We describe a phase-controlled, highly stable interferometer that is ideal for use in long-time and high-temperature studies. We recorded output intensity variations of <0.2% for over 6 h at temperatures up to 150°C. The setup was used to study <i>in situ</i> the temperature and frequency characteristics of a thin polymer film composed of 4-dimethylamino-4′-nitrostilbene doped into poly(methyl methacrylate). The mobility of the dopant molecules, which governed the electro-optic property of the film, was used to probe the dye-doped polymer’s rheology. We demonstrate one application of the interferometer in probing both the α and the β relaxations of the polymer.
© 1999 Optical Society of America
(120.3180) Instrumentation, measurement, and metrology : Interferometry
(120.4640) Instrumentation, measurement, and metrology : Optical instruments
(310.3840) Thin films : Materials and process characterization
(310.6860) Thin films : Thin films, optical properties
F. Ghebremichael and R. J. Knize, "Polymer relaxations determined by use of a temporally and thermally stable interferometer," Opt. Lett. 24, 1481-1483 (1999)