Surface-Grating Eyepiece Manufacturing for Variable Pupillary Distances

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Solution Overview

Problem

Existing eyepieces for head-mounted displays struggle to accommodate a wide range of pupillary distances using a single mold geometry, leading to inefficiencies in manufacturing and compatibility issues.

Innovation Solution

The use of over-sized surface gratings on a master polymer wafer, which are then de-functionalized to create eyepieces with varying center-to-center distances, allowing for a single mold to produce eyepieces that accommodate different pupillary distances.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If a single mold geometry is used for eyepieces, then manufacturing efficiency is improved, but the ability to accommodate different pupillary distances deteriorates

Engineering Contradiction:

Improvemanufacturing efficiencyVSAvoidaccommodation of different pupillary distances

Core Design Contradiction:

ProductivityVSAdaptability or versatility

Solution Approach 1:

The master polymer wafer is divided into multiple regions, each containing surface gratings configured for different pupillary distances. This segmentation allows a single mold to produce eyepieces suitable for different users while maintaining manufacturing efficiency through batch production.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The single mold geometry is designed with universal capability to accommodate multiple pupillary distances by incorporating multiple grating configurations within the same mold. This multi-functionality resolves the contradiction by enabling one mold to serve multiple purposes for different users.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Adaptability or versatility

If multiple mold geometries are used to accommodate different pupillary distances, then adaptability is improved, but device complexity and manufacturing difficulty worsen

Engineering Contradiction:

Improveaccommodation of different pupillary distancesVSAvoidmanufacturing complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

A single mold geometry is designed to be universal, accommodating multiple pupillary distances through integrated grating configurations. This eliminates the need for multiple specialized molds, reducing manufacturing complexity while maintaining adaptability.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The mold is pre-configured with multiple grating patterns during manufacturing, so that the complexity is built into the mold design rather than requiring complex post-processing or multiple molding steps. This preliminary action simplifies the overall manufacturing process.

Inventive Principle:

Principle #10Preliminary action

3Adaptability or versatility

If surface gratings are de-functionalized to reduce grating area, then adaptability to different pupillary distances is improved, but manufacturing precision requirements worsen

Engineering Contradiction:

Improveaccommodation of different pupillary distancesVSAvoidprecision of grating area reduction

Core Design Contradiction:

Adaptability or versatilityVSManufacturing precision

Solution Approach 1:

The grating area is modified by changing the functional parameters of the surface gratings through de-functionalization processes. This allows adjustment of grating dimensions to match different pupillary distances while using standardized manufacturing techniques that control precision.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The de-functionalized grating areas are replicated consistently across multiple eyepieces using the same mold and processing techniques. This copying approach ensures manufacturing precision is maintained while achieving the desired adaptability through controlled reduction of grating areas.

Inventive Principle:

Principle #26Copying

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 efficient manufacturing of eyepieces that can accommodate a range of pupillary distances, improving compatibility and reducing manufacturing complexity.

Implementation Method 1

The eyepiece surface grating areas may be cast and oriented such that a wide range of distances between user pupils may be accommodated

Methodology Applied

Scientific EffectDiffraction: Diffraction Grating

Data Source

PatentUS12455457B2Eyepiece for head-mounted display and method for making the same

Publication Date: 2025.10.28 MAGIC LEAP INC

AI summary

A method, includes providing a wafer including a first surface grating extending over a first area of a surface of the wafer and a second surface grating extending over a second area of the surface of the wafer; de-functionalizing a portion of the surface grating in at least one of the first surface grating area and the second surface grating area; and singulating an eyepiece from the wafer, the eyepiece including a portion of the first surface grating area and a portion of the second surface grating area. The first surface grating in the eyepiece corresponds to an input coupling grating for a head-mounted display and the second surface grating corresponds to a pupil expander grating for the head-mounted display.