Waveguide Molding with Registration Features for Uniform Polymer Films

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Solution Overview

Problem

Existing methods for producing polymer films for optical applications suffer from distortions due to factors like entrapped particulate matter, uneven thickness, and internal stress during the casting and curing process, which affect their suitability for variation-sensitive environments.

Innovation Solution

The use of precisely controlled molds with physical registration features, such as spacer structures and recesses, to maintain parallel orientation and regulate stress distribution, along with a method that avoids singulation processes to produce polymer films with consistent thickness and shape.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If conventional casting methods are used to produce polymer films, then the manufacturing process is simple, but the films exhibit distortions, uneven thickness, and entrapped particulate matter

Engineering Contradiction:
Improvefilm thickness uniformityVSAvoidmold structure complexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The mold is divided into multiple components including a base mold, a core insert, and a cavity mold, each performing a specific function. The base mold provides structural support, the core insert defines the internal waveguide structure, and the cavity mold shapes the external geometry. This segmentation allows precise control of film thickness and shape while simplifying the manufacturing of individual components.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The mold cavities and core inserts are pre-formed with precise geometries before assembly. The mold components are prepared with predetermined dimensions and surface finishes that directly transfer to the final polymer film. This preliminary preparation ensures high manufacturing precision without requiring complex real-time adjustments during the casting process.

Inventive Principle:
Principle #10Preliminary action

2Manufacturing precision

If the mold surfaces are not precisely aligned, then the assembly process is simple, but the resulting film has uneven thickness and distorted shape

Engineering Contradiction:
Improvefilm shape accuracyVSAvoidmold assembly difficulty
Core Design Contradiction:
Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The mold components incorporate asymmetric alignment features such as offset core inserts and non-symmetric cavity configurations. These asymmetric elements provide inherent alignment references that guide the assembly process, ensuring precise relative positioning of mold surfaces. The asymmetry creates natural stop positions and alignment cues that simplify the assembly operation while guaranteeing accurate film geometry.

Inventive Principle:
Principle #4Asymmetry

Solution Approach 2:

Alignment pins, positioning ribs, and interface features serve as intermediary elements between the base mold, core insert, and cavity mold. These intermediary structures mediate the assembly process by providing mechanical references that ensure precise alignment. The intermediaries absorb minor dimensional variations and maintain consistent spacing, making the assembly process both precise and straightforward.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Manufacturing precision

If particulate matter is entrapped during casting, then the casting process is fast, but the film quality deteriorates with visible defects

Engineering Contradiction:
Improvefilm surface qualityVSAvoidcasting cycle time
Core Design Contradiction:
Manufacturing precisionVSProductivity

Solution Approach 1:

The mold design incorporates deliberate venting channels and air escape paths that convert the potentially harmful effect of trapped air and particulate matter into a beneficial expulsion mechanism. The venting features allow gases and contaminants to escape during casting, preventing defects. This approach maintains fast casting cycles while ensuring high film surface quality by actively managing the entrapment of particulate matter.

Inventive Principle:
Principle #22Blessing in disguise (Convert harm into benefit)

4Manufacturing precision

If the polymer material is not properly supported during curing, then the curing process is simple, but internal stress causes distortion and wrinkling

Engineering Contradiction:
Improvefilm dimensional stabilityVSAvoidsupport structure complexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The core insert is nested within the cavity mold, creating a nested structure where the core defines the internal waveguide cavity and the outer mold provides structural support during curing. This nested arrangement allows the polymer material to be supported precisely where needed during the curing process, preventing distortion and wrinkling. The nested structure provides internal support without requiring complex external support systems.

Inventive Principle:
Principle #7Nested doll (Nesting)

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 resulting polymer films exhibit reduced distortions and improved consistency, making them suitable for high-resolution optical imaging systems with predictable physical and optical properties.

Implementation Method 1

irradiating the photocurable material in the space with radiation suitable for photocuring the photocurable material

Methodology Applied
Scientific EffectPhotopolymerization: Photopolymerisation

Data Source

PatentEP4420867B1Method of forming a waveguide
Publication Date: 2026.02.18 MAGIC LEAP INC
  • EP4420867B1 patent drawingFigure 1
  • EP4420867B1 patent drawingFigure 2
  • EP4420867B1 patent drawingFigure 3A~3B

AI summary

A method of forming a waveguide part having a predetermined shape, comprising providing a first mold portion (104a) having a first surface (120a) having a first grating pattern (508, 510) defined thereon; providing a second mold portion (104b) having a second surface (120b) having a second grating pattern (508, 510) defined thereon; providing one or more protrusions (502a, 502b) and one or more recesses (504a), disposed along at least one of the first surface (120a) or the second surface (120b); dispensing a metered amount of a photocurable material (114); adjusting a relative separation between the first surface (120a) and the second surface (120b) so that the photocurable material fills a volume; irradiating the photocurable material in the volume with radiation suitable for photocuring the photocurable material to form a cured film in the shape of the waveguide part; and separating the cured film from the first and second mold portions to provide the waveguide part.