An extended short-wavelength infrared microspectrometer by monolithic integrarion of a 256 × 1 InGaAs linear array detector with wedge-shaped Si/SiO 2 Fabry-Perot variable optical filter.

Steerable lters, as developed by Freeman and Adelson, are a class of rotation-invariant linear operators that may be used to analyze local orientation patterns in imagery. The most common examples of such operators are directional derivatives of Gaussians and their 2-D Hilbert transforms. The inherent symmetry of these lters produces an orientation response that is periodic with period , even w...

Distribution effects such as diffuse global illumination, soft shadows and depth of field, are most accurately rendered using Monte Carlo ray or path tracing. However, physically accurate algorithms can take hours to converge to a noise-free image. A recent body of work has begun to bridge this gap, showing that both individual and multiple effects can be achieved accurately and efficiently. Th...

Radiotherapy wedges constitute an important group within the generic classification of so-called Beam Modification Devices (BMD). Wedges are subdivided into Static, Dynamic, and Omni Wedges sug-groups. The standard static wedge attenuates the beam progressively, in such a way that the dose delivery is higher at the thin side, and lower at the broader side. The slope of the inferior surface has ...

This paper presents the fabrication methodology of a linear variable photonic crystal (PC) filter with narrowband reflection that varies over a broad spectral range along the length of the filter. The key component of the linear variable PC filter is a polymer surface-relief grating whose period changes linearly as a function of its position on the filter. The grating is fabricated using a nano...

Electron tomographic reconstructions suffer from a number of artefacts arising from effects accompanying the processes of acquisition of a set of tilted projections of the specimen in a transmission electron microscope and from its subsequent computational handling. The most pronounced artefacts usually come from imprecise projection alignment, distortion of specimens during tomogram acquisitio...

A device is described for use in confirming the energy constancy of clinical electron beams. A wedge shaped absorber is placed over an ionization chamber leading to an energy dependent response. A measurement under the energy filter is divided by a measurement in air to correct for the inherent energy dependence of the chamber. A nearly linear response is demonstrated.

An analytical design method is proposed for two-dimensional recursive zero-phase wedge filters. It relies on a frequency mapping applied to a 1D IIR low-pass maximally-flat prototype filter of a specified shape. The design is presented in two versions, one entirely analytical, based on the bilinear transform, and another involving a numerical approximation step. This paper focuses on the design...

As the use of linear accelerators operating in flattening filter-free (FFF) modes becomes more widespread, it is important to have an understanding of the surface doses delivered to patients with these beams. Flattening filter removal alters the beam quality and relative contributions of low-energy X-rays and contamination electrons in the beam. Having dosimetric data to describe the surface do...

Measurements of the one-point probability distribution function and higher-order moments (variance, skewness, kurtosis) high-redshift 21 cm fluctuations are among most direct statistical probes non-Gaussian nature structure formation evolution during reionization. However, contamination from astrophysical foregrounds instrument systematics pose significant challenges in measuring these statisti...