Design of anti cavitation hydrophone by deposition of hydrothermally synthesized lead zirconate titanate poly-crystalline film on reverse surface of titanium film front layer

It is difficult to measure the high intensity ultrasound field with generation of acoustic cavitation, since the electrode of hydrophone will be damaged by erosion from acoustic cavitation. Therefore, we proposed the original hydrophone by using hydrothermally synthesized lead zirconate titanate poly-crystalline film deposited on a reverse surface of a titanium film front layer as protection layer, acoustic receiving layer and GND electrode in order to realize a tough anti cavitation hydrophone. We designed two types of hydrophone by numerical computer simulation with MASON´s equivalent circuit for hydrothermally synthesized lead zirconate titanate poly-crystalline film and one dimensional acoustic transmission model for the titanium front layer. The effects by thickness of Ti front layer, specific acoustic impedance of backing material on frequency characteristics of receiving sensitivity were calculated for design of optimum structure of the anti-cavitation hydrophone. One type of hydrophone (TYPE-1) has titanium front layer thinner than 5um and epoxy resin backing material to obtain the flat frequency characteristics of receiving sensitivity. Another type hydrophone (TYPE-2) has 50μm thickness titanium front layer and backing material of titanium. The hydrothermally synthesized lead zirconate titanate poly-crystalline film with thickness of 15 um was deposited on a reverse surface of a titanium film front layer of both type of hydrophone. We can expect to observe the ultrasound waves at focal area of HIFU treatment equipment and in the water vessel of the ultrasound cleaner without any damage by acoustic cavitation and erosion by using both types of hydrophones. It is easier to fabricate the TYPE-2 hydrophone than TYPE-2 hydrophone. Furthermore, we can expect that TYPE-2 hydrophone has 1.5 times higher receiving sensitivity than TYPE-1 hydrophone.