Hologram Layer Transfer for Lightweight Optical Elements

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Solution Overview

Problem

The existing methods for manufacturing optical elements, such as diffraction elements in display devices, face challenges due to warping of hologram materials during interference exposure, which affects the formation of desired interference fringes and diffraction performance, and the use of glass substrates can lead to weight increase and potential breakage.

Innovation Solution

A method involving interference exposure of a hologram forming material on a glass substrate with a marking portion, followed by peeling and affixing the hologram layer to a plastic substrate with alignment marks for precise positioning, using reference and object light as spherical waves, and bonding with an adhesive to minimize warping and weight issues.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If a glass substrate is used to support the hologram material during interference exposure, then warping of the hologram material is suppressed and desired interference fringes can be formed, but the weight of the device increases and the glass substrate may break

Engineering Contradiction:

Improveinterference fringe formationVSAvoiddevice weight

Core Design Contradiction:

Manufacturing precisionVSWeight of moving object

Solution Approach 1:

The manufacturing process is divided into two separate stages: first forming the hologram layer on a glass substrate to ensure precise interference fringe formation, then peeling off the completed hologram layer and mounting it on a lightweight plastic substrate. This segmentation allows each substrate to serve its optimal function without the drawbacks of using glass throughout.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The glass substrate serves as a temporary intermediary medium during the hologram formation process, providing the necessary stability and flatness for precise interference exposure. After the hologram layer is formed, the glass substrate fulfills its purpose and is replaced by a lightweight plastic substrate, eliminating its weight disadvantage while preserving its manufacturing precision benefit.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Manufacturing precision

Engineering Contradiction:

Improveinterference fringe formationVSAvoidsubstrate durability

Core Design Contradiction:

Manufacturing precisionVSReliability

Solution Approach 1:

The process separates the hologram formation stage (using glass substrate for precision) from the final product stage (using plastic substrate for durability). The hologram layer is transferred between substrates, allowing each substrate to be optimized for its specific role without compromising overall reliability.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The glass substrate acts as a temporary intermediary that provides stability during the sensitive interference exposure process. Once the hologram is formed, the fragile glass substrate is replaced with a more durable plastic substrate, eliminating the breakage risk in the final product while maintaining manufacturing precision during production.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Manufacturing precision

If alignment marks are used to position the plastic substrate and hologram layer, then precise alignment is achieved, but additional manufacturing steps are required

Engineering Contradiction:

Improvealignment precisionVSAvoidmanufacturing process simplicity

Core Design Contradiction:

Manufacturing precisionVSEase of manufacture

Solution Approach 1:

Alignment marks are pre-formed on both the plastic substrate and the glass substrate before the hologram exposure process. This preliminary action ensures that when the hologram layer is transferred and mounted on the plastic substrate, precise alignment can be achieved quickly and easily by matching the pre-positioned marks, without requiring complex alignment procedures during assembly.

Inventive Principle:

Principle #10Preliminary action

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 warping effects, maintains desired diffraction performance, and provides a lightweight, impact-resistant optical element with improved alignment and bonding, effectively addressing the limitations of previous methods.

Implementation Method 1

interference exposure on the hologram forming material, thereby forming a hologram layer at the glass substrate

Methodology Applied

Scientific EffectPhotopolymerization: Photopolymerisation

Implementation Method 2

a hologram layer having interference fringes is formed by performing interference exposure using laser light

Methodology Applied

Scientific EffectDiffraction: Diffraction

Data Source

PatentUS11709362B2Method for manufacturing optical element, optical element and display device

Publication Date: 2023.07.25 SEIKO EPSON CORP

AI summary

A method of manufacturing an optical element including, a first step of, after affixing a hologram forming material to a glass substrate having a marking portion, performing interference exposure on the hologram forming material, thereby forming a hologram layer at the glass substrate, and a second step of affixing the hologram layer peeled off from the glass substrate to a plastic substrate having a first alignment mark, wherein in the second step, the first alignment mark on the plastic substrate, and a second alignment mark formed at a position corresponding to the marking portion in the hologram layer during the interference exposure are used to implement positioning of the plastic substrate and the hologram layer.