Optical Wafer Alignment Using Interferometer Feedback
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Solution Overview
Problem
Aligning individual lens elements within a frame is time-consuming and prone to error, and aligning wafers with plural lens elements is challenging due to the difficulty in achieving precise and known offset positioning for efficient lens stack assembly.
Innovation Solution
A method and system using interferometers and actuators to align optical wafers with reflectors and lenses, ensuring precise alignment of optical axes by optical interaction and adjusting positions in three dimensions using output signals from interferometers and actuators, followed by fixing the wafers with curable optical polymer or glue.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If individual lens elements are aligned within a frame, then alignment can be achieved, but the process is time-consuming and prone to error
Solution Approach 1:
The patent divides the alignment process into two segments: first aligning reflectors on wafers using interferometers, then using those aligned reflectors as references to align the actual lens elements. This segmentation allows the complex task of aligning multiple lens elements to be broken down into manageable steps, improving both precision and efficiency
Solution Approach 2:
The patent performs preliminary alignment of reflectors on the wafers before final lens element alignment. By pre-aligning the reflectors as reference markers, the subsequent lens alignment process becomes faster and more accurate, as the reference framework is already established
2Productivity
If wafers with plural lens elements are aligned simultaneously, then time per lens is reduced, but achieving precise and known offset positioning becomes extremely difficult
Solution Approach 1:
The patent introduces reflectors as intermediary reference markers on the wafers. These reflectors serve as mediators between the interferometer measurement system and the actual lens elements, enabling precise positioning of multiple lens elements simultaneously while maintaining known offset relationships
Solution Approach 2:
The patent replaces manual mechanical alignment methods with optical interferometry. By using light-based interferometers to measure and align wafer positions, the system achieves high precision simultaneous alignment of multiple lens elements without the errors inherent in mechanical adjustment methods
3Manufacturing precision
If interferometers and actuators are used to align wafers, then alignment precision is improved, but device complexity increases
Solution Approach 1:
The patent implements a feedback control system where interferometers continuously measure wafer positions and actuators automatically adjust based on these measurements. The system serves itself by using its own measurement data to drive corrections, reducing the need for external intervention and simplifying operation despite the complex hardware
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 quick and accurate alignment of lens elements on wafers, reducing the time required for lens stack assembly and ensuring precise optical axis alignment, thereby improving the efficiency and reliability of lens stack formation.
Implementation Method 1
using a first interferometer to align a first wafer by optical interaction between the interferometer and the reflector on the first wafer
Data Source
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AI summary
The invention provides a method of aligning optical wafers having formed thereon plural lens elements in determined positions, the method comprising: providing a first wafer having at least two lenses formed thereon in fixed and determined relative positions; providing a second wafer having at least two lenses formed thereon in fixed and determined relative positions; using a first interferometer to align a first wafer by optical interaction between the interferometer and a first of the lenses on the first wafer; using a second interferometer to align a second wafer by optical interaction between the interferometer and a first of the lenses on the second wafer; whereby at least a second of the lenses on each of the first and second wafer are thereby aligned with respect to each other.