density metallic powder throughout. The internal cavities are formed by regions of lower density powder, creating a composite structure that optimizes the ratio of mechanical stiffness to weight while achieving complex three-dimensional cavity shapes

Inventive Principle:
Principle #40Composite materials

3Weight of moving object

If separate components are joined to create hollow mirror structures, then weight is reduced, but long term stability and thermal conductivity are negatively influenced

Engineering Contradiction:
Improveweight of optical mirrorVSAvoidlong term stability
Core Design Contradiction:
Weight of moving objectVSReliability

Solution Approach 1:

The hollow mirror structure is created as a single monolithic piece through iterative deposition and sintering of metallic powder layers. This eliminates all joints between separate components, ensuring uniform thermal conductivity throughout the structure and maintaining long-term stability without the degradation that occurs at joints

Inventive Principle:
Principle #5Merging (Combining)

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 approach results in lightweight optical mirrors with enhanced mechanical stiffness, reduced inertial forces, and efficient thermal management, making them suitable for applications like space telescopes and scanning experiments.

Implementation Method 1

applying, for each of the layers, heat at least in a subarea of this layer, thereby fusing or sintering the powder in this subarea and bonding it to a previously deposited layer

Methodology Applied
Scientific EffectSintering: Sintering

Data Source

PatentEP2739998B1Method for manufacturing a mirror comprising at least one cavity and optical mirror
Publication Date: 2017.10.11 FRAUNHOFER GESELLSCHAFT ZUR FORDERUNG DER ANGEWANDTEN FORSCHUNG EV
  • EP2739998B1 patent drawingFigure 1a~1b
  • EP2739998B1 patent drawingFigure 1c~1d
  • EP2739998B1 patent drawingFigure 2~3

AI summary

The invention relates to a method for manufacturing a light weight optical mirror (1) or a mirror (1') comprising at least one cooling channel, the method comprising : - forming a mirror body (2) by ° iteratively depositing a metallic powder in layers (4a, 4b, 4c) and °applying, for each of the layers (4a, 4b, 4c), heat at least in a subarea (5a, 5b, 5c) of this layer (4a, 4b, 4c), thereby fusing or sinterin the powder in this subarea (5a, 5b, 5c) and bonding it to a previously deposited layer (4a, 4b, 4c), the powder remaining in an unfused state in at least one region (6), the method further comprising forming at least one cavity (7) within the carrier (2) by removing the unfused powder from said region (6) and producing a mirror surface (8) at a closed surface (9) of the mirror body (2). The invention further relates to an optical mirror (1) and to an optical device.