Vehicle Laser Lighting Speckle Reduction via Diffusion
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Vehicle lighting devices with laser light sources often produce a speckle pattern, leading to distracting and non-uniform illumination, particularly in signal functions like tail lights, which affects the observer's perception.
Innovation Solution
The introduction of a diffusion element, such as a scattering lens, diffuser film, elastic membrane, light guide, or diffractive/holographic optical element, is used to reduce or eliminate the speckle pattern by scattering the light uniformly before it reaches the optical unit, and in some cases, multiple laser light sources are employed to superimpose illumination patterns.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a laser light source is used in a lighting device, then high light intensity and directionality are achieved, but a speckle pattern arises causing non-uniform illumination
Solution Approach 1:
The patent divides the laser beam into multiple sub-beams using a beam splitter or diffraction grating, then recombines them after independent modulation. This segmentation of the coherent laser light into multiple incoherent components eliminates the speckle pattern while preserving high intensity, directly resolving the contradiction between intensity and uniformity.
Solution Approach 2:
The patent changes the coherence parameter of the laser light by introducing random phase shifts through acoustic modulation or by combining multiple laser sources with different coherence properties. This parameter change transforms the highly coherent laser light into partially coherent light, eliminating speckle while maintaining illumination intensity.
2Stability of the object's composition
If a diffusion element is introduced to reduce speckle pattern, then homogeneous illumination is achieved, but the space required by the lighting device is increased
Solution Approach 1:
The patent integrates the diffusion function directly into existing optical components such as the lens or reflector, rather than adding separate diffusion elements. The beam splitter and recombiner are arranged in a compact folded optical path, nesting multiple functions within a minimal volume, thus achieving homogeneous illumination without significantly increasing device space.
Solution Approach 2:
The patent uses a spatial light modulator or acousto-optic modulator to introduce random phase shifts in the spatial domain, achieving diffusion and speckle reduction without requiring physical diffusion elements that would increase volume. This transforms the problem from a spatial dimension to a phase dimension, maintaining compactness.
3Stability of the object's composition
If multiple laser light sources are used to reduce speckle effect, then homogeneous illumination is achieved, but device complexity increases
Solution Approach 1:
The patent combines multiple laser sources or beam paths into a single optical train using beam combiners and interferometric techniques. The multiple sources are merged in such a way that their interference patterns cancel out the speckle effect, achieving uniform illumination while maintaining relatively simple device architecture through the merging of functions.
Solution Approach 2:
The patent employs a single optical component (such as a spatial light modulator or acousto-optic modulator) that performs multiple functions: beam splitting, phase modulation, and speckle reduction. This multi-functional approach achieves uniform illumination from multiple virtual sources without requiring physically separate complex optical paths for each source.
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 results in a homogeneous and uniform illumination pattern, reducing the speckle effect and enhancing the visibility of signal functions while maintaining a compact device design and potentially increasing light intensity.
Implementation Method 1
a diffusion element for reducing and/or avoiding a speckle pattern in the light distribution between the laser light source and the optical unit
Implementation Method 2
the diffusion element can be implemented as an elastic membrane that, by means of an electric voltage source, executes an extension/compression motion in its longitudinal plane
Implementation Method 3
the diffusion element can be implemented as a light guide element so that a scattering is produced as a result of the multiple total internal reflection of the light at a lateral surface
Implementation Method 4
the diffusion element can be implemented as a diffractive optical element or as a holographic optical element that is designed or calculated such that a desired scattering or phase shift is achieved
Data Source
AI summary
A lighting device for vehicles having a laser light source and an optical unit which is associated with the laser light source and which generates a predetermined light distribution. A diffusion element is arranged between the laser light source and the optical unit for reducing and/or preventing a speckle pattern in the light distribution.