Waveguide Diffractive Volume Holograms Compact Head-Up Display
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Solution Overview
Problem
Conventional waveguide arrangements for data input devices, such as head-up displays, face challenges with high space and weight requirements due to refractive or reflective optical components, and are limited by wavelength specificity and complex embedding processes, while lacking flexibility and efficient beam expansion.
Innovation Solution
A compact waveguide design utilizing three diffractive structures - a first for light coupling, a second for beam expansion, and a third for coupling out - implemented as volume holographic gratings, allowing for wavelength selectivity and efficient beam expansion across multiple directions, enabling flexible use and reduced space and weight.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If refractive or reflective optical components are used for beam shaping, then the optical functionality is achieved, but the installation space requirement and weight increase
Solution Approach 1:
The patent replaces traditional refractive or reflective optical components with diffractive optical elements (DOEs) that use diffraction phenomena to achieve beam shaping. This substitution eliminates the need for bulky mechanical optical components, significantly reducing both weight and installation space while maintaining the required optical functionality for beam expansion and coupling.
Solution Approach 2:
The patent changes the operational parameters by using diffractive structures with specific periodicities and geometries to control light propagation. By adjusting the diffraction grating parameters (period, depth, orientation), the system achieves beam expansion and coupling without requiring additional optical components, thus reducing overall system size and weight.
2Adaptability or versatility
If embedded relief structures are used in waveguide, then beam expansion is achieved, but the manufacturing complexity and technological demand increase
Solution Approach 1:
The patent extracts the beam expansion functionality from the embedded relief structures and implements it through separate diffractive optical elements positioned at strategic locations within the waveguide. This separation simplifies the manufacturing process by eliminating the need for complex embedding and replication of relief structures, while still achieving the required beam expansion capability through diffractive patterns.
Solution Approach 2:
The patent uses diffractive optical elements that can be manufactured through standard lithographic processes, creating precise periodic patterns that replicate the desired beam expansion effect. These copied patterns are easier to manufacture than embedded relief structures, as they can be directly written using photolithography without requiring complex embedding procedures.
3Reliability
If conventional waveguide structures are used, then light guidance is achieved, but wavelength specificity limits flexibility
Solution Approach 1:
The patent designs diffractive optical elements with periodic structures that can be tuned to operate across multiple wavelengths. By adjusting the grating period and geometry, a single DOE can effectively guide and expand beams for different wavelengths (e.g., red, green, blue channels), providing universal functionality that eliminates the need for separate wavelength-specific waveguide structures.
Solution Approach 2:
The patent introduces dynamic control capabilities by making the diffractive structures adjustable or reconfigurable. This allows the waveguide system to adapt its diffraction characteristics in real-time, enabling flexible wavelength selection and beam control without requiring physical reconfiguration of the entire waveguide structure, thus enhancing both reliability and versatility.
4Volume of moving object
If compact waveguide design is implemented, then space and weight are reduced, but manufacturing precision requirements increase
Solution Approach 1:
The patent employs diffractive optical elements that can be manufactured using standard photolithographic copying processes. These processes can achieve the required sub-micron precision for diffractive patterns through master template replication, making the compact design manufacturable with existing industrial capabilities rather than requiring exotic high-precision manufacturing methods.
Solution Approach 2:
The patent optimizes the diffractive structure parameters (grating period, depth, orientation) to balance compactness with manufacturability. By carefully selecting parameters that are achievable with standard fabrication tolerances, the design achieves compact dimensions without pushing manufacturing precision requirements beyond current industrial capabilities.
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 compact, flexible, and efficient waveguide arrangement that effectively expands and directs light beams for data input devices, overcoming previous limitations in space, weight, and wavelength specificity, while enabling independent expansion of color channels and an enlarged eyebox.
Implementation Method 1
a first diffractive structure for receiving light and diffracting the light into the waveguide at an angle greater than the angle of total internal reflection of the waveguide
Implementation Method 2
diffracting the light into the waveguide at an angle greater than the angle of total internal reflection of the waveguide
Implementation Method 3
a second diffractive structure for expanding the light in the waveguide and diffracting the light in the waveguide to couple the light out of the waveguide
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
The invention relates to a waveguide arrangement, which comprises a diffractive incoupling element (11), in particular a volume hologram, a diffractive outcoupling element (13), in particular a volume hologram, and optionally a beam expansion element (12), in particular a volume hologram. The expansion element (12) and the outcoupling element (13) expand a light beam in different directions.