Liquid Crystal Hologram Element for Thin Optical Pattern Projection
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Solution Overview
Problem
Existing light irradiating devices for projecting optical patterns, such as dot patterns, face challenges in reducing thickness while maintaining a simple configuration, due to complex optical systems and large lens thickness.
Innovation Solution
The use of a liquid crystal hologram element with a computer-generated hologram, which diffracts transmitted light into multiple directions, allows for a thin and simple light irradiating device configuration. This element consists of a liquid crystal hologram layer formed from a composition including a liquid crystal compound, with regions having different optical axis directions, and is integrated with a light source that emits light with a narrow spread angle.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If a conventional optical system with lenses and reflecting surfaces is used to reduce device thickness, then the thickness can be reduced, but the device configuration becomes complicated
Solution Approach 1:
The patent combines multiple optical functions (light distribution, pattern projection, and optical path folding) into a single integrated optical element. This element integrates the light guide functionality with diffraction grating structures, eliminating the need for separate lenses and reflecting surfaces while maintaining the optical path length needed for thin-profile operation.
Solution Approach 2:
The optical element serves multiple functions simultaneously: it acts as a light guide to extend the optical path, a diffraction grating to project the dot pattern, and a structural component to maintain device thickness. This multi-functionality reduces the number of separate components needed in the optical system.
2Ease of operation
If a lens is used to distribute light in different directions, then a dot pattern can be projected, but the lens thickness becomes large
Solution Approach 1:
The patent replaces the conventional lens-based light distribution system with a diffraction-based system. Instead of using a thick lens to refract and distribute light, the invention uses a diffraction grating pattern etched into the light guide element, which distributes light through diffraction effects. This substitution dramatically reduces the required thickness while maintaining the dot pattern projection capability.
Solution Approach 2:
The invention changes the fundamental optical parameter from refraction (lens-based) to diffraction (grating-based). By using periodic structures with specific pitch and geometry in the light guide element, the system achieves light distribution in multiple directions with minimal thickness, replacing the thick lens requirement with a thin diffractive structure.
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 enables the projection of clear optical patterns with reduced device thickness and complexity, while maintaining high uniformity in intensity distribution, thus addressing the limitations of existing technologies.
Implementation Method 1
the liquid crystal hologram element diffracts transmitted light in a plurality of different directions
Data Source
AI summary
Provided is a small-sized light irradiating device having a simple configuration that projects an optical pattern. The light irradiating device includes a light source and a liquid crystal hologram element, in which the liquid crystal hologram element diffracts transmitted light in a plurality of different directions, the liquid crystal hologram element includes a liquid crystal hologram layer, the liquid crystal hologram layer is a layer that consists of a computer generated hologram and is formed of a composition including a liquid crystal compound, and the liquid crystal hologram layer further includes a plurality of regions in which directions of optical axes derived from the liquid crystal compound are different from each other.