Slanted Facet Waveguide Dispersion Compensation
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Solution Overview
Problem
Conventional head-mounted display devices have limited field of view (FOV), which hampers user immersion in virtual and augmented reality environments, and increasing the FOV can lead to image dispersion and smearing due to light coupling issues.
Innovation Solution
Incorporating an optical waveguide with a slanted facet and a prism or grating as an input coupler, which directs light to the eyebox while minimizing dispersion by adjusting the light projector's orientation and using output couplers to redirect light appropriately.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If light is coupled through a slanted facet to increase FOV, then the field of view is improved, but image dispersion and smearing occur
Solution Approach 1:
A dispersive element (prism or grating) is introduced as an intermediary component between the light source and the waveguide. This dispersive element pre-compensates for the dispersion that will occur in the waveguide by introducing an equal and opposite dispersion, thereby canceling out the smearing effect while preserving the increased FOV benefits of the slanted facet configuration
Solution Approach 2:
The orientation angle of the slanted facet is optimized to balance FOV enhancement with dispersion control. By carefully selecting the facet angle and compensating dispersion parameters, the system achieves maximum FOV while minimizing image degradation through precise parameter tuning
2Manufacturing precision
If a prism or grating is used as input coupler to reduce dispersion, then image quality is improved, but device complexity increases
Solution Approach 1:
The dispersive element is integrated with the waveguide structure itself rather than being a separate external component. The grating or prism functionality is combined with the waveguide's optical path, reducing the number of discrete components and simplifying the overall device architecture while maintaining dispersion compensation performance
Solution Approach 2:
The slanted facet serves multiple functions: it acts as both the input coupling interface for light and the mounting surface for the dispersive element. This multi-functionality reduces the need for additional separate components and simplifies the optical system design
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 solution enhances the FOV of head-mounted displays, reducing image dispersion and smearing, thereby improving user experience in virtual and augmented reality applications.
Implementation Method 1
The slanted facet includes a grating
Implementation Method 2
a prism located adjacent to the first end of the optical waveguide and separate from the optical waveguide
Implementation Method 3
an optical waveguide that has a first optical surface and a second optical surface opposite to the first optical surface
Data Source
AI summary
An optical device (e.g., a pupil expander) includes a waveguide with a slanted facet. The optical device includes a reflector on the slanted facet and a prism, or a grating at the slanted facet. The prism or the grating compensates for the dispersion of an image light from a display, which reduces smearing of displayed images. The waveguide can be configured for pupil replication in one-dimension or two-dimensions.