We report our experimental study on enhancement of photoacoustic (PA) signal from contrast dye by preilluminationof the dye with continuous wave (CW) light beam other than optical pulse (pulse width nsec)that is employed to irradiate tissue sample for inducing thermoelastic expansion and subsequently, generationof photoacoustic waves. This unique technique is in contrast to the conventional approaches of shift of opticalabsorption peak in the characteristic absorption spectrum of (PA signal) contrast dyes, say, nano-particles by control of the physical parameters including structure, shape and size. Experiments were conducted employing home-built photoacoustic (acoustic resolution) microscopy imaging system for measurement of PAsignal strength induced under various conditions: (1) without any pre-illumination of the dye with CW laserbeam, i.e., only pulse laser beam is employed to irradiate the dye and (2) with pre-illumination of the organic dyeat various time durations of pre-illumination. In this second case, the dye is exposed, rstly, to CW laser beam(of wavelength, 642nm) for a pre-specied time interval that is followed by irradiation of the dye with pulse laser(～6nsec) for inducing PA waves. The experimental results demonstrate that pre-illumination of the organicdye improves signicantly the strength of pulse-laser induced photo-acoustic signal strength. It is a promisingtechnique for end application in biomedical and clinical applications (more specically, for enhancement of PAsignal strength).
展开▼
