Holographic Waveguide Optics for Reduced Viewing Artefacts
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Solution Overview
Problem
Existing optical systems for holographic projections suffer from distracting artefacts on the virtual surface formed by waveguide replicas, which impair the viewing experience due to non-uniform illumination and scattering effects, drawing attention away from the intended holographic reconstruction.
Innovation Solution
The optical system employs a configuration with an optical component that forms a virtual image of the holographic reconstruction far removed from the image of the displayed hologram, minimizing the impact of artefacts by positioning the hologram/image of the display device at infinity or downstream of the viewing system, thereby reducing distractions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If waveguide pupil expanders are used to expand the exit pupil, then the viewing area is increased, but distracting artefacts are generated on the virtual surface
Solution Approach 1:
The patent extracts the harmful artefacts from the viewing experience by positioning the hologram image far away from the virtual reconstruction. The optical component (lens) forms the hologram image at a location (infinity or downstream) that is separated from the virtual image location, effectively removing the artefacts from the viewer's attention focus while preserving the pupil expansion function.
Solution Approach 2:
The optical component (lens) acts as an intermediary that creates separate image planes for the hologram and the virtual reconstruction. This mediator allows the system to maintain both the waveguide pupil expander functionality and the reduction of distracting artefacts by controlling where each image is formed in space.
2Length of stationary object
If the hologram image is positioned close to the virtual reconstruction, then the optical system is more compact, but artefacts distract viewers from the holographic content
Solution Approach 1:
The patent converts the potential harm of having a long optical path (which would increase system size) into a benefit by using the distance separation to eliminate artefact distractions. The long optical path is deliberately used to position the hologram image far from the virtual reconstruction, turning the path length from a disadvantage into the solution for artefact reduction.
3Device complexity
If the image of the displayed hologram is positioned at the virtual image location, then the optical system is simpler, but artefacts on the virtual surface draw attention away from the holographic reconstruction
Solution Approach 1:
The optical component (lens) serves as an intermediary that decouples the hologram image position from the virtual reconstruction position. This allows the system to maintain relative simplicity while achieving the critical separation needed to eliminate artefact distractions, as the lens naturally forms images at different planes based on object distance.
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 configuration significantly improves the viewing experience by allowing viewers to focus on the holographic reconstruction without being distracted by artefacts, enhancing the quality of the holographic display.
Implementation Method 1
the display device is illuminated with coherent light which is spatially modulated in accordance with the hologram and then received by the first lens of the optical relay such that a holographic reconstruction of the picture is formed at the back focal plane of the first lens
Implementation Method 2
The light may then continue to propagate and be received by the second lens of the optical relay such that a relayed image of the display device (i.e. a relayed image of the hologram) may be formed at the back focal plane of the second lens
Implementation Method 3
A first waveguide is positioned near the back focal plane of the second lens and may be arranged to receive the spatially modulated light and replicate that light to expand an exit pupil of the optical system in a first direction
Implementation Method 4
The optical component is arranged to: (a) form a virtual image of the holographic reconstruction upstream of the display device and (b) form an image of the displayed hologram at infinity or downstream of the optical component
Data Source
AI summary
There is provided an optical system having a viewing window. The optical system comprises a display device arranged to spatially modulated light in accordance with a hologram displayed thereon to form a holographic wavefront. The holographic wavefront forms a holographic reconstruction of an image downstream of the display device. The optical system further comprises a waveguide arranged to receive the holographic wavefront and waveguide the holographic wavefront between a pair of reflective surfaces thereof. One surface of the pair of reflective surfaces is partially transmissive such that a plurality of replicas of the holographic wavefront are emitted therefrom. The optical system further comprises an optical component between the holographic reconstruction and the waveguide, wherein the optical component is arranged to (a) form a virtual image of the holographic reconstruction upstream of the display device and (b) form an image of the displayed hologram at infinity or downstream of the waveguide.