<s>
Ultrasound-modulated	B-Algorithm
optical	I-Algorithm
tomography	I-Algorithm
(	O
UOT	O
)	O
is	O
a	O
form	O
of	O
tomography	B-Algorithm
involving	O
ultrasound	B-Application
.	O
</s>
<s>
It	O
is	O
used	O
in	O
imaging	B-Application
of	O
biological	O
soft	O
tissues	O
and	O
has	O
potential	O
applications	O
for	O
early	O
cancer	O
detection	O
.	O
</s>
<s>
Like	O
optical	O
techniques	O
,	O
this	O
method	O
provides	O
high	O
contrast	O
,	O
and	O
the	O
use	O
of	O
ultrasound	B-Application
also	O
provides	O
high	O
resolution	O
.	O
</s>
<s>
1	O
Incoherent	O
Modulation	O
of	O
Light	O
Due	O
to	O
Ultrasound-Induced	O
Variations	O
in	O
Optical	O
Properties	O
of	O
Medium	O
.	O
</s>
<s>
2	O
Variations	O
in	O
Optical	O
Phase	O
in	O
Response	O
to	O
Ultrasound-Induced	O
Displacements	O
of	O
Scatterers	O
.	O
</s>
<s>
With	O
the	O
vibration	O
from	O
focused	O
ultrasound	B-Application
,	O
the	O
local	O
scatterers	O
within	O
the	O
medium	O
will	O
be	O
moved	O
.	O
</s>
<s>
(	O
1	O
)	O
the	O
optical	O
wavelength	O
is	O
much	O
shorter	O
than	O
the	O
mean	O
free	O
path	O
(	O
weak-scattering	O
approximation	O
)	O
and	O
(	O
2	O
)	O
the	O
ultrasound-induced	O
change	O
in	O
the	O
optical	O
path	O
length	O
is	O
much	O
less	O
than	O
the	O
optical	O
wavelength	O
(	O
weak-modulation	O
approximation	O
)	O
.	O
</s>
<s>
After	O
applying	O
diffusion	B-Algorithm
theory	I-Algorithm
,	O
the	O
original	O
G1	O
equation	O
can	O
be	O
further	O
modified	O
as	O
:	O
</s>
<s>
In	O
these	O
equations	O
,	O
ωa	O
represents	O
the	O
acoustic	O
angular	O
frequency	O
,	O
and	O
the	O
n0	O
is	O
the	O
background	O
index	O
of	O
refraction	O
;	O
k0	O
is	O
the	O
magnitude	O
of	O
the	O
optical	O
wave	O
vector	O
in	O
vacuo	O
;	O
A	O
is	O
the	O
acoustic	O
amplitude	O
,	O
which	O
is	O
proportional	O
to	O
the	O
acoustic	O
pressure	O
;	O
ka	O
is	O
the	O
magnitude	O
of	O
the	O
acoustic	O
wavevector	O
;	O
lt	O
 '	O
is	O
the	O
optical	O
transport	O
mean	O
free	O
path	O
;	O
η	O
is	O
the	O
elasto-optical	O
coefficient	O
;	O
ρ	O
is	O
the	O
mass	O
density	O
;	O
represents	O
how	O
ultrasound	B-Application
averagely	O
change	O
the	O
light	O
per	O
free	O
path	O
via	O
index	O
of	O
refraction	O
and	O
displacementare	O
respectively	O
.	O
</s>
<s>
In	O
conclusion	O
,	O
in	O
UOT	O
analytic	O
model	O
,	O
with	O
the	O
help	O
of	O
weak-scattering	O
approximation	O
,	O
weak-modulation	O
approximation	O
,	O
diffusion	B-Algorithm
theory	I-Algorithm
,	O
and	O
Wiener-Khinchin	O
theorem	O
,	O
the	O
relationship	O
between	O
acoustic	O
amplitude	O
and	O
modulated	O
light	O
can	O
be	O
successfully	O
observed	O
.	O
</s>
<s>
There	O
will	O
also	O
be	O
an	O
ultrasound	B-Application
absorber	O
at	O
the	O
bottom	O
of	O
the	O
tank	O
to	O
avoid	O
rebound	O
of	O
ultrasound	B-Application
.	O
</s>
