Patent ID: 7262542

Claim:
An ultrasound radiation device into a material comprising: a piezoelectric substrate; an input interdigital transducer formed on a central surface-part of an upward surface of said piezoelectric substrate; an output interdigital transducer located beside said input interdigital transducer on said central surface-part; another at least one interdigital transducer formed on a surrounding surface-part of said upward surface; and an amplifier, said input interdigital transducer receiving input electric signals E i (i=1, 2, . . . , n) with frequencies f i (i=1, 2, . . . , n), respectively, at a time, exciting elastic waves in said piezoelectric substrate, radiating leaky components of said elastic waves in the form of longitudinal waves into a material, and making a bottom boundary-surface of said material reflect said longitudinal waves back, said output interdigital transducer detecting one of reflected longitudinal waves at said bottom boundary-surface as a delayed output signal, which has one of said frequencies f i in accordance with a distance between said bottom boundary-surface and a top boundary-surface of said material, said amplifier amplifying said delayed output signal and feeding a signal part of an amplified electric signal back to said input interdigital transducer, again, and thus causing a self-oscillation type of delay-line oscillator operating at said one of said frequencies f i , said another at least one interdigital transducer receiving a remaining signal part of said amplified electric signal, exciting an elastic wave in said piezoelectric substrate, radiating a leaky component of said elastic wave in the form of a longitudinal wave into said material, making said longitudinal wave reflect at said bottom boundary-surface and re-reflect at said top boundary-surface of said material, and thus causing a continuous reflection as a chain reaction.