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How does interferometry work?

How does interferometry work!? I can't figure out how two small mirriors, a mile apart, could have the light gathering power of a mile wide mirror. If you could refer me to a good book or web site I would appreciate it

You're right, and interferometer does not have the light gathering power of a single mirror filling the whole space it spans, light gathering power only has to do with physically how big a mirror is.

Where interferometry has an advantage is in resolution (or resolving power). This is how small size objects the telescope can distinguish and this has to do with the biggest dimension of the telescope. So by putting two small mirrors far apart and combining the signal in the right way you can have the resolving power that a single telescope filling the space between them would have.

I'm not sure how basic an introduction you are interested in getting, but here is one suggestion: Astronomical Optical Interferometry. This assumes some knowledge of undergraduate optics, but you might not need that for every part.

NASA's Space Interferometry mission has an on-line explanation that might be more accessible.

March 2002, Karen Masters (more by Karen Masters) (Like this Answer)

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