Photoacoustic microscopy using ultrashort pulses with two different pulse durations

Area of Science:

• Biomedical Optics
• Photoacoustic Imaging
• Microscopy

Background:

• Photoacoustic microscopy (PAM) offers label-free imaging capabilities.
• Distinguishing one-photon and two-photon absorption signals is crucial for advanced PAM applications.
• Current methods for isolating two-photon signals can be complex.

Purpose of the Study:

• To introduce a novel subtraction method for enhanced two-photon photoacoustic microscopy.
• To improve the precision and effectiveness of extracting two-photon absorption signals.
• To enable detailed observation of microstructures using dual-mode absorption.

Main Methods:

• Utilizing ultrashort laser pulses with varying durations (femtoseconds to picoseconds).
• Implementing an image subtraction technique: shorter-pulse images minus longer-pulse images.
• Leveraging the pulse duration-dependent intensity ratio of one-photon and two-photon absorption signals.

Main Results:

• Successfully extracted two-photon photoacoustic images with high fidelity.
• Demonstrated effective separation of one-photon and two-photon absorption signals.
• Achieved precise cross-sectional imaging of silicone hollows containing mixed absorption solutions.

Conclusions:

• The proposed subtraction method reliably isolates two-photon photoacoustic signals.
• This technique enhances the capabilities of photoacoustic microscopy for detailed subsurface imaging.
• The method provides a valuable tool for observing complex microenvironments.