Soft Coupling Section for Bubble-Free Hologram Production

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Solution Overview

Problem

The production of volume reflection holograms with substrate-guided reconstruction beams faces challenges in achieving good optical contact between the coupling element, carrier element, and holographic recording medium, particularly in industrial-scale mass production, due to the complexity and safety concerns associated with using index match liquids.

Innovation Solution

A device with a coupling section made of a material having a shear modulus between 1000 Pa and 50 MPa, allowing for mechanical establishment of bubble-free optical contact without index match liquids, enabling reversible and residue-free coupling and decoupling for efficient industrial-scale production.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If index match liquids are used to establish optical contact between coupling element and holographic recording medium, then good optical contact is achieved, but safety concerns and process complexity increase

Engineering Contradiction:
Improveoptical contact qualityVSAvoidsafety concerns
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent removes index match liquids from the optical coupling process entirely. Instead of using liquid mediators, the invention employs direct mechanical contact between the coupling element and holographic recording medium, eliminating the harmful factor (chemical liquids requiring safety precautions) while maintaining reliable optical contact through precision mechanical design.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent introduces a coupling element with specific mechanical properties (soft material with defined elasticity) as an intermediary between the light beam path and the holographic recording medium. This solid intermediary replaces the liquid index match medium, providing both mechanical support and optical coupling functionality without the safety issues of chemical liquids.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Reliability

If index match liquids are used for optical coupling, then good optical contact is achieved, but production efficiency decreases due to complex handling and removal processes

Engineering Contradiction:
Improveoptical contact qualityVSAvoidproduction efficiency
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

By extracting index match liquids from the process, the patent eliminates the time-consuming steps of liquid application, positioning, and removal. The solid coupling element enables direct mechanical assembly and disassembly, dramatically improving production throughput while maintaining optical contact quality.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The coupling element is designed with self-aligning and self-lubricating properties through its material selection (soft material with specific elasticity). This allows the coupling element to automatically establish and maintain optimal optical contact without requiring external assistance from index match liquids or complex positioning mechanisms, thereby improving production efficiency.

Inventive Principle:
Principle #25Self-service

3Productivity

If mechanical coupling without index match liquids is used, then production efficiency improves, but achieving bubble-free optical contact becomes difficult

Engineering Contradiction:
Improveproduction efficiencyVSAvoidoptical contact quality
Core Design Contradiction:
ProductivityVSManufacturing precision

Solution Approach 1:

The patent changes the material parameters of the coupling element, specifically selecting soft materials with defined elasticity and compliance. These parameter changes enable the coupling element to conform to the holographic recording medium surface, excluding air bubbles while maintaining mechanical stability and optical quality without requiring index match liquids.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The coupling element is designed as a flexible component with specific thickness and elasticity characteristics. This flexible structure allows it to adapt to surface irregularities and maintain intimate contact with the holographic recording medium, ensuring bubble-free optical coupling while enabling easy assembly and disassembly for high-volume production.

Inventive Principle:
Principle #30Flexible shells and thin films

4Ease of manufacture

If reusable coupling elements are used, then cost efficiency improves, but achieving consistent optical contact across multiple uses becomes challenging

Engineering Contradiction:
Improvecost efficiencyVSAvoidoptical contact consistency
Core Design Contradiction:
Ease of manufactureVSReliability

Solution Approach 1:

The patent selects material parameters (elasticity, compliance, surface properties) for the coupling element that maintain their functional characteristics over repeated use cycles. The soft material with defined elasticity returns to its original shape after each coupling event, ensuring consistent optical contact quality across multiple uses without degradation, thereby achieving both cost efficiency and reliability.

Inventive Principle:
Principle #35Parameter changes

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

Enables efficient and bubble-free optical coupling and decoupling, eliminating the need for index match liquids, improving safety and production efficiency, and allowing for high-throughput industrial-scale production of volume reflection holograms with substrate-guided reconstruction beams.

Implementation Method 1

at least the coupling section is made of a material with a shear modulus between 1000 Pa and 50 MPa, preferably between 30,000 Pa and 30 MPa

Methodology Applied
Scientific EffectPressure: Pressure Increase

Implementation Method 2

at least the coupling section is made of a material with a shear modulus between 1000 Pa and 50 MPa, preferably between 30,000 Pa and 30 MPa

Methodology Applied
Scientific EffectElasticity: Elasticity

Data Source

PatentEP3394681B1Device and method for the production of volume reflection holograms with substrate-guided reconstruction beams
Publication Date: 2025.01.08 COVESTRO DEUTSCHLAND AG
  • EP3394681B1 patent drawingFigure 1~2
  • EP3394681B1 patent drawingFigure 3~4
  • EP3394681B1 patent drawingFigure 5~6

AI summary

The invention relates to a device (200, 300, 400, 600) for producing volume reflection holograms with substrate-guided reconstruction beams, comprising the following: at least one flat transparent support element (210, 310, 410, 610) with a first flat face (210.1) and an additional flat face (210.2), at least one master element (206, 306, 406, 606) which can be arranged on the first flat face (210.1) of the support element (210, 310, 410, 610), and at least one optical incoupling element (102, 202, 302, 402, 602) which is designed to optically couple in a light beam (214, 216). At least one coupling section (104, 204, 304, 404, 604) is provided which is designed to mechanically produce an optical contact between the incoupling element (102, 202, 302, 402) and at least one holographic recording medium (208, 308, 408) that can be provided on the additional flat face (210.2) of the support element (210, 310, 410) or which is designed to mechanically produce an optical contact between the additional flat face of the support element (610) and at least one holographic recording medium (608) that can be provided on a flat face (605) of the optical incoupling element (602). At least the coupling section (104, 204, 304, 404, 604) is made of a material with a shear modulus between 1000 Pa and 50 MPa, preferably between 30000 Pa and 30 MPa.