Tunable phase-extraction formulae for simultaneous shape measurement of multiple surfaces with wavelength-shifting...

Area of Science:

• Optical metrology
• Interferometry
• Surface characterization

Background:

• Multiple-beam interference complicates interferometric surface measurement of parallel plates.
• Existing phase-shifting methods require pathlength-dependent techniques like wavelength scanning.
• Optimizing frequency analysis is crucial for accuracy, tolerating dispersion and nonlinearities.

Purpose of the Study:

• To develop advanced phase-shifting algorithms for stacked parallel plate interferometry.
• To address the technical difficulties posed by multiple-beam interference.
• To enable precise surface measurement in complex optical systems.

Main Methods:

• Introduced a new class of phase-shifting algorithms.
• Utilized wavelength scanning to separate interference signals in frequency space.
• Optimized the detection window for frequency analysis to enhance tolerance and noise suppression.

Main Results:

• Demonstrated a new algorithm class for continuous phase detection tuning.
• Successfully measured a four-surface stack of near-parallel plates using a Fizeau interferometer.
• Achieved improved accuracy in surface measurement despite multiple-beam interference.

Conclusions:

• The developed algorithms effectively overcome challenges in interferometric surface measurement of stacked plates.
• The new methods allow for precise and adaptable phase detection across various frequencies.
• This advancement is significant for high-accuracy surface characterization in optical metrology.