CMUTs,
Capacative Micromachined Ultrasound Transducers, are being fabricated to be
integrated in a 1 mm diameter catheter. The catheter will be transported into
the coronary arteries to identify unstable plaque. The CMUTs have to radiate
uniformly to obtain a high quality ultrasound image. To characterize the
surface, and to determine both phase and absolute amplitude of the vibrations of
the CMUT is of great desire.
A
heterodyne interferometer has been built for this purpose. It offers the
possibility of both phase and high resolution absolute amplitude vibrational
measurements without the need of any normalization. The setup can measure
vibrations from 0-1.2GHz. The experimental setup is shown in Fig. 1.
Fig 1: Heterodyne Interferometer for absolute amplitude measurements.
Results
Fig. 2 shows absolute amplitude measurements of a LiNbO3 SAW device. The
SAW-device was excited with a 25MHz RF-signal with power density of 2.0W/m.
