Linear Micro-Display Optical System with Dual Scanning Stages
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Solution Overview
Problem
Current optical scanning systems suffer from a small exit pupil and eyebox, limiting the field of view and requiring the user's eye to be positioned close to the scanning optic, and waveguide-based systems face challenges in scanning light at sufficient angles and rates for image production.
Innovation Solution
The proposed optical system employs a linear illumination source and dual scanning stages to generate a two-dimensional light image, with a waveguide-based configuration using a pupil replication stage to expand the exit pupil and accommodate a more comfortable eye-to-optic distance, and non-waveguide systems using reflective elements to project the exit pupil away from the scanning optics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If a conventional scanning system is used, then the system structure is simple, but the exit pupil and eyebox are small, limiting the field of view and requiring the user's eye to be positioned close to the scanning optic
Solution Approach 1:
The scanning system is divided into multiple independent scanning stages (e.g., first scanning stage, second scanning stage), each responsible for scanning in different dimensions. This segmentation allows the exit pupil to be projected to a larger area while maintaining manageable complexity in each individual stage.
Solution Approach 2:
The patent introduces a second scanning stage that scans in a dimension perpendicular to the first scanning stage. This dimensional expansion transforms the small one-dimensional exit pupil into a larger two-dimensional exit pupil, increasing the eyebox and field of view without simply scaling up the original system.
2Ease of operation
If the user's eye is positioned close to the scanning optic to see the full field of view, then the field of view is maintained, but the comfort and ergonomics of the device deteriorate
Solution Approach 1:
By adding the second scanning stage that operates in a perpendicular dimension, the system creates a two-dimensional exit pupil that can be projected to a larger area. This dimensional approach increases the eyebox size, allowing the user's eye to be positioned at a more comfortable distance while still viewing the full field of view.
3Volume of moving object
If waveguide-based systems are used to compact the design, then the device size is reduced, but the ability to scan light at sufficient angles and rates for image production is limited
Solution Approach 1:
The scanning function is segmented across multiple stages, with each stage handling a portion of the scanning task. This allows the system to achieve high scanning rates by distributing the workload, while the waveguide maintains compact device size. Each scanning stage can operate at optimized speeds for its specific function.
Solution Approach 2:
The patent employs electro-optic elements (such as liquid crystal or electro-optic crystals) to replace traditional mechanical scanning mirrors. This substitution enables faster scanning rates and angles while maintaining the compact form factor provided by the waveguide, as electro-optic modulation occurs without mechanical movement.
4Area of stationary object
If multiple scanning stages are introduced to increase the exit pupil, then the field of view and eyebox are improved, but the device complexity increases
Solution Approach 1:
The patent uses a second scanning stage that scans in a dimension perpendicular to the first stage, creating a two-dimensional exit pupil. This orthogonal arrangement efficiently increases the exit pupil area by utilizing spatial dimensions rather than simply adding more stages in the same dimension, thereby managing device complexity more effectively.
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 configuration allows for larger beam diameters, increased comfort in eye positioning, and simplified waveguide structures, enhancing the field of view and manufacturing efficiency while supporting applications like head-mounted displays and augmented reality.
Implementation Method 1
a linear illumination source configured to emit light
Implementation Method 2
a scanning electro-optic element configured to receive the light and to scan the light
Implementation Method 3
a waveguide configured to receive light from the scanning electro-optic element and to direct the light toward an eyebox
Data Source
AI summary
An optical system comprises a linear illumination source configured to emit light, a first scanning stage configured to receive the light and to scan the light, and a second scanning stage. The linear illumination source is configured to generate light forming a vertical field of view based on the one or more output signals received from a controller modulating the one or more output signals comprising image data defining content. The first scanning stage redirects portions of the light to generate an output defining a horizontal field of view based on the one or more output signals of the controller. The first scanning device combines the vertical field of view and the horizontal field of view in the output light to create a two-dimensional light image of the content. The second scanning stage receives and directs the output of the first scanning stage toward a projected exit pupil.