Holographic Display Expanding Viewing Window via Mask Member
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Solution Overview
Problem
Current holographic display technologies face limitations in providing an expanded viewing window due to binocular parallax and discomfort caused by discrepancies between perceived depth and eye focus, with existing methods like glasses-type and non-glasses-type 3D image display methods restricting the number of viewpoints and causing viewer fatigue.
Innovation Solution
A holographic display apparatus incorporating an eye tracker, spatial light modulator, and a mask member with irregularly arranged light transmission patterns or micro lenses to expand the viewing window by diffraction and interference, allowing for off-axis holographic image reproduction and reducing high-order noise, thereby enhancing viewer comfort and image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If glasses-type or non-glasses-type 3D image display methods are used, then 3D images can be displayed, but the number of viewpoints is limited due to binocular parallax and viewers feel tired due to discrepancy between perceived depth and eye focus
Solution Approach 1:
The patent replaces mechanical 3D display methods (glasses-type, parallax barrier, lenticular) with a holographic display system that uses optical interference and diffraction to generate 3D images. The spatial light modulator creates holographic patterns that diffract light to form multiple viewpoints, eliminating the need for mechanical moving parts or special glasses while providing both comfort and multiple viewpoints simultaneously
Solution Approach 2:
The patent changes the fundamental parameter of light manipulation from simple directional control (in traditional 3D methods) to wavefront modulation using holographic interference patterns. By controlling the amplitude and phase of light waves through the spatial light modulator, the system generates multiple virtual viewpoints and achieves proper depth perception that matches eye focus, resolving the comfort issue
2Area of stationary object
If off-axis technique is used for holographic image reproduction, then viewing window can be expanded, but high-order noise increases
Solution Approach 1:
The patent converts the harmful high-order noise generated by off-axis holographic reproduction into a beneficial effect by using a mask member with specifically designed transmission patterns. The mask selectively blocks high-order diffraction orders (noise) while allowing the zeroth-order and first-order beams (useful light) to pass through, thereby expanding the viewing window while suppressing noise
Solution Approach 2:
The mask member acts as an intermediary element positioned between the spatial light modulator and the observation region. It mediates the light from the holographic display by filtering out harmful high-order noise while preserving and enhancing the useful light paths, thus enabling expanded viewing window without the detrimental noise effects
3Area of stationary object
If mask member with irregular light transmission patterns is introduced, then viewing window is expanded and high-order noise is reduced, but device complexity increases
Solution Approach 1:
The mask member is implemented as a simple, inexpensive, static optical element that can be manufactured using conventional techniques such as photolithography or 3D printing. Rather than using complex active components or programmable devices, the patent employs a fixed mask with predetermined transmission patterns, reducing device complexity while achieving the desired noise reduction and viewing window expansion
Solution Approach 2:
The mask member is designed with segmented or patterned transmission regions that correspond to different spatial frequencies and diffraction orders. By dividing the mask into specific transmission and blocking regions, the system achieves selective noise filtering without requiring a completely complex optical design, simplifying the overall device while maintaining performance
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 provides an expanded viewing window, reduces viewer discomfort, and improves image quality by effectively managing binocular parallax and noise, allowing for more comfortable and immersive holographic image observation without the need for high-precision eye trackers or actuators.
Implementation Method 1
the spatial light modulator forms a hologram pattern and diffracts light according to an input CGH signal, thereby generating a 3D image
Implementation Method 2
A holographic display apparatus incorporating an eye tracker, spatial light modulator, and a mask member with irregularly arranged light transmission patterns or micro lenses to expand the viewing window by diffraction and interference, allowing for off-axis holographic image reproduction and reducing high-order noise
Implementation Method 3
when light is radiated onto a hologram pattern having recorded thereon an interference pattern obtained by interference between light and object light reflected from an original object, the light is diffracted and an image of the original object is reproduced
Data Source
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AI summary
A holographic display apparatus and method capable of providing an expanded viewing window are provided. The holographic display apparatus (100) includes an image processor (160) configured to generate and provide computer generated hologram data (CGH, S180) to a spatial light modulator (130) having a first resolution and facing a mask member (140) having a second resolution, wherein the image processor is further configured to generate a hologram data array (S110-S150) comprising holographic information of the image to be reproduced at the first resolution or a resolution less than the first resolution, to perform, based on the mask, an off-axis phase computation (S160) on the hologram data array at the second resolution, and then, to generate the CHG data (S170-S180) at the first resolution.