Reflective Spatial Light Modulator Waveguide Optical Assembly
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Solution Overview
Problem
Conventional head-mounted display devices are limited by their size and weight, which restricts their ability to provide a wide field of view, hindering user experience in augmented, mixed, and virtual reality applications.
Innovation Solution
A compact optical device with a reflective display and an optical assembly featuring a folded optical path and polarization volume gratings, which increases the effective focal length and allows for a wider field of view by redirecting image light through total internal reflection within a waveguide.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If conventional head-mounted display devices are used, then the device structure is relatively simple, but the field of view is limited and the device size cannot be reduced
Solution Approach 1:
The patent employs a folded optical path design where the light path is redirected multiple times within a compact volume using mirrors and waveguides. This transforms a linear optical path into a multi-dimensional folded structure, effectively increasing the field of view while maintaining a compact device form factor suitable for head-mounted displays
Solution Approach 2:
The optical assembly integrates multiple functional components including waveguides, mirrors, and optical elements within a nested compact structure. The waveguide itself is embedded within the head-mounted display housing, and additional optical elements are positioned within the waveguide structure, creating a space-efficient nested arrangement that maximizes the field of view without increasing overall device size
2Volume of moving object
If the device size is reduced, then the device becomes more compact and wearable, but the field of view becomes even more limited
Solution Approach 1:
The folded optical path design allows the light to travel a longer effective distance through the optical assembly by redirecting it through multiple reflections and waveguide passages. This creates a three-dimensional light path that fits within a compact volume while maintaining an extended field of view, effectively decoupling device volume from field of view size
Solution Approach 2:
The optical assembly is divided into multiple functional segments including input couplers, waveguide sections with different orientations, output couplers, and mirror elements. Each segment performs a specific function in redirecting and processing the light path, allowing the overall system to achieve a wide field of view within a compact segmented structure
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
Enables a head-mounted display device to project images with a wider field of view, enhancing user experience in augmented, mixed, and virtual reality by combining projected images with real-world views while allowing for a see-through mode.
Implementation Method 1
The first in-coupler is configured to receive the image light output by the reflective display and redirect a first portion of the image light so that the first portion of the image light undergoes total internal reflection inside the first waveguide
Data Source
AI summary
An optical device includes a waveguide, a projector, a reflective display, and an in-coupler. The waveguide has a first side and an opposing second side. The projector is configured to project illumination light toward the first side of the waveguide. The reflective display is configured to receive the illumination light and to output image light toward the second side of the waveguide. The in-coupler is configured to receive the image light output by the reflective display and redirect a portion of the image light so that the portion of the image light undergoes total internal reflection inside the waveguide.