Development of Novel Tough Hydrophone with Sensor Head with Hydrothermally PZT Film Deposited on The Back Surface of Titanium Conical Front Plate

We had developed a tough hydrophone using a titanium front plate and hydrothermally synthesized PZT polycrystalline film. Currently, there are two kinds of hydrophones we are developing, one is a tough hydrophone with a cylindrical front plate, and the other is a tough hydrophone with a conical front plate. These two kinds of hydrophones are not decreased their sensitivity even if they are exposed to a sound field with acoustic cavitation in the ultrasound cleaner for a total of 50 hours. However, there are differences in the scratches on the surface of the front plate. In this study, we observed the behavior of acoustic cavitation bubbles around the tip of the hydrophone using a high-speed video camera and a laser light sheet. In the tough hydrophone with a cylindrical front plate, a cavitation bubble cloud has been adhered to the tip of the hydrophone from the beginning of observation. On the other hand, even with a tough hydrophone with a conical front plate, a cavitation bubble cloud was adhered to the tip of the hydrophone at the beginning of observation. However, when the adhered cavitation bubble cloud collided with another cavitation bubble cloud, we were able to observe behavior the adhered cavitation bubble cloud flows along the shape of the tip of the hydrophone.