Photoacoustic imaging is a hybrid imaging modality that is based on the detection of acoustic waves generated by absorption of pulsed light by tissue chromophores such as hemoglobin in blood. For this technique, usually large and costly Q-switched Nd:YAG lasers are used. These lasers provide a pulse energy of at least several milliJoules. In search of alternative light sources, we investigated the use of a small and compact pulsed laser diode to image blood vessels. We proved that a pulsed laser diode can be applied for imaging blood vessels in vivo.
Kolkman, R. G. M., Steenbergen, W., & van Leeuwen, T. (2006). In vivo photoacoustic imaging of blood vessels with a pulsed laser diode. Lasers in medical science, 21(3), 134-139. https://doi.org/10.1007/s10103-006-0384-z