NSF Award
0215407
This Major Research Instrumentation RUI development project expands the capabilities of a low-cost optical apparatus based on a Helium-Neon (HeNe) laser and a Michelson interferometer that can be used to measure refractive index and film-thickness variations in planar polymer samples. The development incorporates a tunable light source and a visible-NIR digital camera imaging system. The use of a coherent HeNe laser light source in the current system greatly limits the versatility of the apparatus because it is limited to differential refractive index measurements. These measurements can only be carried out at 633 nm. The replacement of the coherent HeNe laser with a tunable, low-coherence arc-lamp source makes possible the determination of absolute and differential refractive index. These measurements can be performed at any wavelength, thereby permitting one to characterize the dispersion properties of samples. The addition of a visible-NIR digital camera and a hardware-software image capture system will advance the capabilities of the apparatus by allowing one to resolve graded refractive index profiles in optical materials. An imaging system will permit one to confront optical wave-front distortion problems, arising from surface roughness and sample inhomogeneity, that have plagued previous interferometer systems. The study, involving undergraduate students at a non-Ph.D. granting institution, will also promote training and learning through the integration of research in the educational process. <br/><br/>The expanding use of the internet and the accompanying demand for high-bandwidth transmission media has fueled interests in 'all-optical' networking. Polymers are emerging as key materials in the development of optical networks, owing to their flexibility, light weight, low cost of fabrication, and the potential to create materials with a variety of physical and optical properties. Research and development of optical polymers is currently hindered due to a lack of instrumentation for fully characterizing the bandwidth capacity of candidate materials in the visible and near-infrared (NIR) spectral regions. In particular, there is interest in developing optical imaging systems that allow one to characterize the absolute refractive index, refractive index stability, and overall dispersion properties of new polymeric materials. A secondary goal of this study is to use the new instrument to measure differential and absolute refractive indices in a wide range of freshly prepared polymer films. A collaborative study at the University of Central Florida will focus on the refractive index characteristics of polymer films doped with candidate photochromic compounds. These organic compounds are capable of two-photon induced photoisomerization. When incorporated into a polymer film, the 'switching' characteristics of these compounds make possible three-dimensional holographic data storage.
