|MadSci Network: Astronomy|
Hi Mitchell! The technique of interferometry is where the light waves from two or more telescopes are combined. This increases the resolution (basically a measure of how close two objects can be in the sky and still be seen separately instead of blended together) to the equivalence of a single dish with a diameter equal to the separation between the telescopes. The light gathered by the telescopes is not proportionally increased (that depends on the size of a dish but not on the combination of light from separate telescopes), so this technique is often used to make precision measurements of stellar positions, for example, and not for looking at deep sky objects. Building an interferometer, as you have surmised, will not be easy. You need to decide what wavelength you wish to observe in. Because of the shorter wavelengths involved (by 5 orders of magnitude usually), optical interferometers are much more difficult to build than radio interferometers. You need to know precisely how far apart your telescopes are. They need to be protected from vibrations (such as wind). Combining the waves from two or more radio dishes to give a correct fringe pattern will require knowledge about receivers, amplifiers, and computer programs for data analysis that I cannot say much about. I will refer you to a couple books that may prove useful in helping you determine how to build your own interferometer. "An Introduction to Radio Astronomy" by Bernard F. Burke and Francis Graham-Smith gives some general information about the concepts behind aperture synthesis and some of the imperfections that will need to be accounted for in a real array. "Radio Astronomy" by J.D. Kraus is another good book, slightly more technical than the one by Burke, it covers technical information about many individual telescopes and receivers as well as going into detail about concepts behind radio astronomy. One very technical book that may be of help in building an interferometer is "Optical Shop Testing" by Daniel Malacara (Editor). However, I understand that this is a very mathematically rigorous book. It does have information on testing techniques and may be helpful if you are serious about constructing your own interferometer. Hopefully these sources will help you get started. For others who want more information on interferometers, a quick and easy project demonstrating the fringes resulting from an interferometer can be found at the nasa web site: http://huey.jpl.nasa.gov/olbin/news/aluminium.html Erika
Try the links in the MadSci Library for more information on Astronomy.