Visualisation des champs ultrasonores par interférométrie hétérodyne

Abstract. A high resolution optical system has been designed and deveioped for imaging pulsed ultrasonic fields transmitted in water by piezoelectric transducers. The particle displacement was measured by a compact heterodyne interferometer whose probe beam is reflected by a thin membrane immersed in front of the transducer. Experiments camed out on focused or planar transducers demonstrate the capability of the system to map acoustic fields both in time and spatial domains. The spatial resolution and the dynamic range reached 20 p m and 45 dB and the bandwidth can be enlarged up to 40 MHz. Results are presented in various cross sectional views (B-scans, C-scans and 3D profiles). 1