Talk:Liquid-mirror telescope

message: For the history section:
*
*--Stone 08:40, 30 July 2007 (UTC)

message: It seems pretty obvious that you could simply freeze the liquid. Selection criteria for the material would be...
* does not form big nasty crystals as it cools
* thermal expansion can be well-matched to a container, and not too extreme
* melting point is reasonable
* cheap
* takes and keeps a shine, or can be plated to do so
Plain old lead solder hits most of that pretty well. I don't know if you can coat it with something (aluminum, rhodium, silver...) that has high reflectivity.
72.40.45.79 (talk) 03:43, 18 August 2008 (UTC)
replies: text: There are a variety of methods that can be used to create a large, reflective paraboloid. The problem with using them for a telescope, however, is that it can't be just approximately paraboloidal, it has to be paraboloidal to within optical flatness. The liquid mirror solves this problem because the paraboloid is its neutral energy surface, so any small imperfection is automatically self-correcting (with a caveat about dust floating on mercury). As soon as you freeze it, you lose that property. If the freezing process causes any distortions at all -- even on the scale of wavelengths of light -- your mirror is now no better than one made by a variety of cheap processes. Even if the freezing process causes no distortions, the frame (which formerly only needed to hold the bottom of the liquid pool with an accuracy of a mm or so) now needs to hold the surface as rigidly as the supports of a glass mirror, or once again, it loses its excellent optical properties. In short, it is the quality of being liquid which enables this method to produce an optically perfect large paraboloid cheaply. If it was solid, it would be as expensive as a glass paraboloidal mirror. -- Securiger (talk) 03:10, 9 November 2008 (UTC)
thread_title: Why only straight up?

message: What is the problem of combining a flat refective mirror (which has its point of rotation on the optical axis of the liquid mirror)that can be pointed in almost all directions, to reflect the light onto the liquid mirror? I would imagine creating a flat mirro is quite cheap and easy compared to curved shapeLife is short, but the years are long! (talk) 15:06, 18 March 2011 (UTC)
replies: text: This is such an obvious idea and yet I couldn't see it anywhere in the article. Producing an optically flat surface is much easier than making a mirror. and would allow the telescope to be aimed anywhere. Stub Mandrel (talk) 14:07, 3 April 2015 (UTC)
replies: text:  I too wondered why this is not done. In fact, coming to this article, I presumed an aiming mirror would part of it.  It would seem essential for the telescope to be of any use at all. Only aiming up?  Really?--23.119.204.117 (talk) 05:31, 19 February 2016 (UTC)
replies: text: Adding a large, exactly plane, steerable mirror to the telescope would add greatly to its complexity and cost. It wouldn't be much cheaper than a conventional telescope. DOwenWilliams (talk) 15:31, 19 February 2016 (UTC)
thread_title: Aiming Mirror

message: Mercury mirror is clearly a subset of this article, itself a merge of an earlier version with liquid mirror telescope. The three topics are practically identical, but liquid mirror is both the most general, and the most complete. However, it currently lacks the theory description found in mercury mirror. -- Securiger (talk) 03:02, 9 November 2008 (UTC)
thread_title:  Merge suggestion 

message: One method to reduce the amount of mercury or gallium required is to fill the cylinder with a plastic resin then spin it until the resin sets. The liquid metal can then be the same thickness all across the top of the plastic parabolic shape. Alternatively, the surface of the plastic can be finished to optical flatness and a perfect parabola then metalized. Bizzybody (talk) 08:31, 7 October 2010 (UTC)
thread_title:  Base materials 

message: There is reference to a Rice liquid mirror, and a link but there is no mention of why it is called a Rice mirror in either article. Perhaps a Rice University project or someone else named Rice? Jascal (talk) 07:13, 13 October 2010 (UTC)
thread_title:  Rice mirror? 

message: There is a problem with the redirect of mercury mirror to this article, so I propose a disambiguation article. There is an antique mercury mirror in which 75% tin and 25% mercury were used to give the mirror its shine and a blue tinge. This is seen, for example, at the Hall of Mirrors (Palace of Versailles). See the website for restorer of the Versailles mirrors, http://www.miroir-ancien-vincent-guerre.com/en/antique-mirrors/antique-mirror-restoration.htm and you will see what I mean.
Perhaps a new article is in order about the antique version. I like to saw logs! (talk) 06:59, 14 January 2011 (UTC)
thread_title: De-merge suggestion!

message: I think the title of the article should be Liquid mirror telescope in singular, see WP:PLURAL. Ulflund (talk) 11:12, 4 July 2012 (UTC)
thread_title:  Article title in singular 

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thread_title:  External links modified