7
requirement for measuring the colored sample with lower transmittance.
If the analyzer deviates from orthogonal position of the polarized plane where the light reaches, the
light goes through the alternating light intensity signal with frequency f, and through the
photomultiplier tube, it is converted into an electrical signal with frequency f. The signal which has
been pre-amplified and enters the motor control section, and then goes through the selected
frequency, the amplifier drives, the servo motor driven by a mechanical transmission polarizer, so
that the polarizer and the plane of polarized light generated by the analyzer reaches a quadrature
position, the electrical signal with frequency f disappears, and the servo motor stops.
As the instrument
start
s
working
,
the polarizer
follows the above
process
and
automatically
stop
s
in
the orthogonal
position,
the counter
is cleared
at this time
,
defined as zero
position
. If
the sample
tube
with
the
rotation
α
is placed in
the
sample chamber,
the incident
plane polarized light deviates
from the quadrature position
of the
analyzer
by the
angle
α
.
In accordance with
the above
procedure,
the polarizer
again obtains a new quadrature position
after turning
the polarization
by
angle
α
.
Encoder
counter and
microcontroller
circuit will
turn
the
polarizer
angle
α
,
converting
optical rotation
and display
the measurement results
on the LCD
monitor.
