Low-Profile Beam Splitter With Diffractive Illumination Control

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Solution Overview

Problem

Existing VR, AR, and MR systems are bulky and not compact enough, limiting their potential for enhancing user experience.

Innovation Solution

A low-profile beam splitter is designed with a reduced height and incorporates a diffractive optical element to maintain illumination coverage, reducing the size of the beam splitter without compromising optical functionality.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a beam splitting surface is arranged at 45 degrees to the input surface, then proper beam splitting function is achieved, but the height of the beam splitter increases

Engineering Contradiction:
Improvebeam splitting functionVSAvoidheight of beam splitter
Core Design Contradiction:
ReliabilityVSLength of stationary object

Solution Approach 1:

The patent changes the angle parameter of the beam splitting surface from the conventional 45 degrees to a shallower angle (e.g., 30 degrees), thereby reducing the height of the beam splitter while maintaining its beam splitting functionality through adjusted optical path design

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent compensates for the reduced height by optimizing the lateral dimensions and optical path length, redistributing the optical functionality across different spatial dimensions to maintain performance despite the reduced vertical profile

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Length of stationary object

If the height of the beam splitter is reduced, then the overall system size is decreased, but illumination coverage may be compromised

Engineering Contradiction:
Improveheight of beam splitterVSAvoidillumination coverage
Core Design Contradiction:
Length of stationary objectVSIllumination intensity

Solution Approach 1:

The patent applies diffractive optical elements at specific locations on the beam splitting surface to enhance and redistribute light, ensuring adequate illumination coverage in the reduced-height configuration by concentrating optical energy where needed

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The diffractive optical element acts as an intermediary that modifies the optical path and redistributes light energy, compensating for the reduced illumination coverage that would result from the smaller beam splitter height

Inventive Principle:
Principle #24Intermediary (Mediator)

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 low-profile beam splitter enables more compact VR, AR, and MR systems, providing improved user experience through reduced size and weight while maintaining image quality.

Implementation Method 1

incorporates a diffractive optical element to maintain illumination coverage

Methodology Applied
Scientific EffectDiffraction: Diffraction

Implementation Method 2

a third surface being a polarization splitting prism, arranged at 45° to the second surface and reflective to light of a first polarization state and transmissive to light of a second polarization state

Methodology Applied
Scientific EffectPolarization splitting: Polarisation

Data Source

PatentEP3602176B1Low-profile beam splitter
Publication Date: 2026.01.14 MAGIC LEAP INC
  • EP3602176B1 patent drawingFigure 1
  • EP3602176B1 patent drawingFigure 2
  • EP3602176B1 patent drawingFigure 3~4

AI summary

Examples of light projector systems for directing input light from a light source to a spatial light modulator are provided. For example, an optical device is disclosed which includes a first surface having a diffractive optical element, a second surface normal to the first surface, and a third surface arranged at an angle to the second surface. The third surface may be a beam splitting surface that is reflective to light of a first state and transmissive to light of a second state. The diffractive optical element may receive an input beam made up of light having the first state, and convert the input beam into at least a first diffracted beam at a first diffraction angle such that the first diffracted beam is directed toward the third surface and is reflected by the third surface in a direction substantially parallel to the first surface.