Acoustic
Microscopes
In
addition
to
the
light
and
electron
microscope,
recently
microscopes
using
short
sound
waves
(acoustic)
have
also
been
developed.
It
was
first
in
1949
that
the
Russian
physicist
who
found
that
sound
waves
of
low
frequency
with
a
wavelength
close
to
that
of
light
exist.
However,
at
that
time
the
technology
to
convert
sound
signals
into
light
signals
did
not
exist.
Subsequently
in
the
sixties,
Professor
C.
Quate
of
USA
and
E.
Ash
of
England
developed
this
principle
further
and
used
it
in
microscopy.
The
principle
on
which
the
acoustic
microscope
works
is
based
on
the
fact
that
the
speed
of
sound
in
an
environment
is
directly
related
to
physical
properties
of
that
environment
such
as
the
density
and
elasticity.
The
acoustic
lens
is
a
spherical
surface
ground
into
a
material
such
as
sapphire
through
which
sound
travels
quickly.
The
surface
of
the
lens
is
kept
immersed
in
a,
fluid
of
relatively
tow
density
(generally
water).
