Comment Re:Quick note (Score 4, Informative) 37
Nope, you need the reference phase to still be coherent with the observed object (temporal and spatial), so the interference is only possible between two parts of the same wave (of light), different in space (think two pinholes in a plane through which you collect the light) and/or in time (think delay line, let one part of the line you collected run a longer distance). The first is the famous Young's double slit experiment, the second is the Michelson interferometer.
Also, for reference : frequency of the visible EM fields is in the order of 300THz (300,000GHz).