Vehicle Headlamp Volume Holograms for Robust Light Distribution
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Solution Overview
Problem
Conventional vehicle lighting devices with diffractive surface structures face complexity in manufacturing and are sensitive to mechanical influences, and the calculation of holograms using classic methods is extremely complex, especially for large holograms.
Innovation Solution
The use of volume holograms in a grating cell array, which are independent and easier to calculate, allowing for suppression of higher diffractive orders and adaptation to light source divergence and curvature, along with the option of incorporating Fresnel lenses and nano 3D printing for manufacturing, simplifies the optimization and reduces mechanical sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If diffractive surface structures are used in lighting devices, then light distribution can be controlled, but manufacturing complexity increases and mechanical sensitivity increases
Solution Approach 1:
The patent transitions from two-dimensional surface relief structures to three-dimensional volume holograms. This dimensional change allows the diffractive optical elements to be embedded within the transparent substrate rather than formed on the surface, simplifying manufacturing by using volume-based recording techniques and reducing sensitivity to surface mechanical influences.
Solution Approach 2:
The patent changes the physical state of the diffractive structure from surface-level relief to volumetric modulation within the substrate. This parameter change enables the use of volume holography techniques where the refractive index is modulated throughout the thickness of the substrate, allowing for more robust structures that are less sensitive to mechanical deformation.
2Illumination intensity
If diffractive surface structures are used, then light distribution is achieved, but sensitivity to mechanical influences increases
Solution Approach 1:
By moving from surface structures to volumetric structures embedded within the substrate, the patent creates optical elements that are protected by the substrate material. This dimensional transition reduces mechanical sensitivity as the volume holograms are less susceptible to surface deformation and environmental factors.
3Illumination intensity
If classic methods are used to calculate hologram structures, then desired light distribution can be achieved, but calculation complexity becomes extremely high
Solution Approach 1:
The patent divides the calculation of large holograms into smaller, independent grating cell calculations. Each grating cell can be optimized separately using classic algorithms, and the individual results are then combined to form the complete hologram. This segmentation dramatically reduces computational complexity while maintaining the desired light distribution properties.
4Adaptability or versatility
If multiple diffraction orders are created, then light can be distributed in multiple directions, but manufacturing complexity increases
Solution Approach 1:
The patent applies different local properties to different regions of the hologram by varying the Bragg plane inclinations of individual grating cells. This allows specific diffraction orders to be suppressed or enhanced in different areas, enabling precise control over light distribution directions while simplifying the overall manufacturing process through localized optimization.
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 enables the efficient generation of desired light distributions, such as low-beam or high-beam light patterns, with improved mechanical robustness and simplified manufacturing, allowing for chromatic correction and increased resolution through adaptable Bragg plane inclinations and multiplexing.
Implementation Method 1
The light emanating from a light source is diffracted by the grating cell array in such a way that a light distribution is created in the outer area of the vehicle
Implementation Method 2
at least one of the gratings of the grating cell array is designed as a volume hologram. Multiple or each of the gratings of the grating cell array is/are preferably designed as a volume hologram. Higher diffractive orders may be suppressed in a volume hologram
Implementation Method 3
a hologram is imprinted into a light-sensitive recording material. An object beam and a reference beam are successively applied to individual sections of the recording material
Data Source
AI summary
A lighting device for a vehicle, in particular a headlamp for a vehicle, having at least one light source, from which light emanates during the operation of the lighting device, a diffractive optical unit, including a plurality of gratings, which form a grating cell array, the light passing through the grating cell array during the operation of the lighting device in such a way that a light distribution is created in the outer area of the vehicle, at least one of the gratings of the grating cell array being designed as a volume hologram.