CMB telescopes and optical systems

Abstract

The cosmic microwave background radiation (CMB) is now firmly establishedas a fundamental and essential probe of the geometry, constituents, and birth ofthe observable universe. The CMB is a potent observable because it can bemeasured with precision and accuracy. Just as importantly, theoretical models ofthe universe can predict the characteristics of the CMB to high accuracy, andthose predictions can be directly compared to observations. There are multipleaspects associated with making a precise measurement. In this chapter, we focuson optical components for the instrumentation used to measure the CMBpolarization and temperature anisotropy. We begin with an overview of generalconsiderations for CMB observations and discuss common concepts used inthe community. We next consider a variety of alternatives available for adesigner of a CMB telescope. Our discussion is guided by the ground- andballoon-based instruments that have been implemented over the years. In thesame vein, we compare the arc-minute resolution Atacama CosmologyTelescope (ACT) and the South Pole Telescope (SPT). CMB interferometersare presented briefly. We conclude with a comparison of the four CMBsatellites, Relikt, COBE, WMAP, and Planck, to demonstrate a remarkableevolution in design, sensitivity, resolution, and complexity over the past30 years.