Circular Birefringence

If 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 circular birefringence or optical rotation.
Any phase difference (retardance) between the two circular components produces a rotation of the polarization plane. This is depicted well in this animated tutorial.

SET UP

Circular birefringence has been measured using this setup at Hinds. High sensitivity for circular birefringence (0.001 degree) has been achieved. The signal is detected at 2f.

CALIBRATION

The circular birefringence _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. Hinds Instruments designed a specialized astronomical polarimeter using a circular birefringence signal to detect chiral signatures in astrobiological samples.

PEMs

I/FS50 
II/FS42

SIGNAL DETECTION

Avalanche Photodiode Detector Module (APD-100)
Photodiode Detectors (DET-100)

SIGNAL PROCESSING

Lock-in Amplifier (Signaloc™ 2100)

FURTHER READING

B. Wang, W. Sparks, T. Germer, A. Leadbetter, “A Spectroscopic Polarimeter For Detecting Chiral Signatures In Astrobiological Samples”, SPIE Proceeding, Volume 7441, September 2009.

Email Literature request to Hinds Instruments.

Contact us for more information about circular birefringence.