Multi-Layer Light Guide with Beam Splitter for Homogeneous Illumination
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Solution Overview
Problem
Existing light guiding devices for spatial light modulation in display devices face challenges in achieving homogeneous and constant illumination, particularly for holographic displays, due to variations in light output power and intensity distribution.
Innovation Solution
A light guiding device comprising a light guide with at least two layers and a beam splitter element between them, along with a light decoupling device, which includes a diffractive optical element and a partially-reflective layer, to ensure homogeneous light distribution and high output power, while maintaining a compact and flat structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a light guide is used to illuminate the spatial light modulation device, then the light can be guided and distributed across the display surface, but the illumination homogeneity and constant light power are difficult to achieve
Solution Approach 1:
The light guide is divided into multiple layers (first light guide layer and second light guide layer) with different functions. The first layer handles light input and initial distribution, while the second layer focuses on achieving homogeneous output. This segmentation allows each layer to be optimized for its specific function, improving overall illumination homogeneity without excessive complexity.
Solution Approach 2:
A beam splitter element is introduced as an intermediary component between the two light guide layers. This element partially transmits and partially reflects light, enabling complex light path control and intensity distribution adjustment. The beam splitter acts as a mediator that coordinates the light flow between layers to achieve homogeneous illumination and constant power output.
2Illumination intensity
If multiple layers and beam splitter elements are added to achieve homogeneous illumination, then the light distribution improves, but the device complexity increases
Solution Approach 1:
The beam splitter element serves multiple functions simultaneously: it divides light between layers, controls light intensity distribution, maintains optical path alignment, and contributes to achieving both homogeneous illumination and constant power output. This multi-functionality reduces the need for additional separate components, managing device complexity while improving light distribution.
Solution Approach 2:
The patent employs location-dependent transmission and reflection properties of the beam splitter element, where the optical parameters vary across different positions to achieve uniform light distribution. By carefully designing the spatial variation of optical parameters, the system achieves homogeneous illumination without requiring excessive structural complexity.
3Illumination intensity
If a beam splitter element is used to control light distribution, then homogeneous illumination is achieved, but the device complexity and manufacturing cost increase
Solution Approach 1:
The beam splitter element exhibits location-dependent optical properties, with transmission and reflection characteristics varying across different positions to achieve uniform light distribution. This local quality approach allows the system to achieve homogeneous illumination through material property variation rather than complex structural variations, simplifying manufacturing compared to alternative designs.
4Illumination intensity
If light is coupled out at multiple positions to achieve homogeneous distribution, then the illumination quality improves, but the light guide structure becomes more complex
Solution Approach 1:
The light guide structure is segmented into multiple layers with distinct functions. The first layer handles light input and initial distribution to multiple positions, while the second layer refines the distribution to achieve homogeneous output. This segmentation enables multi-position light coupling without requiring a single complex monolithic structure.
Solution Approach 2:
The beam splitter element serves as an intermediary that enables light to be coupled out at multiple positions while maintaining structural simplicity. By controlling the partial transmission and reflection at strategic locations, the system achieves homogeneous light distribution without requiring complex multi-exit structures.
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
The solution provides a cost-effective and efficient means to achieve homogeneous illumination with constant light power, suitable for two-dimensional and three-dimensional displays, enhancing the quality of displayed information by ensuring uniform light distribution across the spatial light modulation device.
Implementation Method 1
The at least one beam splitter element is designed to partially transmit and reflect incident light propagating in the at least one light guide
Implementation Method 2
The at least one light decoupling device comprises at least one diffractive optical element
Implementation Method 3
a partially-reflective layer, which reflects parts of the light incident thereon and transmits or lets through remaining parts of the light
Data Source
AI summary
The invention relates to a light guiding device for guiding light. The light guiding device comprises at least one light guide, at least one beam splitter element, and at least one light decoupling device. The at least one light guide comprises at least two layers. The at least one beam splitter element is provided between the at least two layers of the at least one light guide, where the at least one beam splitter element is designed for partially transmitting and reflecting incident light propagating in the at least one light guide. The at least one light decoupling device is provided for coupling incident light out of the at least one light guide. Furthermore, the invention also relates to an illumination device and a display device for displaying two-dimensional and/or three-dimensional information comprising such a light guiding device.