Holographic Waveguide Sheet Exposure Layout for 2D Pupil Expansion
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Solution Overview
Problem
Existing methods for preparing two-dimensional pupil expansion holographic waveguide sheets require cumbersome procedures with multiple optical paths and exposures, leading to low preparation efficiency and yield due to interference between gratings.
Innovation Solution
A method involving a single optical path setup with a beam splitter, reflector, and prism, using beam-splitting members to prepare in-coupling, turning, and out-coupling gratings sequentially without optical interference, enabling efficient production of a two-dimensional pupil expansion holographic waveguide sheet.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If three exposure optical paths are set up to sequentially form three gratings, then the two-dimensional pupil expansion holographic waveguide sheet can be prepared, but the procedure becomes cumbersome and preparation efficiency decreases
Solution Approach 1:
The patent combines three separate exposure optical paths into a single integrated optical path. The beam splitter divides one light source into multiple beams that sequentially illuminate different grating regions, while the reflector redirects beams to appropriate exposure positions. This merging approach maintains the quality of three-grating preparation while significantly improving preparation efficiency by eliminating the need to set up and switch between three separate optical paths.
Solution Approach 2:
The patent employs dynamic optical switching using a beam splitter and reflector that can be rotated or adjusted. By rotating the reflector or adjusting the beam splitter angle, different light paths are dynamically switched to expose different gratings (in-coupling, turning, and out-coupling) in sequence using a single light source. This dynamic switching mechanism enables efficient sequential exposure without requiring multiple fixed optical paths.
2Manufacturing precision
If three exposures are performed sequentially on a single waveguide sheet, then all required gratings can be formed, but multiple exposures interfere with each other reducing yield
Solution Approach 1:
The patent segments the exposure process into three distinct sequential steps using a single optical path. The beam splitter and reflector system directs light to expose the in-coupling grating, then turning grating, and finally out-coupling grating in sequence. Each grating exposure is spatially and temporally separated, preventing interference between exposures while ensuring complete formation of all three gratings on the waveguide sheet.
Solution Approach 2:
The beam splitter and reflector act as intermediary optical components that control and direct the single light source to different grating regions in sequence. These intermediaries enable precise control over which grating is being exposed at any given time, preventing cross-interference between exposures while maintaining high preparation yield through systematic light path management.
3Manufacturing precision
If three separate optical paths are constructed, then each grating can be exposed independently, but the device complexity increases
Solution Approach 1:
The patent creates a universal single optical path system that performs multiple functions: it exposes the in-coupling grating, turning grating, and out-coupling grating using one light source and one optical path. The beam splitter and reflector enable this single system to dynamically switch between different exposure tasks, eliminating the need for three separate optical paths while maintaining independent exposure capability for each grating type.
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
Improves preparation efficiency and yield by allowing the formation of all gratings on a single optical path, facilitating large-scale production of the waveguide sheet.
Implementation Method 1
arranging a beam splitter and a reflector with centers thereof on a same straight line... reflected light from the beam splitter is split by the first beam-splitting member
Implementation Method 2
transmitted light passing through the beam splitter is reflected by the reflector and normally incident on a second slanted face of a prism side
Implementation Method 3
reflected light from the beam splitter is split by the first beam-splitting member and normally incident on an upper surface of the prism and a first slanted face of a prism side
Data Source
AI summary
An embodiment of the present application provides a preparation method of a two-dimensional pupil expansion holographic waveguide sheet, a waveguide sheet, and AR glasses. A beam splitter and a reflector are arranged with centers thereof on the same straight line, and a prism is disposed below the beam splitter. A first beam-splitting member is disposed between the beam splitter and a prism, where reflected light from the beam splitter is split by the first beam-splitting member and normally incident on the upper surface of the prism and a first slanted face of the prism side, and transmitted light passing through the beam splitter is reflected by the reflector and normally incident on a second slanted face of the prism side. The exposure member is selectively exposed to the light normally incident on the prism to prepare the two-dimensional pupil expansion holographic waveguide sheet.