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The heart of an ultrasound Imaging system is the electroscoustic transducer;
a device that converts electrical signalsinto a focusedmechanicalwave and
reconverts reflected mechanical echoes from organs and tissue for real-time
image construction. Small, calibrated transducers called hydrophones are
usedto measure the acoustic outputof the transducers usedin these systems.
The first article in this issue describes a hydrophone developed by HP that
has a spot diameterof 50micrometers and a bandwidth greater than 150 MHz,
enabling it to characterize medical imaging rransducers with operating fre-
ouencies exceeding 20MHz.
Measurement accuracy for HP optical power meters and other optical
The 150 -MH z-b a n d w i d t h
m e m b r a n e hydrophone
instruments is the main theme in the next article. TI?e article elso contains
desc r i b e d on page 6. an overview on the theory of measurement.
The si g n a l is generated
by a 20-MHz f o c u sed
Hewlett-Packard holds severalinternal conferences each yearto sllow HP
ult r a s ound t r a n sdu c e r scientists and engineers to share such things as best practices and research
driv ing water into a non- activities, We have five papers from the 1997 conferencesponsored by engi-
li n e a r st at e . See page 11
neers from HP's integrated circuit R&D community.
to identify the parts on
this hydrophone. Improvements in simulation and verification toots for Ie design are the main
topics of the first two oi these 8 rticle s. The first describes the development
Volume 49