Single-Shot Sub-Picosecond Ultrafast Microscopic Imaging Utilizing Spatial-Frequency Multiplexing for Ultrafast...

Area of Science:

• Materials Science
• Optical Engineering
• Physics

Background:

• Ultrafast laser processing creates micro/nanostructures crucial for advanced manufacturing.
• Ultrafast laser-induced events involve non-equilibrium dynamics at femtosecond to picosecond timescales.
• Single-shot ultrafast imaging offers sub-picosecond temporal resolution but often sacrifices spatial resolution.

Purpose of the Study:

• To develop an improved single-shot ultrafast imaging method with enhanced spatial resolution.
• To overcome the spatial resolution bottleneck in microscopic imaging of transient events.
• To enable detailed observation of ultrafast laser-matter interactions.

Main Methods:

• A spatial-frequency multiplexing method using structured illumination was proposed.
• A reconstruction strategy leveraging Fourier domain conjugate symmetry was developed.
• A two-frame microscopic system with a 300 fs frame interval was constructed.

Main Results:

• The proposed reconstruction strategy doubles spatial resolution compared to traditional algorithms.
• The method achieves a spatial resolution close to the diffraction limit.
• A maximum spatial resolution of 1.4 μm was demonstrated.
• The dynamic evolution of plasma induced by femtosecond laser interaction with fused silica was captured in a single shot.

Conclusions:

• The developed imaging technique significantly enhances spatial resolution for ultrafast phenomena.
• The method is feasible for studying ultrafast laser processing and material interactions.
• Provides valuable experimental data for refining theoretical models of laser-matter interactions.