Phonon imaging in 3D with a fibre probe.

Area of Science:

• Biophotonics
• Materials Science
• Acoustic Microscopy

Background:

• Current microscopic imaging techniques often require labels or lack the ability to simultaneously probe mechanical properties.
• There is a need for non-contact, high-resolution imaging methods capable of providing both spatial and mechanical information.

Purpose of the Study:

• To demonstrate a single optical fiber capable of simultaneous 3D spatial and mechanical property measurements of microscopic objects.
• To develop a novel system for label-free, non-contact imaging with high resolution and depth-profiling capabilities.

Main Methods:

• Utilized a novel measurement system with two ultrafast lasers exciting and detecting high-frequency ultrasound from a nano-transducer on an optical fiber tip.
• Developed a signal processing technique for nanometric in-depth spatial measurements from GHz acoustic waves and Brillouin spectroscopy.
• Demonstrated label-free and non-contact imaging on polymer microstructures.

Main Results:

• Achieved optical lateral resolution of 2.5 μm and acoustic depth-profiling precision of 45 nm.
• Simultaneously acquired 3D spatial information and mechanical properties from microscopic objects.
• Showcased the endoscopic potential by proposing an imaging bundle of thousands of fibers.

Conclusions:

• A single ultrasonic imaging fiber can simultaneously provide 3D spatial and mechanical property data.
• This technology advances phonon endomicroscopy, enabling label-free in vivo histology.
• The developed system offers a powerful tool for microscopic analysis and potential biomedical applications.