Angled Surface Relief Grating Etch Depth Detection
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Solution Overview
Problem
The etch rate variability in producing angled surface relief optical gratings leads to inconsistent trench depth, affecting the efficiency of optical components in augmented and virtual reality devices, due to factors like variations in etch source output, material characteristics, and equipment maintenance.
Innovation Solution
A method and system that utilize light measurement to detect the undiffracted and diffracted portions of light as the optical grating is formed, allowing for real-time monitoring of trench depth by comparing light values to predetermined values, ensuring consistent trench depth during the etching process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If direct etching of angled trenches is used to form optical gratings, then the optical components can be manufactured, but the trench depth becomes inconsistent due to etch rate variability
Solution Approach 1:
The patent applies preliminary action by performing in-situ optical measurements during the etching process to detect trench depth in real-time. The system delivers light into the optical grating layer and measures undiffracted and diffracted light portions before the etching is complete, allowing for real-time feedback and adjustment of etching parameters to maintain consistent trench depth despite etch rate variability
Solution Approach 2:
The patent implements feedback by using the measured light values (undiffracted and diffracted portions) to determine trench depth and compare it against target specifications. This feedback loop enables real-time monitoring and adjustment of the etching process, allowing the system to compensate for etch rate variations and maintain manufacturing precision
2Manufacturing precision
If in-situ light measurement is implemented to monitor trench depth, then manufacturing precision improves, but device complexity increases
Solution Approach 1:
The patent applies universality by designing an optical measurement system that can be integrated into the existing etching equipment. The same optical path is used for both the etching process monitoring and the trench depth measurement, allowing the system to perform multiple functions (etching and measurement) using shared components, thereby reducing overall device complexity
Solution Approach 2:
The patent uses light as an intermediary to indirectly measure trench depth without requiring direct physical contact or complex sensing probes inside the etching chamber. By measuring the optical properties (undiffracted and diffracted light) of the material being etched, the system obtains trench depth information through a simple non-invasive optical measurement approach
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 enables precise control of trench depth, resulting in improved consistency and efficiency of optical gratings, reducing downtime and variability in the manufacturing process.
Implementation Method 1
delivering light from a light source into the optical grating layer, and measuring at least one of: an undiffracted portion of the light exiting the optical grating layer, and a diffracted portion of the light exiting the optical grating layer
Data Source
AI summary
Optical grating components and methods of forming are provided. In some embodiments, a method includes providing an optical grating layer, and forming an optical grating in the optical grating layer, wherein the optical grating comprises a plurality of angled trenches disposed at a non-zero angle of inclination with respect to a perpendicular to a plane of the optical grating layer. The method may further include delivering light from a light source into the optical grating layer, and measuring at least one of: an undiffracted portion of the light exiting the optical grating layer, and a diffracted portion of the light exiting the optical grating layer.