Optical Fibre Pupil Expander for Wider Holographic Field of View
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Solution Overview
Problem
Conventional holographic systems face limitations in field of view and compact design due to the need for bulk optic pupil expanders, which restrict the placement and size of display devices in applications like head-up displays, especially when the display device is small and the viewing distance is large.
Innovation Solution
The use of an optical fibre pupil expander, where light from a display device is coupled into input ends of multiple optical fibres, with output ends arranged to form an expanded exit window, increasing the range of angles and viewing area without the need for bulk optics, allowing for a more compact and flexible design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If bulk optic pupil expanders are used in conventional holographic systems, then the field of view is limited and the design is restricted, but the system structure is simple and easy to implement
Solution Approach 1:
The patent replaces bulk optic pupil expanders with an optical fibre-based pupil expander. This substitution uses optical fibres to guide and expand the light from the display device, eliminating the need for complex bulk optic components while achieving the same or better field of view expansion. The optical fibre system is more compact and flexible, allowing for improved adaptability in head-up display applications.
Solution Approach 2:
The patent utilizes the spatial arrangement of multiple optical fibres in a two-dimensional array configuration. By arranging the optical fibres in rows and columns with specific pitch ratios, the system expands the light output in both horizontal and vertical dimensions, achieving comprehensive field of view expansion without requiring large bulk optic components.
2Volume of moving object
If the display device is made small for compact design, then the system size is reduced, but the viewing area and field of view are limited
Solution Approach 1:
The patent employs a two-dimensional array of optical fibres with specific pitch ratios between rows and columns. This dimensional arrangement allows the compact display device to expand light in both horizontal and vertical directions, effectively increasing the viewing area without requiring a larger display device. The optical fibre array acts as a spatial expansion mechanism that decouples display size from viewing area.
Solution Approach 2:
The optical fibre array serves as an intermediary between the small display device and the viewer's eye. It receives light from the compact display and redistributes it across a larger angular space, effectively mediating between the small source and the required viewing area. This intermediary enables compact design while maintaining large viewing area.
3Length of stationary object
If the viewing distance is increased for head-up display applications, then the image can be viewed from farther away, but the field of view and image visibility are reduced
Solution Approach 1:
The patent uses a two-dimensional optical fibre array that expands light in both horizontal and vertical dimensions. This dimensional expansion compensates for the reduced field of view that naturally occurs at increased viewing distances. By providing angular expansion in multiple dimensions, the system maintains adequate field of view even when the display is positioned at optimal head-up display distances.
Solution Approach 2:
The patent replaces conventional bulk optic expansion mechanisms with an optical fibre-based system that provides superior angular expansion. This substitution enables the system to maintain a wide field of view at increased viewing distances, as the optical fibres can be precisely arranged to direct light over larger angular ranges compared to bulk optic approaches.
4Adaptability or versatility
If multiple viewers are supported without additional holographic systems, then the system versatility is improved, but the device complexity increases
Solution Approach 1:
The patent designs the optical fibre array with a configuration that inherently supports multiple viewing positions. By arranging the fibres in a two-dimensional array with specific pitch ratios, the system provides expanded light output that can be viewed from multiple angles simultaneously. This universal design allows a single holographic system to serve multiple viewers without requiring additional display devices or complex switching mechanisms.
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 enhances the field of view and viewing area, enabling movement of the viewer's eyes while maintaining image visibility, and allows for reduced size and weight of the projection system, with the potential to serve multiple viewers without additional holographic systems.
Implementation Method 1
Each of the plurality of light guides is arranged to propagate light received at its input end for output at its output end
Implementation Method 2
A display device displays a diffractive pattern of an image and outputs light encoded with the diffractive pattern
Data Source
AI summary
A holographic system comprises a spatial light modulator and a pupil expander. The spatial light modulator is arranged to display a hologram of an image and to output spatially modulated light encoded with the hologram. In embodiments, the pupil expander comprises a plurality of optical fibres, each optical fibre having an input end and an output end. The pupil expander is arranged so that spatially modulated light output by the spatial light modulator is coupled into the input end of each optical fibre and output from the output end thereof to a viewing area. Each of the plurality of optical fibres is arranged to propagate the received spatially modulated light received at its input end so as to expand an exit pupil of the system in a first dimension, typically corresponding to a dimension of the viewing area.