MODULATORS :: APPLICATIONS :: Wave-plate Retardation Measurement

Wave-plates are an important optical component for light polarization-related measurements. The PEM can be employed to determine both the amplitude and orientation of the retardation of a wave-plate.

SETUP



EQUATION



I1f: 1f signal
IDC: DC signal
A0: PEM’s retardation setting
J2(A0): 2nd order Bessel function
J1(A0): 1st order Bessel function

In this set-up, either the fast axis or the slow axis of the quarter-wave plate is required to be parallel to the PEM’s optical axis. The positive and negative signs of I2f, after calibration, indicate which axis (slow or fast) it is.


APPLICATIONS
Wave-plate inspection and characterization


TYPICAL PEM 
I/FS50 with NIO-1

FURTHER READING
J. C. Kemp, Basic Laboratory set-up for various measurements possible with the photoelastic modulator, Application note, Hinds Instruments, Inc. (1975)

J. Schellman and H. P. Jensen, “Optical Spectroscopy of Oriented Molecules,” Chem. Rev. 87, 1359-1399 (1987).

T. C. Oakberg, “Measurement of Wave-plate Retardation Using a Photoelastic Modulator,” SPIE, 3121, 19-22 (1997)