Study on acoustic detections of Nd:YAG laser induced breakdown at different wavelengths

Abstract

Laser-induced breakdown detection (LIBD) is among many techniques utilizing laser beam to characterize nanoparticles in solution. It is based on the detection of plasma formation resulted from the interaction between particles and laser beam. In acoustic LIBD, the acoustic signal which accompanies the plasma formation is detected by a microphone. In this study, a 1064 nm pulsed laser was used as the laser source for LIBD system instead of the frequently used 532 nm. The presence of colloids in filtered and unfiltered water was investigated using the new system and the result was compared with those from conventional system. The S-curves from 1064 nm system showed similar trend with S-curves from 532 nm system. The presence of larger nanoparticles in unfiltered water resulted in lower breakdown threshold energy. However, the breakdown threshold energy of both filtered and unfiltered water was much higher in the 1064 nm LIBD system. The shifting was attributed to the high absorbance of water at 1064 nm. This research proved the possibility of using 1064 nm pulsed Nd:YAG laser as an alternative wavelength source for LIBD system, nevertheless various setup arrangement might be needed.