Flat Panel Holographic Display Using Segmented Spatial Light Modulators
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Solution Overview
Problem
Conventional 3D displays cause eye strain due to skew and eye tracking focus disconnect, which existing technologies have been unable to effectively address, as they require impractically high pixel densities to create a holographic display capable of controlling light phase and amplitude across a wide area.
Innovation Solution
A flat panel holographic display system using a low-resolution 2D spatial light modulator and two crossed striped high-resolution spatial light modulators to create a narrow angle hologram focused at the viewer's pupil, allowing for standard pixel density and eliminating unnecessary light outside the pupil, with a variable lens system to maintain the focused image plane at the viewer's natural focus distance and adjust image positioning to reduce eye strain.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional holographic display is implemented with wavelength pixel spacing and phase/amplitude control, then holographic image quality is improved, but device complexity and manufacturing difficulty increase to hundreds of billions of pixels
Solution Approach 1:
The patent divides the holographic display system into three separate spatial light modulators: one low-resolution SLM for generating the hologram pattern and two high-resolution striped SLMs for focusing light into the pupil. This segmentation allows each component to have optimized resolution requirements, avoiding the need for a single ultra-high-resolution panel with hundreds of billions of pixels.
Solution Approach 2:
The patent transitions from a 2D panel approach to a 3D optical path approach by using multiple SLMs at different spatial positions and orientations. The crossed striped patterns in the two high-resolution SLMs create a 3D focusing effect that directs light precisely to the pupil, effectively adding dimensional complexity to solve the pixel density problem.
2Area of stationary object
If light field is controlled across wide area, then holographic coverage is improved, but light waste increases outside the viewer's pupils
Solution Approach 1:
The patent applies local quality by concentrating high-resolution light control only at the pupil location using the two crossed striped SLMs, while the main hologram generation SLM uses low resolution. This ensures that computational resources and light control precision are applied only where needed (at the pupil), rather than uniformly across the entire display area.
Solution Approach 2:
The patent extracts and focuses only the necessary light that will enter the pupil, using the variable lens and crossed striped SLMs to direct light precisely to the pupil position. Light that would otherwise fall outside the pupil is eliminated or redirected, reducing energy waste while maintaining full holographic coverage within the pupil.
3Device complexity
If focused image plane is fixed at screen distance, then display simplicity is maintained, but eye strain increases due to focus disconnect
Solution Approach 1:
The patent implements a dynamic focused image plane that can move along the optical axis using a variable lens. This allows the focus distance to be adjusted to match the perceived depth of holographic objects, enabling the eyes to focus naturally at different distances rather than being fixed at screen distance, thereby eliminating eye strain from focus disconnect.
Solution Approach 2:
The system uses eye tracking cameras to detect pupil positions and head movements, then feeds this information back to adjust the variable lens and SLM content accordingly. This feedback loop ensures the focused image plane and hologram position are continuously optimized to match the viewer's natural focus and head position, preventing eye strain.
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 effectively reduces eye strain by placing the focused image plane at the viewer's natural focus distance and adjusting image positioning to match head movements, providing a more comfortable and immersive viewing experience without the need for impractically high pixel densities.
Implementation Method 1
Each with the ability to control both the phase and amplitude of its sourced light
Implementation Method 2
Each with the ability to control both the phase and amplitude of its sourced light
Implementation Method 3
The two items comprising 103 create a lens variable in both focal length and position. It focuses the light of the narrow angle hologram from 102 down to a holodot 104 at the pupil of eye 105
Implementation Method 4
The purpose of item 101 is to provide parallel Laser light for item 102
Data Source
AI summary
An apparatus for creating a holodot comprising of a low resolution 2 dimensional spatial light modulator (SLM) and two crossed striped high resolution spatial light modulators. The first SLM creates a 2D image and the second two focus the light into an observer's pupil.