Fig. 1: Principle of photoacoustic imaging.
From: Deep tissue photoacoustic imaging with light and sound
a Physical process for photoacoustic signal generation and detection. Short-pulse optical illumination excites the target, resulting in optical absorption and, subsequently, nonradiative relaxation. This is followed by thermoelastic expansion, causing an ultrasound wave to propagate away from the absorber to ultrasound detectors (adapted from ref. 8). b Optical absorption spectrum of common biological molecules (adapted from ref. 139). The strong absorption of hemoglobin in the visible and near-infrared bands allows for angiographic imaging by PACT. HbO2 oxygenated hemoglobin, HbR deoxygenated hemoglobin, MbO2 oxygenated myoglobin, MbR reduced myoglobin, DNA deoxyribonucleic acid, RNA ribonucleic acid.
