Phase Plate Fabrication for Laser Backlight Color Separation
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Solution Overview
Problem
Conventional liquid crystal display (LCD) systems in head-mounted devices suffer from low light transmissivity, leading to reduced brightness and immersive visual experience in virtual, augmented, and mixed reality applications.
Innovation Solution
A phase plate is fabricated using an interferometer system to create a hologram of pinholes, which focuses red, green, and blue components of a laser backlight onto respective subpixels in the LCD, enhancing light transmissivity by adjusting the phase and focusing the light beam.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If conventional LCD systems are used in head-mounted devices, then the device structure is simple, but light transmissivity is low resulting in reduced brightness
Solution Approach 1:
A phase plate is introduced as an intermediary optical component between the backlight and LCD layers. The phase plate modulates the phase of incident light to improve light transmissivity through the LCD stack, thereby increasing brightness without requiring fundamental changes to the conventional LCD structure
Solution Approach 2:
The phase plate changes the phase parameter of incident light to optimize light transmission characteristics. By adjusting the phase of light waves, the system achieves improved brightness while maintaining the existing LCD architecture
2Illumination intensity
If light transmissivity is improved using phase adjustment, then brightness increases, but manufacturing precision requirements increase
Solution Approach 1:
The desired phase modulation pattern is pre-calculated and encoded into a hologram design before fabrication. This preliminary design step allows the phase plate to be manufactured with standard precision while achieving the required phase adjustment for improved brightness
Solution Approach 2:
A hologram is used as a template or copy of the desired phase pattern. The hologram serves as a master design that can be replicated in the phase plate fabrication process, ensuring consistent phase modulation without requiring ultra-precise direct fabrication
3Illumination intensity
If conventional LCD systems are used, then device size is larger, but light transmissivity is low
Solution Approach 1:
The phase plate serves as a compact intermediary component that significantly improves light transmissivity within the existing display volume. This allows the system to achieve higher brightness without increasing the overall device size
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 solution significantly improves light transmissivity, resulting in increased brightness and higher quality images, expanding the field of view and reducing the physical size of the display while enhancing power efficiency.
Implementation Method 1
exposing the photopolymer layer to a collimated laser light... The photopolymer layer may be fabricated via an exposure technique that exposes the photopolymer layer to a collimated laser light
Implementation Method 2
A phase plate is fabricated using an interferometer system to create a hologram of pinholes, which focuses red, green, and blue components of a laser backlight onto respective subpixels in the LCD, enhancing light transmissivity by adjusting the phase and focusing the light beam
Implementation Method 3
The collimated light may pass through at least one of the exposure mask itself to create a collimated beam or the plurality of pinholes to create a spherical wavefront... generate the hologram
Data Source
AI summary
According to examples, a phase plate may include a transparent substrate and a photopolymer layer attached to the transparent substrate. The photopolymer layer may adjust a backlight via a phase adjustment and focusing. The phase plate may focus a plurality of red, green, and blue components of the backlight onto respective red, green, and blue subpixels of a thin-film-transistor (TFT) layer deposited thereon. A distance between the photopolymer layer of the phase plate and the plurality of red, green, and blue subpixels of the thin-film-transistor (TFT) layer may be in a range from about 200 μm to about 500 μm. In some examples, the phase plate may be part of a liquid crystal display (LCD) apparatus along with a red, green, blue (RGB) laser to provide backlight; a grating light guide to transmit the backlight; and a liquid crystal display (LCD) layer on the thin-film-transistor (TFT) layer.