What is collimation: Definition and 14 Discussions

A collimated beam of light or other electromagnetic radiation has parallel rays, and therefore will spread minimally as it propagates. A perfectly collimated light beam, with no divergence, would not disperse with distance. However, diffraction prevents the creation of any such beam.Light can be approximately collimated by a number of processes, for instance by means of a collimator. Perfectly collimated light is sometimes said to be focused at infinity. Thus, as the distance from a point source increases, the spherical wavefronts become flatter and closer to plane waves, which are perfectly collimated.
Other forms of electromagnetic radiation can also be collimated. In radiology, X-rays are collimated to reduce the volume of the patient's tissue that is irradiated, and to remove stray photons that reduce the quality of the x-ray image ("film fog"). In scintigraphy, a gamma ray collimator is used in front of a detector to allow only photons perpendicular to the surface to be detected.The term collimated may also be applied to particle beams – a collimated beam – where typically shielding blocks of high density materials (such as lead, bismuth alloys, etc) may be used to absorb or block peripheral particles from a desired forward direction, especially a sequence of such absorbing collimators. This method of particle collimation is routinely deployed and is ubiquitous in every particle accelerator complex in the world. An additional method enabling this same forward collimation effect, less well studied, may deploy strategic nuclear polarization (magnetic polarization of nuclei) if the requisite reactions are designed into any given experimental applications.

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  1. phi_skr

    A Question about detector and lens

    Light from the sample is collimated light. For imaging, does the spectrometer requires a lens to focus the collimated light on the entrance slits of the detector. Using the beam splitter, the collimated light from the sample is directed toward the spectrometer. Previously, we used a lens to...
  2. R

    A About collimation in Czerny-Turner spectrometers

    Goodmorning, I'm designing an unfolded Czerny-Turner spectrometer like the one in picture I'm trying to use toroidal mirrors to decrease off axis astigmatism. In my first try i made an optimal off-axis collimator (Mirror 1), a mirror that has a good collimation in both the planes: the plane...
  3. skaiser

    I Issues collimating my laser with 4f system

    I am using 2 lenses in a 4f configuration. The input is a large collimated beam (632nm). After passage through the 2 lenses the beams vertical dimension remains constant, however, the horizontal dimension get smaller, as if it is being focused only in the horizontal direction. Does anyone have...
  4. B

    I What is really happening in collimation of rays?

    Ok so if an object is placed at the focal point of a convex lens, it will have it's rays collimated -- which I assumed to mean that all rays would end up parallel to each other. But then, I saw this diagram of a simple compound microscope from Hecht "Optics" 5th ed: And I noticed that all...
  5. Zahid Iftikhar

    Collimation of an Electron Beam by the Anode of a CRT

    Please help me in understanding the function of anode. As in image attached you see, once the electron beam is emitted from cathode and filtered by grid, it enters into the one or series of anodes. As anode is positively charged, so, to my understanding it has no electric field inside its hollow...
  6. S

    Is There a Commercially Available Filter for Collimation by Filtering?

    Hello! If one were to push uncollimated light through a tube of inner radius R and length L, coated with matte black - the maximum incidence angle it will allow through would be ATAN2(R, L). On the other end of the tube, only the "most collimated" fraction of light would exit - a very small...
  7. AnTiFreeze3

    Stargazing How useful are collimation eyepieces?

    How useful are collimation eyepieces? I wouldn't shell out the money for a laser collimator, but some of the eyepieces (like this one) are as cheap as $30, and appear to work very well. My scope came with a collimation cap, but even after trying to collimate my telescope, I'm still not sure...
  8. 1

    High energy proton beam collimation

    Hi all, my question is not strictly related with physics and I don't know if it is the right section. Anyway I have a problem with a collimator: I need 100micron (or maybe smaller) collimator, but the high energy (60-70 MeV) of the beam need a material which is at last 5mm thick, (tungsten...
  9. F

    Ideal optical collimation system

    Hi, I have been stuck on a project that I am working on. I am trying to collect light using optics from a FOV of 200x200mm at 200mm distance. I have two major problems: 1. My detector is small so I need to collimate the light (my application is not imaging so I don't worry about the...
  10. T

    Synchrotron radiation collimation

    Can someone please explain why the synchrotron radiation is very collimated? not only with equations and not only with words, both please. But anyway any efforts is really appreciated :) Thank you
  11. W

    Shear Interferometer to test collimation

    Hello everyone, I am trying to test the collimation of light emerging from an off-axis parabolic mirror. My mirror has a diameter of 0.5m or so. The focal length is about 5m. The light source I am using is a red laser focused at a pinhole. To test the collimation of this point source, I am...
  12. N

    Why Is My Zhumell Dobsonian's Laser Collimator Missing the Secondary Mirror?

    I have a 12" Zhumell Dobsonian and I've been trying all day to collimate it and can't get it lined up right. This is what it looks like when peering into the eyepiece holder: http://img184.imageshack.us/img184/4786/christmasscope008dx6.jpg Can anyone tell me if this is a secondary mirror or...
  13. T

    IR-light focusing and collimation

    HI, I am thinking of how can i focus and make a home made collimation to an IR beam. I have a lens and an IR-led mounted to a center of a focal point. But its hard to collimate the beam properly without visual sight to IR. B/w-video cams are usually lit with a series of IR leds to have enough...
  14. R

    Can someone tell me what is the best collimation material for this application?

    I need a collimation material that is faily cheap and has a reflectivity of about 95% for both infrared and visible light. I know polished aluminum meets the criteria for the infrared, and the fused silica also works well for the visible spectrum, but I need somthing that can collimate both.