See-Through AR Waveguide Lens Assembly for Finite Focus
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Solution Overview
Problem
Existing augmented reality display systems, particularly see-through head-mounted displays, face challenges in providing a high-quality and comfortable viewing experience due to geometric and ocular requirements, leading to issues like eyestrain and poor image quality from the mismatched focal planes of computer-generated and real-world images.
Innovation Solution
The use of a fixed lens assembly with a proximal and distal static lens positioned on either side of a waveguide in an augmented image insertion element, shifting the apparent focus of computer-generated images from infinity to a finite distance while maintaining the focal plane of real-world images unchanged, achieved through specific lens configurations and optical design optimizations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a waveguide is used to direct CGI to the eye, then the device can be compact and wearable, but the CGI appears focused at infinity while real objects are at finite distance, causing eyestrain
Solution Approach 1:
The optical system is segmented into multiple lens assemblies: a first lens assembly for correcting focus of real objects and a second lens assembly for adjusting apparent focus of CGI. This segmentation allows independent optimization of each function, resolving the contradiction between compact waveguide design and comfortable viewing by distributing focus control across separate optical elements.
Solution Approach 2:
Lens assemblies are introduced as intermediary elements between the waveguide and the eye. These intermediaries modify the optical path to reconcile the infinite focus of the waveguide with the finite distance at which users naturally view objects, enabling both compact form factor and viewing comfort.
2Ease of operation
If the focal plane of CGI is shifted to finite distance, then viewing comfort improves, but the focal plane of real-world images shifts, requiring additional optical correction
Solution Approach 1:
The optical correction function is segmented into two specialized lens assemblies: one dedicated to correcting real object focus and another dedicated to adjusting CGI apparent focus. This division allows each assembly to be optimized for its specific function, managing the increased optical complexity through functional specialization rather than requiring a single complex adjustable system.
3Reliability
If static fixed lenses are used to correct focus, then the optical system remains simple and reliable, but the focal plane mismatch between CGI and real objects cannot be resolved
Solution Approach 1:
The optical system transitions from static to dynamic focus control through the introduction of lens assemblies with different optical powers positioned in specific locations within the optical path. This dynamic configuration allows the system to simultaneously address focal plane mismatch while maintaining simplicity and reliability through fixed lens positions rather than adjustable mechanisms.
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 solution provides a reliable and high-quality viewing experience by ensuring that both computer-generated and real-world images are in focus at the same distance, reducing eyestrain and improving user experience in augmented reality displays.
Implementation Method 1
a waveguide for directing a computer generated image into central viewing axis of an eye
Implementation Method 2
the one or more lenses positioned behind of the waveguide being pre-configured to shift an apparent focus of the CGI from infinity to a finite distance
Implementation Method 3
the one or more lenses positioned in front of the waveguide being pre-configured to nullify an overall focusing power of the optical device
Data Source
AI summary
Fixed position optical devices for displaying augmented reality images are provided herein. In one embodiment an optical device includes a AIIE having a waveguide that reflects a computer generated image along a central viewing axis, the computer generated image being received from an image generator optically coupled to the waveguide, and a fixed lens assembly for coupling a background image with the computer generated image to create the augmented reality display, the fixed lens assembly including a proximal lens disposed on one side of the waveguide, the proximal lens being fixedly spaced apart from the waveguide at a first distance, and a distal lens disposed on an opposing side of the AIIE from the one side, the distal lens being fixedly spaced apart from the waveguide at a second distance.