Quantitative detection of stochastic microstructure in turbid media by photoacoustic spectral matching

Quantitative detection of stochastic microstructure in turbid media remains a challenge to both optical and acoustical observation. A method of photoacoustic spectral matching is proposed to solve this problem. This method allows us to quantitatively detect the characteristic dimension of stochastic microstructures using a long wavelength. Using a working wavelength of about 375 μm, we accurately measure the dimensions (49, 94.8, and 199 μm) of particles hidden in turbid phantoms. Since stochastic microstructures composed of particles commonly appear in tissue, this method might provide an insight into the physiological and pathological processes deep within organisms.