Microscope Objective Alignment via Aberration Compensation
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Solution Overview
Problem
The alignment of high numerical aperture objective and pupil relay modules in optical microscopes for patterned substrates inspection is critical for maintaining image quality and resolution, but improper alignment leads to blurriness, distortion, increased measurement errors, and reduced throughput.
Innovation Solution
A method and system where the objective and pupil relay modules are configured to introduce and compensate for aberration components, allowing for precise alignment through measuring a combined aberration indicator and iteratively adjusting their optical alignment until a predetermined target is reached, utilizing techniques like null alignment and wavefront sensing to minimize residual aberrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the objective and pupil relay module are not properly aligned, then image quality deteriorates due to blurriness and distortion, but alignment adjustment increases inspection time
Solution Approach 1:
The system performs self-alignment by automatically measuring the combined aberration indicator and adjusting the optical alignment without requiring manual intervention or external alignment tools, thereby achieving high precision alignment while maintaining inspection throughput
Solution Approach 2:
The alignment process uses feedback from the measured combined aberration indicator to iteratively adjust the optical alignment of the objective and pupil relay module, converging on the optimal alignment position that minimizes residual aberrations
2Measurement precision
If manual alignment methods are used, then alignment can be performed, but measurement precision and resolution are reduced due to operator variability and lack of feedback
Solution Approach 1:
The patent replaces manual mechanical alignment methods with an optical measurement system that uses the combined aberration indicator to quantify misalignment, substituting subjective manual adjustment with objective optical measurement and automated feedback control
Solution Approach 2:
The combined aberration indicator serves as an intermediary metric that translates the complex optical alignment state into a measurable quantity, enabling precise alignment adjustment through feedback control without requiring direct observation of the optical path
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 ensures accurate alignment, reducing residual aberrations to below 25 mλ, thereby enhancing image quality, resolution, and inspection efficiency by maintaining optimal optical performance.
Implementation Method 1
The objective is configured to introduce an objective aberration component and the pupil relay module is configured to have a corresponding pupil relay module aberration component such that the pupil relay module aberration component compensates said objective aberration component
Implementation Method 2
measuring a combined aberration indicator indicative of a combined aberration resulting from the optical combination of the objective and pupil relay module
Data Source
AI summary
The presently disclosed subject matter provides a method for aligning an objective and a pupil relay module of a microscope. The objective is configured to introduce an objective aberration component and the pupil relay module is configured to have a corresponding pupil relay module aberration component such that the pupil relay module aberration component compensates said objective aberration component when the pupil relay module is accurately aligned with the objective. The method comprises: (a) measuring a combined aberration indicator indicative of a combined aberration resulting from the optical combination of the objective and pupil relay module; (b) adjusting an optical alignment of the objective and pupil relay module based on the measured combined aberration indicator; (c) iterating (a) and (b) until the measured combined aberration indicator reaches a predetermined combined aberration indicator target thereby achieving accurate alignment.