PURPOSE: To eliminate the distortion of an image at the time of low magnification generated by the non-coincidence of a mechanical scanning axis and the direction of the regular structure in a specimen, by providing a means for changing azimuth resolving power corresponding to magnification.
CONSTITUTION: A lower electrode 205 is formed to one end surface of a lens material 200 by vapor deposition and a piezoelectric membrane 220 comprising ZnO is formed thereon by vapor deposition. Further, two concentric circular upper electrodes 230, 210 are provided on said membrane 220 and electric input terminals 240, 250 are respectively provided to said electrodes 230, 210 to constitute an F-number variable sonic wave transducer 300. By changing over the upper electrodes 230, 210 to be used and ultrasonic frequency to be used corresponding to magnification, an F-number and a wavelength are changed and azimuth resolving power is changed in conjunction with the magnification.
ISHIKAWA KIYOSHI
KATAKURA KAGEYOSHI
