Light-field Mixed Reality System with Pin-light Array
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Solution Overview
Problem
Conventional mixed reality combiners fail to effectively combine artificially created light-fields with real-world light-fields, leading to visual conflicts due to limitations in providing correct monocular depth cues and accommodating different focal distances, resulting in blurred images and imperfections like dust speckles and eye movements.
Innovation Solution
A light-field mixed reality system that uses a pin-light array and an optical light modulator to generate and project a virtual light-field, which is then combined with real-world light using a combiner, allowing the eye to naturally focus on different distances and providing realistic depth cues by temporal-multiplexing always-in-focus light-field components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional combiners are used to combine artificially created light-fields with real-world light-fields, then the system structure is simple, but visual conflicts occur due to inability to provide correct monocular depth cues and accommodate different focal distances
Solution Approach 1:
The patent segments the light-field projection into multiple focal planes, with each plane corresponding to a specific depth. The combiner is divided into multiple optical zones that direct light from different focal planes to the observer's eye at different angles, enabling correct monocular depth cues without visual conflicts.
Solution Approach 2:
The patent adds the focal distance dimension to the traditional 2D display by creating a 3D light-field with multiple focal planes. The combiner uses angular multiplexing to encode depth information in the angular distribution of light rays, transforming a planar display into a volumetric light-field display.
2Measurement precision
If fast varifocal lenses and mirrors are used to create correct monocular depth cues, then depth accuracy is improved, but the components are delicate and suffer from optical imperfections
Solution Approach 1:
The patent extracts the varifocal functionality from delicate mechanical lenses and mirrors and replaces it with a static combiner structure that achieves focal adjustment through optical path manipulation. The focal length changes are accomplished by switching between different optical zones in the combiner rather than moving mechanical components.
Solution Approach 2:
The patent replaces the mechanical varifocal lens system with an optical path manipulation system using a static combiner. The focal length adjustment is achieved through optical path differences created by the combiner's micro-prism or grating structure, eliminating moving mechanical parts and their associated imperfections.
3Ease of manufacture
If displays with actively controlled optical image distance are used, then artificial blur is created, but measurement errors occur due to individual eye differences and it does not provide correct light-field
Solution Approach 1:
The patent creates multiple copies of the light-field at different focal planes simultaneously, rather than sequentially adjusting focus. Each focal plane is a static copy of the display content at the appropriate depth, allowing the observer's eye to naturally accommodate to different distances without requiring precise measurement or active control.
Solution Approach 2:
The patent pre-calculates and pre-positions light rays from different focal planes in the combiner structure before the observer views the display. The optical paths for all focal distances are prepared in advance, eliminating the need for real-time measurement and adjustment during observation.
4Reliability
If microlens array or point-light array backlight is used for spatial multiplexing, then correct light-field is achieved, but commercially attractive image resolution requires special small pitch high-resolution displays that are bulky or non-transparent
Solution Approach 1:
The patent uses a dynamic combiner structure that can be manufactured with standard display technologies. The combiner's micro-prism or grating elements are arranged to create the light-field effect, allowing flexibility in design and manufacturing while achieving correct light-field properties without requiring specialized bulky components.
5Adaptability or versatility
If optical path expander combiners or multi-layer waveguides are used to provide images in multiple focal distances, then depth range is improved, but visible artifacts occur due to deliberate switching of displayed images between focal planes
Solution Approach 1:
The patent maintains continuous light-field projection across all focal planes simultaneously, rather than switching between planes. The combiner structure continuously directs light from all focal planes to the observer's eye, ensuring smooth transitions and eliminating visible artifacts during focal plane changes or eye movements.
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 system enables realistic mixing of virtual and real objects with correct eye accommodation, offering a practically infinite range of depths, high image resolution, and low image persistence, suitable for small form-factor glasses in mixed reality applications.
Implementation Method 1
the combiner configured for reflecting the modulated virtual light-field and projecting a projected virtual light-field
Implementation Method 2
the combiner further configured for transmitting natural light from the real world towards the eye box
Implementation Method 3
the optical light modulator being configured for modulating the incident light-field and generating a modulated virtual light-field
Data Source
AI summary
Light-field mixed reality system, comprising: a pin-light array generating an incident light-field illuminating an optical light modulator; the optical light modulator being configured for modulating the incident light-field and generating a modulated virtual light-field; and a combiner configured for reflecting the modulated virtual light-field and projecting a projected virtual light-field defining an eye box region along a projection axis; wherein the projected virtual light-field further forms an exit pupil of the pin-light array within the eye box and a virtual image of the optical light modulator, along the projection axis in front of the exit pupil, or behind the exit pupil; and wherein the combiner is further configured for transmitting natural light from the real world towards the eye box, such that both projected virtual light-field and natural light are projected within the eye box.