Use of angular distribution of differential photoacoustic cross-section data for estimating source size

Abstract

A method to quantify morphological parameters of photoacoustic (PA) source from its angular distribution of differential photoacoustic cross-section (DPACS) is discussed. The DPACS for spheroidal particles with varying aspect ratio (AR) and the Chebyshev particles with different waviness and deformation parameters has been calculated using Green’s function approach. The DPACS as a function of measurement angle of those particles has been fitted with tri-axes ellipsoid form factor model to estimate the shape parameters. It is found that an enhancement of the DPACS occurs as the surface area of the source normal to the direction of measurement is increased. It decreases as the thickness of the source along the direction of measurement increases. For example, the DPACS in case of a spheroid for AR = 1:6 is 1.7 times greater than that of a particle with AR = 1:3 along θ = 0° The tri-axes ellipsoid model determines the size information of the spheroids accurately (error 10%). Estimated volumes for Chebyshev particles differ within ±10% with respect to the nominal values for≤most of the cases. The approach reported here may find application in practice to assess cellular morphology.