Features of the Left Ventricular Functional Geometry in Patients with Myocardial Diseases with Varying Degrees of Systolic Dysfunction.

We revealed some features of the left ventricular functional geometry in patients with myocardial diseases with different degrees of left ventricular systolic dysfunction. A negative correlation was found between the spatio-temporal heterogeneity of the kinetics of the left ventricular wall during systole and ejection fraction in normal heart and in systolic dysfunction. The differences in the quantitative characteristics of the functional geometry between patients and normal subjects and between different groups of patients depended on the severityof left-ventricular systolic dysfunction. In particular, spatial heterogeneity index that characterizes heterogeneity of systolic movement of the wall segments and end-systolic Fourier shape-power index characterizing complexity of the left ventricle shape during systole differed significantly in the examined groups of patients and have the greatest diagnostic power.

Generation of pure two-beam interference grating structures in an optical fiber with a femtosecond infrared source and a phase mask.

Fiber Bragg gratings were fabricated in all-silica core fiber by focusing 125-fs 800-nm pulses with an 80-mm lens through a phase mask with 4.28-microm pitch onto a fiber sample. When the phase-mask-fiber separation was 5 mm the observed structure was clearly the result of two-beam interference between the +/- 1 orders. The elimination of the remaining 9 orders is a consequence of the walk-off experienced by the mask orders and the short duration of the femtosecond pulse. This effect is unique to the fabrication of Bragg gratings with femtosecond sources and would not be observed with a longer pulse duration or incoherent UV sources.

Apodization technique for fiber grating fabrication with a halftone transmission amplitude mask.

Experimental results of fiber Bragg gratings fabricated with halftone amplitude transmission masks and 10-cm-long phase masks are presented for the first time to our knowledge. The performance of the devices is evaluated in terms of their spectral characteristics and deviation from linear group delay. Good out-of-band sidelobe suppression of -27 dB and group-delay ripple of ?9.5 ps is achieved for fully apodized grating devices.

Bragg gratings in defect-free germanium-doped optical fibers.

Bragg gratings have been written in germanium-doped optical fibers that have been treated to remove the UV absorption bands associated with oxygen-deficient defects. When one is using high-intensity 193-nm light from an ArF excimer laser to fabricate the gratings, the refractive index increases and the grating transmission spectra are similar to those obtained in standard (untreated) fiber.

Fabrication of refractive microlens arrays by excimer laser ablation of amorphous Teflon.

The fabrication of refractive microlens arrays by the technique of excimer laser ablation of doped amorphous Teflon combined with the subsequent annealing and melting of the produced polymer islands is described. The microlenses obtained are optically clear from the far UV (190 m) to the near IR (2000 nm) and are of good optical quality. They vary in size from 50 to 385 µm in diameter with numerical apertures between 0.2 and 0.3. Utilization of these microlenses for material processingby excimer lasers at 193 nm is demonstrated, and possible applications are discussed.

Dependence of the damage and transmission properties of fused silica fibers on the excimer laser wavelength.

The damage and transmission properties of selected commercially available fused silica fibers have been measured as a function of excimer laser wavelength. Two-photon absorption and color center formation in fused silica currently limit the use of these fibers at the excimer wavelengths of 193 nm (ArF) and 248 nm (KrF).