<s>
A	O
corner	B-Algorithm
reflector	I-Algorithm
is	O
a	O
retroreflector	O
consisting	O
of	O
three	O
mutually	O
perpendicular	O
,	O
intersecting	B-Algorithm
flat	O
surfaces	O
,	O
which	O
reflects	O
waves	O
directly	O
towards	O
the	O
source	O
,	O
but	O
translated	B-Algorithm
.	O
</s>
<s>
The	O
three	O
intersecting	B-Algorithm
surfaces	O
often	O
have	O
square	O
shapes	O
.	O
</s>
<s>
Radar	B-Application
corner	B-Algorithm
reflectors	I-Algorithm
made	O
of	O
metal	O
are	O
used	O
to	O
reflect	O
radio	O
waves	O
from	O
radar	B-Application
sets	O
.	O
</s>
<s>
Optical	O
corner	B-Algorithm
reflectors	I-Algorithm
,	O
called	O
corner	B-Algorithm
cubes	I-Algorithm
or	O
cube	O
corners	O
,	O
made	O
of	O
three-sided	O
glass	O
prisms	O
,	O
are	O
used	O
in	O
surveying	O
and	O
laser	O
ranging	O
.	O
</s>
<s>
Therefore	O
,	O
the	O
ray	O
direction	O
goes	O
from	O
to	O
to	O
to	O
,	O
and	O
it	O
leaves	O
the	O
corner	B-Algorithm
reflector	I-Algorithm
with	O
all	O
three	O
components	O
of	O
direction	O
exactly	O
reversed	O
.	O
</s>
<s>
Radar	B-Application
corner	B-Algorithm
reflectors	I-Algorithm
are	O
designed	O
to	O
reflect	O
the	O
microwave	O
radio	O
waves	O
emitted	O
by	O
radar	B-Application
sets	O
back	O
toward	O
the	O
radar	B-Application
antenna	O
.	O
</s>
<s>
This	O
causes	O
them	O
to	O
show	O
a	O
strong	O
"	O
return	O
"	O
on	O
radar	B-Application
screens	O
.	O
</s>
<s>
A	O
simple	O
corner	B-Algorithm
reflector	I-Algorithm
consists	O
of	O
three	O
conducting	O
sheet	O
metal	O
or	O
screen	O
surfaces	O
at	O
90°	O
angles	O
to	O
each	O
other	O
,	O
attached	O
to	O
one	O
another	O
at	O
the	O
edges	O
,	O
forming	O
a	O
"	O
corner	O
"	O
.	O
</s>
<s>
To	O
create	O
a	O
corner	B-Algorithm
reflector	I-Algorithm
that	O
will	O
reflect	O
radar	B-Application
waves	O
coming	O
from	O
any	O
direction	O
,	O
8	O
corner	B-Algorithm
reflectors	I-Algorithm
are	O
placed	O
back-to-back	O
in	O
an	O
octahedron	O
(	O
diamond	O
)	O
shape	O
.	O
</s>
<s>
In	O
maritime	O
navigation	O
they	O
are	O
placed	O
on	O
bridge	O
abutments	O
,	O
buoys	O
,	O
ships	O
and	O
,	O
especially	O
,	O
lifeboats	O
,	O
to	O
ensure	O
that	O
these	O
show	O
up	O
strongly	O
on	O
ship	O
radar	B-Application
screens	O
.	O
</s>
<s>
Corner	B-Algorithm
reflectors	I-Algorithm
are	O
placed	O
on	O
the	O
vessel	O
's	O
masts	O
at	O
a	O
height	O
of	O
at	O
least	O
above	O
sea	O
level	O
(	O
giving	O
them	O
an	O
approximate	O
minimum	O
horizon	O
distance	O
of	O
)	O
.	O
</s>
<s>
Marine	B-Algorithm
radar	I-Algorithm
uses	O
X-band	B-Algorithm
microwaves	O
with	O
wavelengths	O
of	O
,	O
so	O
small	O
reflectors	O
less	O
than	O
across	O
are	O
used	O
.	O
</s>
<s>
In	O
aircraft	O
navigation	O
,	O
corner	B-Algorithm
reflectors	I-Algorithm
are	O
installed	O
on	O
rural	O
runways	O
,	O
to	O
make	O
them	O
show	O
up	O
on	O
aircraft	O
radar	B-Application
.	O
</s>
<s>
In	O
optics	B-Algorithm
,	O
corner	B-Algorithm
reflectors	I-Algorithm
typically	O
consist	O
of	O
three	O
mirrors	O
or	O
reflective	O
prism	O
faces	O
which	O
return	O
an	O
incident	O
light	O
beam	O
in	O
the	O
opposite	O
direction	O
.	O
</s>
<s>
Five	O
arrays	O
of	O
optical	O
corner	B-Algorithm
reflectors	I-Algorithm
have	O
been	O
placed	O
on	O
the	O
Moon	O
for	O
use	O
by	O
Lunar	O
Laser	O
Ranging	O
experiments	O
observing	O
a	O
laser	O
's	O
time-of-flight	O
to	O
measure	O
the	O
Moon	O
's	O
orbit	O
more	O
precisely	O
than	O
was	O
possible	O
before	O
.	O
</s>
<s>
Automobile	O
and	O
bicycle	O
tail	O
lights	O
are	O
molded	O
with	O
arrays	O
of	O
small	O
corner	B-Algorithm
reflectors	I-Algorithm
,	O
with	O
different	O
sections	O
oriented	O
for	O
viewing	O
from	O
different	O
angles	O
.	O
</s>
<s>
Thin	O
plastic	O
with	O
microscopic	O
corner	B-Algorithm
reflector	I-Algorithm
structures	O
can	O
be	O
used	O
as	O
tape	O
,	O
on	O
signs	O
,	O
or	O
sewn	O
or	O
molded	O
onto	O
clothing	O
.	O
</s>
<s>
Corner	B-Algorithm
reflectors	I-Algorithm
can	O
also	O
occur	O
accidentally	O
.	O
</s>
<s>
Tower	O
blocks	O
with	O
balconies	O
are	O
often	O
accidental	O
corner	B-Algorithm
reflectors	I-Algorithm
for	O
sound	O
and	O
return	O
a	O
distinctive	O
echo	O
to	O
an	O
observer	O
making	O
a	O
sharp	O
noise	O
,	O
such	O
as	O
a	O
hand	O
clap	O
,	O
nearby	O
.	O
</s>
<s>
Similarly	O
,	O
in	O
radar	B-Application
interpretation	O
,	O
an	O
object	O
that	O
has	O
multiple	O
reflections	O
from	O
smooth	O
surfaces	O
produces	O
a	O
radar	B-Application
return	O
of	O
greater	O
magnitude	O
than	O
might	O
be	O
expected	O
from	O
the	O
physical	O
size	O
of	O
the	O
object	O
.	O
</s>
<s>
This	O
effect	O
was	O
put	O
to	O
use	O
on	O
the	O
ADM-20	O
Quail	O
,	O
a	O
small	O
missile	O
which	O
had	O
the	O
same	O
radar	B-Application
cross	O
section	O
as	O
a	O
B-52	O
.	O
</s>
