Common-path interferometry with tilt carrier for surface measurement of complex optics

Area of Science:

• Optical Engineering
• Metrology
• Interferometry

Background:

• Common-path interferometers reduce systematic errors but pose optical design challenges.
• Traditional systems prioritize on-axis beam quality, neglecting off-axis performance.
• Accurate surface measurement of complex optics requires advanced metrology solutions.

Purpose of the Study:

• To introduce a novel common-path non-null interference system for complex optical surface measurement.
• To overcome the optical design difficulties associated with off-axis beams in common-path systems.
• To enhance accuracy and reduce calibration complexity in optical metrology.

Main Methods:

• Development of a common-path non-null interference system utilizing wide field-of-view (FOV) lens groups.
• Implementation of strategies to ensure high-quality on-axis and off-axis beams with wave aberrations below 0.1λ.
• Optimization of lens and aperture parameters to prevent pseudo reference beam generation from off-axis beams.
• Utilization of a fiber-array-based point-source generator for versatile, tilted test beam generation.

Main Results:

• The proposed system effectively eliminates systematic errors and simplifies calibration.
• Achieved superior wave aberration control (<0.1λ) for both on-axis and off-axis fields of view.
• Successfully prevented pseudo reference beam formation through optimized optical design.
• Demonstrated high accuracy and time savings in measuring parabolic and cylindrical mirrors.

Conclusions:

• The novel common-path non-null interference system offers a robust solution for complex optical surface metrology.
• The system's design overcomes limitations of classical interferometers, providing enhanced performance for both on-axis and off-axis beams.
• This versatile system achieves high accuracy and efficiency, validated by measurements of various optical components.