Diffraction effects for interferometric measurements due to imaging aberrations.

Area of Science:

• Optical Engineering
• Metrology
• Surface Characterization

Background:

• Aspheric surfaces are critical optical components requiring high-precision measurement.
• Interferometers with null correctors are commonly used but introduce imaging aberrations.
• These aberrations, combined with diffraction, limit measurement accuracy and introduce artifacts.

Purpose of the Study:

• To develop a concise methodology for analyzing the impact of imaging aberrations and diffraction on interferometric measurements of aspheric surfaces.
• To quantify the limitations imposed by astigmatic field curves, Talbot effect, and Fresnel edge diffraction.
• To validate the analytical model through simulations and experimental measurements.

Main Methods:

• Utilized astigmatic field curves to define and analyze imaging aberrations.
• Incorporated the Talbot effect and Fresnel edge diffraction to model diffraction coupling.
• Validated the analytical framework using computer simulations and interferometric measurements with a CGH null corrector.

Main Results:

• Demonstrated how imaging aberrations and diffraction effects interact to limit measurement accuracy.
• Identified filtering of high-frequency surface features and artifacts near boundaries as key limitations.
• Validated the developed methodology, showing good agreement between simulations and experimental data.

Conclusions:

• The proposed methodology provides a robust framework for understanding and mitigating measurement errors in aspheric surface characterization.
• Accurate analysis of aberration-diffraction coupling is essential for high-fidelity interferometric measurements.
• This work contributes to improving the precision and reliability of optical component manufacturing and testing.