MODULATORS :: APPLICATIONS :: Optical Rotation
If a linearly polarized light passes through a chiral media, for example, a solution of chiral molecules, the polarization plane of the incident light will be rotated. This is called optical rotation (or natural optical rotation in order to distinguish from Faraday rotation in a magnetic field).
Any phase difference (retardance) between the two circular components produces a rotation of the polarization plane.
SETUP
Optical rotation has been measured using these two setups at Hinds. High sensitivity for optical rotation (0.001 degree) has been achieved. The signal is detected at 2f.
CALIBRATION
The optical rotation
r is proportional to V
2f/V
DC. If the second polarizer is in a precision rotator, the system may be calibrated by removing the sample, varying the rotator angular position and recording V
2f/V
DC vs. the rotator position.
APPLICATIONS
Chiral analysis in chemistry, pharmaceutical and biological industries
TYPICAL PEMs
I/FS50 II/FS42 FURTHER READING
J. C. Kemp, Basic Laboratory setup for various measurements possible with the photoelastic modulator, Application note, Hinds Instruments, Inc. (1975)
T. C. Oakberg, Linear Birefringence and Optical Rotation, Application note, Hinds Instruments, Inc. (1992).