Phase shifting interferometry from two normalized interferograms with random tilt phase-shift.

Area of Science:

• Optical Metrology
• Interferometry
• Phase Measurement

Background:

• Phase shifting interferometry (PSI) is crucial for precise surface measurements.
• Random tilt phase shifts and vibrations often introduce errors in traditional PSI.
• Existing methods may require costly and highly accurate phase shifters.

Purpose of the Study:

• To develop a novel PSI method capable of handling random tilt phase shifts.
• To enhance accuracy and speed in phase distribution retrieval.
• To reduce the dependency on high-precision phase shifters.

Main Methods:

• Utilizing two normalized interferograms with random tilt phase shifts.
• Extracting the tilted phase-shift plane from the phase difference of normalized interferograms.
• Employing a special points fitting method to analyze phase difference distribution for tilt extraction.

Main Results:

• Successfully retrieved phase distributions from two normalized frames after calculating tilt phase shift.
• Demonstrated high accuracy and speed compared to the three-step iterative method in simulations and experiments.
• Validated the method's applicability to both open and closed fringe patterns.

Conclusions:

• The proposed method effectively eliminates small tilt-shift errors caused by vibrations.
• It accurately detects large tilt phase shifts, making it suitable for phase-tilting interferometry.
• This approach relaxes requirements for phase shifter accuracy, potentially enabling high-precision analysis in vibrated environments without costly equipment.