No abstract

ABSTRACT:The polarized and depolarized components of light scattering by pure poly-(methyl methacrylate) (PMMA) were measured as a function of temperature above and below T •. The PMMA sample used was prepared by a very careful procedure in which the evaporable monomer, initiator, and chain transfer agent were distilled in a closed vacuum system and in-situ polymerization was carried out above T •. The measured intensities were favorably compared with the values calculated from thermal density fluctuation in the temperature range from 20 to 140oC. The measured intrinsic Hv intensity was fairly close to the value calculated assuming a randomly oriented anisotropic liquid for PMMA. Our experiment showed no evidence for an ordered structure in pure PMMA glass, as is found in pure polystyrene glass.

Laser recording on novel optical recording media with thermal coloration is reported. The basic recording mechanism is thermally induced chemical reaction between a coloring reagent and a coupling reagent that are deposited in vacuum, separated by a light absorbing layer. Transmittance changes on a 1-μm size recording pit have been observed by writing with a laser diode at 830 nm. This medium is colored blue, red, or black by selecting a coloring reagent layer. It is applied to multicolor recording by accumulating units of media.

An optical waveguide intersection on the same level, inducing no light leak, with higher refractive index in the intersecting point than in the guides, is proposed. This intersection is formed easily by the photopolymerization method, introducing double exposure at the intersecting point (typical guide width, ~0.1 mm; Deltan ~0.5% in the guide; and ~1% in the intersection). Very low losses were observed in the intersections, while large leak losses were observed in ordinary intersections, where the refractive index was equal to that of the guides. Observed losses were in good agreement with calculated ones.

An unusual temperature dependence of light scattering properties by pure polystyrene (PS) was observed in the temperature range of 30-170°C: the and intensities minimized near T,, and the H intensity changed with measuring temperatures. These phenomena can be explained by "the scrambling effects of incident and scattered light" during transmission through the sample, as previously pointed out for PS glass by Claiborne and Crist. The PS sample used was prepared by a very careful procedure in which the evaporable monomer, initiator, and chain transfer agent were distilled in a closed vacuum system and in situ polymerization was carried out above T,. The corrected intensity for PS glass was favorably compared with the values calculated from the thermal density fluctuation, indicating that PS glass was in a frozen state near T,. The corrected Hv intensity for PS glass was nearly equal to the heretofore calculated value, assuming a randomly oriented anisotropic liquid for PS. Our experimental results showed no evidence for an ordered structure in pure PS glass, as is found in pure poly(methyl methacrylate) glass, but PS rubber has a partially oriented state.