Virtual Light Source via Waveguide Diffractive Optical Element
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Solution Overview
Problem
In various photographic and video capture situations, particularly in augmented reality systems, it is challenging to provide illumination where a physical light source cannot be placed, such as for gaze tracking and iris recognition, as existing solutions fail to effectively create a virtual illumination source that mimics a light source at a different location.
Innovation Solution
An optical device utilizing a planar waveguide with diffractive optical elements (DOEs) that directs and collimates light to create a virtual light source, allowing the light to appear as if it emanates from a specific location, including the use of infrared radiation to avoid interference with real or computer-generated images.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a physical light source is placed near the camera for illumination, then illumination intensity is improved, but the light source interferes with the user's view and cannot be positioned in head-mounted displays
Solution Approach 1:
The patent creates a virtual light source that copies the optical effect of a physical light source without requiring actual physical presence. The waveguide system generates light that appears to originate from a specific location in space, providing illumination while avoiding the physical constraints and interference problems of actual light sources in head-mounted displays
Solution Approach 2:
The waveguide acts as an intermediary between the light source and the target object. Light is coupled into the waveguide and transported through it, then extracted at a different location to illuminate the target. This intermediary system allows light to reach positions where physical sources cannot be placed without directly interfering with the user's view
2Adaptability or versatility
If a virtual light source is created using waveguide technology, then the light can be positioned at any desired location, but the complexity of the optical system increases
Solution Approach 1:
The waveguide system serves multiple functions: it transports light from a source, positions it virtually at different locations, and extracts it for illumination. This multi-functional approach consolidates what would otherwise require separate components into a single integrated system, managing complexity while providing positioning flexibility
Solution Approach 2:
The patent replaces mechanical positioning of physical light sources with optical manipulation within the waveguide. Instead of physically moving or repositioning light sources, the system uses optical coupling and waveguide propagation to achieve virtual positioning, reducing mechanical complexity while maintaining adaptability
3Reliability
If visible light is used for illumination, then image capture is improved, but it interferes with computer-generated images and real-world viewing
Solution Approach 1:
The patent uses different wavelengths (infrared) for illumination in specific locations where needed for capture, while keeping visible light transmission intact for user viewing. This local differentiation of optical properties allows simultaneous optimization of image capture quality and visual experience without mutual interference
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
Enables effective illumination for applications like gaze tracking and iris recognition by creating a virtual light source that can be positioned at any desired location, improving image capture and biometric data collection without interfering with the user's view.
Implementation Method 1
The diffractive optical element (DOE) distributes the light entering the waveguide via total internal reflection
Implementation Method 2
A diffractive optical element (DOE) is formed across the waveguide. The DOE distributes the light entering the waveguide
Implementation Method 3
an optical device for generating illumination that appears to emanate from a location different from the actual light source
Data Source
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AI summary
An optical device is disclosed for generating illumination that appears to emanate from a location different from the actual light source. The device includes a waveguide having opposed first and second planar faces. A light source is positioned to direct light into the waveguide. A diffractive optical element (DOE) is formed across the waveguide. The DOE distributes the light entering the waveguide via total internal reflection and couples the light out of the surface of said first face.