Ultrasonic/acoustic transducer

A transducer, comprising:—

• a. a vibrator body comprising:—
• i. a first part for generating and/or receiving acoustic or ultrasonic waves resonating at a first resonance frequency;
• acoustically coupled to
• ii. a second part for generating and/or receiving acoustic or ultrasonic waves at a second resonance frequency and,
• b. a matching layer having a substantially single acoustic impedance, the matching layer coupled to said vibrator body wherein the thickness of the matching layer is a quarter wavelength of the ultrasonic or acoustic waves in the matching layer so as, in use, to acoustically match the first part and the second part to a medium;
• wherein the acoustic impedance of the first part is acoustically matched into the medium by said matching layer and the acoustic impedance of the second part is acoustically matched into the medium by a first matching layer and a second matching layer, said first matching layer being said first part and said second matching layer being said matching layer wherein the thickness of the matching layer lies between an odd multiple of the quarter wavelength thickness of the second matching layer of the second part and the quarter wavelength thickness of the matching layer of the first part.

A transducer comprising:—

• a. a vibrator body comprising:—
• i. a first part for generating and/or receiving acoustic or ultrasonic waves;
• acoustically coupled to
• ii. a second part for generating and/or receiving acoustic or ultrasonic waves and,
• b. a matching layer having a substantially single acoustic impedance, the matching layer coupled to said vibrator body wherein the thickness of the matching layer is a quarter wavelength of the ultrasonic or acoustic waves in the matching layer so as, in use, to acoustically match the first part and the second part to a medium;
• wherein the acoustic impedance of the first part is acoustically matched into the medium by said matching layer and the acoustic impedance of the second part is acoustically matched into the medium by a first matching layer and a second matching layer, said first matching layer being said first part and said second matching layer being said matching layer wherein the quarter wavelength thickness of the matching layer of the first part is substantially an odd multiple of the quarter wavelength thickness of the second matching layer of the second part.