Soldered Reflective Optical Element for Laser Beam Deflection

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Solution Overview

Problem

Current reflective optical elements for dynamic laser beam deflection are expensive to manufacture and have limited geometrical flexibility due to complex surface machining requirements, leading to two-part designs with problematic adhesive connections and thermal resistance issues.

Innovation Solution

A single-part reflective optical element is created using a solder connection between a base body and a plate-shaped reflective element, where the reflective element is made from materials like silicon with a low thermal expansion coefficient, and the base body can be made from various materials, including metals and ceramics, with integrated cooling features and a thin, elastically deformable design, allowing for optimized mechanical and thermal performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If complex surface machining (e.g., glaze milling) is performed to achieve high reflectance, then reflectance is improved, but manufacturing cost and complexity increase substantially

Engineering Contradiction:
ImprovereflectanceVSAvoidmanufacturing complexity
Core Design Contradiction:
Illumination intensityVSDevice complexity

Solution Approach 1:

The reflective optical element is divided into two separate components: a base body and a plate-shaped reflective element. The base body can be manufactured using simpler processes, while the reflective element is separately prepared with the required optical surface properties, then joined to the base body. This segmentation allows each component to be optimized independently, reducing overall manufacturing complexity while maintaining high reflectance.

Inventive Principle:
Principle #1Segmentation

2Ease of manufacture

If two-part design with adhesive connection is used to simplify manufacturing, then ease of manufacture is improved, but thermal resistance increases and service life decreases

Engineering Contradiction:
ImprovemanufacturabilityVSAvoidservice life
Core Design Contradiction:
Ease of manufactureVSReliability

Solution Approach 1:

The joining method is changed from adhesive bonding to soldering. This parameter change in the joining process enables direct metallic bonding between the base body and reflective element, which provides superior thermal conductivity and mechanical strength compared to adhesives. The soldered joint maintains thermal pathways essential for heat dissipation while ensuring long-term reliability under thermal and mechanical loads.

Inventive Principle:
Principle #35Parameter changes

3Ease of manufacture

If two-part design is used to avoid complex machining, then ease of manufacture is improved, but precision and stiffness are compromised

Engineering Contradiction:
ImprovemanufacturabilityVSAvoidalignment precision
Core Design Contradiction:
Ease of manufactureVSManufacturing precision

Solution Approach 1:

The plate-shaped reflective element is prepared in advance with precise dimensions and surface properties before joining to the base body. This preliminary preparation includes cutting from silicon wafers or other optical materials with controlled thickness and surface quality. By pre-processing the reflective element to exact specifications, the subsequent joining process becomes simpler while maintaining high precision, as the critical dimensions are already established before assembly.

Inventive Principle:
Principle #10Preliminary action

4Strength

If thick reflective element is used to increase mechanical strength, then strength is improved, but thermal conductivity and responsiveness decrease

Engineering Contradiction:
Improvemechanical strengthVSAvoidthermal response
Core Design Contradiction:
StrengthVSTemperature

Solution Approach 1:

The reflective element is designed as a thin plate structure with optimized thickness. This thin-film approach reduces thermal mass and improves thermal responsiveness, allowing rapid heat dissipation from the reflective surface. The thin plate geometry is supported by the soldered connection to the base body, which provides mechanical strength and thermal conduction pathways, enabling the thin reflective element to achieve both mechanical adequacy and thermal performance.

Inventive Principle:
Principle #30Flexible shells and thin films

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 reduces manufacturing costs, enhances thermal conductivity, and improves mechanical strength and stiffness, enabling flexible geometrical designs and reduced thermal strain, while maintaining high reflectance and precision, thus addressing the limitations of existing technologies.

Implementation Method 1

a surface of a base body and a plate-shaped reflective element are connected to one another in a planar manner and with material continuity by means of a solder connection

Methodology Applied
Scientific EffectSoldering: Soldering

Implementation Method 2

Silicon has a good thermal conductivity so that an effective cooling can be reached

Methodology Applied
Scientific EffectThermal conduction: Conduction (thermal)

Data Source

PatentUS9588338B2Reflective optical element for a dynamic deflection of a laser beam and method for manufacture thereof
Publication Date: 2017.03.07 FRAUNHOFER GESELLSCHAFT ZUR FORDERUNG DER ANGEWANDTEN FORSCHUNG EV

AI summary

The invention relates to reflective optical elements for a dynamic deflection of a laser beam and to a manufacturing method for these reflective elements. It is the object of the invention to provide reflective optical elements for a dynamic deflection of laser beams which can be manufactured less expensively and which are flexible in their geometrical design so that they achieve improved properties in dynamic operation. In the reflective optical element in accordance with the invention, a surface of a base body and a plate-shaped reflective element are connected to one another in a planar manner and with material continuity by means of a solder connection.