Optika Italy POL-X Manual De Instrucciones página 6

The light, generated by the yellow LED (1), passes through the collector lens (2), and the polarizer (3) and be-
comes plane linear polarized light. It then decomposes into ordinary and extraordinary beams, passing through
the half-wave plate, and a triplex view-aspect will occur in the viewing field. The light is then analyzed by the
polarization analyzer (5).
Normally the polarizer and the analyzer are placed so that their polarization planes are parallel or perpendicu-
lar to each other. When no sample has been put in the test tube the triplex viewing field should be uniformly
bright in the parallel case (see fig. 2 c) or uniformly dark in the perpendicular case. To tare the system rotate
the scale knob (8), controlling the scale (7) and the polarization analyzer (5), until all three fields has the same
light intensity as in fig. 2 c.
When the test tube (4) with the optically active sample is inserted in the sample chamber, the plane polarized
light will be rotated by an angle and the viewing field will change. Observing through the eye lens (6), you can
see a mid-bright (or dark) and left/right-dark (or bright) triplex viewing field of unequal intensity of illumination
(see Fig. 2a and 2b).
Fig. 2 a,b) The viewing field after having inserted the liquid to be tested and before adjusting the polarization
analyzer. c) The viewing field when no sample has been inserted. After having rotated the polarization analyzer.
The illumination intensity is here equal.
Rotate the scale knob until the illumination intensity of the viewing field (dark viewing field) becomes equal.
At this point the analyzer has been rotated with exactly the same angle as the liquid has rotated the polarized
light. The angle of scale rotation can be read from the magnifying glasses that are mounted in front of the vernier
(see Fig.3).
The scale is divided into 360 divisions and each division indicates 1°.
The vernier is divided into 20 divisions which are equal to 19 divisions of the scale, and the vernier can be used
to obtain a direct reading to the extent of 0.05° (see Fig.3). The scale and the polarization analyzer are fixed
integrally.
For very accurate readings, the errors due to scale and vernier eccentricity can be compensated by reading the
angles on both sides, and by taking an average of the two readings.
Fig.2
Fig.3
The magnified display of the scale.
In this example the angle of rotation is 9.30 °
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