Ultrasonic transducer

An ultrasonic transducer, comprising:

• a piezoelectric element in a round shape that generates an ultrasonic sound wave;
• an acoustic lens that converges the ultrasonic sound wave;
• and
• an acoustic matching layer that decreases a reflection of the ultrasonic sound wave from a subject,
• wherein the piezoelectric element has a center having a hole through which an optical fiber that guides a light of a light source passes,
• the ultrasonic transducer transmits and receives the ultrasonic sound wave while emitting the light,
• the optical fiber is disposed such that a distal end of the optical fiber does not pass through the acoustic lens, and
• the acoustic lens has a color of transparency or semitransparency and a shape in a depressed surface such that the light of the distal end of the optical fiber reaches the subject.

An ultrasonic transducer, comprising:

• a piezoelectric element in a round shape that generates an ultrasonic sound wave having a wavelength λ;
• an acoustic lens that converges the ultrasonic sound wave;
• and
• an acoustic matching layer that decreases a reflection of the ultrasonic sound wave from a subject,
• wherein the piezoelectric element has a center having a hole through which an optical fiber that guides a light of a light source passes,
• the ultrasonic transducer transmits and receives the ultrasonic sound wave while emitting the light,
• the acoustic lens has a material using a resin with a withstand voltage, mainly polymethylpentene,
• the acoustic matching layer has a thickness set to λ/4 by not using a polyparaxylylene coating for ensuring the withstand voltage of the acoustic matching layer,
• the piezoelectric element and the acoustic matching layer have shapes in a planar surface,
• the optical fiber is disposed such that a distal end of the optical fiber does not pass through the acoustic lens, and
• the acoustic lens is transparent or semitransparent and has a shape in a depressed surface such that the light of the distal end of the optical fiber reaches the subject.