Free-form Window Elements with Hermetic Soldered Edges

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Solution Overview

Problem

Existing methods for producing window elements with optical coatings are limited by the need for rectangular shapes, which restricts their adaptation to small-dimensioned sensors or detectors, and result in unsuitable series production due to high complexity and susceptibility to faults, with glued window elements being only quasi-hermetic and prone to gas permeability issues.

Innovation Solution

A method using high-energy beams to process the peripheral edge areas of carrier materials for free-form window elements with rounded edges, allowing for hermetic soldering and eliminating the need for additional adhesion promoter layers, thereby enabling the production of cost-effective, small-format, optically transparent window elements with flexible shapes that maintain low radiation penetration and long-term stability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If rectangular frame-shaped window elements are used, then ease of manufacture is improved, but adaptability to small-dimensioned sensors and detectors deteriorates

Engineering Contradiction:
Improveease of manufactureVSAvoidadaptability to sensors
Core Design Contradiction:
Ease of manufactureVSAdaptability or versatility

Solution Approach 1:

The patent transitions from symmetric rectangular window elements to asymmetric freeform window elements with customized shapes that precisely match the specific geometry of small-dimensioned sensors and detectors. This allows optimal adaptation to different sensor formats while maintaining manufacturability through standardized production processes.

Inventive Principle:
Principle #4Asymmetry

Solution Approach 2:

The patent enables continuous variation of window element parameters including shape, size, and edge geometry to match different sensor requirements. By changing the geometric parameters from fixed rectangular forms to customizable freeform shapes, the system achieves high adaptability while maintaining production efficiency.

Inventive Principle:
Principle #35Parameter changes

2Ease of manufacture

If adhesive layers are used to seal window elements, then ease of manufacture is improved, but hermetic sealing reliability deteriorates

Engineering Contradiction:
Improveease of manufactureVSAvoidhermetic sealing
Core Design Contradiction:
Ease of manufactureVSReliability

Solution Approach 1:

The patent replaces the chemical bonding mechanism of adhesive layers with a mechanical/thermal bonding mechanism using soldering. This substitution eliminates the gas permeability issues inherent in adhesive-based sealing while achieving superior hermetic sealing reliability, particularly important for vacuum-tight applications.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the bonding parameter from adhesive-based chemical bonding to solder-based thermal bonding. This parameter change fundamentally improves the hermetic sealing properties by creating a metal-to-metal or metal-to-ceramic connection that is impermeable to gas molecules, enabling true vacuum compatibility.

Inventive Principle:
Principle #35Parameter changes

3Adaptability or versatility

If individual production of small window elements is used, then adaptability to small sensors is improved, but productivity deteriorates

Engineering Contradiction:
Improveadaptability to small sensorsVSAvoidproductivity
Core Design Contradiction:
Adaptability or versatilityVSProductivity

Solution Approach 1:

The patent employs segmentation by producing multiple customized freeform window elements simultaneously on a single large substrate through scribing and breaking techniques. This allows individual customization of each window element's shape and size while maintaining high productivity through batch production, eliminating the need for time-consuming individual manufacturing.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent applies preliminary action by first creating scribe lines and fracture patterns on the complete substrate before actual separation. This preliminary structuring enables efficient breakdown into individual window elements, transforming a potentially complex individual production process into a streamlined batch operation.

Inventive Principle:
Principle #10Preliminary action

4Manufacturing precision

If peripheral edge areas are not removed, then manufacturing precision is maintained, but interference radiation increases

Engineering Contradiction:
Improvemanufacturing precisionVSAvoidinterference radiation
Core Design Contradiction:
Manufacturing precisionVSObject-affected harmful factors

Solution Approach 1:

The patent extracts the problematic peripheral edge areas surrounding the optical window elements through selective removal processes. By taking out these edge regions that cause stray light and interference radiation, the system eliminates harmful optical effects while preserving the precision of the remaining window element geometry through controlled removal processes.

Inventive Principle:
Principle #2Taking out (Extraction)

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 method ensures a permanently reliable, hermetically gas-tight or vacuum-tight soldered connection under alternating thermal loads while minimizing interference radiation, and allows for the production of free-form window surfaces with increased long-term stability and reduced production complexity.

Implementation Method 1

a) coating the optical coating (2) with a protective layer (3), which is etchable in the sense of a sacrificial protective layer for an etch-resistant optical coating (2), b) selective removal of the protective layer (3) and the optical coating (2) from the substrate (1) in the peripheral edge area (62) by local removal of a desired optically effective freeform surface (61)

Methodology Applied
Scientific EffectLaser ablation: Laser Ablation

Implementation Method 2

with rounded edges with radii R between 50 and 150 μm

Methodology Applied
Scientific EffectLaser processing: Laser

Data Source

PatentEP2997406B1Method for producing window elements that can be soldered into a housing in a hermetically sealed manner and free-form window elements produced in accordance with said method
Publication Date: 2021.09.29 JENOPTIK OPTICAL SYSTEMS GMBH
  • EP2997406B1 patent drawingFigure 1a~1f
  • EP2997406B1 patent drawingFigure 2a~2g
  • EP2997406B1 patent drawingFigure 3a~3g

AI summary

The invention relates to a method for producing window elements which can be soldered into a housing in a hermetically sealed manner and which have an optical coating, and to free-form window elements produced in accordance with the method. The problem of the invention, of finding an improved possibility for producing optical window elements which can be soldered into a housing in a hermetically sealed manner and which have an optical coating, said window elements permitting a permanently reliable gas- and vacuum-tight solder connection to a metal housing, is solved according to the invention in that, after the typical application of optical coatings (2), a protective layer (3) in the form of a sacrificial layer that can be etched is applied to the optical coating (2), both layer systems (2, 3) are selectively removed by means of a processing beam (4) of high-energy radiation in order to remove a desired optically active free-form surface (61) in the edge areas (62) thereof by local processing for window elements having an arbitrary geometric design, so that the protective layer remains on the optical coating as a lift-off mask, which is lifted off by an etching process that selectively attacks only the protective layer and not the optical coating after the application of a metallisation (7) for a solder layer (8), and the metallisation is retained only on the peripheral edge areas (62) that surround the free-form surfaces.