Page 99 - Tandem Techniques
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Page 80
Figure 2 22
Polarization Modulation
This an example of a general principle which was first described by Brewster and given the term photo
elasticity. Electro-optic Modulizers, that are used in some modern instruments, operate in a similar way.
Practical Chiral Measuring Devices
The successful development of a Chiral monitor, based on optical rotation measurement, hinges on the
Faraday effect. If a plane polarized beam of light passes through a medium that is subjected to a strong
magnetic field, the plane of the polarized beam is rotated a small angle (a), where (a) is given by,
where, (V) is the Verdet Constant,
(d) is the path length
and (H) is the magnetic field strength.
The magnetic field is generated in an air core coil inside of which, is a rod made from glass having a
high Verdet constant. Now,
H=iN
where, (i) is the current through the coil, and (N) is the number of turns in the coil. Thus,
a = VdiN
