Novel fibre lasers as excitation sources for photoacoustic tomography and microscopy

Two custom fibre lasers have been developed. One is designed for widefield photoacoustic tomography (PAT) and uses a custom drawn large core diameter fibre (100 mu m) to provide high pulse energies (5mJ). It also provides a variable pulse repetition frequency (100Hz-400Hz) and pulse duration (10-150ns) and is compact (of comparable dimensions to a desktop PC) and does not require external water cooling. This system was used to acquire in vivo images of the subcutaneous microvasculature in the human palm. The second laser is designed for Optical Resolution Photoacoustic Microscopy (OR-PAM) and provides a high quality beam (M-2<1.1), pulse energies >1 mu J with a pulse repetition frequency (PRF) up to 2MHz, and a 532nm emission wavelength. The high PRF of this laser was exploited for ultra-fast image acquisition. The compact size and enhanced functionality of these lasers offers a major opportunity to facilitate the translation of photoacoustic imaging to practical applications in medicine and biology.