<s>
An	O
imaging	B-Algorithm
spectrometer	I-Algorithm
is	O
an	O
instrument	O
used	O
in	O
hyperspectral	B-Application
imaging	I-Application
and	O
imaging	O
spectroscopy	O
to	O
acquire	O
a	O
spectrally-resolved	O
image	O
of	O
an	O
object	O
or	O
scene	O
,	O
often	O
referred	O
to	O
as	O
a	O
datacube	B-Algorithm
due	O
to	O
the	O
three-dimensional	O
representation	O
of	O
the	O
data	O
.	O
</s>
<s>
Example	O
imaging	B-Algorithm
spectrometer	I-Algorithm
types	O
include	O
:	O
filtered	O
camera	O
,	O
whiskbroom	B-Algorithm
scanner	I-Algorithm
,	O
pushbroom	O
scanner	O
,	O
integral	O
field	O
spectrograph	O
(	O
or	O
related	O
dimensional	O
reformatting	O
techniques	O
)	O
,	O
wedge	O
imaging	B-Algorithm
spectrometer	I-Algorithm
,	O
Fourier	O
transform	O
imaging	B-Algorithm
spectrometer	I-Algorithm
,	O
computed	B-Algorithm
tomography	I-Algorithm
imaging	I-Algorithm
spectrometer	I-Algorithm
(	O
CTIS	O
)	O
,	O
image	O
replicating	O
imaging	B-Algorithm
spectrometer	I-Algorithm
(	O
IRIS	O
)	O
,	O
coded	O
aperture	O
snapshot	O
spectral	O
imager	O
(	O
CASSI	O
)	O
,	O
and	O
image	O
mapping	O
spectrometer	O
(	O
IMS	O
)	O
.	O
</s>
<s>
Imaging	B-Algorithm
spectrometers	I-Algorithm
are	O
used	O
specifically	O
for	O
the	O
purpose	O
of	O
measuring	O
the	O
spectral	O
content	O
of	O
light	O
and	O
electromagnetic	O
light	O
.	O
</s>
<s>
The	O
imaging	B-Algorithm
spectrometer	I-Algorithm
works	O
by	O
imaging	O
a	O
radiation	O
source	O
onto	O
what	O
is	O
called	O
a	O
"	O
slit	O
"	O
by	O
means	O
of	O
a	O
source	O
imager	O
.	O
</s>
<s>
The	O
practical	O
application	O
of	O
imaging	B-Algorithm
spectrometers	I-Algorithm
is	O
they	O
are	O
used	O
to	O
observe	O
the	O
planet	O
Earth	O
from	O
orbiting	O
satellites	O
.	O
</s>
<s>
Venus	O
express	O
,	O
orbiting	O
Venus	O
,	O
had	O
a	O
number	O
of	O
imaging	B-Algorithm
spectrometers	I-Algorithm
covering	O
NIR-vis-UV	O
.	O
</s>
<s>
The	O
lenses	O
of	O
the	O
prism	O
spectrometer	O
are	O
used	O
for	O
both	O
collimation	O
and	O
re-imaging	O
;	O
however	O
,	O
the	O
imaging	B-Algorithm
spectrometer	I-Algorithm
is	O
limited	O
in	O
its	O
performance	O
by	O
the	O
image	O
quality	O
provided	O
by	O
the	O
collimators	O
and	O
re-imagers	O
.	O
</s>
<s>
The	O
refracting	O
lenses	O
used	O
in	O
the	O
imaging	B-Algorithm
spectrometer	I-Algorithm
limit	O
performance	O
by	O
the	O
axial	O
chromatic	O
aberrations	O
of	O
the	O
lens	O
.	O
</s>
<s>
Imaging	B-Algorithm
spectrometers	I-Algorithm
are	O
meant	O
to	O
produce	O
well	O
resolved	O
images	O
.	O
</s>
<s>
In	O
order	O
for	O
this	O
to	O
occur	O
,	O
imaging	B-Algorithm
spectrometers	I-Algorithm
need	O
to	O
be	O
made	O
with	O
few	O
optical	O
surfaces	O
and	O
have	O
no	O
aspherical	O
optical	O
surfaces	O
.	O
</s>
