What sort of telescope is used to observe the CMB?
Like light at any other wavelength the general system is a dish to collect and focus the radiation, a way of feeding the radiation to the instruments, and then the instruments themselves which are used to detect and record the signals. For microwaves the dish, or set of dishes, is made of a material (metal) which reflects microwaves. The focussed radiation is transported to the receivers by means of “wave-guides”, which are pipes specially tuned to transmit microwave signals. Then the detectors come in two types. “Bolometers” involve technology developed to detect infra-red radiation. They are essentially tiny pieces of special materials which absorb the microwave radiation. This in turn induces a minute change in temperature which is detected by a thermal sensor. These temperature variations are picked up in an electrical circuit and stored on computer. The other technology involves high performance transistors, which work in much the same way as the input circuitry of a radio receive
