<s>
Liquid	B-Device
crystal	I-Device
on	I-Device
silicon	I-Device
(	O
LCoS	B-Device
or	O
LCOS	B-Device
)	O
is	O
a	O
miniaturized	O
reflective	O
active-matrix	B-Device
liquid-crystal	I-Device
display	I-Device
or	O
"	O
microdisplay	O
"	O
using	O
a	O
liquid	B-Device
crystal	I-Device
layer	O
on	O
top	O
of	O
a	O
silicon	O
backplane	O
.	O
</s>
<s>
LCoS	B-Device
was	O
initially	O
developed	O
for	O
projection	O
televisions	O
but	O
is	O
now	O
used	O
for	O
wavelength	O
selective	O
switching	O
,	O
structured	B-General_Concept
illumination	I-General_Concept
,	O
near-eye	O
displays	O
and	O
optical	O
pulse	O
shaping	O
.	O
</s>
<s>
By	O
way	O
of	O
comparison	O
,	O
some	O
LCD	B-Device
projectors	I-Device
use	O
transmissive	O
LCD	B-Device
,	O
allowing	O
light	O
to	O
pass	O
through	O
the	O
liquid	B-Device
crystal	I-Device
.	O
</s>
<s>
In	O
an	O
LCoS	B-Device
display	O
,	O
a	O
CMOS	O
chip	O
controls	O
the	O
voltage	O
on	O
square	O
reflective	O
aluminium	O
electrodes	O
buried	O
just	O
below	O
the	O
chip	O
surface	O
,	O
each	O
controlling	O
one	O
pixel	O
.	O
</s>
<s>
At	O
the	O
time	O
,	O
the	O
primary	O
use	O
of	O
LCos	B-Device
projectors	O
was	O
in	O
the	O
military	O
and	O
scientific	O
fields	O
due	O
to	O
their	O
large	O
and	O
bulky	O
size	O
.	O
</s>
<s>
However	O
,	O
in	O
the	O
late	O
1990s	O
,	O
companies	O
like	O
JVC	O
and	O
Hughes	O
Electronics	O
began	O
developing	O
smaller	O
and	O
more	O
affordable	O
LCos	B-Device
projectors	O
for	O
commercial	O
use	O
.	O
</s>
<s>
However	O
,	O
manufacturers	O
continued	O
to	O
refine	O
the	O
technology	O
,	O
and	O
today	O
's	O
LCos	B-Device
projectors	O
have	O
largely	O
overcome	O
this	O
issue	O
.	O
</s>
<s>
SXRD	O
was	O
an	O
evolution	O
of	O
LCos	B-Device
technology	O
that	O
used	O
even	O
smaller	O
pixels	O
and	O
a	O
higher	O
resolution	O
,	O
resulting	O
in	O
an	O
even	O
more	O
accurate	O
image	O
.	O
</s>
<s>
Another	O
significant	O
development	O
in	O
the	O
history	O
of	O
LCos	B-Device
projectors	O
came	O
in	O
2006	O
when	O
JVC	O
introduced	O
its	O
D-ILA	B-Device
(	O
Direct-Drive	O
Image	O
Light	O
Amplifier	O
)	O
technology	O
.	O
</s>
<s>
D-ILA	B-Device
was	O
an	O
improvement	O
over	O
traditional	O
LCos	B-Device
projectors	O
in	O
that	O
it	O
eliminated	O
the	O
need	O
for	O
a	O
polarizing	O
filter	O
,	O
resulting	O
in	O
a	O
brighter	O
and	O
more	O
vibrant	O
image	O
.	O
</s>
<s>
The	O
D-ILA	B-Device
technology	O
has	O
since	O
become	O
a	O
popular	O
choice	O
for	O
home	O
theater	O
enthusiasts	O
.	O
</s>
<s>
In	O
recent	O
years	O
,	O
LCos	B-Device
projectors	O
have	O
continued	O
to	O
evolve	O
,	O
with	O
manufacturers	O
introducing	O
features	O
like	O
4K	O
resolution	O
and	O
HDR	O
(	O
High	O
Dynamic	O
Range	O
)	O
support	O
.	O
</s>
<s>
LCos	B-Device
projectors	O
are	O
now	O
available	O
at	O
a	O
range	O
of	O
price	O
points	O
,	O
from	O
affordable	O
models	O
for	O
home	O
theater	O
use	O
to	O
high-end	O
professional	O
models	O
used	O
in	O
commercial	O
installations	O
.	O
</s>
<s>
Overall	O
,	O
the	O
history	O
of	O
LCos	B-Device
projectors	O
is	O
one	O
of	O
innovation	O
and	O
improvement	O
.	O
</s>
<s>
From	O
their	O
early	O
days	O
as	O
bulky	O
military	O
and	O
scientific	O
equipment	O
to	O
today	O
's	O
sleek	O
and	O
affordable	O
consumer	O
models	O
,	O
LCos	B-Device
projectors	O
have	O
come	O
a	O
long	O
way	O
.	O
</s>
<s>
LCos	B-Device
display	O
systems	O
typically	O
consist	O
of	O
three	O
main	O
components	O
:	O
the	O
LCos	B-Device
panel	O
,	O
the	O
light	O
source	O
,	O
and	O
the	O
optical	O
system	O
.	O
</s>
<s>
The	O
LCos	B-Device
panel	O
is	O
the	O
heart	O
of	O
the	O
display	O
system	O
.	O
</s>
<s>
Each	O
pixel	O
is	O
made	O
up	O
of	O
a	O
liquid	B-Device
crystal	I-Device
layer	O
,	O
a	O
reflective	O
layer	O
,	O
and	O
a	O
silicon	O
substrate	O
.	O
</s>
<s>
The	O
liquid	B-Device
crystal	I-Device
layer	O
controls	O
the	O
polarization	O
of	O
light	O
that	O
passes	O
through	O
it	O
,	O
while	O
the	O
reflective	O
layer	O
reflects	O
the	O
light	O
back	O
towards	O
the	O
optical	O
system	O
.	O
</s>
<s>
The	O
silicon	O
substrate	O
is	O
used	O
to	O
control	O
the	O
individual	O
pixels	O
and	O
provides	O
the	O
necessary	O
electronics	O
to	O
drive	O
the	O
LCos	B-Device
panel	O
.	O
</s>
<s>
The	O
light	O
source	O
is	O
used	O
to	O
provide	O
the	O
necessary	O
illumination	O
for	O
the	O
LCos	B-Device
panel	O
.	O
</s>
<s>
The	O
most	O
common	O
light	O
source	O
used	O
in	O
LCos	B-Device
display	O
systems	O
is	O
a	O
high-intensity	O
lamp	O
.	O
</s>
<s>
The	O
optical	O
system	O
is	O
responsible	O
for	O
directing	O
the	O
light	O
from	O
the	O
light	O
source	O
onto	O
the	O
LCos	B-Device
panel	O
and	O
projecting	O
the	O
resulting	O
image	O
onto	O
a	O
screen	O
or	O
other	O
surface	O
.	O
</s>
<s>
There	O
are	O
two	O
main	O
types	O
of	O
LCos	B-Device
display	O
systems	O
:	O
transmissive	O
and	O
reflective	O
.	O
</s>
<s>
Transmissive	O
LCos	B-Device
displays	O
use	O
a	O
backlight	O
behind	O
the	O
LCos	B-Device
panel	O
to	O
provide	O
illumination	O
,	O
while	O
reflective	O
LCos	B-Device
displays	O
use	O
the	O
ambient	O
light	O
in	O
the	O
environment	O
to	O
illuminate	O
the	O
LCos	B-Device
panel	O
.	O
</s>
<s>
Reflective	O
LCos	B-Device
displays	O
are	O
more	O
power-efficient	O
and	O
offer	O
better	O
contrast	O
ratios	O
than	O
transmissive	O
displays	O
,	O
but	O
are	O
typically	O
more	O
expensive	O
to	O
manufacture	O
.	O
</s>
<s>
The	O
white	O
light	O
is	O
separated	O
into	O
three	O
components	O
(	O
red	O
,	O
green	O
and	O
blue	O
)	O
and	O
then	O
combined	O
back	O
after	O
modulation	O
by	O
the	O
3	O
LCoS	B-Device
devices	O
.	O
</s>
<s>
Both	O
Toshiba	O
's	O
and	O
Intel	O
's	O
single-panel	O
LCOS	B-Device
display	O
program	O
were	O
discontinued	O
in	O
2004	O
before	O
any	O
units	O
reached	O
final-stage	O
prototype	O
.	O
</s>
<s>
There	O
were	O
single-panel	O
LCoS	B-Device
displays	O
in	O
production	O
:	O
One	O
by	O
Philips	O
and	O
one	O
by	O
Microdisplay	O
Corporation	O
.	O
</s>
<s>
Forth	B-Device
Dimension	I-Device
Displays	I-Device
continues	O
to	O
offer	O
a	O
Ferroelectric	O
LCoS	B-Device
display	O
technology	O
(	O
known	O
as	O
Time	O
Domain	O
Imaging	O
)	O
available	O
in	O
QXGA	O
,	O
SXGA	O
and	O
WXGA	O
resolutions	O
which	O
today	O
is	O
used	O
for	O
high	O
resolution	O
near-eye	O
applications	O
such	O
as	O
Training	O
&	O
Simulation	O
,	O
structured	B-General_Concept
light	I-General_Concept
pattern	O
projection	O
for	O
AOI	O
.	O
</s>
<s>
Citizen	O
Finedevice	O
(	O
CFD	O
)	O
also	O
continues	O
to	O
manufacturer	O
single	O
panel	O
RGB	O
displays	O
using	O
FLCoS	B-Device
technology	O
(	O
Ferroelectric	O
Liquid	B-Device
Crystals	I-Device
)	O
.	O
</s>
<s>
They	O
manufacture	O
displays	O
in	O
multiple	O
resolutions	O
and	O
sizes	O
that	O
are	O
currently	O
used	O
in	O
pico-projectors	B-General_Concept
,	O
electronic	B-Algorithm
viewfinders	I-Algorithm
for	O
high	O
end	O
digital	O
cameras	O
,	O
and	O
head-mounted	B-General_Concept
displays	I-General_Concept
.	O
</s>
<s>
Whilst	O
initially	O
developed	O
for	O
large-screen	O
projectors	O
,	O
LCoS	B-Device
displays	O
have	O
found	O
a	O
consumer	O
niche	O
in	O
the	O
area	O
of	O
pico-projectors	B-General_Concept
,	O
where	O
their	O
small	O
size	O
and	O
low	O
power	O
consumption	O
are	O
well-matched	O
to	O
the	O
constraints	O
of	O
such	O
devices	O
.	O
</s>
<s>
LCoS	B-Device
devices	O
are	O
also	O
used	O
in	O
near-eye	O
applications	O
such	O
as	O
electronic	B-Algorithm
viewfinders	I-Algorithm
for	O
digital	O
cameras	O
,	O
film	O
cameras	O
,	O
and	O
head-mounted	B-General_Concept
displays	I-General_Concept
(	O
HMDs	O
)	O
.	O
</s>
<s>
These	O
devices	O
are	O
made	O
using	O
ferroelectric	O
liquid	B-Device
crystals	I-Device
(	O
so	O
the	O
technology	O
is	O
named	O
FLCoS	B-Device
)	O
which	O
are	O
inherently	O
faster	O
than	O
other	O
types	O
of	O
liquid	B-Device
crystals	I-Device
to	O
produce	O
high	O
quality	O
images	O
.	O
</s>
<s>
Google	O
's	O
initial	O
foray	O
into	O
wearable	O
computing	O
,	O
Google	O
glass	O
,	O
also	O
uses	O
a	O
near-eye	O
LCoS	B-Device
display	O
.	O
</s>
<s>
It	O
combined	O
a	O
single-chip	O
1080p	O
LCOS	B-Device
display	O
and	O
image	O
sensor	O
from	O
OmniVision	O
with	O
ASTRI	O
's	O
optics	O
and	O
electronics	O
.	O
</s>
<s>
LCoS	B-Device
is	O
particularly	O
attractive	O
as	O
a	O
switching	O
mechanism	O
in	O
a	O
wavelength-selective	O
switch	O
(	O
WSS	O
)	O
.	O
</s>
<s>
LCoS-based	O
WSS	O
were	O
initially	O
developed	O
by	O
Australian	O
company	O
Engana	O
,	O
now	O
part	O
of	O
Finisar	O
.	O
</s>
<s>
The	O
LCoS	B-Device
can	O
be	O
employed	O
to	O
control	O
the	O
phase	O
of	O
light	O
at	O
each	O
pixel	O
to	O
produce	O
beam-steering	O
where	O
the	O
large	O
number	O
of	O
pixels	O
allow	O
a	O
near	O
continuous	O
addressing	O
capability	O
.	O
</s>
<s>
This	O
simple	O
optical	O
design	O
incorporates	O
polarisation	O
diversity	O
,	O
control	O
of	O
mode	O
size	O
and	O
a	O
4-f	O
wavelength	O
optical	O
imaging	O
in	O
the	O
dispersive	O
axis	O
of	O
the	O
LCoS	B-Device
providing	O
integrated	O
switching	O
and	O
optical	O
power	O
control	O
.	O
</s>
<s>
The	O
input	O
light	O
from	O
a	O
chosen	O
fibre	O
of	O
the	O
array	O
is	O
reflected	O
from	O
the	O
imaging	O
mirror	O
and	O
then	O
angularly	O
dispersed	O
by	O
the	O
grating	O
which	O
is	O
at	O
near	O
Littrow	O
incidence	O
,	O
reflecting	O
the	O
light	O
back	O
to	O
the	O
imaging	O
optics	O
which	O
directs	O
each	O
channel	O
to	O
a	O
different	O
portion	O
of	O
the	O
LCoS	B-Device
.	O
</s>
<s>
The	O
path	O
for	O
each	O
wavelength	O
is	O
then	O
retraced	O
upon	O
reflection	O
from	O
the	O
LCoS	B-Device
,	O
with	O
the	O
beam-steering	O
image	O
applied	O
on	O
the	O
LCOS	B-Device
directing	O
the	O
light	O
to	O
a	O
particular	O
port	O
of	O
the	O
fibre	O
array	O
.	O
</s>
<s>
As	O
the	O
wavelength	O
channels	O
are	O
separated	O
on	O
the	O
LCoS	B-Device
the	O
switching	O
of	O
each	O
wavelength	O
is	O
independent	O
of	O
all	O
others	O
and	O
can	O
be	O
switched	O
without	O
interfering	O
with	O
the	O
light	O
on	O
other	O
channels	O
.	O
</s>
<s>
WSS	O
based	O
on	O
MEMS	B-General_Concept
and/or	O
liquid	B-Device
crystal	I-Device
technologies	O
allocate	O
a	O
single	O
switching	O
element	O
(	O
pixel	O
)	O
to	O
each	O
channel	O
which	O
means	O
the	O
bandwidth	O
and	O
centre	O
frequency	O
of	O
each	O
channel	O
are	O
fixed	O
at	O
the	O
time	O
of	O
manufacture	O
and	O
cannot	O
be	O
changed	O
in	O
service	O
.	O
</s>
<s>
In	O
addition	O
,	O
many	O
designs	O
of	O
first-generation	O
WSS	O
(	O
particularly	O
those	O
based	O
on	O
MEMs	B-General_Concept
technology	O
)	O
show	O
pronounced	O
dips	O
in	O
the	O
transmission	O
spectrum	O
between	O
each	O
channel	O
due	O
to	O
the	O
limited	O
spectral	O
‘	O
fill	O
factor’	O
inherent	O
in	O
these	O
designs	O
.	O
</s>
<s>
LCoS-based	O
WSS	O
,	O
however	O
,	O
permit	O
dynamic	O
control	O
of	O
channel	O
centre	O
frequency	O
and	O
bandwidth	O
through	O
on-the-fly	O
modification	O
of	O
the	O
pixel	O
arrays	O
via	O
embedded	O
software	O
.	O
</s>
<s>
The	O
ability	O
of	O
an	O
LCoS-based	O
WSS	O
to	O
independently	O
control	O
both	O
the	O
amplitude	O
and	O
phase	O
of	O
the	O
transmitted	O
signal	O
leads	O
to	O
the	O
more	O
general	O
ability	O
to	O
manipulate	O
the	O
amplitude	O
and/or	O
phase	O
of	O
an	O
optical	O
pulse	O
through	O
a	O
process	O
known	O
as	O
Fourier-domain	O
pulse	O
shaping	O
.	O
</s>
<s>
As	O
an	O
example	O
,	O
an	O
LCoS-based	O
Programmable	O
Optical	O
Processor	O
(	O
POP	O
)	O
has	O
been	O
used	O
to	O
broaden	O
a	O
mode-locked	O
laser	O
output	O
into	O
a	O
20nm	O
supercontinuum	O
source	O
whilst	O
a	O
second	O
such	O
device	O
was	O
used	O
to	O
compress	O
the	O
output	O
to	O
400	O
fs	O
,	O
transform-limited	O
pulses	O
.	O
</s>
<s>
Passive	O
mode-locking	O
of	O
fiber	O
lasers	O
has	O
been	O
demonstrated	O
at	O
high	O
repetition	O
rates	O
,	O
but	O
inclusion	O
of	O
an	O
LCoS-based	O
POP	O
allowed	O
the	O
phase	O
content	O
of	O
the	O
spectrum	O
to	O
be	O
changed	O
to	O
flip	O
the	O
pulse	O
train	O
of	O
a	O
passively	O
mode-locked	O
laser	O
from	O
bright	O
to	O
dark	O
pulses	O
.	O
</s>
<s>
Structured	B-General_Concept
light	I-General_Concept
using	O
a	O
fast	O
ferroelectric	O
LCoS	B-Device
is	O
used	O
in	O
3D-superresolution	O
microscopy	O
techniques	O
and	O
in	O
fringe	B-Algorithm
projection	I-Algorithm
for	O
3D-automated	O
optical	O
inspection	O
.	O
</s>
<s>
One	O
of	O
the	O
interesting	O
applications	O
of	O
LCoS	B-Device
is	O
the	O
ability	O
to	O
transform	O
between	O
modes	O
of	O
few-moded	O
optical	O
fibers	O
which	O
have	O
been	O
proposed	O
as	O
the	O
basis	O
of	O
higher	O
capacity	O
transmission	O
systems	O
in	O
the	O
future	O
.	O
</s>
<s>
Similarly	O
LCoS	B-Device
has	O
been	O
used	O
to	O
steer	O
light	O
into	O
selected	O
cores	O
of	O
multicore	O
fiber	O
transmission	O
systems	O
,	O
again	O
as	O
a	O
type	O
of	O
Space	O
Division	O
Multiplexing	O
.	O
</s>
<s>
LCoS	B-Device
has	O
been	O
used	O
as	O
a	O
filtering	O
technique	O
,	O
and	O
hence	O
a	O
tuning	O
mechanism	O
,	O
for	O
both	O
semiconductor	O
diode	O
and	O
fiber	O
lasers	O
.	O
</s>
