Diffraction Grating Layout for Faster Beam Writing Alignment
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Solution Overview
Problem
Conventional methods for producing optical image light guides in virtual image near-eye display systems are time and capital intensive.
Innovation Solution
A method involving the digital production of a diffraction pattern in a mold substrate using a beam writing system that aligns diffractive optics with preferred write directions, reducing write time by orienting grating vectors perpendicular to the beam writing machine's axes, and employing stepped patterns to create straight line features.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional methods are used to produce optical image light guides, then the diffraction pattern can be fabricated, but the process is time and capital intensive
Solution Approach 1:
The patent applies preliminary action by pre-calculating and pre-orienting the grating vectors of the diffractive optics perpendicular to the beam writing machine's axes before the actual writing process. This preparation allows the beam writing system to write along the preferred directions (x and y axes) rather than requiring complex angular adjustments during fabrication, significantly reducing write time while maintaining optical precision
Solution Approach 2:
The patent segments the diffraction pattern into multiple diffractive optics (in-coupling, turning, out-coupling gratings) with distinct grating vectors. Each grating is independently oriented perpendicular to the beam writing axes, allowing sequential writing along preferred directions. This segmentation enables the beam writing system to efficiently fabricate each component without requiring continuous angular repositioning, thereby reducing overall fabrication time
2Manufacturing precision
If diffractive optics are written at arbitrary orientations, then the beam writing system can write any pattern, but periodic errors and angular misalignments increase
Solution Approach 1:
The patent employs asymmetry by deliberately orienting the grating vectors perpendicular to the beam writing machine's axes rather than using symmetric or arbitrary orientations. This asymmetric alignment with the machine's coordinate system simplifies the writing process by allowing the beam to travel along the x and y axes without complex angular deviations, thereby reducing periodic errors and improving angular alignment precision
Solution Approach 2:
The patent applies local quality by optimizing the orientation of each specific grating vector according to the local requirements of that diffractive optic. Each grating (in-coupling, turning, out-coupling) is oriented perpendicular to the beam writing axes in its specific location, allowing the beam writing system to write along the preferred directions (x and y axes) with minimal periodic errors and maximum angular precision for each local component
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
Significantly reduces the time required to fabricate diffractive optics on the mold substrate, improving efficiency and output image quality by minimizing periodic errors and angular misalignments.
Implementation Method 1
The present disclosure provides for a substrate and method of making same. In a first exemplary non-claimed embodiment, a substrate includes a flat surface having a first diffractive optic, a second diffractive optic, and a third diffractive optic disposed in the flat surface
Data Source
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AI summary
A method of fabricating a substrate includes providing a substrate having a flat surface and a beam writing system operable to write in a first direction and a second direction, wherein the second direction is perpendicular to the first direction, The method further includes providing a diffraction grating layout pattern having a first diffraction grating, a second diffraction grating, and a third diffraction grating. The method also includes locating the substrate in the beam writing system, whereby the beam writing system is operable to write into the flat surface, and aligning one of the first, second, and third diffraction gratings parallel with the beam writing system first direction. Additionally, the method includes writing the diffraction grating layout pattern into the substrate flat surface via the beam writing machine.