Holographic Projection Filtering for Stray Light Suppression
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Solution Overview
Problem
Holographic projection devices in vehicles can deflect sunlight or ambient light in a way that it is perceived as disturbing stray light, which can interfere with the viewer's experience.
Innovation Solution
Incorporating a holographic filter that deflects light not originating from the primary light source at specific angles and wavelengths, preventing it from reaching the viewer's eye, while allowing intended light to be projected as a three-dimensional image through a first volume hologram.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a volume hologram is used to deflect light for image projection, then the desired image can be displayed to the viewer, but unwanted stray light from sunlight or ambient light is also deflected and perceived as disturbing light
Solution Approach 1:
The patent divides the holographic system into two separate components: a first volume hologram for deflecting desired light to create the image, and a holographic filter (second volume hologram) for deflecting unwanted stray light. This segmentation allows each component to be optimized for its specific function, resolving the contradiction between image visibility and stray light suppression.
Solution Approach 2:
The holographic filter acts as an intermediary element positioned between the incoming light and the first volume hologram. It selectively deflects unwanted light before it reaches the primary hologram, while allowing desired light to pass through for image projection. This intermediary approach eliminates stray light without compromising the main imaging function.
2Object-affected harmful factors
If the holographic filter deflects all light at certain angles, then stray light is eliminated, but the desired image light may also be affected
Solution Approach 1:
The holographic filter is designed with wavelength-specific properties, being selective about which wavelengths of light it deflects. It targets specific wavelength ranges associated with stray light sources (like sunlight) while allowing other wavelengths carrying the desired image information to pass through. This local quality approach ensures stray light elimination without compromising image projection accuracy.
Solution Approach 2:
The patent utilizes wavelength as a distinguishing parameter to differentiate between desired and unwanted light. The holographic filter is configured with specific diffraction characteristics for particular wavelength ranges, allowing it to selectively deflect stray light while transmitting image-carrying light. This parameter-based differentiation maintains image reliability while eliminating harmful stray light.
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
Effectively prevents unwanted stray light from being perceived, ensuring clear image projection by redirecting it away from the viewer's eye, enhancing the visibility of the intended image.
Implementation Method 1
light not originating from the primary light source, which strikes the first volume hologram at a predetermined solid angle and would otherwise be deflected into unwanted stray light, can be deflected by the holographic filter
Implementation Method 2
The holographic projection device can be designed to deflect an incoming image using the first volume hologram, so that a viewer can perceive it when they position their eye within a predetermined viewing area
Implementation Method 3
If this hologram is then illuminated by light in a predetermined manner, a reconstruction of the recorded image takes place in a known manner, so that a viewer can perceive it
Data Source
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AI summary
The invention relates to a holographic projection device for generating an image which a viewer can perceive if the viewer's eye (A) is positioned in a predetermined field of view and the viewer is looking at the projection device (1) at a predetermined viewing angle, the projection device (1) having a first volume hologram which, when impinged upon by light from a useful light source, deflects said light to generate the image. The first volume hologram further has the characteristic that light which does not originate from the useful light source and strikes the first volume hologram at a predetermined solid angle would deflect such that it is perceptible as unwanted interfering light, wherein the projection device (1) has a holographic filter (12) which - deflects the light which does not originate from the useful light source and would strike the first volume hologram at the predetermined solid angle, before the light strikes the first volume hologram, such that it is not perceptible as unwanted interfering light, and/or - deflects the light which does not originate from the useful light source and strikes the first volume hologram at the predetermined solid angle, after the deflection by the first volume hologram, such that it is not perceptible as unwanted interfering light.