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(kol -ă-may-ter) A device used to produce a parallel or near parallel beam of light or other radiation in an instrument. One example, used in spectroscopes, is a converging lens or mirror at whose focal point is a narrow slit upon which light is focused from behind.



an optical device used to produce beams of parallel rays. A collimator consists of an objective lens or concave mirror in whose focal plane the illuminated object is placed. The opening of an opaque stop, such as a narrow slit of constant or adjustable width, is most commonly used for this purpose. The relative positions of the lens and the object are set by attaching them inside the body of the instrument, which is usually tubular. The blackened inner walls of the instrument’s body absorb rays whose direction does not coincide with the direction desired.

The parallel nature of the beam emerging from a collimator is approximate. Rays emanating from one point of the object cannot be exactly mutually parallel because of diffraction and aberrations of the lens. The finiteness of the dimensions of the object results in the spreading of beams coming from various points on the object. The focal distance, the focal aperture, and the quality of correction of aberrations of the lens, as well as the shape and dimensions of the object, are selected according to the purpose of the collimator and the conditions of its use.

Collimators are used in astronomy to align large measuring instruments and determine their collimation error, in spectral instruments to produce light beams that are directed into a dispersing system, and in various measuring, testing, and opticomechanical instruments used for alignment. They are part of autocollimating devices.


An instrument which produces parallel rays of light.
A device for confining the elements of a beam within an assigned solid angle.
References in periodicals archive ?
This conclusion was later repeatedly confirmed by experiments with collimators directed westward, eastward, northward, or rotated in the horizontal plane counterclockwise with periods of 1, 2, 3, 4, 5, 6, 12 hours.
The neutron flux density after the collimator will be one order of magnitude less ([[PHI].
With the aid of the multileaf collimator, IMRT fields can treat targets more efficiently because they allow the physician to better conform the high-dose region to the tumor.
In much the same way that cameras collect rays of light to produce photographs, collimators filter streams of gamma rays to create images of radiopharmaceutical distribution.
This report analyzes the worldwide markets for Gamma/Scintillation Cameras in US$ Thousand by the following Product Segments: Gamma Cameras, Collimators, Gantry, Nuclear Medicine Patient Tables, Computerized Video Display Consoles, and Computer Workstations.
Earlier, when the collimator-equipped devices were immobile (with one collimator directed West and another East), we showed that histograms from either of the collimators would have their analogs (similar shapes) from the other collimator lagging behind by half a day [6] (i.
The size of the beam entering the detector after passing through the specimen is controlled by selecting one of seven collimators, ranging in area from 0.
Currently, when performing SPECT imaging, researchers place pinhole collimators on gamma cameras to obtain high-resolution images, but the tradeoff for this high resolution is a smaller field of view.
Collimators are used in radiology treatment to limit X-ray beams to the dimensions and angular spread required.
The use of collimators, isolating directed [alpha]-particle beams, allowed us to start studies on the spatial regularities in the change of the histogram shape.