Waveguide Grating Optical Device Miniaturization
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Solution Overview
Problem
Existing optical devices for portable devices are bulky and require a polarizing beam splitter or TIR prism to separate illumination and image light paths, leading to increased optical path length and size, which hinders miniaturization.
Innovation Solution
A waveguide device with diffractive grating structures is used to change the propagation direction of polarized beams, allowing for the omission of polarizing beam splitters or TIR prisms, and incorporating a reflective-type light valve and projection lens to reduce optical path length and device size, while varying grating structures achieve diffraction efficiency for expanded light-emitting areas and homogenized light beams.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a polarizing beam splitter or TIR prism is used to separate illumination and image light paths, then the light path separation is achieved, but the optical path length and device size increase
Solution Approach 1:
The patent combines the light path separation function into the waveguide device itself through diffractive grating structures, eliminating the need for separate polarizing beam splitters or TIR prisms. The waveguide device integrates both light propagation and path separation functions, reducing the overall optical path length and device size while maintaining effective light path separation.
Solution Approach 2:
The patent extracts the light path separation function from traditional separate components (polarizing beam splitter or TIR prism) and integrates it into the waveguide device through diffractive gratings. This extraction and reintegration reduces the number of discrete components and shortens the optical path length.
2Ease of manufacture
If a polarizing beam splitter or TIR prism is used to separate illumination and image light paths, then the light path separation is achieved, but the device size increases
Solution Approach 1:
The waveguide device merges the light path separation function with the light propagation function, eliminating the need for separate polarizing beam splitters or TIR prisms. This integration reduces the overall device footprint and occupied space while maintaining effective light path separation.
Solution Approach 2:
The patent uses diffractive grating structures within the waveguide to achieve light path separation in a planar, two-dimensional configuration rather than requiring three-dimensional stacked components. This dimensional approach reduces the overall device size and occupied space.
3Productivity
If different diffractive structures are used in different parts of the grating, then the diffraction efficiency distribution is improved, but the manufacturing complexity increases
Solution Approach 1:
The patent applies different diffractive grating structures to different regions of the waveguide device based on local requirements. By varying the grating parameters (such as period, depth, or orientation) in different areas, the diffraction efficiency is optimized for specific light paths or wavelengths, achieving prescribed distribution of diffraction efficiency throughout the device.
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 reduces the optical path length and overall device size, shortens the back focus of the projection lens, and enables miniaturization of optical devices by expanding light-emitting areas and homogenizing incoming light beams.
Implementation Method 1
A waveguide device with diffractive grating structures is used to change the propagation direction of polarized beams
Implementation Method 2
The first polarized beam passes through the first surface, the first grating and the second surface in succession
Data Source
AI summary
An optical device includes a waveguide device, a reflective-type light valve and a projection lens. The waveguide device receives a first polarized beam and includes a first surface, a second surface and the first grating. The first grating is disposed in a path of the first polarized beam to change a propagation direction of the first polarized beam, and the first polarized beam passes through the first surface, the first grating and the second surface in succession. The reflective-type light valve is disposed downstream from the second surface of the waveguide device to convert the first polarized beam into an image beam. The projection lens is disposed downstream from the reflective-type light valve, and the image beam passing through the second surface of the waveguide device, the first grating and the projection lens in succession.