Holographic Projector Ghost Image Elimination via Waveguide Sub-Holograms
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Solution Overview
Problem
Holographic projection systems face issues with ghost images due to different light propagation paths through waveguides, leading to reduced image quality and potential safety concerns, especially at non-infinite image distances where the size of the display device is similar to the viewing aperture.
Innovation Solution
The system divides the field of view into spatial areas and calculates smaller holograms for each portion, displaying each sub-hologram on a different sub-area of the display device to reduce the likelihood of light from multiple replicas reaching a viewing position, thereby minimizing ghost images without degrading image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If a full-size hologram is displayed on the entire display device, then complete image content is provided, but ghost images occur due to multiple replicas reaching the viewing position
Solution Approach 1:
The display device is divided into multiple sub-areas, with each sub-area displaying a different sub-hologram. This segmentation ensures that light from only one replica reaches each viewing position, eliminating ghost images while maintaining complete image content through the aggregation of all sub-holograms.
2Object-affected harmful factors
If the display device size is reduced to fit the viewing aperture, then ghost images are reduced, but the viewing window size is limited
Solution Approach 1:
The waveguide creates multiple spatial replicas of the holographic wavefront in different locations. By distributing sub-holograms across multiple sub-areas of the display device and utilizing the waveguide's replica generation capability, the system effectively expands the viewing window in spatial dimensions while maintaining the benefit of reduced ghost images through selective light path control.
3Object-affected harmful factors
If sub-holograms are displayed on separate sub-areas, then ghost images are eliminated, but the display device requires multiple distinct regions
Solution Approach 1:
Multiple sub-areas of the display device work together to display different sub-holograms that collectively form the complete image. The waveguide structure serves multiple functions by generating replicas that distribute light from each sub-area to appropriate viewing positions, eliminating the need for separate display devices while maintaining the ghost image elimination benefit.
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
This approach effectively reduces or eliminates ghost images by spacing out hologram replicas, ensuring that only one instance of each sub-hologram's light reaches the viewer, maintaining image quality and preventing ghost content while allowing for the entire image to be viewed from any given location.
Implementation Method 1
The display device is arranged to spatially modulate light in accordance with a hologram displayed thereon
Implementation Method 2
The waveguide is arranged to receive a holographic wavefront modulated in accordance with the hologram and output a plurality of replicas of the holographic wavefront
Implementation Method 3
a waveguide having an input arranged to receive the holographic wavefront, and a first surface and a second surface arranged to waveguide the holographic wavefront therebetween
Data Source
AI summary
A holographic projector is provided. The holographic projector includes a display device arranged to form a holographic wavefront by spatially modulating light in accordance with a hologram displayed thereon, a waveguide having an input arranged to receive the holographic wavefront, and a first surface and a second surface arranged to waveguide the holographic wavefront therebetween. The first surface of the waveguide is partially reflective-transmissive such that a plurality of replicas of the holographic wavefront are emitted therefrom. A size of the hologram is less than a size of an entrance pupil of a viewing system for receiving the holographic wavefront from the first surface of the waveguide and the hologram includes a first sub-hologram of a first region of an image adjoined to a second sub-hologram of a second region of the image.