Optic cavitation in an ultrasonic field

Area of Science:

• Physics
• Acoustics
• Optics

Background:

• Cavitation bubbles can be generated using various methods, including laser-induced processes.
• Understanding bubble dynamics is crucial for applications in fields like sonochemistry and medical treatments.
• The interplay between acoustic fields and laser-generated bubbles is not fully understood.

Purpose of the Study:

• To investigate the dynamics of cavitation bubbles generated by femtosecond laser pulses in an ultrasonic field.
• To analyze the influence of the acoustic cycle phase on bubble behavior and cavitation luminescence.
• To determine the relationship between bubble collapse characteristics and luminescence yield.

Main Methods:

• Generation of cavitation bubbles using low-energy femtosecond laser pulses in water.
• Application of an external ultrasonic field to influence bubble dynamics.
• Observation of bubble evolution using CCD photography.
• Measurement of cavitation luminescence with photomultiplier detectors.
• Correlation of bubble behavior with the phase of the acoustic cycle.

Main Results:

• Femtosecond laser pulses successfully generated cavitation bubbles in water.
• The ultrasonic field significantly expanded the initially small laser-generated bubbles.
• Cavitation luminescence was observed within specific, narrow intervals of the acoustic seeding phase.
• The intensity of cavitation luminescence was highly sensitive to the sphericity of the bubble collapse.

Conclusions:

• Laser-generated cavitation bubbles can be effectively manipulated by ultrasonic fields.
• Acoustic phase plays a critical role in both bubble dynamics and the occurrence of cavitation luminescence.
• Bubble collapse symmetry is a key factor governing the efficiency of light emission in this process.