2
5.
Disconnect
the
power
meter
,
and
connect
to
your
DUT
,
and
the
rest
of
your
measurement
setup
,
making
sure
to
move
the
bers
as
little
as
possible
.
Setting
the
State
of
P
olarization
The
state
of
polarization
of
a
signal
can
be
described
by
a
position
on
the
P
oincare
sphere
.
This
position
is
can
be
expressed
in
spherical
coordinates
by
two
angles
,
called
"
B
and
P
.
P
is
the
optical
angle
about
the
'equator'
of
the
sphere
(that
is
,
2
P
is
the
angle
of
'longitude').
"
B
is
half
the
angle
of
elevation
from
the
equatorial
plane
(that
is
,
2"
B
is
the
angle
of
'latitude').
The
coordinates
for
describing
the
state
of
polarization
The
state
of
polarization
is
always
relative
to
the
output
from
the
polarizing
lter
.
There
are
two
ways
of
setting
the
state
of
polarization,
by
specifying
the
position
of
the
/4
and
/2
retarder
plates
,
or
by
specifying
"
B
and
P
,
the
coordinates
on
the
P
oincare
sphere
.
Setting
a
State
of
P
olarization
2-3