Reflection-mode multiple-illumination photoacoustic sensing to estimate optical properties

Area of Science:

• Biomedical Optics
• Photoacoustics
• Light-Matter Interactions

Background:

• Multiple-illumination photoacoustic tomography (MI-PAT) shows potential for quantitative reconstruction of optical properties in turbid media.
• Developing robust measurement techniques is crucial for advancing quantitative sensing in photoacoustics.

Purpose of the Study:

• To analyze a reflection-mode multiple-illumination photoacoustic method for estimating optical scattering properties.
• To explore the method's limitations in optical property estimation and depth-dependent fluence compensation.

Main Methods:

• A 532 nm pulsed laser spot was translated over a sub-surface absorber in a scattering medium.
• Photoacoustic amplitudes were measured at depths of 3, 4, and 5 mm.
• A light propagation model fitted measured amplitudes to estimate optical properties.

Main Results:

• Optical scattering properties were estimated with errors of 5.7% and 12.7% at 5 mm depth for specific scattering coefficients.
• Estimation accuracy decreased with increasing reduced scattering coefficient.
• Estimated parameters enabled depth-dependent fluence compensation for improved photoacoustic imaging quantitation.

Conclusions:

• The reflection-mode MI-PAT method can estimate optical scattering properties in turbid media.
• The method's accuracy is influenced by the scattering coefficient.
• This technique supports quantitative photoacoustic imaging through fluence compensation.