Optical Element Manufacturing Low Surface Roughness Adhesive
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Solution Overview
Problem
Augmented reality (AR) glasses often experience image blurriness due to the use of adhesives for bonding diffraction elements to light guide plates, which scatter diffracted light and prevent clear image display.
Innovation Solution
A method of manufacturing optical elements involving the formation of liquid crystal layers with specific alignment patterns and adhesive layers with low surface roughness, ensuring precise bonding between light guide plates and liquid crystal layers to maintain image clarity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If adhesive is used to bond diffraction element to light guide plate, then bonding is achieved, but light scattering occurs causing image blurriness
Solution Approach 1:
The patent removes the adhesive layer from the optical path by bonding the diffraction element directly to the light guide plate substrate without any adhesive material in between. This extraction of the harmful adhesive eliminates light scattering while maintaining bonding strength through direct contact and refraction-based coupling.
Solution Approach 2:
The patent introduces a refractive index matching layer as an intermediary between the diffraction element and light guide plate. This mediator has a refractive index that bridges the gap between the two materials, enabling effective light coupling and bonding without using adhesive materials that cause scattering.
2Strength
If adhesive layer is formed for bonding, then bonding is achieved, but surface roughness increases causing light scattering
Solution Approach 1:
The patent extracts the adhesive layer entirely from the bonding interface, replacing it with direct substrate-to-diffraction element contact. This eliminates the source of surface roughness while maintaining bonding through mechanical adhesion and refraction coupling at the interface.
Solution Approach 2:
The patent changes the bonding mechanism from chemical adhesive bonding to physical refraction-based bonding. By adjusting the refractive index parameters of the materials and interface design, achieving bonding without requiring adhesive layers that inherently create surface roughness.
3Ease of manufacture
If conventional bonding method is used, then manufacturing is simplified, but diffracted light intensity varies excessively
Solution Approach 1:
The patent uses a refractive index matching layer as a mediator that ensures uniform light transmission across the bonding interface. This intermediary layer compensates for manufacturing tolerances and maintains consistent diffracted light intensity while keeping the manufacturing process relatively simple.
Solution Approach 2:
The patent optimizes the refractive index parameter of the bonding interface to maximize light transmission uniformity. By carefully selecting and controlling the refractive index of the materials and interface layer, the system achieves consistent diffracted light intensity without complex manufacturing procedures.
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
The method ensures that diffracted light intensity variation is within ±40%, preventing blurriness and allowing for clear image display in AR glasses by minimizing surface roughness and scattering of light.
Implementation Method 1
light (projection light) projected from a display is diffracted (refracted) using a diffraction element to be incident into one end part of a light guide plate
Implementation Method 2
bonding using an adhesive such as a pressure sensitive adhesive is considered as a method of bonding the diffraction element to the light guide plate
Implementation Method 3
performing first exposure by performing interference exposure on a surface of the first photo-alignment film to form, on the first photo-alignment film, an alignment pattern in which a direction of an optical axis derived from a liquid crystal compound changes while continuously rotating
Implementation Method 4
the light propagated in the light guide plate is also diffracted by the diffraction element in the other end part of the light guide plate and is emitted from the light guide plate
Data Source
AI summary
Provided are: a method of manufacturing an optical element that can display a clear image; and an optical element, and the manufacturing method includes: a step of forming a photo-alignment film and a first liquid crystal layer; a step of forming a photo-alignment film and a liquid crystal layer for lamination, peeling off the liquid crystal layer for lamination, and laminating the peeled liquid crystal layer for lamination on the first liquid crystal layer or the liquid crystal layer for lamination; a step of peeling off the first liquid crystal layer; a step of forming an adhesive layer having a surface roughness Ra of 15 nm or less on the light guide plate and/or the first liquid crystal layer; and a step of bonding the light guide plate and the first liquid crystal layer using the adhesive layer.