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Topography stitching in the spatial frequency domain for the representation of mid-spatial frequency errors
Applied Optics
|October 18, 2022
Summary
This study presents a novel method to unify surface error descriptions in optical fabrication. It bridges the gap between figure and finish errors, improving data exchange across optical design, manufacturing, and characterization.
Area of Science:
- Optical Engineering
- Materials Science
- Metrology
Background:
- Sub-aperture fabrication techniques like diamond turning, ion beam figuring, and bonnet polishing are crucial in optical manufacturing.
- These techniques address various spatial frequency errors, but their effects are interconnected, especially in the mid-spatial frequency (MSF) region.
- Current methods often treat figure (deterministic) and finish (statistical) errors separately, leading to a gap in understanding their combined impact.
Purpose of the Study:
- To develop a generalized surface description that integrates different spatial frequency error regimes.
- To facilitate seamless data exchange between optical design, manufacturing, and characterization disciplines.
- To bridge the gap between deterministic and statistical surface error representations.
Main Methods:
- Stitching amplitude and unwrapped phase spectra from surface topography measurements at multiple magnifications.
- Developing an alternative representation for surface errors across different regimes.
- Utilizing Zernike polynomials for figure errors and power spectral density (PSD) functions for roughness, but proposing a unified approach.
Main Results:
- A unified surface description method is presented, effectively combining data from various measurement scales.
- The proposed representation successfully bridges the gap between figure and finish errors.
- Mid-spatial frequency (MSF) errors are effectively described within this generalized framework.
Conclusions:
- The developed generalized surface description enhances versatility in optical fabrication.
- This approach improves the understanding and management of combined figure and finish errors.
- It enables more efficient and integrated workflows in optical design, manufacturing, and metrology.
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