Photo-acoustic distance sensor based on high-speed nano-second pulsed fiber laser

We present a fiber photoacoustic distance sensor using a high-speed nano-second pulsed fiber laser. This laser has a high-repetition rate of 50 kHz and a high pulse energy more than 500 nJ to interrogate the distance between the sample and the detector of photo-acoustic (PA) signal. The linear slope of the distance under test can be measured for the time interval between the laser pulse and the PA signal.