Polarization Volume Hologram Lens for Lightweight AR Displays
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Solution Overview
Problem
Conventional head-mounted display devices are limited by their size and weight, which hinders their application in providing enhanced virtual-reality and augmented-reality experiences.
Innovation Solution
The use of polarization volume holographic (PVH) lenses, which are thinner and lighter than conventional optical elements, offering polarization selectivity, wavelength selectivity, and angular selectivity, is introduced to reduce the size and weight of head-mounted displays.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional optical elements and assemblies are used in head-mounted displays, then optical performance can be achieved, but the size and weight of the device increase
Solution Approach 1:
The patent changes the physical parameters of the optical element by using a volume holographic grating structure with specific pitch (e.g., 500-2000 nm) and refractive index modulation, transforming the conventional thick optical element into a thin film structure that achieves the same optical function with reduced weight
Solution Approach 2:
The patent employs composite material structures including transparent substrates with embedded volume holographic gratings, combining materials with different optical properties (refractive indices) to achieve both lightweight construction and required optical performance for waveguide coupling
2Reliability
If conventional optical elements and assemblies are used in head-mounted displays, then optical performance can be achieved, but the device dimensions increase
Solution Approach 1:
The patent transforms the optical element from a conventional thick lens or prism structure into a thin film volume holographic grating with thickness on the order of micrometers, achieving waveguide coupling functionality with minimal added thickness to the head-mounted display device
Solution Approach 2:
The patent transitions from conventional three-dimensional optical elements to a two-dimensional thin film grating structure inscribed within a transparent substrate, eliminating the need for thick optical paths while maintaining optical coupling efficiency through precise grating pitch and orientation control
3Weight of stationary object
If polarization volume holographic lenses are used, then device size and weight are reduced, but manufacturing complexity increases
Solution Approach 1:
The patent employs preliminary photoalignment layer patterning and UV exposure procedures to pre-establish the helical grating structure orientation and pitch before final polymerization, simplifying the overall manufacturing process by preparing the optical anisotropic material in a controlled sequential manner
Solution Approach 2:
The patent replaces conventional mechanical grinding, polishing, and coating processes with photochemical methods including UV exposure and photopolymerization to create the volume holographic grating structure, eliminating complex mechanical manufacturing steps while achieving precise grating geometry
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 PVH lenses enable more compact and lightweight head-mounted displays, improving the user's experience in virtual and augmented reality by providing advanced optical performance while minimizing the device's physical dimensions.
Implementation Method 1
The optically anisotropic molecules are arranged in helical configurations... focusing, with the lens, the first light while transmitting the second light through the lens without focusing the second light
Implementation Method 2
The optically transparent substrate includes optically anisotropic molecules between the first optical surface and the second optical surface... having a first phase on a reference plane parallel to the first optical surface
Data Source
AI summary
A lens may include optically anisotropic molecules arranged in helical structures. The lens may include a first portion, a second portion located around the first portion, and a third portion located around the second portion. The first portion may include a first helical structure having a first helical pitch. The second portion may include a second helical structure having a second helical pitch distinct from the first helical pitch. The third portion may include a third helical structure having a third helical pitch distinct from the first helical pitch and the second helical pitch. The second helical pitch may have a length that is between a length of the first helical pitch and a length of the third helical pitch.