Time-directional filtering of wrapped phase for observing transient phenomena with parallel phase-shifting...

Area of Science:

• Optical Metrology
• Fluid Dynamics
• Acoustics

Background:

• Parallel phase-shifting interferometry (PPSI) combined with high-speed cameras allows observation of dynamic phenomena.
• Removing static phase is crucial for analyzing time-varying phase maps in high-speed observations.
• Traditional methods require phase unwrapping before static phase removal, which can introduce errors.

Purpose of the Study:

• To develop a method for removing static phase without phase unwrapping in high-speed PPSI.
• To enable direct visualization of fast phenomena like fluid flow and sound in air.
• To simplify and improve the accuracy of high-speed phase map analysis.

Main Methods:

• A novel time-directional filtering method is proposed.
• The method removes static phase directly from wrapped phase maps.
• No phase unwrapping is required, avoiding potential errors.

Main Results:

• Static phase is effectively removed from high-speed phase maps.
• Simultaneous visualization of fluid flow and sound is achieved at 42,000 frames per second.
• The time-directional filtering method demonstrates its efficacy in enhancing visualization.

Conclusions:

• Phase unwrapping is unnecessary for static phase removal in high-speed PPSI.
• The proposed time-directional filtering method offers a more direct and accurate approach.
• This technique advances the capability for observing and analyzing fast dynamic events.