Schwartz et al. devised an analytical model to depict the photothermal expansion of a homogenous sample, factoring in a single laser pulse. They considered the laser heating profile and performed numerical simulations on heterogeneous samples comprising two adjacent materials. This study aimed to elucidate the dependence of signal transduction efficiency and spatial resolution on laser pulse width, pulse shape, sample thermalization time and interfacial thermal resistance, etc. and found this model in good agreement with their previous experimental investigations. However, in many cases AFM-IR samples do not conform to the geometries de-scribed in literature. Particularly, many samples consist of absorbers embedded within a larger matrix, such as inclusion bodies inside a cell , metal soaps in paint layers or even organelles .