A Compact Dual-Crystal Modulated Birefringence Measurement 
System for Microgravity Applications

Jeffrey R. Mackey and Kamal K. Das
NASA Lewis Research Center, Cleveland, Ohio 44135

Shelley S. Anna and Gareth H. McKinley
Department of Mechanical Engineering
Massachusetts Institute of Technology, Cambridge, MA 02139


A compact modulated birefringence measurement system has been developed for use in microgravity fluid physics applications with non-Newtonian fluids such as polymer solutions.  This instrument uses a dual-crystal transverse electro-optic modulator capable of modulation frequencies in excess of 100 MHz.  The two crystals are modulated 180o out-of-phase from each other.   The theoretical framework governing the development of this instrument using Mueller-Stokes polarization matrices is discussed.  Several ground-based experiments are performed to compare this system with the theoretical results. Results from this transverse electro-optic modulator based birefringence measurement system agree well with the theory.  The instrument is also very stable and robust, making it suitable for the extreme acceleration environments to be encountered in a NASA Black Brandt sounding rocket.

Published  Meas. Sci. & Tech, 10 (10), 1999, p 946-955.