ULTRASONIC PIEZOELECTRIC ELEMENT AND SENSOR, AND MANUFACTURE OF SPECTRUM MICROSCOPE AND PIEZOELECTRIC ELEMENT

摘要

PURPOSE: To ensure high spatial resolution by preventing generation of noise due to edge ultrasonic wave transmitted from the edge part of an ultrasonic piezoelectric element. CONSTITUTION: The ultrasonic piezoelectric element 1 comprises a lower electrode 2, an upper electrode 3 of identical shape, and a piezoelectric membrane 4 sandwiched between and deposited on the upper surface of a coupler 5. The lower electrode 2 is rotary shifted by an angle α1 from the axis 8 of the coupler 5 whereas the upper electrode 3 is rotary shifted by an angle α2 from the axis 8 of the coupler 5. The following relationship α1 -α2 =180 deg./n is satisfied, where (n) is the order of rotation (integer) of axis symmetric electrode. The lower and upper electrodes 2, 3 can be deposited relatively easily using a mask of same profile produced through electrical discharge machining, for example. An ultrasonic transmission surface is formed at the intersection of the lower and upper electrodes 2, 3 overlapping by an angle 180 deg./n. The ultrasonic transmission surface includes a point and bottom part. Edge ultrasonic waves, radiated from the point and bottom part, interfere each other and disappear. Consequently, noise due to edge ultrasonic wave can be eliminated.