Cylindrical Waveguide Aberration-Free Optical System
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Solution Overview
Problem
Current augmented reality optical systems using flat waveguides face challenges in fitting curved prescriptions and achieving high-quality image projection without aberrations, as they require complex software and are difficult to manufacture for mass market production.
Innovation Solution
The use of a cylindrical waveguide with concentric surfaces allows light to propagate without aberration, combined with input optics that ensure all rays from a pixel enter the waveguide at the same angle, enabling two-dimensional pupil expansion and integration into wearable devices like glasses or visors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a flat waveguide is used for augmented reality display, then the structure is simple and easy to manufacture, but the image quality deteriorates due to aberrations and it cannot fit curved prescriptions
Solution Approach 1:
The patent applies curvature to the waveguide surface by using a cylindrical waveguide instead of a flat planar waveguide. The cylindrical shape with concentric inner and outer surfaces enables the waveguide to fit curved prescriptions while maintaining manufacturing feasibility through conventional cylindrical forming processes
Solution Approach 2:
The patent changes the geometric parameters of the waveguide from flat to cylindrical with specific radius ratios. By controlling the ratio between inner and outer radii, the system achieves aberration-free image propagation while maintaining ease of manufacture through standardized cylindrical geometries
2Manufacturing precision
If a cylindrical waveguide with concentric surfaces is used, then image quality is improved by eliminating aberrations, but the device complexity increases
Solution Approach 1:
The cylindrical waveguide with concentric surfaces provides inherent optical path equality for all rays from a given object point, eliminating aberrations without requiring complex alignment mechanisms or additional optical elements
Solution Approach 2:
The cylindrical geometry with concentric surfaces automatically ensures that all rays from a single object point travel equal optical paths and arrive at the image plane in phase, providing self-aligning aberration-free imaging without requiring external correction mechanisms
3Manufacturing precision
If complex software is used to achieve high-quality image projection, then image quality is improved, but the device complexity and manufacturing difficulty increase
Solution Approach 1:
The patent replaces complex software-based image correction with a purely optical solution using cylindrical waveguide geometry. The physical structure itself provides the aberration correction that would otherwise require complex computational algorithms and processing
Solution Approach 2:
By changing from flat to cylindrical geometry with controlled radius ratios, the system achieves high-quality image projection through optical design rather than software processing, simplifying the overall system architecture
4Area of stationary object
If a flat waveguide is used, then the eye-box size is limited, but the device structure remains simple
Solution Approach 1:
The cylindrical waveguide geometry naturally expands the eye-box area by providing a curved optical path that accommodates a wider range of viewing angles and positions, increasing the effective viewing area without requiring additional complex optical components
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 results in a compact, high-performance optical system that can be easily manufactured and aligned, fitting curved prescriptions and providing a large eye-box for a wide field of view without the need for precise alignment or complex software, suitable for mass production.
Implementation Method 1
the light is in-coupled to the waveguide via a diffraction grating (or similar) and traverses inside the waveguide (by means of total internal reflection) to a similar out-coupler
Implementation Method 2
This collimates the image-bearing light in both horizontal and vertical (tangential and sagittal) planes. The collimated light is coupled into the waveguide by in-coupler 40, which may be a linear diffraction grating or a holographic grating (other options include refractive optics such as prisms). This diffracts the light into the glass or plastic waveguide or substrate 30 at an angle greater than critical angle.
Implementation Method 3
These angles are determined by the refractive index n of the waveguide. Typical values are n=1.5 and a critical angle of 42 degrees and a guiding angle of perhaps 60 to 70 degrees to the normal.
Data Source
AI summary
An optical system is provided and includes: a cylindrical waveguide, having concentric inner and outer surfaces defining a common cylinder axis; and input optics, arranged to receive light from an image source and to cause the light to enter the cylindrical waveguide so that all rays originating from the same pixel of the image source are incident on a surface of the cylindrical waveguide at the same angle relative to the surface normal and at the same angle relative to a plane normal to the cylinder axis, at each point of incidence, the in- coupled light thereby retaining its direction angle as it propagates along the cylindrical waveguide. An optical display device, which can form part of a head-mounted display can be provided using the optical system.