Photoacoustic tomography of tissue subwavelength microstructure with a narrowband and low frequency system

Based on the analyzed relationship between the microstructure and the spectral parameters of photoacoustic signal, a tomography scheme with a narrowband and low frequency is designed to evaluate the subwavelength microstructure of tissues. Experiments show that this approach can differentiate the subwavelength microstructures of two melanomas-like samples, where their structure scales (49 and 199 μm) are much smaller than the working wavelength 0.3–1.5 mm of the imaging system. Since the microstructure is an effective indicator to tissue characteristics, the proposed imaging scheme could have the potential to classify different tissue types and achieve improved diagnosis in deep tissues.