Multilayer Glass Stack Slicing for Precise Reflective Layer Orientation

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Solution Overview

Problem

Existing methods for fabricating optical components with complex structures, such as multilayered glass elements, struggle with precise separation and orientation of layers, which is crucial for achieving accurate image guidance and superimposition in near-eye displays.

Innovation Solution

A method and device for fabricating blanks from a compound glass stack by aligning the stack to cutting planes, using an autocollimator to adjust tilt angles and position, and cutting with a wire saw to ensure light-reflecting layers are centered and oriented correctly within the slices.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If conventional slicing methods are used without precise alignment, then the manufacturing process is simple and fast, but the orientation precision of light reflecting layers deteriorates

Engineering Contradiction:
Improveorientation precision of light reflecting layersVSAvoidalignment device complexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent applies preliminary action by performing alignment of the compound glass stack to the cutting planes before the actual slicing process. The autocollimator is used to adjust tilt angles and position of the stack in advance, ensuring that light reflecting layers are correctly oriented with respect to cutting planes before separation occurs. This preliminary alignment step guarantees precision in the final product without compromising the simplicity of the subsequent cutting operation.

Inventive Principle:
Principle #10Preliminary action

2Manufacturing precision

If alignment adjustment is performed before cutting, then the orientation of light reflecting layers is precise, but the manufacturing time increases

Engineering Contradiction:
Improveposition accuracy of light reflecting layersVSAvoidalignment adjustment time
Core Design Contradiction:
Manufacturing precisionVSLoss of time

Solution Approach 1:

The patent replaces manual alignment operations with an automated optical measurement and adjustment system. The autocollimator provides precise measurement of tilt angles and position, enabling automatic adjustment of the compound glass stack orientation. This substitution of mechanical alignment with optical-mechanical automated control reduces the time required for alignment while maintaining high position accuracy of light reflecting layers.

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

3Manufacturing precision

If the compound glass stack is not aligned to cutting planes, then the cutting process is faster and simpler, but the light reflecting layers are misoriented in the slices

Engineering Contradiction:
Improveorientation of light reflecting layersVSAvoidcutting process simplicity
Core Design Contradiction:
Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The patent introduces an intermediary alignment system consisting of the autocollimator and adjustment mechanisms that mediate between the compound glass stack and the cutting process. This intermediary device ensures that the stack is properly oriented relative to cutting planes before slicing begins, guaranteeing correct orientation of light reflecting layers in the final slices while maintaining cutting process simplicity through automated positioning.

Inventive Principle:
Principle #24Intermediary (Mediator)

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

Enhances the precision of slice separation, allowing for accurate orientation and positioning of light-reflecting layers, improving the functionality of optical components in near-eye displays.

Implementation Method 1

adjusting the tilt angles of the plane of the compound glass stack with respect to the cutting planes using an autocollimator

Methodology Applied
Scientific EffectAutocollimation:

Implementation Method 2

the slices are cut from the compound glass stack using a wire saw with a multitude of parallel sections of one or more cutting wires

Methodology Applied
Scientific EffectAbrasion: Abrasion

Data Source

PatentEP4501569B1Method and apparatus for slicing a multilayered glass element
Publication Date: 2025.11.19 LUMUS LTD
  • EP4501569B1 patent drawingFigure 1~3
  • EP4501569B1 patent drawingFigure 4~5(d)
  • EP4501569B1 patent drawingFigure 6(a)~8

AI summary

The invention concerns a method for fabricating blanks for light-guide optical elements (1) from a compound glass stack (3), the compound glass stack (3) comprising a multitude of glass plates (5) bonded together, wherein light reflecting layers (7) are arranged between the glass plates (5), wherein the method comprises cutting slices (9) from the compound glass stack (3) along parallel cutting planes (11). The compound glass stack (3) is aligned to the cutting planes (11) so that the light reflecting layers (7) have a defined orientation with respect to the side faces (13, 15) of the slices (9) after cutting. The compound glass stack (3) has a plane (16) having a defined orientation with respect to the light reflecting layers (7) within the compound glass stack (3), so that the light reflecting layers (7) within the slices (9) are correctly oriented when the cutting planes (11) run parallel to the plane (16) of the compound glass stack (3). The alignment of the compound glass stack (3) to the cutting planes (11) comprises - adjusting the tilt angles of the plane (16) of the compound glass stack (3) with respect to the cutting planes (11) using an autocollimator (22), and - adjusting the position of the compound glass stack (3) in a direction obliquely, preferably perpendicular to the cutting planes (11). The compound glass stack (3) is held fixed to a holder (23) in its aligned orientation and cut into slices (9), the slices (9) forming blanks for light-guide optical elements (1).