Surface plasmons generated at a silver-polyimide interface and the guided modes coupled into planar films cause dips in the reflectivity curve of a transparent dielectric-silver-polyimide-air structure. These minima in the reflectivity curve were used to measure the polyimide thickness as well as the real and imaginary parts of the polymer refractive index (extinction). Precision within 1% of the polymer coat thickness was achieved through the use of this technique over the range 0.5-10 µm. In some cases, this technique is capable of yielding a precision of ~ 10% on the imaginary part of the polymer refractive index and provides a useful method for determining the performance of a low-loss polymer waveguide. Techniques in fitting the experimental reflectivity data to obtain the optical constants are also described.

The first detailed photoluminescence (PL) study of as-grown CdGeAs 2 samples obtained from three different sources is presented. The study was carried out in the 5-100 K temperature range and laser excitation densities 0.5-5 W cm −2 . PL spectra collected on samples from all sources showed a PL band near 355 meV which is assigned to an (e, A 0 ) transition to the deep native double acceptor 315 meV above the valence band edge. Samples from one source which contained substantially lower levels of oxygen also had about an order of magnitude lower values of absorption coefficient below the band gap and showed also a single PL band in their PL spectra.

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Laser Doppler velocimetry permits the recording of phasic red cell flux during the cardiac cycle in the myocardial microcirculation. Its pattern is determined by both coronary arterial inflow and venous outflow. The pattern of red cell flux may be characteristic for a region-probably determined by difference in tissue pressure (attributable to the pattern of muscle fibre shortening and collagen tethering) and changes in capillary length and density.