PURPOSE To compare conventional and spiral CT studies of the larynx. METHODS Ten patients had both conventional and spiral CT studies of the neck using 5-mm section collimation and 5-mm increments. The spiral scans also were reconstructed at 2-mm increments. Five patients had two spiral CT larynx studies with 5-mm and 2-mm collimation. Two observers independently rated the visibility of laryn...

Micro-optics are widely used in numerous applications, such as beam shaping, collimation, focusing and imaging. We use femtosecond 3D printing to manufacture free-form micro-optical elements. Our method gives sub-micrometre accuracy so that direct manufacturing even on single-mode fibres is possible. We demonstrate the potential of our method by writing different collimation optics, toric lense...

Centrifugal pressure of matter spiralling onto black holes, have long been known to produce standing or oscillating shocks. The post-shock disc puffs up in the form of a torus, which intercepts soft photons from the outer Keplerian disc and inverse Comptonizes them to produce hard photons. The post-shock region also produces jets. We study the interaction of both hard photons and soft photons, ...

Surface plasmons offer the exciting possibility of improving the functionality of optical devices through the subwavelength manipulation of light. We show that surface plasmons can be used to shape the beams of edge-emitting semiconductor lasers and greatly reduce their large intrinsic beam divergence. Using quantum cascade lasers as a model system, we show that by defining a metallic subwavele...

We have argued that MHD turbulence in an accretion disk naturally produces hoop-stresses, and that in a geometrically-thick flow these stresses could both drive and collimate an outflow. We based this argument on an analogy of turbulent MHD fluids to viscoelastic fluids, in which azimuthal shear flow creates hoop-stresses that cause a variety of flow phenomena, including the Weissenberg effect ...

Experience indicates that beam collimation will be an essential element of the next generation e+elinear colliders. A proposal for using nonlinear lenses to drive beam tails to large amplitudes was presented in a previous paper [l]. Here we study the optimization of such systems including effects of wakefields and optical aberrations. Protection and design of the scrapers in these systems are d...