# Talk:Collimated light

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## Small-angle non-collimation

The light reaching me from that part of the sun that I see at the left edge of the sun's disk is not parallel to that from the right edge, since they're half a degree apart. Is it because 1/2 degree is so small that it's considered collimated, or should the article's statement to that effect be considered an error? Michael Hardy 01:21, 8 Nov 2004 (UTC)

Corrected the article to reflect the non-collimated (deviation of +-0,5degrees) nature of the sunlight on earth. Santtus 13:00, 15 July 2005 (UTC)

I think that there is a problem due to the vagueness of any definitions available to me. The fact that the sun's distance is extremely large compared to any earth-bound imaging element makes the light from any point of the object arrive in a practically parallel rays to the sides of the said element. The opposite sides of the disk of the sun do arrive in differently aligned rays, however. What is it that collimated light means, actually? Santtus 21:25, 5 November 2006 (UTC)

## Combine with Collimating Lenses?

I agree that this should be combined with and redirected to collimating lenses. axharr 21:36, 4 Nov 2006 (EST)

I very strongly disagree that the Collimating Lens stub should be merged into Collimated Light or vice versa. Collimating Lens topic needs to address the action and even the design of collimators, at a minimum using lenses with coherent light (a pretty easy place to start). An example or three with actual numbers would be appreciated, as well. Collimated light needs to be specific about the parallelism of rays in a collimated beam, interference patterns between coherent spherical wave fronts and (mutually) coherent plane (collimated) wavefronts and/or spherical wavefronts, etc. --Light should describe the beam, --Lens should describe the apparati. Onlyocelot 11:03, 21 April 2007 (UTC)

I strongly agree with Onlyocelot. These two topics are each worthy of their own text books. The lens and the light are related but two different things.

## A bibliography a propos of?

Collimators for Thermal Neutron Radiography an Overview by J.C. Domanus and J.F.W. Markgraf (Jan 1, 2001)

Areal parabolic collimators for the Keck II telescope (Lick Observatory technical reports) by Brian M Sutin (1995)

-vs-

Absorption and Scattering of Light by Small Particles (Wiley Science Paperback Series) by Craig F. Bohren and Donald R. Huffman (1998)

Interferometry in Speckle Light: Theory and Applications by P. Jacquot and J.-M. Fournier (Oct 27, 2000)

Stephenkoski 07:13, 2 May 2007 (UTC)StephenKoski

## Concerning Laser collimation

The observation about laser light being automatically collimated is partially true and only for gas lasers. Diode lasers (far more common, e.g. laser pointers are diode lasers) are not collimated at all, so much that in most applications they are fitted with a collimating lens. —Preceding unsigned comment added by 193.205.81.1 (talk) 12:15, 8 November 2007 (UTC)

## Frequency of collimating a telescope

I think that the sentence "Most amateur reflector telescopes need to be re-collimated every few years to maintain optimum performance" is a bit misleading. Many amateur reflector telescopes are Newtonians/Dobs, and their users should probably better collimate them before every observing session, especially if the telescope was moved. --M. Tewes (talk) 19:45, 6 January 2012 (UTC)