Top 10 similar words or synonyms for uncollimated

unpolarised    0.682895

lighta    0.676188

decollimated    0.669820

noncollimated    0.669643

unfocussed    0.668773

andcollimating    0.646892

retroreflects    0.635049

unscattered    0.633172

colliminated    0.616997

nonmonochromatic    0.615706

Top 30 analogous words or synonyms for uncollimated

Article Example
SeHCAT Patients may be given instructions to fast prior to capsule administration; it should be noted that there is significant variation in clinical practice in this regard. The effective dose of radiation for an adult given 370 kBq of SeHCAT is 0.26 mSv. (For comparison, the radiation exposure from an abdominal CT scan is quoted at 5.3 mSv and annual background exposure in the UK 1-3 mSv.) Measurements were originally performed with a whole-body counter but are usually performed now with an uncollimated gamma camera. The patient is scanned supine or prone with anterior and posterior acquisition from head to thigh 1 to 3 hours after taking the capsule. Scanning is repeated after 7 days. Background values are subtracted and care must be taken to avoid external sources of radiation in a nuclear medicine department.
Specific radiative intensity For the present purposes, the light from a star can be treated as a practically collimated beam, but apart from this, a collimated beam is rarely if ever found in nature, though artificially produced beams can be very nearly collimated. For some purposes the rays of the sun can be considered as practically collimated, because the sun subtends an angle of only 32′ of arc. The specific (radiative) intensity is suitable for the description of an uncollimated radiative field. The integrals of specific (radiative) intensity with respect to solid angle, used for the definition of spectral flux density, are singular for exactly collimated beams, or may be viewed as Dirac delta functions. Therefore the specific (radiative) intensity is unsuitable for the description of a collimated beam, while spectral flux density is suitable for that purpose.
Spectral flux density For the present purposes, the light from a star, and for some particular purposes, the light of the sun, can be treated as a practically collimated beam, but apart from this, a collimated beam is rarely if ever found in nature, though artificially produced beams can be very nearly collimated. The spectral radiance (or specific intensity) is suitable for the description of an uncollimated radiative field. The integrals of spectral radiance (or specific intensity) with respect to solid angle, used above, are singular for exactly collimated beams, or may be viewed as Dirac delta functions. Therefore, the specific radiative intenstity is unsuitable for the description of a collimated beam, while spectral flux density is suitable for that purpose. At a point within a collimated beam, the spectral flux density vector has a value equal to the Poynting vector, a quantity defined in the classical Maxwell theory of electromagnetic radiation.
Aperture In optics, an aperture is a hole or an opening through which light travels. More specifically, the aperture and focal length of an optical system determine the cone angle of a bundle of rays that come to a focus in the image plane. The aperture determines how collimated the admitted rays are, which is of great importance for the appearance at the image plane. If an aperture is narrow, then highly collimated rays are admitted, resulting in a sharp focus at the image plane. A wide aperture admits uncollimated rays, resulting in a sharp focus only for rays coming from a certain distance. This means that a wide aperture results in an image that is sharp for things at the correct distance. The aperture also determines how many of the incoming rays are actually admitted and thus how much light reaches the image plane (the narrower the aperture, the darker the image for a given exposure time). In the human eye, the pupil is the aperture.
Phase-contrast X-ray imaging The purpose of the latter mask is simply to create insensitive regions between adjacent pixels, and its use can be avoided if specialized detector technology is employed. In this way, the EI configuration is simultaneously realized for all pixel rows of an area detector. This plurality of individual beamlets means that no scanning is required – the sample is placed downstream of the sample mask and imaged in a single shot (two if phase retrieval is performed). Although the set-up perhaps superficially resembles that of a grating interferometer, the underpinning physical mechanism is different. GI is an intrinsically coherent method, in which an incoherent source can be used only provided it is made sufficiently coherent through collimation via the source grating. In contrast, EI is an incoherent technique, and was in fact proven to work with both spatially and temporally incoherent sources, without any additional source aperturing or collimation. Quantitative phase retrieval was also demonstrated with (uncollimated) incoherent sources, showing that in some cases results analogous to the synchrotron gold standard can be obtained. The highly simplified set-up, which however does not lead to reduced phase sensitivity, results in a number of advantages, which include reduced exposure time for the same source power, reduced radiation dose, robustness against environmental vibrations, and easier access to high X-ray energy. Moreover, since their aspect ratio is not particularly demanding, masks are cheap, easy to fabricate (e.g.do not require X-ray lithography) and can already be scaled to large areas. The method is easily extended to phase sensitivity in two directions, for example, through the realization of L-shaped apertures for the simultaneous illumination of two orthogonal edges in each detector pixel. More generally, while in its simplest implementation beamlets match individual pixel rows (or pixels), the method is highly flexible, and, for example, sparse detectors and asymmetric masks can be used. So far, the method has been successfully demonstrated in areas such as security scanning, biological imaging, material science, paleontology and others; adaptation to 3D (computed tomography) was also demonstrated. Alongside simple translation for use with conventional x-ray sources, there are substantial benefits in the implementation of EI with coherent synchrotron radiation, among which high performance at very high X-ray energies and angular resolutions higher than in other approaches.