Physics Help Forum Why array of telescope is used?

 Aug 26th 2015, 10:58 AM #1 Member     Join Date: Jun 2014 Posts: 67 Why array of telescope is used? To increase the resolution of an instrument, smaller wavelength and larger aperture is desirable. It is mentioned in some textbooks that the "effective" diameter of a telescope can be increased by using arrays of smaller telescopes. I just wonder why it is possible because every telescope is separated.
 Aug 26th 2015, 12:08 PM #2 Physics Team     Join Date: Jun 2010 Location: Naperville, IL USA Posts: 2,271 To increase resolution the images that each telescope obtains must be precisely aligned and then combined. This is relatively easy to do with radio telescopes, as the signals from each are electrical in nature and so can be combined electronically. It is much more difficult to do this with optical telescopes, as it requires very precisley aligned system to mirrors to bring the images from all the scopes to a point where they can be combined. For some examples, see: https://en.wikipedia.org/wiki/Astron...interferometer
 Aug 26th 2015, 10:35 PM #3 Member     Join Date: Jun 2014 Posts: 67 I think as they are using arrays of telescopes they certainly get better resolutions, I am just not quite sure about the effect of diffraction on smaller apertures. If I look through a circular tube with diameter D which consists of many smaller tubes inside, like a bundle of drinking straws, and if the diameter of these drinking straws are small compared to the wavelength of visible light, can we still get the same resolution as looking through the big tube with diameter D but no drinking straws inside?
 Aug 27th 2015, 03:11 AM #4 Senior Member     Join Date: Apr 2008 Location: Bedford, England Posts: 668 Size isn't everything There are two reasons for bigger telescopes being better, One is Resolution, the other is for collection of as many of the rare photons from distant sources as possible. Given a number of photons per metre arriving from the distant object, a large Collecting Area will obviously catch more photons. The resolution is more subtle and is based on how far apart the most distant points on the telescope are. Building a single huge telescope presents practical mechanical problems. However, with (very) precise alignment, the photons from two or more telescopes can be combined to give a resolution based on how far apart the most distant points on the array of telescopes are. __________________ You have GOT to Laugh !

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