Arrays of antenna-coupled bolometers using transition edge sensors

We are developing antenna-coupled transition edge sensor (TES) bolometer arrays for use in the measurement of the cosmic microwave background polarization. We have designed and built a prototype antenna-coupled bolometer pixel. This design uses a double slot dipole antenna on a silicon hemispherical lens, fed with superconducting niobium microstrip. Microstrip filters are used to define the frequency band of the optical response, which is centered at 217 GHz with 40% bandwidth. The microstrip is terminated into a load resistor on a silicon nitride suspension, adjacent to a TES which is used to measure the dissipated power. l discuss our progress in the development of the prototype pixel chips as well as the baseline design of a bolometer array for POLARBEAR, a CMB polarization experiment.