Features of the application of sound-transparent metallized foils for the calibration of hydrophones using optical interferometry in free field

А.М. Еnyakov, S.I. Kuznetsov

FSUE “VNIIFTRI”, Mendeleevo, Moscow region, Russia

Al’manac of Modern Metrology № 3 (27) 2021, pages 85–103

Annotation. The features of the use of a polyethylene terephthalate foil with a thickness of several micrometers for tracking the vibrational displacement in an ultrasonic wave in the frequency range from 1 to 20 MHz with further conversion of the vibrational velocity to the acoustic pressure during the calibration of hydrophones are considered. One side of the foil is coated with a thin layer of metal to improve the reflection of the laser beam of the interferometric displacement amplitude meter. It is shown that the adequacy of the vibrations of the foil and water particles in the incident ultrasonic wave depends on the acoustic resistance and the thickness of the foil. The frequency dependences of the ultrasonic wave transmission coefficient for introducing corrections to the results of measuring the vibrational velocity of a foil of different thickness are calculated and the uncertainties of these corrections are estimated.

Key words: hydrophone calibration, vibrational velocity, laser interferometer, PET film, ultrasound.

Full texts of articles are available only in Russian in printed issues of the magazine.