Focusing Elements

Focusing Elements. Two ion optical components are usually placed between the accelerator and the sample chamber. A magnetic field separates any He-, He, or He+ from the He++ beam. A quadrupole magnetic lens then shapes the beam and focusses it into the sample chamber. 

Focusing elements to steer ions into mass analyzer(s)... 

Lin et al. 1985 Wade and Meyyappan 1987 Wey and Kessler 1989) the insonification is broadcast throughout the specimen, and the detection is by a focused optical probe that measures local surface tilt on the surface of the specimen. But in the scanning acoustic microscope both the illumination and the detection are performed by focusing elements and, since these are focused at the same point, the configuration may be described as confocal. The first con-focal acoustic microscopes worked in transmission and, although this is now of mainly historical interest, the transmission arrangement will be described first because in some respects it is simpler and will serve to introduce some principles. 

Thus, dispersion is governed by the fineness of the grating ruling d and the focal length f of the focusing element... 

The wideband holographic imaging technique is a wavefront image reconstruction, or focusing, technique that eliminates the need for physical focusing elements such as lenses or curved reflectors. This technique is essentially a way to mathematically focus the imaging data that are completely unfocused in the actual hardware implementation. 

Once the the energy resolution requirements are established the vertical collimation of a synchrotron radiation beam is defined. This is not so with the horizontal divergence of the beam, where focusing elements in the beam path can increase the intensity of the sample considerably with nearly no deterioration of the wavelength... 

Our primary use of reflectors has been as elements in a Fabry-Perot resonator (cf. Section VI). If reflectors are used as focusing elements instead of lenses, it is common to use nonnormal incidence to avoid truncation losses. The choice of reflecting optics with nonnormal incidence does introduce aberrations in the reflected field, the most serious of which is coma (Murphy, 1987). 

The simplest optics making use of the full undulator peak is a pinhole camera without focusing elements. The only optical element necessary is a plane mirror in order to elevate the beam out of the plane of the storage ring, to reduce the background due to Bremsstrahlung and to cut the harmonics (Fig. 10 b). 

At present only a pinhole geometry without focusing elements has been studied. The SAXS resolution would in this case be more limited as for the real-time camera with Lmax x 4500 A. Focuring in the horizontal plane would, however, be possible by sagittal focusing via the second crystal [47],... 

Confocal Microscopy A microscopic technique used to produce three-dimensional images of specimens that actually have considerable depth. A series of shallow depth-of-field image slices through a thick specimen are obtained. The three-dimensional image is then obtained by reconstruction so that no out-of-focus elements contribute to the final image. 

A series of ion-focusing elements (ion lenses) similar to those developed for double-focusing mass spectrometers have been utilized to introduce the ions into the quadrupole. Also, photon blockers have eliminated interference effects due to the presence of large numbers of photons reaching the detector. Therefore, background signals have been largely ehminated in modem ICP-MS instmments. 

Each spectrometer for sequential or simultaneous multi-element plasma AES measurements is equipped with a monochromator in order to (i) have an adequate wavelength selection, and (ii) collect as much light as possible from a selected spectrum area in the radiation source. A monochromator consists of a) an entrance slit, b) a collimator to produce a parallel beam of radiation, (c) a dispersing element (a prism or a grating), d) a focusing element reforming the specific dispersed narrow bands of radiation, and (e) one or more exit slits to isolate the desired spectral band or bands. 

In an Ebert monochromator the entrance slit and exit slit are either side of the grating and a single concave spherical mirror is used as a collimating and focusing element (Figure 125). Wavelength scanning and selection of a... 

MicroChannel plate (MCP) optics [1] offer the possibility of low mass and relatively low cost focusing elements for use over a very wide X-ray energy range (0.1-100 keV). 

It is this optic which is envisaged as the focusing element in a high energy X-ray telescope, the concept of such a telescope which will be discussed in a companion paper at this workshop [7]. 

U = Undulator M = Optical Cavity mirror B = Bending magnets and focusing elements C = Radiofrequency cavity. 

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