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Edge location by use of optical phase variation
1Department of Mechanical Engineering, Hong Kong University of Science and Technology, Hong Kong.
Applied Optics
|March 18, 2008
Summary
This study introduces a novel optical edge location method using phase variation in a differential interferometer. This technique offers high accuracy and resolution, unaffected by light intensity fluctuations or stray light.
Area of Science:
- Optics and Photonics
- Metrology
- Interferometry
Background:
- Traditional optical edge location relies on light intensity, which is susceptible to environmental and source variations.
- These variations in intensity and triggering levels limit the accuracy and precision of conventional edge detection methods.
Purpose of the Study:
- To develop a robust and accurate method for optical edge location.
- To overcome the limitations of intensity-based methods by utilizing phase variations.
Main Methods:
- A modified differential interferometer was employed to detect phase variations across an edge.
- The second derivative of the phase was utilized as a zero-crossing signal for precise edge determination.
- Theoretical analysis and experimental verification were performed to validate the method.
Main Results:
- The maximal slope of the phase variation precisely indicates the edge position.
- The developed method demonstrates high resolution and accuracy in edge location.
- Experimental results confirm the feasibility and reliability of the phase variation technique.
Conclusions:
- Phase variation in a modified differential interferometer provides a superior method for optical edge location.
- This technique is robust against stray light and light source intensity fluctuations.
- The method offers a significant advancement in precision metrology for edge detection.
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