CMB interferometry
  Interferometry has been a very successful tool for measuring anisotropies in the cosmic microwave background. Interferometers provided the first constraints on CMB anisotropies on small angular scales (l~10000) in the 1980s and then in the late 1990s and early 2000s made ground-breaking measurements of the CMB power spectrum at intermediate and small angular scales covering the l-range ~100-4000. In 2002 the DASI made the first detection of CMB polarization which remains a major goal for current and future CMB experiments. Interferometers have also made major contributions to the detection and surveying of the Sunyaev-Zel'dovich (SZ) effect in galaxy clusters. In this short review I cover the key aspects that made interferometry well-suited to CMB measurements and summarise some of the central observations that have been made. I look to the future and in particular to HI intensity mapping at high redshifts that could make use of the advantages of interferometry. 
Clive Dickinson
astro-ph.CO astro-ph.IM