Immersed Fresnel Structure Manufacturing via Liquid Polymer Curing
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Solution Overview
Problem
Existing methods for manufacturing immersed Fresnel structures, such as those used in virtual reality eye tracking, face practicality issues due to difficulties in manufacturing index-matched fluid and Fresnel structures with matching shapes, leading to unevenness and inclusions.
Innovation Solution
A method involving the application of a first liquid polymer to a substrate, illumination to modify its properties, and a second liquid polymer to a Fresnel structure, followed by stacking and further illumination to create an immersed Fresnel structure with refractive index matching, facilitating the integration into near-eye displays for eye tracking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If index-matched fluid and Fresnel structure are molded separately and attached using index matching glue, then manufacturing flexibility is improved, but manufacturing precision deteriorates due to difficulty in achieving matching shapes and presence of unevenness and inclusions
Solution Approach 1:
The patent merges the index-matched fluid and Fresnel structure into a single integrated molding process. The liquid polymer is applied to the Fresnel structure and then cured to form a unified piece, eliminating the need for separate molding and gluing operations. This resolves the contradiction by achieving both manufacturing flexibility (through liquid polymer application) and manufacturing precision (through integrated curing that eliminates interface defects).
Solution Approach 2:
The patent applies the liquid polymer to the Fresnel structure before final curing, allowing the polymer to conform to the Fresnel structure's shape in advance. This preliminary application ensures perfect shape matching and eliminates interface defects that would occur with post-assembly gluing methods.
2Manufacturing precision
If index-matched fluid is packaged into a molded Fresnel structure, then manufacturing precision is improved, but ease of operation deteriorates due to difficulty in product shipping and handling
Solution Approach 1:
The patent uses a curable liquid polymer that transitions from a liquid state (easy to handle and ship) to a solid state (integrated and precise) through UV curing. This dynamic state change allows the product to be shipped in a flexible, damage-resistant liquid form and then cured to achieve precise integration, resolving the contradiction between shipping ease and integration precision.
3Device complexity
If Fresnel structure is manufactured with traditional methods, then manufacturing simplicity is improved, but manufacturing precision deteriorates due to unevenness on Fresnel tips and inclusions in the fluid structure
Solution Approach 1:
The patent replaces traditional mechanical molding and assembly processes with a UV curing process. The liquid polymer is applied and then cured using UV light, which eliminates mechanical contact that causes unevenness and inclusions. This substitution maintains manufacturing simplicity while dramatically improving surface uniformity and eliminating defects.
Solution Approach 2:
The patent changes the physical state of the polymer from liquid to solid through UV curing. This parameter change allows the material to flow and conform perfectly to the Fresnel structure, eliminating surface unevenness and inclusions that occur with traditional solid-state molding methods.
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 enables the production of immersed Fresnel structures with reduced unevenness and inclusions, improving manufacturing practicality and optical performance for eye tracking applications in virtual reality systems.
Implementation Method 1
The first liquid polymer is then illuminated with light to change at least one property of the first liquid polymer and obtain a modified polymer attached to the first surface of the substrate
Implementation Method 2
The stacked Fresnel structure is then illuminated with light to obtain an immersed Fresnel structure
Implementation Method 3
The immersed Fresnel structure transmits light in the first band and directs light in a second band (e.g., infrared light) different than the first band to a first position
Data Source
Figure 1
Figure 2A
Figure 2B
AI summary
A method is presented herein for manufacturing an immersed Fresnel structure. A first liquid polymer is applied to a first surface of a substrate, the substrate having a second surface that is opposite the first surface. The first liquid polymer is illuminated with light to change at least one property of the first liquid polymer and obtain a modified polymer attached to the first surface of the substrate. A second liquid polymer is applied to at least a portion of a surface of a Fresnel structure. The second surface of the substrate is applied to an outer surface of the second liquid polymer applied to the Fresnel structure to obtain a stacked Fresnel surface. The stacked Fresnel surface is illuminated with light to obtain an immersed Fresnel structure. The immersed Fresnel structure can be used as part of a near-eye display.