Multi-frame interferometric imaging with a femtosecond stroboscopic pulse train for observing irreversible phenomena

Area of Science:

• Optics and Photonics
• Materials Science
• Nonlinear Dynamics

Background:

• Understanding ultrafast phenomena requires high temporal resolution imaging.
• Traditional methods often lack the speed to capture transient events like material deformation or wave propagation.
• Laser-induced processes create dynamic changes that are challenging to visualize.

Purpose of the Study:

• To develop and demonstrate a high-speed, single-shot, multi-frame interferometric imaging technique.
• To enable the recording of multiple interferometric images with femtosecond exposure times.
• To capture events within a 50 nanosecond window following a single excitation event.

Main Methods:

• Utilized a doubling cavity to generate a synchronized femtosecond pulse train for stroboscopic illumination.
• Employed a framing camera with gated exposure windows synchronized to the pulse train.
• Integrated a Michelson interferometer to extract phase and displacement information from recorded images.

Main Results:

• Successfully recorded multiple interferometric images with femtosecond exposure times over a 50 ns event window.
• Demonstrated the technique by monitoring laser-induced deformation in a silicon nitride membrane.
• Visualized the propagation of high-amplitude acoustic waves in the membrane.

Conclusions:

• The developed technique provides unprecedented temporal resolution for studying fast irreversible phenomena.
• Applicable to diverse fields including crack branching, shock-induced damage, cavitation, and dielectric breakdown.
• Offers a powerful new tool for fundamental research in dynamic processes.