Field Lens Optical Structure Reduces Diffraction Fringes
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Solution Overview
Problem
Holographic three-dimensional display devices using field lenses with stacked multi-layer bulk holographic gratings suffer from diffraction fringes caused by angle and wavelength selective characteristics, leading to messy rainbow fringes that affect the display effect.
Innovation Solution
A field lens with an optical structure that blocks part of the visible light from being incident on or emitted from the lens body, specifically designed to reduce diffraction fringes by controlling the angle of light diffraction and exit, using a lens body with at least two grating layers and an optical structure on one side to manage light reflection and emission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If multi-layer bulk holographic gratings are used to converge light in a field lens, then light convergence capability is improved, but diffraction fringes are generated causing messy rainbow patterns that deteriorate display effect
Solution Approach 1:
The field lens is divided into multiple grating layers, with each layer responsible for specific wavelength ranges. The first grating layer handles longer wavelengths while the second grating layer handles shorter wavelengths, segmenting the diffraction problem to reduce overall fringe interference
Solution Approach 2:
The patent extracts and removes the diffraction fringes from the visible display area by positioning them outside the effective viewing cone. The optical design ensures that diffracted light orders are directed away from the observer's position, effectively taking out the harmful diffraction patterns from the display field
2Illumination intensity
If external natural light is reflected by multi-layer substrates and transmitted through gratings, then display brightness is improved, but angle and wavelength selective characteristics cause diffraction fringes
Solution Approach 1:
Different regions of the optical system are assigned different functions: the first grating layer is optimized for longer wavelengths with specific diffraction angles, while the second grating layer is optimized for shorter wavelengths. Each layer's structural parameters are locally optimized to minimize diffraction fringes in the respective wavelength range while maintaining brightness
Solution Approach 2:
The patent applies preliminary anti-action by pre-calculating and pre-positioning the diffraction fringes outside the viewing area before the display operation begins. The optical design ensures that diffraction patterns are directed to specific angular positions that fall outside the observer's field of view, preventing fringe interference in advance
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 effectively reduces the number of diffraction fringes observed, thereby improving the display effect by blocking unwanted light and optimizing light exit angles, enhancing the clarity of the holographic display.
Implementation Method 1
a holographic grating has angle and wavelength selective characteristics, the reflected light of the external natural light by the field lens causes the generation of diffraction fringes
Implementation Method 2
The optical structure is used to block at least part of the visible light from being incident on one side of the lens body and/or to block at least part of the visible light from being emitted toward the second side of the lens body
Implementation Method 3
External natural light is reflected by multi-layer substrates and then transmitted and diffracted by the multi-layer bulk holographic gratings
Data Source
AI summary
A field lens and a display device are provided. The field lens includes a lens body and an optical structure. The lens body includes at least two layers of gratings. Along a direction perpendicular to a plane where the lens body is located, the lens body includes a first side and a second side. The optical structure is located on a side of at least one grating layer close to the second side. The optical structure is used to block at least part of the visible light from being incident on one side of the lens body and/or to block at least part of the visible light from being emitted toward the second side of the lens body after being reflected by the gratings.