Biomedical Engineering Reference
In-Depth Information
Laser
Pulse Ultrasound Wave
Dumper
Ultrasound Transducer
y
x
Coupler
z
Background Scattered Light
Sample
Scattered Light
by Ultrasound Wave
Knife Edge
Photodetector
Fig. 2.24.
The experimental setup of the optical cross-sectional imaging system
with pulsed ultrasound wave assistance
Spherical Piezoelectric
Ceramic
Dumper
Coupler
a b
Fig. 2.25.
A ultrasound transducer head.
a
is a spherical piezoelectric ultrasound
transducer.
b
is an ultrasound transducer head, which consists of a piezoelectric
transducer attached by rubber and a damper
on the same axis and in the same same direction. The pulsed ultrasound
wave travels through the sample and scatters some of the incident beam.
The scattered light is detected on the other side of the sample with a PIN
photo-detector, positioned behind a knife edge that blocks light that is not
scattered by the ultrasound wave. The signal from the detector is recorded
with a digital storage oscilloscope up to a 20 MHz bandwidth. The time-
dependent scattered light intensity is synchronized from the start pulse of
the ultrasound wave.
Figure 2.25 shows a piezoelectric ceramic and an ultrasound transducer
head designed specially for use in this experiment. The piezoelectric ceramic
ultrasound transducer in Fig. 2.2a has a spherical shape with a 25.0 mm ra-
