Adding interferometry for CMBPol

Interferometry offers an alternative to imaging of the CMB. Some systematic errors may be easier to control than in the imaging case. Adding interferometry is capable of correlating signals from a large number of antennas, more than is currently possible with traditional multiplying interferometers. Many of the technologies required for a space-based adding interferometer for CMB studies are the same as for imaging systems. We evaluate those critical components which are different from imagers.