Optical Grating Pitch Measurement via Deflection Angle Analysis
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Solution Overview
Problem
Existing optical devices, such as those used in virtual and augmented reality, often exhibit nonuniform properties like grating pitch and orientation variations due to substrate imperfections and deposition issues, leading to performance inconsistencies.
Innovation Solution
A measurement system and method that uses a stage, optical arm, and detector arms with focusing lenses to project and detect light beams, allowing for the determination of local nonuniformities in grating pitches and orientations by analyzing deflection angles and displacements, thereby assessing the performance of optical devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If optical devices are fabricated using conventional methods, then manufacturing is simpler and faster, but nonuniform properties such as grating pitch and orientation variations occur
Solution Approach 1:
The patent applies preliminary action by measuring and characterizing the optical device properties before the device is fully fabricated. The measurement system captures grating pitch and orientation data during or immediately after the fabrication process, allowing for real-time quality control and identification of nonuniformities before the device is deployed. This enables corrective measures to be taken during manufacturing to improve uniformity without significantly reducing productivity.
2Ease of manufacture
If substrate deposition is performed on uneven supporting surfaces, then manufacturing process is simpler, but substrate tilting and distortions occur
Solution Approach 1:
The patent implements feedback by using the measurement system to detect substrate tilting and distortions caused by uneven supporting surfaces during deposition. The system measures the actual grating properties and compares them against expected uniform values, providing feedback about substrate quality. This feedback loop enables identification of problematic substrates or deposition conditions, allowing for corrective actions to maintain manufacturing precision while keeping the process simple.
3Device complexity
If conventional measurement methods are used, then measurement system is simpler, but detection of nonuniformity is insufficient
Solution Approach 1:
The patent applies segmentation by dividing the measurement system into multiple independent components: a light source, a detector array, and a control system. Each component performs a specific function - the light source illuminates the optical device, the detector array captures multiple parameters simultaneously, and the control system processes the data to identify nonuniformities. This segmented approach enables high-precision measurement of grating pitch and orientation variations while keeping each individual component relatively simple and manageable.
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
Enables precise measurement of local nonuniformities in optical devices, helping to identify and address substrate distortions and imperfections, thus improving the consistency and performance of optical systems.
Implementation Method 1
the laser operable to project light beams to the beam splitter that are deflected at a beam angle θ along the light path to the stage
Implementation Method 2
The detector arm includes a detector actuator configured to scan the detector arm and rotate the detector arm about the axis, a first focusing lens, and a detector
Data Source
AI summary
Embodiments of the present disclosure relate to measurement systems and methods for diffracting light. The measurement system includes a stage, an optical arm, and one or more detector arms. The method of diffracting light includes a method of diffracting light is provided, including projecting light beams having wavelength λlaser to a first zone of a first substrate at the fixed beam angle θ0 and the maximum orientation angle ϕmax, obtaining a displacement angle Δθ, determining a target maximum beam angle θt-max, wherein θt-max=θ0+Δθ, and determining a test grating pitch Pt-grating by a modified grating pitch equation Pt-grating=λlaser/(sin θt-max+sin θ0). The measurement system and method allow for measurement of nonuniform properties of regions of an optical device, such as grating pitches and grating orientations.