Image Waveguide with Offset Reflective End Surface
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Solution Overview
Problem
Conventional near-to-eye optical systems for head-mounted displays (HMDs) face limitations in field of view, size, and efficiency due to the use of input lenses, angle-sensitive dichroic mirrors, and holographic diffraction gratings, which restrict their practical applications in virtual and augmented reality.
Innovation Solution
An image waveguide with parallel and opposing reflective surfaces, an in-coupling region for light reception, a reflective end surface offset from perpendicular to change the light angle, and an out-coupling region to output light at a reduced angle, allowing for improved light propagation and expanded field of view without the need for total internal reflection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If conventional optical systems use input lenses, angle-sensitive dichroic mirrors, and holographic diffraction gratings, then the system can guide light, but the field of view is limited and the device size increases
Solution Approach 1:
The patent extracts and eliminates the need for input lenses, angle-sensitive dichroic mirrors, and holographic diffraction gratings from the optical system. By using a waveguide with parallel reflective surfaces and a reflective end surface, the system achieves light guidance without these complex components, thereby expanding the field of view and reducing device complexity.
Solution Approach 2:
The patent changes the optical parameters by using parallel reflective surfaces with specific angular relationships. The reflective end surface is offset from perpendicular to change the light angle from a first angle of incidence to a second angle of incidence, optimizing light propagation without requiring complex optical components.
2Loss of energy
If conventional optical systems are used in HMDs, then the system can function, but power loss increases and efficiency decreases
Solution Approach 1:
The patent converts the potential harm of light loss through multiple reflections into a benefit by using parallel reflective surfaces with high reflectivity. The reflective end surface offset from perpendicular minimizes the number of reflections needed to change light angles, reducing cumulative power loss while maintaining efficient light guidance.
3Volume of moving object
If conventional optical systems are used, then the system can provide near-to-eye display, but the device size and cost increase
Solution Approach 1:
The patent merges multiple optical functions into a single waveguide structure with parallel reflective surfaces. The in-coupling region, reflective surfaces, reflective end surface, and out-coupling region are integrated into one compact component, eliminating the need for separate lenses, mirrors, and gratings, thereby reducing device size and simplifying manufacturing.
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 field of view and reduces power loss, enabling a more efficient and compact near-to-eye imaging system capable of providing virtual and augmented reality experiences with improved user positioning flexibility.
Implementation Method 1
a reflective end surface positioned at an end of the waveguide and offset from perpendicular to the first and second reflective surfaces to reflect the light to a second angle of incidence with respect to the second reflective surface that is less than the first angle of incidence
Data Source
AI summary
An image waveguide includes first and second reflective surfaces being substantially parallel and opposing each other. The waveguide receives light from an in-coupling region through the first reflective surface, the light received at a first angle of incidence with respect to the second reflective surface. A reflective end surface positioned at an end of the waveguide and offset from perpendicular to the first and second reflective surfaces reflects the light to a second angle of incidence with respect to the second reflective surface that is less than the first angle of incidence. The light exits through an out-coupling region disposed on the first reflective surface to output the light at the second angle of incidence from the waveguide out the first reflective surface.