2
2
Setting
a
State
of
P
olarization
This
chapter
describes
the
two
ways
of
setting
a
State
of
P
olarization,
By
positioning
the
polarizing
lter
,
the
/2,
and
the
/4
plates
.
By
positioning
the
polarizing
lter
,
and
then
specifying
the
desired
position
on
the
P
oincare
sphere
.
Setting
up
the
Hardware
Note
When
you
are
setting
up
your
hardware
,
it
is
absolutely
vital
that
the
bers
are
xed,
and
remain
unmoved
for
the
whole
of
the
measurement.
Moving
the
bers
changes
the
state
of
polarization.
Typically
,
you
will
connect
the
polarization
controller
directly
after
your
source
,
and
before
your
device
under
test
(DUT).
Before
connecting
to
the
rest
of
your
measurement
setup
,
you
should
set
the
position
of
the
polarizing
lter
.
Setting
the
P
osition
of
the
P
olarizing
Filter
The
polarizing
lter
should
be
set
to
maximize
the
signal.
This
means
aligning
the
polarizing
lter
with
the
greatest
linear
polarization
of
the
source
.
(Light
from
laser
sources
is
elliptically
polarized).
Setting
a
State
of
P
olarization
2-1