<s>
A	O
microbolometer	B-Algorithm
is	O
a	O
specific	O
type	O
of	O
bolometer	B-Application
used	O
as	O
a	O
detector	O
in	O
a	O
thermal	O
camera	O
.	O
</s>
<s>
Unlike	O
other	O
types	O
of	O
infrared	O
detecting	O
equipment	O
,	O
microbolometers	B-Algorithm
do	O
not	O
require	O
cooling	O
.	O
</s>
<s>
A	O
microbolometer	B-Algorithm
is	O
an	O
uncooled	O
thermal	O
sensor	O
.	O
</s>
<s>
A	O
microbolometer	B-Algorithm
consists	O
of	O
an	O
array	O
of	O
pixels	B-Algorithm
,	O
each	O
pixel	B-Algorithm
being	O
made	O
up	O
of	O
several	O
layers	O
.	O
</s>
<s>
The	O
cross-sectional	O
diagram	O
shown	O
in	O
Figure	O
1	O
provides	O
a	O
generalized	O
view	O
of	O
the	O
pixel	B-Algorithm
.	O
</s>
<s>
Each	O
company	O
that	O
manufactures	O
microbolometers	B-Algorithm
has	O
their	O
own	O
unique	O
procedure	O
for	O
producing	O
them	O
and	O
they	O
even	O
use	O
a	O
variety	O
of	O
different	O
IR	O
absorbing	O
materials	O
.	O
</s>
<s>
Because	O
microbolometers	B-Algorithm
do	O
not	O
undergo	O
any	O
cooling	O
,	O
the	O
absorbing	O
material	O
must	O
be	O
thermally	O
isolated	O
from	O
the	O
bottom	O
ROIC	O
and	O
the	O
bridge	O
like	O
structure	O
allows	O
for	O
this	O
to	O
occur	O
.	O
</s>
<s>
After	O
the	O
array	O
of	O
pixels	B-Algorithm
is	O
created	O
the	O
microbolometer	B-Algorithm
is	O
encapsulated	O
under	O
a	O
vacuum	O
to	O
increase	O
the	O
longevity	O
of	O
the	O
device	O
.	O
</s>
<s>
The	O
microbolometer	B-Algorithm
array	O
is	O
commonly	O
found	O
in	O
two	O
sizes	O
,	O
320×240	O
pixels	B-Algorithm
or	O
less	O
expensive	O
160×120	O
pixels	B-Algorithm
.	O
</s>
<s>
Current	O
technology	O
has	O
led	O
to	O
the	O
production	O
of	O
devices	O
with	O
640×480	O
or	O
1024x768	O
pixels	B-Algorithm
.	O
</s>
<s>
There	O
has	O
also	O
been	O
a	O
decrease	O
in	O
the	O
individual	O
pixel	B-Algorithm
dimensions	O
.	O
</s>
<s>
The	O
pixel	B-Algorithm
size	O
was	O
typically	O
45	O
μm	O
in	O
older	O
devices	O
and	O
has	O
been	O
decreased	O
to	O
12	O
μm	O
in	O
current	O
devices	O
.	O
</s>
<s>
As	O
the	O
pixel	B-Algorithm
size	O
is	O
decreased	O
and	O
the	O
number	O
of	O
pixels	B-Algorithm
per	O
unit	O
area	O
is	O
increased	O
proportionally	O
,	O
an	O
image	O
with	O
higher	O
resolution	O
is	O
created	O
,	O
but	O
with	O
a	O
higher	O
NETD	O
(	O
Noise	O
Equivalent	O
Temperature	O
Difference	O
(	O
differential	O
)	O
)	O
due	O
to	O
smaller	O
pixels	B-Algorithm
being	O
less	O
sensitive	O
to	O
IR	O
radiation	O
.	O
</s>
<s>
There	O
is	O
a	O
wide	O
variety	O
of	O
materials	O
that	O
are	O
used	O
for	O
the	O
detector	O
element	O
in	O
microbolometers	B-Algorithm
.	O
</s>
<s>
Industry	O
currently	O
manufactures	O
microbolometers	B-Algorithm
that	O
contain	O
materials	O
with	O
TCRs	O
near	O
−2%	O
/K	O
.	O
</s>
<s>
Although	O
many	O
materials	O
exist	O
that	O
have	O
far	O
higher	O
TCRs	O
,	O
there	O
are	O
several	O
other	O
factors	O
that	O
need	O
to	O
be	O
taken	O
into	O
consideration	O
when	O
producing	O
optimized	O
microbolometers	B-Algorithm
.	O
</s>
<s>
The	O
two	O
most	O
commonly	O
used	O
IR	O
radiation	O
detecting	O
materials	O
in	O
microbolometers	B-Algorithm
are	O
amorphous	O
silicon	O
and	O
vanadium	O
oxide	O
.	O
</s>
<s>
A	O
problem	O
with	O
some	O
potential	O
materials	O
is	O
that	O
to	O
create	O
the	O
desirable	O
properties	O
their	O
deposition	O
temperatures	O
may	O
be	O
too	O
high	O
for	O
CMOS	B-Device
fabrication	O
processes	O
.	O
</s>
<s>
Amorphous	O
Si	O
(	O
a-Si	O
)	O
thin	O
films	O
can	O
easily	O
be	O
integrated	O
into	O
the	O
CMOS	B-Device
fabrication	O
process	O
using	O
low	O
deposition	O
temperatures	O
,	O
is	O
highly	O
stable	O
,	O
has	O
a	O
fast	O
time	O
constant	O
,	O
and	O
has	O
a	O
long	O
mean	O
time	O
before	O
failure	O
.	O
</s>
<s>
To	O
create	O
the	O
layered	O
structure	O
and	O
patterning	O
using	O
the	O
CMOS	B-Device
fabrication	O
process	O
requires	O
temperatures	O
to	O
stay	O
below	O
200˚C	O
on	O
average	O
.	O
</s>
<s>
Vanadium	O
oxide	O
thin	O
films	O
may	O
also	O
be	O
integrated	O
into	O
the	O
CMOS	B-Device
fabrication	O
process	O
although	O
not	O
as	O
easily	O
as	O
a-Si	O
for	O
temperature	O
reasons	O
.	O
</s>
<s>
Many	O
phases	O
of	O
VOx	O
exist	O
although	O
it	O
seems	O
that	O
x≈	O
1.8	O
has	O
become	O
the	O
most	O
popular	O
for	O
microbolometer	B-Algorithm
applications	O
.	O
</s>
<s>
A	O
thermal	O
imaging	O
camera	O
with	O
a	O
Vanadium	O
Oxide	O
Micro-bolometer	O
detector	O
is	O
more	O
stable	O
,	O
compact	O
,	O
and	O
sensitive	O
compared	O
with	O
any	O
other	O
technology	O
though	O
VOx	O
is	O
older	O
technology	O
.	O
</s>
<s>
The	O
use	O
of	O
infrared	O
optical	O
antennae	O
together	O
with	O
small-size	O
microbolometer	B-Algorithm
materials	O
can	O
enhance	O
its	O
detection	O
efficiency	O
.	O
</s>
<s>
Most	O
microbolometers	B-Algorithm
contain	O
a	O
temperature	O
sensitive	O
resistor	O
which	O
makes	O
them	O
a	O
passive	O
electronic	O
device	O
.	O
</s>
<s>
In	O
1994	O
one	O
company	O
,	O
Electro-Optic	O
Sensor	O
Design	O
(	O
EOSD	O
)	O
,	O
began	O
looking	O
into	O
producing	O
microbolometers	B-Algorithm
that	O
used	O
a	O
thin	O
film	O
transistor	O
(	O
TFT	O
)	O
,	O
which	O
is	O
a	O
special	O
kind	O
of	O
field	O
effect	O
transistor	O
.	O
</s>
<s>
This	O
property	O
enables	O
,	O
for	O
example	O
,	O
the	O
mounting	O
of	O
uncooled	O
microbolometer	B-Algorithm
thermal	O
imagers	O
on	O
helmets	O
.	O
</s>
<s>
The	O
sensitivity	O
is	O
partly	O
limited	O
by	O
the	O
thermal	O
conductance	O
of	O
the	O
pixel	B-Algorithm
.	O
</s>
<s>
Microbolometer	B-Algorithm
technology	O
was	O
originally	O
developed	O
by	O
Honeywell	O
starting	O
in	O
the	O
late	O
1970s	O
as	O
a	O
classified	O
contract	O
for	O
the	O
US	O
Department	O
of	O
Defense	O
.	O
</s>
